Our objective was to evaluate the relationship between subjective classification of dental-arch shape, objective analyses via arch-width measurements, and the fitting with the fourth-order polynomial equation.
Long term clinical and bacterial effetcx of xylitol on paitnets with fixed or...EdwardHAngle
Background: The objective of this study was to evaluate long-term clinical and bacterial effects of using 6 g of
xylitol per day for 3 months on patients with full fixed orthodontic appliances.
Methods: The study was a pilot clinical trial that included 41 subjects who were undergoing orthodontic
treatment. The subjects were randomly divided into three groups. Group A received xylitol chewing gum, group B
received xylitol dissolvable chewable tablets, and Group C served as the control group and did not receive xylitol
gums or tablets. Clinical examination and the collection of plaque and saliva samples were carried out at baseline
and 3, 6, and 12 months. All three groups were given oral hygiene instruction and were put on a 6-month cleaning
and topical fluoride schedule. Plaque scores and bacterial counts were used to evaluate the effectiveness of the
different approaches at reducing the caries risk.
Results: Xylitol groups did not experience any more reduction in plaque score, plaque MS counts, or salivary MS
counts than the control group nor did they have lower values at any of the time points. Chewing gum did not
significantly increase the incidence of debonded brackets over the other groups.
Conclusions: Xylitol does not have a clinical or bacterial benefit in patients with fixed orthodontic appliances. Oral
hygiene instructions and 6-month topical fluoride application were effective at reducing plaque scores and bacterial
counts in patients with full fixed appliances regardless of whether or not xylitol was used.
Gingival recession—can orthodontics be a cure? evidence from a case presentationEdwardHAngle
Does orthodontic treatment help or hinder a patient’s periodontal status? What factors affect the
periodontium? Can those factors be managed in a way that remedies existing periodontal issues?
A 35-year-old woman presented with severe gingival recession and a unilateral Class II
malocclusion. The treatment plan was to correct the malocclusion in a way that torques the roots
more onto bone and to change her dental hygiene methods. With an extensive review of the
literature, this case review attempts to make sense of the enigma of gingival recession and
demonstrates an excellent treatment solution to concomitant orthodontic and periodontal
problems.
Effects of rapid palatal expansion on the sagittal and vertical dimensions of...EdwardHAngle
The purpose of this study was to use cone-beam computed tomography imaging to examine the skeletal and dental changes in the sagittal and vertical dimensions after rapid palatal expansion.
Transverse growth of the maxilla and mandible in untreated girls with low, av...EdwardHAngle
The purpose of this study was to investigate maxillary and mandibular transverse growth in
untreated female subjects with low, average, and high mandibular plane angles longitudinally from ages 6 to 18.
Malposition of unerupted mandibular second premolar in children with cleft li...EdwardHAngle
Objective: To determine whether distoangular malposition of the unerupted mandibular second
premolar (MnP2) is more frequent in children with unilateral clefts of the lip and palate.
Materials and Methods: This retrospective study examined panoramic radiographs from 45 patients
with unilateral clefts of the lip and/or palate who had no previous orthodontics. A control
sample consisted of age- and sex-matched patients. The distal angle formed between the long
axis of MnP2 and the tangent to the inferior border was measured. The mean, standard deviation,
and range were calculated for the angles measured in the cleft and the control groups. The
significance of the differences between the means was evaluated by the paired t-test. The angles
of the cleft and noncleft sides were also measured and compared.
Results: The mean inclination of the MnP2 on the cleft side was 73.6°, compared with 84.6° in
the control group. This difference was highly significant statistically (P < .0001). The difference
in angles from the cleft and noncleft sides was 0.7°, not statistically significant. A significant association
was found between clefting and distoangular malposition of the developing MnP2, suggesting
a shared genetic etiology. This association is independent of the clefting side, ruling out
possible local mechanical effects.
Conclusion: Clinicians should be aware of the potential for anomalous development of MnP2 in
children with clefts.
Long term clinical and bacterial effetcx of xylitol on paitnets with fixed or...EdwardHAngle
Background: The objective of this study was to evaluate long-term clinical and bacterial effects of using 6 g of
xylitol per day for 3 months on patients with full fixed orthodontic appliances.
Methods: The study was a pilot clinical trial that included 41 subjects who were undergoing orthodontic
treatment. The subjects were randomly divided into three groups. Group A received xylitol chewing gum, group B
received xylitol dissolvable chewable tablets, and Group C served as the control group and did not receive xylitol
gums or tablets. Clinical examination and the collection of plaque and saliva samples were carried out at baseline
and 3, 6, and 12 months. All three groups were given oral hygiene instruction and were put on a 6-month cleaning
and topical fluoride schedule. Plaque scores and bacterial counts were used to evaluate the effectiveness of the
different approaches at reducing the caries risk.
Results: Xylitol groups did not experience any more reduction in plaque score, plaque MS counts, or salivary MS
counts than the control group nor did they have lower values at any of the time points. Chewing gum did not
significantly increase the incidence of debonded brackets over the other groups.
Conclusions: Xylitol does not have a clinical or bacterial benefit in patients with fixed orthodontic appliances. Oral
hygiene instructions and 6-month topical fluoride application were effective at reducing plaque scores and bacterial
counts in patients with full fixed appliances regardless of whether or not xylitol was used.
Gingival recession—can orthodontics be a cure? evidence from a case presentationEdwardHAngle
Does orthodontic treatment help or hinder a patient’s periodontal status? What factors affect the
periodontium? Can those factors be managed in a way that remedies existing periodontal issues?
A 35-year-old woman presented with severe gingival recession and a unilateral Class II
malocclusion. The treatment plan was to correct the malocclusion in a way that torques the roots
more onto bone and to change her dental hygiene methods. With an extensive review of the
literature, this case review attempts to make sense of the enigma of gingival recession and
demonstrates an excellent treatment solution to concomitant orthodontic and periodontal
problems.
Effects of rapid palatal expansion on the sagittal and vertical dimensions of...EdwardHAngle
The purpose of this study was to use cone-beam computed tomography imaging to examine the skeletal and dental changes in the sagittal and vertical dimensions after rapid palatal expansion.
Transverse growth of the maxilla and mandible in untreated girls with low, av...EdwardHAngle
The purpose of this study was to investigate maxillary and mandibular transverse growth in
untreated female subjects with low, average, and high mandibular plane angles longitudinally from ages 6 to 18.
Malposition of unerupted mandibular second premolar in children with cleft li...EdwardHAngle
Objective: To determine whether distoangular malposition of the unerupted mandibular second
premolar (MnP2) is more frequent in children with unilateral clefts of the lip and palate.
Materials and Methods: This retrospective study examined panoramic radiographs from 45 patients
with unilateral clefts of the lip and/or palate who had no previous orthodontics. A control
sample consisted of age- and sex-matched patients. The distal angle formed between the long
axis of MnP2 and the tangent to the inferior border was measured. The mean, standard deviation,
and range were calculated for the angles measured in the cleft and the control groups. The
significance of the differences between the means was evaluated by the paired t-test. The angles
of the cleft and noncleft sides were also measured and compared.
Results: The mean inclination of the MnP2 on the cleft side was 73.6°, compared with 84.6° in
the control group. This difference was highly significant statistically (P < .0001). The difference
in angles from the cleft and noncleft sides was 0.7°, not statistically significant. A significant association
was found between clefting and distoangular malposition of the developing MnP2, suggesting
a shared genetic etiology. This association is independent of the clefting side, ruling out
possible local mechanical effects.
Conclusion: Clinicians should be aware of the potential for anomalous development of MnP2 in
children with clefts.
