The stability of class ii

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The stability of class ii

  1. 1. Stability and retention in class II division I malocclusion Evidence related to stability of class II D1 malocclusion  Relationship between stability and pattern of extraction  Relationship between different treatment mechanics and stability  Surgical versus conventional treatment 1. Relationship between stability and pattern of extraction Post-treatment stability in Class II nonextraction and maxillary premolar extraction protocols, Guilherme. 2012 Aim: To cephalometrically compare the overjet, overbite, and molar and canine relationship stability of Class II malocclusion treatment with and without maxillary premolar extractions. Method: Two groups of 30 patients each with pre- and posttreatment matching characteristics and satisfactory finishing were used. Group 1 consisted of 30 patients treated with nonextraction at a mean pretreatment age of 12.14 years, while group 2 consisted of 30 patients treated with maxillary first premolar extractions at a mean pretreatment age of 12.87 years. Lateral cephalograms obtained before and after treatment and at a mean of 8.2 years after the end of treatment were compared. Results: longterm stability of the overjet, overbite, and molar and canine relationships were similar in the groups. There were significant but weak correlations between treatment changes in overjet, overbite, and canine relationships with their long-term posttreatment changes.
  2. 2. Conclusion: Nonextraction and maxillary premolar extraction treatment of complete Class II malocclusion have similar long-term posttreatment stability in terms of overjet, overbite, and canine and molar relationships Long-term stability of Class II malocclusion treated with 2- and 4-premolar extraction protocols , Janson , 2009 objective of this study was to cephalometrically compare the stability of complete Class II malocclusion treatment with 2 or 4 premolar extractions after a mean period of 9.35 years. A sample of 57 records from patients with complete Class II malocclusion was selected and divided into 2 groups. Group 1 consisted of 30 patients with an initial mean age of 12.87 years treated with extraction of 2 maxillary premolars. Group 2 consisted of 27 patients with an initial mean age of 13.72 years treated with extraction of 4 premolars. group 1 had a statistically greater OJ relapse than group 2. On the other hand, group 2 had a statistically greater molar-relationship relapse toward Class II. There were significant positive correlations between the amounts of treatment and posttreatment dentoalveolar-relationship changes. Conclusions of complete Class II malocclusions with 2 maxillary premolar extractions or 4 premolar extractions had similar long-term posttreatment stability. 2. Relationship between different treatment mechanics and stability Long-term stability of Class II, Division 1, nonextraction cervical face-bow therapy: II. Cephalometric analysis. Elms 1996 The long-term stability of Class II, Division 1 nonextraction therapy, using cervical face-bows with full fixed orthodontic appliances was evaluated for 42
  3. 3. randomly selected patients. Each patient was treated by the same practitioner, with the same techniques, and the treatment goals had been attained for all patients. Pretreatment records were taken at a mean age of 11.5 years; the posttreatment and postretention records were taken 3.0 and 11.6 years later, respectively. The ratio of treatment proclination of incisors to posttreatment retroclination is approximately 5:1. Similarly, for every 3 degrees of molar tip back, there was approximately 1 degree of relapse. It is concluded that nonextraction therapy for Class II malocclusion can be largely stable when the orthodontist ensures proper patient selection and compliance and attains treatment objectives. Long-Term Stability of Class II Correction with the Twin Force Bite Corrector Chebber 2010 Follow-up studies of Class II patients have shown insignificant tendency to return to the original malocclusion after treatment with small increases in overjet and overbite and partial relapse of the molar relationships. Proper interdigitation of the posterior occlusion after bracket removal appears to be an important contributor to the stability of the correction. Occlusal stability of adult Class II Division 1 treatment with the Herbst appliance, Bock During recent years, some articles have been published on Herbst appliance treatment in adult patients, an approach that has been shown to be most effective in Class II treatment in both early and late adulthood. However, no results on stability have yet been published. Our objective was to analyze the
