Effects on the dental arch form using a /certified fixed orthodontic courses by Indian dental academy

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Effects on the dental arch form using a /certified fixed orthodontic courses by Indian dental academy

  1. 1. Effects on the Dental Arch Form Using a Preadjusted Appliance with Premolar Extraction in Class I Crowding INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2.  In the cases of malocclusion with anterior crowding premolar extractions are often indicated.  Studies which have been done earlier show that the dental arch dimensions before and after treatment were maintained, while morphological changes were few in the lower dental arch and the area of the upper anterior teeth increased. www.indiandentalacademy.com
  3. 3.  There is no report on the effects of premolar extraction on positional changes of the anterior teeth and dental arch form with use of a preadjusted appliance.  A preadjusted appliance uses a preformed wire to perform treatment with sliding mechanics; thus, it is considered important to describe its effects on the dental arch form. www.indiandentalacademy.com
  4. 4. Objective  The aim of this study was to determine effects of treatment with a preadjusted appliance after extraction of premolars on the positional relationships of the upper and lower anterior teeth, as well as the dental arch form in patients with Class I crowding. www.indiandentalacademy.com
  5. 5. Materials and methods  The subjects were 26 patients with Class I crowding (20.17 SD 12.15 years ) who under went treatment using a preadjusted appliance (MBT system, 0.022 slot) and attained a favorable occlusion. www.indiandentalacademy.com
  6. 6.  They were divided into the nonextraction (n 10, 25.66 SD 17.0 years) and extraction (n 16, 16.75 SD 6.3 years) groups. The inclusion criteria were as follows:  Skeletal structure rated as Skeletal I and demonstrating  Angle Class I malocclusion.  No abnormality in the dental crown morphology.  No restorative materials or occlusal wear that could have an effect on the measurements.  No temporomandibular joint derangement.  Patients who had not undergone lateral expansion or distal movement of the molars. www.indiandentalacademy.com
  7. 7.  Cast models and lateral cephalometric radiographs before and after treatment were used as study materials. For measuring the three-dimensional coordinates of the FA point of each tooth, a three- dimensional coordinate measuring device was used.  The three-dimensional coordinate values were obtained according to Otani’s method,then projected to the reference plane and converted into two-dimensional coordinates. www.indiandentalacademy.com
  8. 8.  The dental arch configuration was expressed by a quartic polynominal expression, y =ax2 + bx4, using Mathematica 5.1 (Wolfram Research, Champaign, Ill) to calculate the log F value (F a3/b) from the coefficients of the quadratic and quartic terms, which represented the dental arch configuration.  A dental arch configuration with a smaller log F value indicated a squared type, while that with a larger log F value indicated a tapered type. www.indiandentalacademy.com
  9. 9.  For analysis of lateral cephalometric radiographs, SNA, SNB, facial angle, and mandibular plane were measured as well as U1- FH, L1-Mand, U1-APo, and L1-APo www.indiandentalacademy.com
  10. 10.  The maximum width of the crown, anterior and posterior lengths and widths of the dental arch, and archlength discrepancy between the upper and lower arch were determined using cast models prepared at the time of the first examination www.indiandentalacademy.com
  11. 11.  Each item was measured three times by the same examiner using a digital micrometer caliper and a model measuring instrument .To determine the mean of the three measurements, the mean and standard deviation were calculated for each of the subjects in the extraction and nonextraction groups www.indiandentalacademy.com
  12. 12. Statistical Analysis  The log F values for the extraction and nonextraction groups were compared using a Mann-Whitney U test, while those before and after treatment were compared using a Wilcoxon signed-ranks test  For cephalometric analysis, radiographs obtained before and after treatment were compared between the extraction and nonextraction groups. www.indiandentalacademy.com
  13. 13.  For comparisons between groups, an unpaired t-test was used, while a paired ttest was used to compare radiographs obtained before and after treatment in each group  For model analysis, comparisons were made between the extraction and nonextraction groups using an unpaired t-test www.indiandentalacademy.com