Increased occurrence of dental anomalies associated with infraocclusion of de...EdwardHAngle
Objective: To test the null hypothesis that there is no relationship between infraocclusion and the
occurrence of other dental anomalies in subjects selected for clear-cut infraocclusion of one or
more deciduous molars.
Materials and Methods: The experimental sample consisted of 99 orthodontic patients (43 from
Boston, Mass, United States; 56 from Jerusalem, Israel) with at least one deciduous molar in
infraocclusion greater than 1 mm vertical discrepancy, measured from the mesial marginal ridge of
the first permanent molar. Panoramic radiographs and dental casts were used to determine the
presence of other dental anomalies, including agenesis of permanent teeth, microdontia of
maxillary lateral incisors, palatally displaced canines (PDC), and distal angulation of the mandibular
second premolars (MnP2-DA). Comparative prevalence reference values were utilized and
statistical testing was performed using the chi-square test (P< .05) and odds ratio.
Results: The studied dental anomalies showed two to seven times greater prevalence in the
infraocclusion samples, compared with reported prevalence in reference samples. In most cases,
the infraoccluded deciduous molar exfoliated eventually and the underlying premolar erupted
spontaneously. In some severe phenotypes (10%), the infraoccluded deciduous molar was
extracted and space was regained to allow uncomplicated eruption of the associated premolar.
Conclusion: Statistically significant associations were observed between the presence of
infraocclusion and the occurrence of tooth agenesis, microdontia of maxillary lateral incisors,
PDC, and MnP2-DA. These associations support a hypothesis favoring shared causal genetic
factors. Clinically, infraocclusion may be considered an early marker for the development of later
appearing dental anomalies, such as tooth agenesis and PDC.
Craniofacial growth in untreated skeletal class i subjects with low, average,...EdwardHAngle
The dental measurements showed few changes with growth in all groups. In terms of skeletal measurements from ages 9 to 18, similar growth changes were found between the sexes in most angular measurements, but males had larger values in linear measurements than females.
Effects of bonded rapid palatal expansion on the transverse dimensions of the...EdwardHAngle
The purpose of this study was to examine the maxillary response on the transverse dimensions to rapid palatal expansion (RPE) by using cone-beam computed tomography (CBCT).
Influence of common fixed retainers on the diagnostic quality of cranial magn...EdwardHAngle
Introduction: Orthodontists are often asked to remove fixed retainers before magnetic resonance imaging
(MRI). This study was undertaken to assess the effects of 2 commonly used fixed retainers on MRI distortion
and whether they should be removed. Methods: MRI scans were performed on a dry skull with Twistflex (Dentaurum,
Ispringen, Germany) and Ortho Flex Tech (Reliance Orthodontic Products, Itasca, Ill) retainers. Two
neuroradiologists independently ranked the distortions. The influence of the fixed retainers' alloys, their distance
to the area of diagnosis, location, strength of the magnetic field, and the spin-echo sequence were examined.
Statistical analysis included kappa and Pearson chi-square tests. Results: Ortho Flex Tech retainers caused
no distortion. Twistflex retainers caused distortion in 46% of the tests in areas close to the retainer (tongue
and jaws). Maxillary fixed retainers and the combination of maxillary and mandibular fixed retainers further
increased the distortion. Greater distortion was observed with 3-T magnetic fields and T1-weighted spin-echo
sequences. Conclusions: Removal of the Ortho Flex Tech retainer is unnecessary before MRI. Removal of
the Twistflex should be considered if the MRI scans are performed to diagnose areas close to the fixed retainers,
when 3-T magnetic fields and T1-weighted sequences are used, and when both maxillary and mandibular fixed
retainers are present.
Role of polycystin 1 in bone remodeling- orthodontic tooth movement study in ...EdwardHAngle
Objective: To test the hypothesis that polycystin-1 (PC1) is involved in orthodontic tooth movement as a mechanical sensor.
Materials and Methods: The response to force application was compared between three mutant and four wild-type 7-week-old mice. The mutant mice were PC1/Wnt1-cre, lacking PC1 in the craniofacial region. An orthodontic closed coil spring was bonded between the incisor and the left first molar, applying 20 g of force for 4 days. Micro–computed tomography, hematoxylin and eosin staining, and tartrate-resistent acid phosphatase (TRAP) staining were used to study the differences in tooth movement among the groups.
Results: In the wild-type mice the bonded molar moved mesially, and the periodontal ligament (PDL) was compressed in the compression side. The compression side showed a hyalinized zone, and osteoclasts were identified there using TRAP staining. In the mutant mice, the molar did not move, the incisor tipped palatally, and there was slight widening of the PDL in the tension area. Osteoclasts were not seen on the bone surface or on the compression side. Osteoclasts were only observed on the other side of the bone—in the bone marrow.
Conclusions: These results suggest a difference in tooth movement and osteoclast activity between PC1 mutant mice and wild-type mice in response to orthodontic force. The impaired tooth movement and the lack of osteoclasts on the bone surface in the mutant working side may be related to lack of signal from the PDL due to PC1 deficiency.
Mandibular arch form the relationship between dental and basal anatomyEdwardHAngle
We investigated mandibular dental arch form at the levels of both the clinically relevant application points of the orthodontic bracket and the underlying anatomic structure of the apical base. The correlation of both forms was evaluated and examined to determine whether the basal arch could be used to derive a standardized clinical arch form.
ABSTRACT
Objective: To evaluate the role of age as a moderator of bone regeneration patterns and
symphysis remodeling after genioplasty.
Method: Fifty-four patients who underwent genioplasty at the end of their orthodontic treatment
were divided into three age groups: younger than 15 years at the time of surgery (group 1), 15 to
19 years (group 2), and 20 years or older (group 3). Twenty-three patients who did not accept
genioplasty and had a follow-up radiograph 2 years after the end of their orthodontic treatment
were used as a control group. Patients were evaluated at three time points: immediate preoperative
(T1), immediate postoperative (T2,) and 2 years postsurgery (T3).
Results: The mean genial advancement at surgery was similar for the three age groups, but the
extent of remodeling around the repositioned chin was greater in group 1, less in group 2, and still
less in group 3. Symphysis thickness increased significantly during the 2-year postsurgery interval
for the three groups, and this increase was significantly greater in group 1 than in group 3.
Remodeling above and behind the repositioned chin also was greater in the younger patients. This
was related to greater vertical growth of the dentoalveolar process in the younger patients. There
was no evidence of a deleterious effect on mandibular growth.
Conclusion: The outcomes of forward-upward genioplasty include increased symphysis
thickness, bone apposition above B point, and remodeling at the inferior border. When indications
for this type of genioplasty are recognized, early surgical correction (before age 15) produces a
better outcome in terms of bone remodeling. (Angle Orthod. 0000;00:000–000.)
Malposition of unerupted mandibular second premolar in children with palatall...EdwardHAngle
Objective: To test the hypotheses that (1) the distal angulation of unerupted mandibular premolar
(MnP2) is significantly greater in children with palatally displaced canines (PDC) than in those in
a control sample; and (2) delayed tooth formation is significantly more frequent in children with
both malposed MnP2 and PDC than in children with PDC only.
Materials and Methods: We examined retrospectively panoramic radiographs from 43 patients
with PDC who had no previous orthodontics. A control sample consisted of age- and sex-matched
patients. The distal angle formed between the long axis of MnP2 and the tangent to the inferior
border was measured. Dental age was evaluated using the Koch classification.
Results: A significant difference was observed between the mean inclination of the right side
MnP2 in the PDC group (75.4 degrees) and that of the control group (85.8 degrees). This difference
was highly statistically significant (P < .0001). The same evaluation was carried out for the
left side, with similar results. The average dental age was found to be delayed in patients who
showed both abnormalities (malposed MnP2 and PDC) compared with patients who showed the
PDC anomaly only.