  4. 4. short-term occlusal stability of Herbst therapy in adults with Class II Division 1 malocclusions. Methods:The subjects comprised 26 adults with Class II Division 1 malocclusions exhibiting a Class II molar relationship$0.5 cusp bilaterally or $1.0 cusp unilaterally and an overjet of $4.0 mm. The average treatment time was 8.8months (Herbst phase) plus 14.7 months (subsequent multi-bracket phase). Study casts from before and after treatment and after an average retention period of 32 months were analyzed. Results: After retention, molar relationships were stable in 77.6% and canine relationships in 71.2% of the teeth. True relapses were found in 8.2% (molar relationships) and 1.9% (canine relationships) of the teeth. Overjet was stable in 92.3% and overbite in 96.0% of the patients; true relapse did not occur. Conclusions: Herbst treatment showed good occlusal stability 2.5 years after treatment in adults with Class II Division 1 malocclusions. Stability of Class II, Division 1 Treatment with the Headgear-Activator Combination Followed by the Edgewise Appliance Janson, 2004 This study assessed the stability of the headgear-activator combination treatment, followed by edgewise mechanotherapy, 5.75 years after treatment. The experimental group consisted of 23 patients who were evaluated during treatment and after treatment. Two compatible control groups consisting of 15 Class II, division 1 patients and 24 normal occlusion individuals were used. This enabled us to evaluate the changes during treatment and after treatment, respectively. Results showed that the anteroposterior dentoalveolar changes and the maxillary and the mandibular positions remained stable in the long term.
  5. 5. However, there was a slight relapse of the maxillomandibular relationship probably because the maxilla resumed its normal development and the mandibular growth rate was smaller than in the control group. The overbite demonstrated a statistically significant relapse that was directly proportional to the amount of its correction. Initial Class II malocclusion severity (ANB and Wits), and initial molar relationship did not present any correlation with molar relationship and overjet relapse. However, the initial overjet presented a low but statistically significant correlation with molar relationship relapse and overjet relapse. 3. Surgical versus conventional treatment Long-term comparison of treatment outcome and stability of Class II patients treated with functional appliances versus bilateral sagittal split ramus osteotomy.Berger 2005 The objective of this study was to compare the treatment outcomes and stability of patients with Class II malocclusion treated with either functional appliances or surgical mandibular advancement. The early-treatment group consisted of 30 patients (15 girls, 15 boys), with a mean age of 10 years 4 months (range, 7 years 5 months to 12 years 5 months), who received either Fränkel II (15 patients) or Herbst appliances (15 patients). The surgical group consisted of 30 patients (23 female, 7 male), with a mean age of 27 years 2 months (range, 13 years 0 months to 53 years 10 months). They were treated with bilateral sagittal split ramus osteotomies with rigid fixation. Lateral cephalograms were taken for the early-treatment group at T1 (initial records), T2 (completion of functional appliance treatment), and Tf (completion of comprehensive treatment). In the surgical group, lateral cephalograms were taken at T1 (initial records), T2 (presurgery), T3
  6. 6. (postsurgery), and Tf (completion of comprehensive treatment). The average times from the completion of functional appliance treatment or surgery to the final cephalograms were 35.8 months and 34.9 months, respectively. In the functional appliance group, the mandible continued to grow in a favorable direction even after discontinuation of the functional appliance. Both groups had stable results over time. Both groups finished treatment with the same cephalometric measurements. Significant skeletal and soft tissue changes were noted in the treatment groups due to either functional or surgical advancement of the mandible. More vertical relapse was noted in the surgical group than in the functional group. This study suggests that early correction of Class II dentoskeletal malocclusions with functional appliances yields favorable results without the possible deleterious effects of surgery. Long-term follow-up of ClassII adults treated with orthodontic camouflage: a comparison with orthognathic surgery outcomes Mihalik 2003 Looking at long-term stability of adult Class II treatment it was found that overbite was equally stable in both groups, but overjet relapsed twice as often in surgery patients. Stability of skeletal Class II correction with 2 surgical techniques: The sagittal split ramus osteotomy and the total mandibular subapical alveolar osteotomy, Valmy 2001 Combined orthodontic and surgical treatment of severe Class II dentoskeletal deformities with the use of the bilateral sagittal split ramus osteotomy is a