  14. 14. Protocol for Preadjusted Appliance Technique  The subjects examined in the present study were treated using a preadjusted appliance (0.022 0.028 inch slot, MBT set up) according to the following procedure. The bracket height was set using the Mc- Laughlin and Bennett method for performing indirect bonding.  The arch form (tapered, ovoid, square) was selected in accordance with the dental arch form, which was determined at the time of the first examination. www.indiandentalacademy.com
  15. 15.  After completing leveling and alignment of the lateral teeth using a 0.016-inch round heat-activated Ni-Ti wire and a 0.019 *0.025 inch heat-activated Ni- Ti wire, a 0.019 * 0.025 inch stainless steel wire was attached for performing distal movement of the canine, followed by leveling and alignment of the incisor www.indiandentalacademy.com
  16. 16. Results dental arch configuration  For the upper dental arch configuration, no statistically significant differences were observed before treatment between the extraction and nonextraction groups  for the upper dental arch form after treatment, the log F values of the extraction group were significantly larger (P >0.05), as the median was -0.33 and interquartile range was 2.29, compared with -2.76 and 3.07, respectively, for the nonextraction group www.indiandentalacademy.com
  17. 17.  In contrast, no statistically significant difference was observed for the lower dental arch configuration before and after treatment or between the extraction and nonextraction groups www.indiandentalacademy.com
  18. 18. Analysis of cephalometric radiology  the extraction and nonextraction groups before treatment demonstrated that the mean U1- APo of the extraction group (9.71 mm) was significantly larger than that of the nonextraction group  However, no statistically significant differences were observed for other measurements obtained using the skeletal and dental measurements. www.indiandentalacademy.com
  19. 19. www.indiandentalacademy.com
  20. 20.  As for the dental arch configuration after treatment, the mean L1-APo of the extraction group (4.40 mm) was significantly smaller than that of the nonextraction group (6.56 mm) (P < .01). However, no statistically significant differences were observed for the other measurements.  When the quantity of changes before and after treatment were compared, a statistically significant difference was observed between the extraction and nonextraction groups for U1-APo, which was decreased by 1.31 mm in the extraction group and increased by 1.43 mm in the nonextraction group www.indiandentalacademy.com
  21. 21. Analysis of cast models  comparisons of the cast models before treatment between the extraction and nonextraction groups revealed statistically significant differences in the upper posterior width (UPW) and lower posterior width (LPW).  The intermolar widths of the upper and lower arches of the extraction group were smaller www.indiandentalacademy.com
  22. 22. www.indiandentalacademy.com
  23. 23.  Comparisons of the models after treatment revealed statistically significant differences in UPW, LPW, upper posterior length (UPL), and lower posterior length (LPL) between the groups. Also, the intermolar width and length of the upper and lower arches were smaller in the extraction group  In the extraction group, comparisons of the models before and after treatment revealed a significant difference in UPW, while the intermolar width of the upper arch was decreased. www.indiandentalacademy.com
  24. 24.  Statistically significant differences were observed for upper arch length (UAL) and lower arch length (LAL) before and after treatment, while the upper and lower anterior lengths were increased.  Statistically significant differences were also observed for UPL and LPL; the UPL and LPL were decreased.  In the nonextraction group, comparisons of the models before and after treatment revealed significant differences in UAL and UPL, while the upper anterior and posterior lengths were increased. www.indiandentalacademy.com
  25. 25.  As for maximum crown width, the extraction group showed significantly greater widths for all teeth except the second molar in the upper arch. In the lower arch, the width of the canine, as well as the first and second premolars, was significantly greater www.indiandentalacademy.com
  26. 26.  In addition, the arch length discrepancy (ALD) at the time of the first examination in the extraction group was significantly greater for both the upper (8.16 mm) and lower arches (6.54 mm) compared with those (1.29 mm and 1.82 mm, respectively) in the nonextraction group www.indiandentalacademy.com