Conclusion: Both hypotheses are retained. Statistically, PDC and MnP2 malposition are significantly
associated suggesting a common genetic etiology, despite taking place on opposite jaws.
While the presence of PDC or MnP2 anomaly has been associated with a delay in tooth formation,
we find the presence of both anomalies to show a more profound delay. Our findings suggest a
delay in tooth formation as a possible common genetic mechanism for these 2 malposition anomalies.
Angular changes and their rates in concurrence to developmental stages of the...EdwardHAngle
In the early developmental stage of the mandibular second premolar (MnP2), it is not unusual to find the tooth extremely angulated to the lower border of the mandible, as seen in the panoramic roentgenogram. On eruption, the tooth, in most cases, is close to being upright. However, impaction or other types of malocclusions due to its ectopic eruption are not rare.
Purpose: To assess the amount of dental and skeletal expansion and stability after surgically assisted
rapid maxillary expansion (SARPE).
Patients and Methods: Data from 20 patients enrolled in this prospective study were collected before
treatment, at maximum expansion, at the removal of the expander 6 months later, before any second
surgical phase, and at the end of orthodontic treatment, using posteroanterior cephalograms and dental
casts.
Results: With SARPE, the mean maximum expansion at the first molar was 7.48 1.39 mm, and the
mean relapse during postsurgical orthodontics was 2.22 1.39 mm (30%). At maximum, a 3.49 1.37
mm skeletal expansion was obtained, and this expansion was stable, such that the average net expansion
was 67% skeletal.
Conclusion: Clinicians should anticipate a loss of about one third of the transverse dental expansion
obtained with SARPE, although the skeletal expansion is quite stable. The amount of postsurgical relapse
with SARPE appears quite similar to the changes in dental-arch dimensions after nonsurgical rapid palatal
expansion, and also quite similar to dental-arch changes after segmental maxillary osteotomy for
expansion.
Short term and long-term stability of surgically assisted rapid palatal expan...Dr Sylvain Chamberland
Introduction: The purpose of this article is to present further longitudinal data for short-term and long-term
stability, following up our previous article in the surgery literature with a larger sample and 2 years of stability
data. Methods: Data from 38 patients enrolled in this prospective study were collected before treatment, at maximum
expansion, at removal of the expander 6 months later, before any second surgical phase, at the end of
orthodontic treatment, and at the 2-year follow-up, by using posteroanterior cephalograms and dental casts.
Results: With surgically assisted rapid palatal expansion (SARPE), the mean maximum expansion at the first
molar was 7.60 6 1.57 mm, and the mean relapse was 1.83 6 1.83 mm (24%). Modest relapse after completion
of treatment was not statistically significant for all teeth except for the maxillary first molar (0.99 6 1.1 mm). A
significant relationship (P-.0001) was observed between the amount of relapse after SARPE and the posttreatment
observation. At maximum, a skeletal expansion of 3.58 6 1.63 mm was obtained, and this was stable.
Conclusions: Skeletal changes with SARPE were modest but stable. Relapse in dental expansion was almost
totally attributed to lingual movement of the posterior teeth; 64% of the patients had more than 2 mm of dental
changes. Phase 2 surgery did not affect dental relapse.
Increased occurrence of dental anomalies associated with infraocclusion of de...EdwardHAngle
Objective: To test the null hypothesis that there is no relationship between infraocclusion and the
occurrence of other dental anomalies in subjects selected for clear-cut infraocclusion of one or
more deciduous molars.
Materials and Methods: The experimental sample consisted of 99 orthodontic patients (43 from
Boston, Mass, United States; 56 from Jerusalem, Israel) with at least one deciduous molar in
infraocclusion greater than 1 mm vertical discrepancy, measured from the mesial marginal ridge of
the first permanent molar. Panoramic radiographs and dental casts were used to determine the
presence of other dental anomalies, including agenesis of permanent teeth, microdontia of
maxillary lateral incisors, palatally displaced canines (PDC), and distal angulation of the mandibular
second premolars (MnP2-DA). Comparative prevalence reference values were utilized and
statistical testing was performed using the chi-square test (P< .05) and odds ratio.
Results: The studied dental anomalies showed two to seven times greater prevalence in the
infraocclusion samples, compared with reported prevalence in reference samples. In most cases,
the infraoccluded deciduous molar exfoliated eventually and the underlying premolar erupted
spontaneously. In some severe phenotypes (10%), the infraoccluded deciduous molar was
extracted and space was regained to allow uncomplicated eruption of the associated premolar.
Conclusion: Statistically significant associations were observed between the presence of
infraocclusion and the occurrence of tooth agenesis, microdontia of maxillary lateral incisors,
PDC, and MnP2-DA. These associations support a hypothesis favoring shared causal genetic
factors. Clinically, infraocclusion may be considered an early marker for the development of later
appearing dental anomalies, such as tooth agenesis and PDC.
Craniofacial growth in untreated skeletal class i subjects with low, average,...EdwardHAngle
The dental measurements showed few changes with growth in all groups. In terms of skeletal measurements from ages 9 to 18, similar growth changes were found between the sexes in most angular measurements, but males had larger values in linear measurements than females.
Effects of bonded rapid palatal expansion on the transverse dimensions of the...EdwardHAngle
The purpose of this study was to examine the maxillary response on the transverse dimensions to rapid palatal expansion (RPE) by using cone-beam computed tomography (CBCT).
Influence of common fixed retainers on the diagnostic quality of cranial magn...EdwardHAngle
Introduction: Orthodontists are often asked to remove fixed retainers before magnetic resonance imaging
(MRI). This study was undertaken to assess the effects of 2 commonly used fixed retainers on MRI distortion
and whether they should be removed. Methods: MRI scans were performed on a dry skull with Twistflex (Dentaurum,
Ispringen, Germany) and Ortho Flex Tech (Reliance Orthodontic Products, Itasca, Ill) retainers. Two
neuroradiologists independently ranked the distortions. The influence of the fixed retainers' alloys, their distance
to the area of diagnosis, location, strength of the magnetic field, and the spin-echo sequence were examined.
Statistical analysis included kappa and Pearson chi-square tests. Results: Ortho Flex Tech retainers caused
no distortion. Twistflex retainers caused distortion in 46% of the tests in areas close to the retainer (tongue
and jaws). Maxillary fixed retainers and the combination of maxillary and mandibular fixed retainers further
increased the distortion. Greater distortion was observed with 3-T magnetic fields and T1-weighted spin-echo
sequences. Conclusions: Removal of the Ortho Flex Tech retainer is unnecessary before MRI. Removal of
the Twistflex should be considered if the MRI scans are performed to diagnose areas close to the fixed retainers,
when 3-T magnetic fields and T1-weighted sequences are used, and when both maxillary and mandibular fixed
retainers are present.
Role of polycystin 1 in bone remodeling- orthodontic tooth movement study in ...EdwardHAngle
Objective: To test the hypothesis that polycystin-1 (PC1) is involved in orthodontic tooth movement as a mechanical sensor.
Materials and Methods: The response to force application was compared between three mutant and four wild-type 7-week-old mice. The mutant mice were PC1/Wnt1-cre, lacking PC1 in the craniofacial region. An orthodontic closed coil spring was bonded between the incisor and the left first molar, applying 20 g of force for 4 days. Micro–computed tomography, hematoxylin and eosin staining, and tartrate-resistent acid phosphatase (TRAP) staining were used to study the differences in tooth movement among the groups.