  7. 7. routine procedure in orthodontic practices. However, an alternative surgical technique, the total mandibular subapical alveolar osteotomy, could be used for the same purpose. The aim of this investigation was to compare the stability of the sagittal split ramus osteotomy with the total mandibular subapical alveolar osteotomy in the correction of dentoskeletal Class II malocclusions. Forty patients that exhibited Class II dentoskeletal relationships were included in the study. Twenty of these patients had mandibular advancement with the sagittal split ramus osteotomy; the remaining 20 patients had advancement of the whole lower alveolar segment with the total mandibular subapical alveolar osteotomy. The cephalograms studied were taken before the surgical procedure (T1 = 4 weeks before operation), immediately after the procedure (T2 = 10 days after surgery), and 1 year later (T3). The results of this study show that both procedures are equally stable when correcting Class II malocclusions. This was proved by the stability of the correction of overjet, B point, and incisor- mandibular plane angle. There were no statistically significant differences between or within the groups in the position of these landmarks over time. There was a statistically significant change in the position of pogonion from T1 to T2 (P < .0028) between the groups, although at T3 this difference was not significant (P < .05). There were no significant changes in face height either within or between the groups over time. The hard/soft tissue interactions for the total mandibular subapical alveolar osteotomy were as follows: The lower lip advanced 60% to the incisor movement; soft tissue B′ point responded with a 130% advancement in relation to the change in its hard tissue counterpart. Soft tissue pogonion advanced 90% in relation to the hard tissue landmark. The data suggest that the total mandibular alveolar osteotomy is the treatment of choice for the correction of severe dentoalveolar retrusive Class II malocclusion for which alteration of the mentolabial sulcus is desirable.
  8. 8. Cause of relapse after treatment of class II D1 malocclusion 1. Local factors causing relapse (forward in the upper arch, backward in the lower arch, or both) due to PD changes or dental relapse. 2. Differential growth of the maxilla relative to the mandible. Future mandibular growth is also important for the stability of overjet correction. A significant backwards (clockwise) mandibular growth rotation can lead to an increase in overjet as the lower incisors are also rotated downwards and backwards. The resultant increase in vertical facial dimension with this type of growth rotation also reduces lip competency, which predisposes to relapse. 3. Continued habits 4. Soft tissue factors 5. Iatrogenic or Delayed treatment failure specially in surgical treatment. 6. Idiopathic causes eg: ICR 7. Combination Factors that be considered to control relapse potential 1. Regarding AP changes in the lower incisors: In Class II treatment, it is important not to move the lower incisors too far forward, if happen should be permanently retained. 2. Regarding the AP changes in upper incisors: Ensuring that the upper incisors are retracted sufficiently to be in control of the lower lip. 3. Regarding the occlusion: Proper interdigitation of the posterior occlusion after bracket removal appears to be an important contributor to the stability of the correction. Significant amounts of relapse were observed by Pancherz9 and Wieslander2002 in cases treated to unstable occlusal relationships.
  9. 9. 4. Regarding anteroposterior change: Overcorrection of the occlusal relationships as a finishing procedure is an important step in controlling tooth movement that would lead to Class II relapse. Even with good retention, 1 to 2 mm of anteroposterior change caused by adjustments in tooth position is likely to occur after treatment, particularly if Class II elastics were employed. This change occurs relatively quickly after active treatment stops. 5. Regarding growing patient: who has a class II skeletal at the start and treated by on camouflaging or comprehensive functional-fixed appliance treatment, further growth (which depend on age and geneder) almost surely will result in some loss of the correction as the original growth pattern persists. This relapse tendency can be controlled in one of two ways. • Continue headgear to the upper molars on a reduced basis (at night, for instance) in conjunction with a retainer to hold the teeth in alignment. • Functional appliance of the activator-bionator type to hold both tooth position and the occlusal relationship. The construction bite for the functional appliance is taken without any mandibular advancement—the idea is to prevent a Class II malocclusion from recurring, not to actively treat one that already exists. The functional appliance will be worn only part time, typically just at night, and daytime retainers of conventional design also will be needed to control tooth position during the first few months. 6. Regarding the treated deep overbite: A. Good interincisal angle. The interincisal angle must be corrected (average 135°) in addition to the overbite being reduced in order to prevent re-eruption of the incisors after treatment. B. Correct mandibular incisor edge-centroid relationship.