  27. 27. Discussion  In the present study of Class I crowding patients, no statistically significant differences were observed for the configuration of the upper and lower arches at the time of the first examination between the extraction and nonextraction groups. These results suggest that the dental arch form might be determined irrespective of the amount of discrepancy. www.indiandentalacademy.com
  28. 28.  The dental arch form for the lower arch between Japanese and Indian females with normal occlusion was studied by Ukere et al, they reported that Japanese females had a smaller and more squared dental arch form, and showed more considerable variation than the Indian subjects  In the present study, the log F value for the upper dental arch was significantly increased from -1.35 before treatment to -0.33 after treatment in the extraction group. Since the log F value of the extraction group after treatment was larger than that of the nonextraction group (-2.76), the dental arch demonstrated a tapered pattern. www.indiandentalacademy.com
  29. 29.  In the nonextraction group, no statistically significant differences in log F values were observed for the upper and lower arch between the groups before and after treatment, indicating no changes in the dental arch form  Hnat et al reported, the dental arch form might be compensated by an increase in dental arch length. Accordingly, it can be considered that a decline in number of teeth might produce a tapered pattern. www.indiandentalacademy.com
  30. 30.  Heiser et al studied the dental arch form using a three- dimensional methodwith extraction and nonextraction groups and reported that the anterior length of the upper dental arch was increased as a result of extraction, while the area of the anterior teeth was increased in both groups  for the subjects in the present study, the width was greater for all teeth, excluding the upper second molar, in the extraction group than in the nonextractrion group. www.indiandentalacademy.com
  31. 31.  In addition, the widths of the canine and first and second premolars were greater in the lower arch. Accordingly, it was considered that crowding might be produced by the width of the crown.  Shigenobu et al speculated that ALD might be important for a symmetrical crowding pattern of the anterior teeth.  It was considered that tapering of the upper dental arch in the present extraction group, which showed a large ALD value, might have resulted from an increase in anterior arch length to resolve crowding of the anterior teeth produced by a large amount of tooth width www.indiandentalacademy.com
  32. 32.  BeGole et al suggested that intermolar width was likely to be increased by nonextraction treatment, and Weinberg and Sadowsky reported that the dental arch expanded as a whole because of the performance of nonextraction therapy. In the present study, the length increased in the extraction group, whereas the intercanine and intermolar widths did not. www.indiandentalacademy.com
  33. 33.  As for the dynamic state of the upper and lower anterior teeth, U1-APO was significantly reduced after treatment in the extraction group, which demonstrated posterior movement of the upper anterior teeth. Because U1-FH did not show any changes, it was considered that the teeth might have moved in a posterior direction by sliding mechanics, while the torque of the upper anterior teeth was kept and controlled properly  This result also suggested that a torque of -17* and angulation of 4* incorporated to the bracket for the upper central incisor would function effectively www.indiandentalacademy.com
  34. 34.  For the inclination of the lower anterior teeth, no significant difference was observed between before and after treatment. The lower incisor moved toward the posterior direction after treatment in the extraction group and toward the anterior direction in the nonextraction group. Nevertheless, a torque of -6* and angulation of 0* incorporated to the bracket for the lower incisor might be effective www.indiandentalacademy.com
  35. 35.  Further, space remained after improvement of anterior teeth crowding, which suggested that the space was closed by mesial movement of the molars, as the intermolar width and anterior length of the dental arch were reduced  One of the out come of this study is that the sum of tooth widths of teeth anterior of the canine is greatly involved in determining the dental arch form. www.indiandentalacademy.com
  36. 36. CONCLUSION  It is necessary to select an arch form that assumes a possible tapered pattern of the upper dental arch after extraction treatment in patients with Class I crowding www.indiandentalacademy.com