Results: In the wild-type mice the bonded molar moved mesially, and the periodontal ligament (PDL) was compressed in the compression side. The compression side showed a hyalinized zone, and osteoclasts were identified there using TRAP staining. In the mutant mice, the molar did not move, the incisor tipped palatally, and there was slight widening of the PDL in the tension area. Osteoclasts were not seen on the bone surface or on the compression side. Osteoclasts were only observed on the other side of the bone—in the bone marrow.
Conclusions: These results suggest a difference in tooth movement and osteoclast activity between PC1 mutant mice and wild-type mice in response to orthodontic force. The impaired tooth movement and the lack of osteoclasts on the bone surface in the mutant working side may be related to lack of signal from the PDL due to PC1 deficiency.
Mandibular arch form the relationship between dental and basal anatomyEdwardHAngle
We investigated mandibular dental arch form at the levels of both the clinically relevant application points of the orthodontic bracket and the underlying anatomic structure of the apical base. The correlation of both forms was evaluated and examined to determine whether the basal arch could be used to derive a standardized clinical arch form.
ABSTRACT
Objective: To evaluate the role of age as a moderator of bone regeneration patterns and
symphysis remodeling after genioplasty.
Method: Fifty-four patients who underwent genioplasty at the end of their orthodontic treatment
were divided into three age groups: younger than 15 years at the time of surgery (group 1), 15 to
19 years (group 2), and 20 years or older (group 3). Twenty-three patients who did not accept
genioplasty and had a follow-up radiograph 2 years after the end of their orthodontic treatment
were used as a control group. Patients were evaluated at three time points: immediate preoperative
(T1), immediate postoperative (T2,) and 2 years postsurgery (T3).
Results: The mean genial advancement at surgery was similar for the three age groups, but the
extent of remodeling around the repositioned chin was greater in group 1, less in group 2, and still
less in group 3. Symphysis thickness increased significantly during the 2-year postsurgery interval
for the three groups, and this increase was significantly greater in group 1 than in group 3.
Remodeling above and behind the repositioned chin also was greater in the younger patients. This
was related to greater vertical growth of the dentoalveolar process in the younger patients. There
was no evidence of a deleterious effect on mandibular growth.
Conclusion: The outcomes of forward-upward genioplasty include increased symphysis
thickness, bone apposition above B point, and remodeling at the inferior border. When indications
for this type of genioplasty are recognized, early surgical correction (before age 15) produces a
better outcome in terms of bone remodeling. (Angle Orthod. 0000;00:000–000.)
Malposition of unerupted mandibular second premolar in children with palatall...EdwardHAngle
Objective: To test the hypotheses that (1) the distal angulation of unerupted mandibular premolar
(MnP2) is significantly greater in children with palatally displaced canines (PDC) than in those in
a control sample; and (2) delayed tooth formation is significantly more frequent in children with
both malposed MnP2 and PDC than in children with PDC only.
Materials and Methods: We examined retrospectively panoramic radiographs from 43 patients
with PDC who had no previous orthodontics. A control sample consisted of age- and sex-matched
patients. The distal angle formed between the long axis of MnP2 and the tangent to the inferior
border was measured. Dental age was evaluated using the Koch classification.
Results: A significant difference was observed between the mean inclination of the right side
MnP2 in the PDC group (75.4 degrees) and that of the control group (85.8 degrees). This difference
was highly statistically significant (P < .0001). The same evaluation was carried out for the
left side, with similar results. The average dental age was found to be delayed in patients who
showed both abnormalities (malposed MnP2 and PDC) compared with patients who showed the
PDC anomaly only.
Conclusion: Both hypotheses are retained. Statistically, PDC and MnP2 malposition are significantly
associated suggesting a common genetic etiology, despite taking place on opposite jaws.
While the presence of PDC or MnP2 anomaly has been associated with a delay in tooth formation,
we find the presence of both anomalies to show a more profound delay. Our findings suggest a
delay in tooth formation as a possible common genetic mechanism for these 2 malposition anomalies.
Angular changes and their rates in concurrence to developmental stages of the...EdwardHAngle
In the early developmental stage of the mandibular second premolar (MnP2), it is not unusual to find the tooth extremely angulated to the lower border of the mandible, as seen in the panoramic roentgenogram. On eruption, the tooth, in most cases, is close to being upright. However, impaction or other types of malocclusions due to its ectopic eruption are not rare.
Purpose: To assess the amount of dental and skeletal expansion and stability after surgically assisted
rapid maxillary expansion (SARPE).
Patients and Methods: Data from 20 patients enrolled in this prospective study were collected before
treatment, at maximum expansion, at the removal of the expander 6 months later, before any second
surgical phase, and at the end of orthodontic treatment, using posteroanterior cephalograms and dental
casts.
Results: With SARPE, the mean maximum expansion at the first molar was 7.48 1.39 mm, and the
mean relapse during postsurgical orthodontics was 2.22 1.39 mm (30%). At maximum, a 3.49 1.37
mm skeletal expansion was obtained, and this expansion was stable, such that the average net expansion
was 67% skeletal.
Conclusion: Clinicians should anticipate a loss of about one third of the transverse dental expansion
obtained with SARPE, although the skeletal expansion is quite stable. The amount of postsurgical relapse
with SARPE appears quite similar to the changes in dental-arch dimensions after nonsurgical rapid palatal
expansion, and also quite similar to dental-arch changes after segmental maxillary osteotomy for
expansion.
Short term and long-term stability of surgically assisted rapid palatal expan...Dr Sylvain Chamberland
Introduction: The purpose of this article is to present further longitudinal data for short-term and long-term
stability, following up our previous article in the surgery literature with a larger sample and 2 years of stability
data. Methods: Data from 38 patients enrolled in this prospective study were collected before treatment, at maximum
expansion, at removal of the expander 6 months later, before any second surgical phase, at the end of
orthodontic treatment, and at the 2-year follow-up, by using posteroanterior cephalograms and dental casts.
Results: With surgically assisted rapid palatal expansion (SARPE), the mean maximum expansion at the first
molar was 7.60 6 1.57 mm, and the mean relapse was 1.83 6 1.83 mm (24%). Modest relapse after completion
of treatment was not statistically significant for all teeth except for the maxillary first molar (0.99 6 1.1 mm). A
significant relationship (P-.0001) was observed between the amount of relapse after SARPE and the posttreatment
observation. At maximum, a skeletal expansion of 3.58 6 1.63 mm was obtained, and this was stable.
Conclusions: Skeletal changes with SARPE were modest but stable. Relapse in dental expansion was almost
totally attributed to lingual movement of the posterior teeth; 64% of the patients had more than 2 mm of dental
changes. Phase 2 surgery did not affect dental relapse.
Effects on the dental arch form using a /certified fixed orthodontic courses ...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Aims: This study evaluated the subjective experience of masticatory performance and masticatory efficiency in partially edentulous patients rehabilitated with three different types of removable partial dentures (RPDs). Materials and methods: This was a crossover randomized study, which was carried out at the prosthodontics clinic of the University of Ghana Dental School clinic. Sixteen patients requiring RPDs but had never worn one before were consecutively recruited for the study. Three different RPDs [i.e., cobalt chromium, acrylic, and thermoplastic resin (iFlex)] were fabricated for each patient. Masticatory efficiency was assessed using a singlesieve method after chewing raw carrots. The subjective experience of masticatory performance was also assessed using a questionnaire after 1 week of using each denture. Results: The cobalt-chromium denture recorded the highest masticatory efficiency (31.4%), and the iFlex denture recorded the lowest (27.9%).