  10. 10.  Possibly the most important factor in overbite stability in all treated cases is correction of the relationship between the mandibular incisor edge and the maxillary incisor root centroid  This is measured as the distance between the perpendicular projections of these two points on the maxillary plane (0–2 mm).  This may be achieved by either retraction of the maxillary incisor root centroid using fixed appliances with palatal root torque, or proclination of the mandibular incisors to advance their edges.  The decision depends on a number of factors including the facial profile, PD support and growth potential.  If a patient has a retrognathic mandible, it is possible to procline the maxillary incisors and to either surgically advance the mandible or in a growing patient to use a functional appliance to help advance the mandibular incisors.  In a patient with good facial profile aesthetics, the treatment may be carried out with fixed appliances alone, so long as the palatal alveolar process is thick enough to allow retraction of the maxillary incisor root centroid. The crowns of the incisor teeth should also be maintained within the zone of soft tissue equilibrium between the musculature of the tongue and the lips. An interesting proposition is that in Class II division 2 malocclusions it may be possible to intrude and torque the maxillary incisor roots palatally, allowing the mandibular incisor crowns to be proclined and hence occupy the position previously occupied by the maxillary incisor crowns, thus maintaining the incisor complex within the zone of soft tissue equilibrium. C. Proclination of the lower labial segment in Class II cases. This may still be unstable in the long term due to pressure from the lower lip.(Mills 1979)
  11. 11. Therefore, long-term retention may be required in such cases and must be discussed with the patient prior to treatment. D. Avoid change in intermaxillary height in non-growing patients. The extrusion of molars in non-growing patients is unstable, as the muscular forces from the pterygo-masseteric sling will re-intrude the molars if the posterior vertical face height has not accommodated their extrusion. E. Vertical facial growth. it continues well into the late teenage years. As the pattern of facial growth does not tend to change following treatment it is prudent to place a bite-plane on the maxillary removable retainer after the completion of orthodontic treatment. This may be worn on a part-time basis in order to maintain the corrected overbite until vertical facial growth has subsided. using active removable upper retainer made so that the lower incisors will encounter the baseplate of the retainer if they begin to slip vertically behind the upper incisors. The procedure, in other words, is to build a potential biteplate into the retainer, which the lower incisors will contact if the bite begins to deepen. The retainer does not separate the posterior teeth. Because vertical growth continues into the late teens, a maxillary removable retainer with a bite plane often is needed for several years after fixed appliance orthodontics is completed 7. Regarding the treated anterior open bite: • Continue stopping the habit with tongue spur which is questionable for its effectiveness • a maxillary retainer with bite blocks (or a functional appliance) to impede eruption • high-pull headgear.
  12. 12. Common Questions related to this topic Are There Any Circumstances in Which Lower Incisor Proclination Is Likely to Be Stable? 1. Pre-existing lip trap 2. Digit habit 3. Incisors held artificially upright by the occlusion (such as a class II division 2) (Mills, 1973) 4. following orthognathic surgery in class III malocclusion (Artun et al., 1990) Is Lower Incisor Proclination Likely to Exacerbate Gingival Recession? Uncontrolled incisor proclination is inadvisable and risks further recession. However, the association between proclination and recession is weak and
  13. 13. unpredictable. A retrospective study of 300 adult patients undergoing orthodontic treatment demonstrated an average increase in lower incisor recession of just 0.14 mm with incisor proclination (Allais and Melsen, 2003).

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