  37. 37. Wolfgang Heiser, Andreas Niederwanger, Beatrix Bancher, Gabriele Bittermann, Nikolaus Neunteufel, Siegfried Kulmer AJODO;2004;126 Three-dimensional dental arch and palatal form changes after extraction and nonextractiontreatment. Part 1. Arch length www.indiandentalacademy.com
  38. 38.  Most investigators believe that the success of orthodontic treatment is judged by the long term stability of the results. Treatment decisions are strongly influenced by this thinking. The “extraction versus nonextraction” debate is almost as old as the specialty of orthodontics.  Today, most orthodontists find themselves some where in the middle, treating some patients with extractions and some without.  Karl Popper said that one of the biggest mistakes a scientist can make is to always try to prove his own thesis rather than seeking arguments that disprove it. www.indiandentalacademy.com
  39. 39. OBJECTIVE  The purpose of this study was to investigate changes in arch length, and irregularity index in patients treated with and without premolar extractions www.indiandentalacademy.com
  40. 40. MATERIAL AND METHODS  All patients had been treated in the private orthodontic practice of the first author . The only criterion for inclusion was good occlusion at bracket removal.  Neither cephalometric characteristics nor postretention occlusion was considered in sample selection. All patients wore removable retainers; no fixed retainers were used. The groups were formed before the follow- up examination. Records were collected at 4 points: pretreatment, bracket removal, end of retention, and follow-up. www.indiandentalacademy.com
  41. 41.  The nonextraction group consisted originally of 25 Class II patients (19 girls, 6 boys; average age, 11 years 4 months) who were treated between 1981 and 1991 with fixed appliances (straightwire) without premolar extractions. The follow-up examination was carried out 6.3 years out of retention. Twenty-two patients (17 women, 5 men; average age, 20 years 7 months) returned for the follow- up examination. The mean irregularity index was 5.1 before orthodontic treatment. The average active treatment time was 1 year 9 months; the average retention period was 1 year 3 months. www.indiandentalacademy.com
  42. 42.  The extraction group consisted originally of 24 patients (18 girls, 6 boys; average age, 13 years 7 months) who were treated between 1981 and 1991 with fixed appliances (straightwire) and premolar (first or second) extractions. Twenty patients (16 women, 4 men; average age, 21 years 10 months) were examined at follow-up. The mean irregularity index was 5.8 before orthodontic treatment www.indiandentalacademy.com
  43. 43.  The average active treatment time was 1 year 9 months, and the average retention period was 1 year 10 months. The follow-up examination was carried out 4 years 8 months out of retention www.indiandentalacademy.com
  44. 44.  The complete treatment time for the nonextraction group was 3 years; this was considerably shorter than the treatment time for the extraction group—3 years 7 months.  The average active treatment time was 1 year 9 months, and the average retention period was 1 year 10 months. The follow-up examination was carried out 4 years 8 months out of retention. www.indiandentalacademy.com
  45. 45.  The groups’ irregularity index values differed, although this difference was not statistically significant. The mean irregularity index values at the end of retention and at follow-up were almost identical for both patient groups www.indiandentalacademy.com
  46. 46.  Accurate alginate mandibular and maxillary impressions were taken for each patient at pretreatment, bracket removal, the end of retention, and follow-up. The impressions were poured in stone, and the maxillary model was provided with a split-cast  With the aid of an anatomic face-bow, the maxillary model was mounted skull-related onto a semi-adjustable SAM 2 articulator . Then the mandibular model was mounted joint-related to the maxillary model according to a central wax record. www.indiandentalacademy.com
  47. 47. System of coordinates  Casts mounted in a SAM 2 articulator can be transferred exactly to the 3-dimensional (3D) digitizer.  The 3D digitizer has a measuring pin that is connected to the electronic precision gauge and moves freely in all 3 planes of space.  The digital signals of each measured point were calculated as the x, y, and z coordinates by means of custom software www.indiandentalacademy.com
  48. 48.  Missing points could be entered as such into the computer. If a second molar was missing, the area up to the first molars was calculated. If deciduous molars were still present, their mesiobuccal and mesiolingual cusps were digitized. www.indiandentalacademy.com