Neural Network in Developing Software for Indentifying Arch Formijaia
The treatment of Class I malocclusion treatment is to arrange the teeth position in a good arch form. Arch
form consists of tooth size and arch dimension (intercanine width, canine depth, intermolar width, molar
depth). Several ways are developed to describe arch form. A lot of methods used to describe arch form
qualitatively. The objective of this study is to develop qualitative arch form diagnostic references using
artificial neural network from pre-post treatment dental cast scanning result. Pre-post orthodontic
treatment dental casts (1990-2006) from Post Graduate Clinic Faculty of Dentistry University of Indonesia
and 3 other orthodontists were gathered and scanned. Data were measured using Image Tool and analyzed
using Stata 9. ANOVA was used to compare arch forms (square, oval, tapered) and gender (male and
female), with each component of arch dimension upper and lower jaw, before and after treatment; and also
arch perimeter to kinds of treatment The results were compiled to determine variables in building the
software for analyzing arch form qualitatively. The data from190 pre-post orthodontic treatment dental
casts consisted of 42 male (22.1%) and 148 female (77.9%) treated without extraction (32.63%), 4
Premolars extraction (48.42%), Upper Premolars extraction (11.05%), atypical extraction (7.90%).
Gender and all variables from pre treatment did not influence arch form, except kinds of treatment.
Therefore, only post treatment data are included for arch form analysis. The shape of arch form (square,
oval and tapered) can be described qualitatively by software using artificial neural network. This software
could describe arch form with the accuracy of 76.3158%. This study concluded that Intercanine width,
Canine depth, Intermolar width, and molar depth were variables that influenced arch form. A software
using artificial neural network to describe arch form qualitatively could be used for diagnostic reference to
Class I malocclusion orthodontic post treatment
transverse dentoskeletal features of anterior open bite in the mixed dentitio...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The development of human dentition from adolescence to adulthood has been the subject of extensive study by numerous dentists, orthodontists and other experts in the past. While prevention and cure of dental diseases, surgical reconstitution to address teeth anomalies and research studies on teeth and development of the dental arch during the growing up years has been the main concerns across the past decades, in recent years, substantial effort has been evident in the field of mathematical analysis of the dental arch curve, particularly of children from varied age groups and diverse ethnic and national origins. The proper care and development of the primary dentition into permanent dentition is of major importance and the dental arch curvature, whose study has been related intimately by a growing number of dentists and orthodontists to the prospective achievement of ideal occlusion and normal permanent dentition, has eluded a proper definition of form and shape. Many eminent authors have put forth mathematical models to describe the teeth arch curve in humans. Some have imagined it as a parabola, ellipse or conic while others have viewed the same as a cubic spline. Still others have viewed the beta function as best describing the actual shape of the dental arch curve. Both finite mathematical functions as also polynomials ranging from 2nd order to 6th order have been cited as appropriate definitions of the arch in various studies by eminent authors. Each such model had advantages and disadvantages, but none could exactly define the shape of the human dental arch curvature and factor in its features like shape, spacing and symmetry/asymmetry. Recent advances in imaging techniques and computer-aided simulation have added to the attempts to determine dental arch form in children in normal occlusion. This paper presents key analysis models & compares them through some secondary research study.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
Follow us on: Pinterest
Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
263778731218 Abortion Clinic /Pills In Harare ,sisternakatoto
263778731218 Abortion Clinic /Pills In Harare ,ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group of receptionists, nurses, and physicians have worked together as a teamof receptionists, nurses, and physicians have worked together as a team wwww.lisywomensclinic.co.za/
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Subjective classification and objective analysis of the mandibular dental arch form of orthodontic patients
1. Subjective classification and objective analysis of
the mandibular dental-arch form of orthodontic
patients
Kazuhito Araia
and Leslie A. Willb
Tokyo, Japan, and Boston, Mass
Introduction: Our objective was to evaluate the relationship between subjective classification of dental-arch
shape, objective analyses via arch-width measurements, and the fitting with the fourth-order polynomial
equation. Methods: Twenty-seven pretreatment mandibular dental casts (from 13 males and 14 females;
ages, 12-31 years) were selected. Standardized photographs of the arches were serially organized from tapered
to square by 10 examiners. The mean position in the ranking of each cast was calculated as a rank of each arch
form. The dental casts were analyzed with a 3-dimensional laser scanning system. Dental-arch widths at the
canines and molars were measured, and then a fourth-order polynomial equation was fit to each arch.
Correlations between the rank of arch shape and the objective measurements were statistically tested.
Results: The arch forms having the greatest variations among the examiners were those with an intermediate
(ovoid) ranking. Statistically significant correlations were found between the ranks of arch shape, arch dimen-
sions, and the polynomial equation analyses. Conclusions: Subjective clinical assessments were generally
in agreement at the extremes of tapered and square arch forms; the exceptions were arches with an ovoid
shape. There were statistically significant correlations between subjective dental-arch classifications and
dental-arch dimensions, as well as the ratio determined from these variables and polynomial equation
analyses. Therefore, fourth-order polynomial equations might be an important factor in the quantitative
analysis of dental-arch form in orthodontic patients. (Am J Orthod Dentofacial Orthop 2011;139:e315-e321)
O
ne goal of orthodontic treatment is to create an
individualized dental arch that is ideal for the pa-
tient.1-3
The original dental-arch form of the pa-
tient is mimicked to achieve stable treatment results
because an arch form that has been orthodontically
modified has a tendency to return to its original width.4,5
Therefore, reliable evaluation and accurate analysis of
the patient’s pretreatment dental-arch form are essential
steps for orthodontic diagnosis.
In general, subjective classification methods with 3
or 5 simple shape categories have been commonly ap-
plied to evaluate the initial dental-arch form during
the orthodontic diagnostic process.6-8
For example,
the subjective classification method, which uses 3
recommended shapes of tapered, ovoid, and square
forms, has been widely used in the clinic to select
prefabricated orthodontic archwires for a specific
patient.8
However, general human error can be expected in
subjective analysis; therefore, the intraoperator and inter-
operator reproducibility of these evaluations might be in-
accurate. Additionally, although a mathematical definition
of these square, ovoid, and tapered dental-arch forms has
been proposed, clinical application of this evaluation
method for computer analysis is still rather limited.9
Another common analysis of the dental-arch form is
measuring canine and molar widths for clinical and re-
search purposes.10
These transverse dimensions are usu-
ally measured at the cusp tips or other anatomic
structures of the tooth crown. One considerable advan-
tage of this method is the numeric analysis of the
dental-arch form. Additionally, determination of the
canine-molar width ratio has been also used as a simple
quantification method and has been widely used in a
clinical setting.11
a
Professor and chair, Department of Orthodontics, Nippon Dental University,
Tokyo, Japan.
b
Chair and Anthony A. Gianelly Professor of Orthodontics, Boston University
Goldman School of Dental Medicine, Boston, Mass.
The authors report no commercial, proprietary, or financial interest in the prod-
ucts or companies described in this article.
Reprint requests to: Kazuhito Arai, Department of Orthodontics, Nippon Dental
University, 1-9-20 Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan; e-mail, drarai@
tky.ndu.ac.jp.
Submitted, April 2009; revised and accepted, December 2009.
0889-5406/$36.00
Copyright Ó 2011 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2009.12.032
e315
ONLINE ONLY
2. In comparison, objective numeric analysis methods,
which use particular geometric and mathematical
models, have been developed to quantitatively describe
the dental-arch forms of orthodontic patients.12-27
For
instance, a parabola or second-order polynomial,19
beta function,18
cubic spline function,20
and fourth-
order or larger polynomial equations have all been ap-
plied.13,21-25
Recently, AlHarbi et al26
compared these
functions and concluded that the fourth-order polyno-
mial function (y 5 ax4
1 bx3
1 cx2
1 dx 1 e) was
the most reasonable equation for analysis when the ob-
jective was to describe the general smooth curvature of
the dental arch.
Application of fourth-order polynomials to represent
the dental-arch form has several advantages for dental-
arch form analysis.13,21-25
According to Lu,13
1 advan-
tage of the fourth-order polynomial curve-fitting
method is that the coefficients of each term can be sim-
ply associated with specific aspects of the arch form. The
coefficients of the fourth (x4
or quartic) and second (x2
or quadratic) terms describe the square and tapered
shapes of dental-arch forms, respectively. Although
a large fourth-order coefficient “a” indicates a square
arch form, a large second-order coefficient “c” describes
a tapered arch form. Consequently, the fourth-order
polynomial equation has been applied extensively on
the basis of this hypothesis.13,21-25
For example,
Hayama et al23
evaluated the relationship between max-
illary and mandibular dental-arch forms and found
statistically significant positive correlations for all coef-
ficients. Richards et al16
applied the fourth-order poly-
nomial equation to analyze the correlation between
twin subjects and concluded that this equation can ac-
curately represent dental-arch shape. Additionally, Fer-
rario et al17
investigated dental-arch size differences
between the sexes using this equation. However, little
research has been conducted to compare the mathemat-
ical description of the dental-arch form with the subjec-
tive evaluations and the objective width measurements
made by clinicians as orthodontic diagnostic tools.
The purpose of this study was to evaluate the rela-
tionship between the results of both a subjective classi-
fication by human judgment and 2 objective analytic
methods by using dental-arch dimension measurements
and the fourth-order polynomial equation for analysis of
the dental-arch form of orthodontic patients.
MATERIAL AND METHODS
A total of 27 pretreatment casts from 13 male and 14
female subjects, ranging in age from 12 to 31 years
(mean age, 16.5 6 5.0 years), were selected from 720
records at the Harvard School of Dental Medicine
Teaching Clinic in Boston, Mass. The following inclusion
criteria were required: (1) complete dentition, excluding
third molars; (2) no prosthetic crowns and minimal resto-
rations; (3) minimal signs of occlusal attrition; and (4) min-
imal spacing. Subjects with severe crowding (.10 mm)
and transposed teeth were excluded from the analysis.
This sample size was first analyzed and determined to
provide an adequate statistical power (80%, b 5 0.2) for
detection of a correlation coefficient of 0.5 for a 5 0.05
and 0.6 for a 5 0.01.
All selected subjects signed informed consent
forms granting permission for their records to be used
in research. A detailed protocol of this project was ap-
proved by the Committee on Human Studies of Harvard
Medical School and Harvard School of Dental Medicine
(X040501-1).
Standardized occlusal photographs of the mandibu-
lar dental casts of the 27 mandibular arches were taken
with a digital camera (DSC-F55V, Sony, Japan) and
printed in actual size (Fig 1, A). Photographs of the
mandibular dental arches were organized in a series
from tapered to square shapes by 10 members of the
Fig 1. A, Digital photograph of a dental cast (cast 11); B,
reference points determined on the cloud data in shaded
display (cast 11).
e316 Arai and Will
April 2011 Vol 139 Issue 4 American Journal of Orthodontics and Dentofacial Orthopedics
3. Department of Orthodontics (5 teaching staff members
and 5 fourth-year and third-year residents) from the De-
partment of Growth and Development, Harvard School
of Dental Medicine, Boston, Mass, and Department of
Orthodontics, Nippon Dental University, Tokyo, Japan.
Each examiner evaluated the 27 dental arches and
ranked them from most tapered (1) to most square
(27). The average rank given to a particular cast by all
10 examiners was determined to generate a mean rank
for the dental arch. The standard deviation of the mean
rank was also calculated for each dental arch. For exam-
ple, a dental cast photograph ranked as most tapered (1)
by 7 examiners and the second most tapered (2) by the
other 3 examiners would receive an overall mean rank
of 1.3 6 0.5. This dental arch was then placed into the
shape continuum near the most tapered side. The exam-
iners were asked to judge the dental-arch form using their
usual clinical evaluation method, and no discussion or
calibration sessions occurred before the evaluations.
The dental casts were also scanned and analyzed with
a 3-dimensional dental cast-measuring system. This
system consisted of a laser-scanning unit (Surflacer
VMS- 100F/ UNISN, Osaka, Japan) and a computer-
aided design (CAD) software program (Surfacer version
9.0. Imageware Inc., Ann Arbor, Mich).27,28
The reference points digitized on the image of each
cast were the midpoints of the incisal edges, the canine
cusp tips, and the buccal cusps of the premolars and the
first and second molars (Fig 1, B). The midpoint between
the mesiobuccal and distobuccal cusp tips of the first
and second molars was then computed and used to de-
fine the molar position. Only 1 point was used for each
molar to eliminate the effects of rotation, resulting in
a single point for the position of the tooth.
X and y coordinate data were extracted, and the dis-
tances between bilateral reference points for the canines
and the first and second molars were calculated as ca-
nine width, first molar width, and second molar width,
respectively. The canine-first molar and canine-second
molar ratios (percentages) were also calculated. Then
the means and standard deviations of canine width, first
molar width, second molar width, canine-first molar ra-
tio, and canine-second molar ratio were calculated.
Additionally, these coordinate sets were used to fit
a fourth-order polynomial equation (y 5 ax4
1 bx3
1
cx2
1 dx 1 e) to the 14 reference points for a dental
arch by using the least squares method (Fig 2). Then,
the coefficients of fourth-order and second-order terms
(“a” and “c,” respectively) could be determined from this
equation for each dental arch. The means and standard
deviations of the “a” and “c” terms were also calculated.
The nonparametric Spearman rank correlations (rs)
between the mean rankings of the dental-arch forms,
the canine and molar widths and ratios, and the “a”
and “c” coefficients derived from the equations were sta-
tistically analyzed. The Pearson correlation coefficients
(r) between the dental-arch width and ratios, as well as
the “a” and “c” terms, were also calculated and statisti-
cally analyzed with the Fisher z-transformation.29
Two statistical analysis methods for correlations were
used in this research: (1) the nonparametric Spearman
rank correlation to rank data and (2) the Pearson coeffi-
cient of correlation for continuous data.
To evaluate the reliability of the dental-arch form
ranking, photographs of 10 casts were randomly selected
from the sample. These standardized photographs were
ranked twice from tapered to square shapes by the
same examiner (K.A.), with an interval of 2 weeks
between evaluations, to determine intraexaminer
reliability. The same determination was made once by
another examiner (L.A.W.) to evaluate interexaminer re-
liability. Nonparametric Spearman rank correlations of
intraexaminer and interexaminer reliability were 0.71
(P 5 0.03) and 0.93 (P 0.01), respectively.
To evaluate the reliability of landmark location, 10
dental casts were randomly selected from the sample.
The following 10 reference points were determined: in-
cisal edges of the central incisors, canine cusp tips, buc-
cal cusp tips of the first premolars, and mesial and distal
buccal cusp tips of the first molar on the left side of the
dental arch. The same examiner (K.A.) determined 100
reference points in duplicate to evaluate intraexaminer
reliability, with 2 weeks between evaluations. The same
determination was made once by another examiner
(L.A.W.) to evaluate interexaminer reliability. The mean
differences between the 2 determinations by the same
examiner were 0.21 mm (SD, 0.21 mm) in the sagittal
plane and 0.17 mm (SD, 0.19 mm) in the transverse
plane. The mean differences between the 2 examiners
were 0.19 mm (SD, 0.22 mm) in the sagittal plane and
0.21 mm (SD, 0.19 mm) in the transverse plane.
RESULTS
The correlations between the means and standard
deviations of the subjective evaluation rankings for all
dental-arch forms are shown in Figure 3. The dental-
arch forms ranked as most tapered or most square had
small standard deviations, and interexaminer agreement
among examiners was obtained. In contrast, the arch
forms exhibiting relatively greater standard deviations, in-
dicating interexaminer variation in the evaluation, were
those with an intermediate ranking (ovoid arch form).