  49. 49.  Arch length was defined as the sum of the distances of the various digitized points around the arch  The arch lengths of the maxilla (upper length, UL) were measured at the following points—  UL 3  UL4  UL5 www.indiandentalacademy.com
  50. 50.  The arch lengths of the mandible (lower length, LL) were measured at the following points—  LL4  LL5 www.indiandentalacademy.com
  51. 51. Error study  To assess measurement precision and reliability, 5 models were randomly selected. They were mounted on the 3D digitizer and measured 3 times www.indiandentalacademy.com
  52. 52. Data analysis  The 2 patient groups (nonextraction and extraction) were compared by independent t test to identify statistically significant differences between pretreatment, bracket removal, end of retention, and follow-up (t test for independent samples).  Changes between pretreatment, bracket removal, end of retention, and follow-up within the same group were analyzed by paired t test (t test for dependent samples). Statistical significance was determined at P < .05, P <.01, and P < .001 www.indiandentalacademy.com
  53. 53. RESULT Arch length  The nonextraction group had a statistically significant increase (P < .05) in UL3 of 2.06 mm and in UL4 of 3.27 mm between pretreatment and bracket removal. This was probably the effect of treatment.  In the nonextraction group, UL3 and UL4 rebounded (decreased) slightly from bracket removal to end of retention; this was significant only for UL3 (P <.05).  From end of retention to follow-up, UL3 and UL4 behaved contrarily: UL3 increased slightly (not significantly), whereas UL4 decreased significantly (P < .001) . UL5 lost length slightly from every evaluation period to the next. www.indiandentalacademy.com
  54. 54.  Between pretreatment and followup, UL3 increased 1.5 mm, UL4 remained almost stable (0.06 mm), and UL5 decreased 1.45 mm.  In the extraction group, statically significant decreases (P .001) were found for UL3, UL4, and UL5 between pretreatment and bracket removal as the treatment result of premolar extraction. www.indiandentalacademy.com
  55. 55.  All the other changes in UL3, UL4, and UL5 were nonsignificant, with the exception of the decrease in UL4 (P< .01) from the end of retention to follow-up.  Comparing the nonextraction and extraction groups, UL3, UL4, LL4, and LL5 showed almost identical changes between bracket removal and end of retention.  In the nonextraction group, LL4 increased from pretreatment to bracket removal, but the increase (0.59mm) was not significant. Arch length continued to decrease to follow-up. www.indiandentalacademy.com
  56. 56.  The decrease of 1.38 mm from end of retention to follow-up was statistically significant (P <.05). All gained arch length was lost between bracket removal and end of retention, resulting in a net decrease from pretreatment and follow-up www.indiandentalacademy.com
  57. 57.  LL5 decreased over all the observation periods in both patient groups. For the nonextraction group, the loss was significant (P< .001) only between bracket removal and end of retention. For LL4 and LL5, the extraction group showed a highly significant decrease from pretreatment to bracket removal (P < .001); this was the consequence of premolar extraction. Both arch lengths decreased further until follow-up. Although the losses were significant from bracket removal to end of retention (P< .01 and P <.001), they were not significant between end of retention and follow-up. www.indiandentalacademy.com
  58. 58. DISCUSSION Arch length  For nonextraction patients, Sadowsky et al found maxillary arch lengths were unchanged during and after treatment. Bishara et al and Glenn et al demonstrated a postretention decrease in arch length. These results contrast with the findings in this study of a net increase in the maxillary arch length UL3 of 1.62 mm between pretreatment and follow-up for the nonextraction group. www.indiandentalacademy.com
  59. 59.  La Cruz et al took almost the same measuring points used in this study and copied them to the occlusal plane to get a 2-dimensional (2D) picture; in the present study, the 3D changes could be calculated. This means that changes in the curve of Spee have influenced the length measurements. Present study findings contrast with the decrease in arch length found in that study. www.indiandentalacademy.com