Statistically significant positive correlations were
found between the mean rankings of the dental-arch
forms, the widths and ratios of the canine and the first
and second molars, and the fourth-order term “a” of
Arai and Will e317
American Journal of Orthodontics and Dentofacial Orthopedics April 2011 Vol 139 Issue 4
4. the equation. Statistically significant negative correla-
tions were found between the mean rankings, the
canine-molar ratios, and the second-order term “c” of
the equation (Table I). The highest statistically signifi-
cant positive correlation was observed between the
mean rank and canine width. In contrast, the highest
negative correlation was obtained between the mean
rank and the second-order term “c” (Table I).
Statistically significant positive correlations were
found between the canine-first molar ratio and the
second-order term “c,” and between the canine-second
molar ratio and the fourth-order term “a.” Statistically
significant negative correlations were found between ca-
nine width, first molar width, second molar width, and
canine-second molar ratio and “c” (Table II).
DISCUSSION
Several subjective methods of classification have
been used to evaluate the characteristics of a patient’s
pretreatment dental-arch form for orthodontic diagno-
sis and treatment planning.6-8
In this study, arch forms
were subjectively ranked from tapered to square by 10
examiners, according to their own clinical evaluation
methods without any calibration sessions among
examiners. The arches ranked closest to either end of
the continuum varied the least among examiners,
suggesting that dental-arch forms that were distinctively
tapered or square were easier to classify. This result indi-
cates that the visual cognitive ability of the trained clini-
cian can almost instantaneously recognize the
differences between characteristics of complex dental-
arch shapes that are subtly distinct without a measuring
device, resulting in consistent classifications of arches
with the simple description of “tapered” or “square.”
These results also indicate that this type of subjective
classification with ranking becomes relatively more dif-
ficult for dental-arch forms that are intermediate, such
as the ovoid shape. Therefore, this difficulty in classify-
ing intermediate arch forms might result in unreliable
classification of the ovoid shape and suggests that cali-
bration should be performed among examiners before
classification and that quantitative analysis can be im-
portant, especially for the boundaries between tapered
and ovoid and between ovoid and square shapes.7
Addi-
tionally, relatively high interevaluator and intraevaluator
reliabilities of a subjective classification of dental-arch
forms by using a set of standard arch form templates
was recently reported.30
Therefore, additional study
might be necessary to compare these classification
methods.
There were statistically significant positive correla-
tions between rank and dental-arch widths (Table I).
This result suggests that wider dental arches had a ten-
dency to be ranked as square shapes. Also, there were
statistically significant negative correlations between
the ranks and ratios of the canines and the first and sec-
ond molars. Therefore, dental-arch forms with canines
that are wide relative to both the first and second molars
had a tendency to be square. In comparison, the highest
positive correlation was obtained between rank and ca-
nine width. These results indicate that the examiners
might predominantly focus on individual variations in
Fig 2. Example of dental-arch form analyses. Reference
points for each tooth and the polynomial equation with the
curve on the dental-arch form are shown (cast 11). The
results of the analyses were (1) mean rank 6 SD, 21.6
6 2.7; (2) canine width, 28.04 mm; (3) first molar width,
46.12 mm; (4) canine-first molar ratio, 59.56%; (5) second
molar width, 51.53 mm; (6) canine-second molar width ra-
tio, 54.41%; (7) “a,” 6.970 3 10À5
; and (8) “c,” 0.013.
Fig 3. Correlation between rank of dental-arch form and
standard deviation of the ranking.
e318 Arai and Will
April 2011 Vol 139 Issue 4 American Journal of Orthodontics and Dentofacial Orthopedics
5. canine width during classification and also support
a clinical system of preformed archwires that varies the
canine widths only.8
Additionally, canine width mea-
surements made with calipers might serve as a quantita-
tive analysis of dental-arch form for preformed
orthodontic archwire selection in the clinic. For example,
based on this study, the mean 6 standard deviation of
canine width was 25.98 6 3.02 mm. Therefore, the
ovoid arch shape can be mathematically defined as a ca-
nine width between 22.96 and 29.00 mm. To apply this
range of canine width for ovoid dental-arch shapes as
a standard in preformed archwire selection,8
further
studies in Class I normal occlusion and other Angle clas-
sifications7
might be required.
Statistically significant positive and negative correla-
tions between the subjective rankings of dental-arch
forms and objective quantitative analyses by using the
coefficients “a” and “c” of the fourth-order polynomial
equation were found, respectively (Table I). These find-
ings indicate that a tapered dental-arch form has a large
“c,” and a square dental-arch form has a large “a,” sup-
porting the hypothesis of Lu.13
Therefore, dental-arch
forms can be quantitatively analyzed, including the ref-
erence points on every tooth, by the result of the fitted
fourth-order term “a” and the second-order term “c”
of the dental arch, even in intermediate ovoid arches.
Additionally, the curve created by the equation results
in a smooth flexible curve, which represents all potential
tooth positions for the dental arch and, therefore, can be
used as an archwire template for each patient.13,26
There were statistically significant correlations be-
tween all arch-width measurements and canine-molar
ratios and the second-order term “c” (Table II). For ex-
ample, wider canines had smaller “c” values in the poly-
nomial equation fitted to the dental arch. On the other
hand, only the canine-second molar ratio was significantly
correlated with the fourth-order term “a” (Table II). These
results suggest that the more posterior teeth exert
a greater influence on the polynomial curve by the
fourth-order term “a.” Therefore, the second-order
term “c” is the main element for consideration in the
mathematical analysis with the polynomial equation
curve and of greater significance than the fourth-order
term “a” for the anterior region. Additionally, the
fourth-order term “a” can serve as a modifier for the
curve fitting in the posterior area of the dental-arch
form. Although we analyzed dental-arch forms without
much crowding, mathematical curve fitting for the
Table I. Means and standard deviations of the canines, first and second molar widths, canine-first and canine-second
molar ratios, and fourth-order and second-order terms of coefficients of the equation (“a” and ”c”) of the dental arch
forms
Canine
width (mm)
First molar
width (mm)
Canine-firstmolar
ratio (%)
Second molar
width (mm)
Canine-second molar
ratio (%)
Fourth-order
term “a”
Second-order
term “c”
Mean 25.98 45.55 60.67 50.50 51.44 4.942E-05 0.030
SD 3.02 3.49 6.37 3.45 4.77 2.649E-05 0.019
rs 0.820 0.582 À0.535 0.445 À0.651 0.656 À0.840
Z-transformation 4.183 2.969 À2.728 2.269 3.318 3.344 À4.283
P value 0.0001y
0.0030y
0.0064y
0.0233* 0.0009y
0.0008y
0.0001y
Results of the statistical analyses by nonparametric Spearman rank correlations between the mean rank and canine width, first and second molar
widths, canine-first molar and canine-second molar ratios, and “a” and “c.”
*P 0.05; y
P 0.01.
Table II. Pearson coefficient of correlation (r) between the dental arch width and ratios and “a” and “c” were also
calculated and statistically analyzed with the Fisher z-transformation
“a” “c”
r P value r P value
Canine width 0.364 0.0619 À0.683 0.0001y
First molar width 0.091 0.6541 À0.638 0.0002y
Canine-first molar ratio À0.050 0.8050 0.596 0.0008y
Second molar width À0.214 0.2880 À0.392 0.0422*
Canine-second molar ratio 0.616 0.0004y
À0.593 0.0008y
*P 0.05; y
P 0.01.
Arai and Will e319
American Journal of Orthodontics and Dentofacial Orthopedics April 2011 Vol 139 Issue 4
6. dental arch with crowding has also been reported.31
Therefore, how crowding and asymmetries affect the
arch form and whether this observation has an implica-
tion on the ranking method can be studied by using the
fourth-order polynomial equation in a future study.
The disadvantage of the fourth-order polynomial
equation is the current lack of simplicity for daily use
in a clinical setting to fit the curve onto the dental
arch. However, a software program fitting polynomial
equations to the dental arch is available,32
and some
computer systems with 3-dimensional technology for
dental cast analysis, diagnosis, and treatment planning
have recently been introduced and are rapidly spreading
in orthodontics.33-35
Soon, it is likely that this
technology will be readily available in orthodontic
offices. Based on the results of this study, the fourth-
order polynomial equation can be applied to estimate
the dental-arch forms of orthodontic patients with an
accurate and a flexible mathematical expression.
CONCLUSIONS
1. Subjective clinical assessments were generally in
agreement at the extremes of tapered and square
dental-arch forms, but the exceptions were arches
with an ovoid shape.
2. There were statistically significant correlations be-
tween subjective dental-arch classifications and
dental-arch dimensions, as well as the ratio deter-
mined from these variables and polynomial equa-
tion analyses.
3. Coefficients of fourth-order polynomial equations
were significantly correlated with individual vari-
ations in the size and shape of dental-arch forms
and might be a reliable tool for quantitative
analysis of dental-arch form in orthodontic
patients.
REFERENCES
1. Hawley CA. Determination of the normal arch, and its application
to orthodontia. Dent Cosmos 1905;47:541-52.
2. Angle EH. Treatment of malocclusion of the teeth and fractures of
the maxillae. Angle’s system. 7th ed. Philadelphia: S.S. White;
1907. p. 21-4.
3. Sarver DM, Proffit WR, Ackerman JL. Diagnostic and treatment
planning in orthodontics. In: Graber TM, Vanarsdall RL Jr, editors.
Orthodontics: current principles and techniques. 3rd ed. St Louis:
Mosby; 1994. p. 57.
4. Case CS. Principles of retention in orthodontia. Int J Orthod Oral
Surg 1920;6:627-58.
5. Riedel RA. A review of the retention problem. Angle Orthod 1960;
30:179-99.
6. Ricketts RM. Design of arch form and details for bracket placement
(catalog number P-365). Denver, Colo: Rocky Mountain Ortho-
dontics; 1979.
7. Nojima K, McLaughlin RP, Isshiki Y, Sinclair PM. A comparative
study of Caucasian and Japanese mandibular clinical arch forms.
Angle Orthod 2001;71:195-200.
8. McLaughlin RP, Bennett JC. Arch form considerations for stability
and esthetics. Rev Esp Ortod 1999;29(Suppl 2):46-63.
9. Noroozi H, Nik TH, Saeeda R. The dental arch form revisited. Angle
Orthod 2001;71:386-9; erratum, 525.
10. Moorrees CFA. The dentition of the growing child. A longitudinal
study of dental development between three and eighteen years of
age. Cambridge, Mass: Harvard University Press; 1959.
11. Williams PN. Dental engineering and the normal arch. Dent Cos-
mos 1918;60:483-90.
12. de la Cruz A, Sampson P, Little RM,Artun J, Shapiro PA. Long-term
changes in arch form after orthodontic treatment and retention.
Am J Orthod Dentofacial Orthop 1995;107:518-30.
13. Lu KH. An orthogonal analysis of the form, symmetry and asym-
metry of the dental arch. Arch Oral Biol 1966;11:1057-69.
14. Pepe SH. Polynomial and catenary curve fits to human dental
arches. J Dent Res 1975;54:1124-32.
15. Sampson PD. Dental arch shape: a statistical analysis using conic
sections. Am J Orthod 1981;79:535-48.
16. Richards LC, Townsend GC, Brown T, Burgess VB. Dental arch
morphology in south Australian twins. Arch Oral Biol 1990;35:
983-9.
17. Ferrario VF, Sforza C, Miani A Jr, Tartaglia G. Mathematical defi-
nition of the shape of dental arches in human permanent healthy
dentitions. Eur J Orthod 1994;16:287-94.
18. Braun S, Hnat WP, Fender DE, Legan HL. The form of the human
dental arch. Angle Orthod 1998;68:29-36.
19. Battagel JM. Individualized catenary curves: their relationship to
arch form and perimeter. Br J Orthod 1996;23:21-8.
20. BeGole EA. Application of the cubic spline function in the descrip-
tion of dental arch form. J Dent Res 1980;59:1549-56.
21. Ferrario VF, Sforza C, Schmitz JH, Colombo A. Quantitative
description of the morphology of the human palate by
a mathematical equation. Cleft Palate Craniofac J 1998;35:
396-401.
22. Ferrario VF, Sforza C, Colombo A, Carvajal R, Duncan V,
Palomino H. Dental arch size in healthy human permanent denti-
tions: ethnic differences as assessed by discriminate analysis. Int J
Adult Orthod Orthognath Surg 1999;14:153-62.
23. Hayama K, Arai K, Ishikawa H. Correlation between upper and
lower dental arch forms by fitting of fourth-order polynomials. Or-
thod Waves 2000;59:303-11.
24. Uzuka S, Arai K, Ishikawa H. Polynomial curve superimpositions on
dental arch forms with normal occlusions. Orthod Waves 2000;59:
32-42.
25. Shikano C, Arai K, Ishikawa H. Evaluation of dental arch form in
normal occlusion—fitting of fourth-order polynomials on FA
points. Orthod Waves 2001;61:69-77.
26. AlHarbi S, Alkofide EA, AlMadi A. Mathematical analyses of dental
arch curvature in normal occlusion. Angle Orthod 2008;78:281-7.
27. Arai K, Ishikawa H. Application of non-ontact three-dimensional
shape measuring system to dental cast—reduction of blind region.
Orthod Waves 1999;58:148-53.
28. Ronay V, Miner RM, Will LA, Arai K. Mandibular arch form: the re-
lationship between dental and basal anatomy. Am J Orthod Den-
tofacial Orthop 2008;134:430-8.
29. Norman GR, Steiner DL. Biostatistics. The bare essentials. 2nd ed.
Hamilton, Ontario, Canada: B. C. Decker; 2000.
30. Trivi~no T, Siqueira DF, Scanavini MA. A new concept of mandibu-
lar dental arch forms with normal occlusion. Am J Orthod Dento-
facial Orthop 2008;133:10.e15-22.
e320 Arai and Will
April 2011 Vol 139 Issue 4 American Journal of Orthodontics and Dentofacial Orthopedics
7. 31. Wellens H. Applicability of mathematical curve-fitting procedures
to late mixed dentition patients with crowding: a clinical-experi-
mental evaluation. Am J Orthod Dentofacial Orthop 2007;
131:160.e17-25.
32. Noroozi H, Djavid GE, Moeinzad H, Teimouri AP. Prediction of arch
perimeter changes due to orthodontic treatment. Am J Orthod
Dentofacial Orthop 2002;122:601-7.
33. Boyd RL, Miller RJ, Vlaskalic V. The Invisalign system in adult or-
thodontics: mild crowding and space closure cases. J Clin Orthod
2000;34:203-12.
34. Marcel TJ. Three-dimensional on-screen virtual models. Am J
Orthod Dentofacial Orthop 2001;119:666-8.
35. Mah J, Sachdeva R. Computer-assisted orthodontic treatment: the
SureSmile process. Am J Orthod Dentofacial Orthop 2001;120:85-7.
Arai and Will e321
American Journal of Orthodontics and Dentofacial Orthopedics April 2011 Vol 139 Issue 4