  60. 60.  Sadowsky et al found that mandibular arch length was unchanged during treatment; we detected increases in nboth mandibular and maxillary arch length between pretreatment and bracket removal for the nonextraction group  Sadowsky et al and Glenn et al,studying nonextraction groups, found that mandibular arch length did not increase significantly during treatment but showed significant postretention reductions. These findings for the mandibular arch correspond to present studywww.indiandentalacademy.com
  61. 61.  For the extraction group, our finding of mandibular arch- length reduction agreed with Little et al and Bishara et al  On the other hand, Little et al and Herberger demonstrated that arch-length decrease is accompanied by mandibular incisor crowding  Further more, recrowding has often been noted even in patients treated with mandibular incisor extraction www.indiandentalacademy.com
  62. 62.  Comparing the lengths of the maxillary and mandibular arches, a different behavior in the nonextraction group can be seen. Whereas the maxillary arch had a net increase in arch length (UL3), LL4 decreased. In the extraction group, the maxillary and mandibulararch lengths increased slightly from bracket removal to follow-up . www.indiandentalacademy.com
  63. 63.  In both the nonextraction and extraction groups, UL3 increased from end of retention to follow-up. This could be the result of torque relapse. The increase of UL3 is in contrast to the decrease of almost all other length measurements (UL4, LL4, and LL5).  Generally speaking, maxillary and mandibular arch lengths tended to decrease, with few exceptions www.indiandentalacademy.com
  64. 64. CONCLUSION  This study investigated changes in maxillary and mandibular arch lengths in patients treated with edgewise appliances, with and without premolar extractions. The results were----  In the maxilla, arch length UL3 increased in nonextraction patients; all other lengths in both arches and both groups decreased  The relapse tendency was less in the maxillary arch than in the mandibular.  The extraction group showed similar relapse tendencies in both arches www.indiandentalacademy.com
  65. 65. Ellen A. BeGole, Deborah L. Fox, and Cyril Sadowsky AJODO;1998;113 Analysis of change in arch form with premolar expansion www.indiandentalacademy.com
  66. 66.  The arch forms of 38 cases (53 nonextraction and 23 extraction arches) in which expansion, while maintaining arch form, was the objective of the practitioner, were analyzed before treatment, after treatment, and an average of 6 to 8 years after retention.  The cubic spline was used to fit a curve representing arch form. By superimposing the spline curves, changes in arch form were analyzed with the variables rebound change (RC), rebound index (RI), rebound number (RN), and stability number (SN). Traditional linear intraarch dimensions were also analyzed www.indiandentalacademy.com
  67. 67.  Analysis of variance was used to determine differences between the maxillary and mandibular arches and between the extraction and nonextraction cases.  Pearson correlation coefficients between spline variables and arch width variables were also computed. There was significantly more expansion in the maxillary arch than the mandibular arch during treatment, irrespective of extraction or nonextraction strategies www.indiandentalacademy.com
  68. 68.  In the nonextraction cases, a greater amount of net expansion was achieved for all dimensions for the maxillary arch as compared with the mandibular arch.  Overall, a relatively high stability in arch form was found. The findings suggest that stability may not be related to the amount of change produced during treatment. www.indiandentalacademy.com
  69. 69.  Significant expansion can be gained throughout the premolar regions and may be expected to be stable.  The order of greatest net arch width gained was for the second premolars followed by first premolars, molars, and then the canines.  The intercanine widths for both arches decreased toward pretreatment values, but were more stable in the maxillary arch in nonextraction cases. The cubic spline permits measurement of change in arch form both during treatment and retention periods. www.indiandentalacademy.com
  70. 70. CONCLUSIONS  Use of the cubic spline permits measurement of changes in shape and size, but does not distinguish between them.  There does not appear to be any meaningful relationship between the amount of change duringtreatment and the degree of stability of a case  Significant stable expansion of the premolar and molar widths may be possible in both the maxillary and mandibular arches in nonextraction cases. www.indiandentalacademy.com
  71. 71. www.indiandentalacademy.com Thank you For more details please visit www.indiandentalacademy.com

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