A long-term evaluation of treated Class II division 2 malocclusions: a retrospective study model analysis

Comprehensive Deciphering the Complexity of the Deep Bite: Insight from Animal Model to Human Subjects

Deep bite is a malocclusion phenotype, defined as the misalignment in the vertical dimension of teeth and jaws and characterized by excessive overlap of the upper front teeth over the lower front teeth. Numerous factors, including genetics, environmental factors, and behavioral ones, might contribute to deep bite. In this study, we discuss the current clinical treatment strategies for deep bite, summarize the already published findings of genetic analysis associated with this complex phenotype, and their constraints. Finally, we propose a comprehensive roadmap to facilitate investigations for determining the genetic bases of this complex phenotype development. Initially, human deep bite phenotype, genetics of human deep bite, the prevalence of human deep bite, diagnosis, and treatment of human deep bite were the search terms for published publications. Here, we discuss these findings and their limitations and our view on future strategies for studying the genetic bases of this complex phenotype. New preventative and treatment methods for this widespread dental issue can be developed with the help of an understanding of the genetic and epigenetic variables that influence malocclusion. Additionally, malocclusion treatment may benefit from technological developments like 3D printing and computer-aided design and manufacture (CAD/CAM). These technologies enable the development of personalized surgical and orthodontic guidelines, enhancing the accuracy and effectiveness of treatment. Overall, the most significant results for the patient can only be achieved with a customized treatment plan created by an experienced orthodontic professional. To design a plan that meets the patient's specific requirements and expectations, open communication between the patient and the orthodontist is essential. Here, we propose to conduct a genome-wide association study (GWAS), RNAseq analysis, integrating GWAS and expression quantitative trait loci (eQTL), micro and small RNA, and long noncoding RNA analysis in tissues associated with deep bite malocclusion in human, and complement it by the same approaches in the collaborative cross (CC) mouse model which offer a novel platform for identifying genetic factors as a cause of deep bite in mice, and subsequently can then be translated to humans. An additional direct outcome of this study is discovering novel genetic elements to advance our knowledge of how this malocclusion phenotype develops and open the venue for early identification of patients carrying the susceptible genetic factors so that we can offer early prevention and treatment strategies, a step towards applying a personalized medicine approach.

The consequences of living with a severe malocclusion: A review of the literature

AIM

To facilitate the orthognathic shared decision-making process by identifying and applying existing research evidence to establish the potential consequences of living with a severe malocclusion.

METHODS

A comprehensive narrative literature review was conducted to explore the potential complications of severe malocclusion. A systematic electronic literature search of four databases combined with supplementary hand searching identified 1024 articles of interest. A total of 799 articles were included in the narrative literature review, which was divided into 10 themes: Oral Health Related Quality Of Life; Temporomandibular Joint Dysfunction; Masticatory Limitation; Sleep Apnoea; Traumatic Dental Injury; Tooth Surface Loss; Change Over Time; Periodontal Injury; Restorative Difficulty; and Functional Shift and Dual Bite. A deductive approach was used to draw conclusions from the evidence available within each theme.

RESULTS

The narrative literature review established 27 conclusions, indicating that those living with a severe malocclusion may be predisposed to a range of potential consequences. With the exception of Oral Health Related Quality Of Life, which is poorer in adults with severe malocclusion than those with normal occlusions, and the risk of Traumatic Dental Injury, which increases when the overjet is >5 mm in the permanent and 3 mm in the primary dentition, the evidence supporting the remaining conclusions was found to be of low to moderate quality and at high risk of bias.

CONCLUSION

This article summarises the findings of a comprehensive narrative literature review in which all of the relevant research evidence within a substantive investigative area is established and evaluated. Notwithstanding limitations regarding the quality of the available evidence; when combined with clinical expertise and an awareness of individual patient preferences, the conclusions presented may facilitate the orthognathic shared decision-making process and furthermore, may guide the development of the high-quality longitudinal research required to validate them.

The rationale for orthodontic retention: piecing together the jigsaw

Retaining teeth in their corrected positions following orthodontic treatment is one of the most challenging aspects of orthodontic practice. Despite much research, the rationale for retention is not entirely clear. Teeth tend to revert to their pre-treatment positions due to periodontal and gingival, soft tissue, occlusal and growth factors. Changes may also follow normal dentofacial ageing and are unpredictable with great variability. In this overview, each of these factors are discussed with their implications for retention, along with adjunctive procedures to minimise relapse. The state of current knowledge, methods used to assess relapse, factors regarded as predictive of or associated with stability as well as overcorrection are outlined. Potential areas requiring further investigation are suggested. The way in which the clinician may manage current retention practice, with a need for individualised retention plans and selective retainer wear, is also considered.

Efficiency and outcome quality of Herbst-Multibracket appliance therapy in Class II:2 patients

OBJECTIVES

The aim of this retrospective investigation was to generate representative data on the efficiency and outcome quality of Class II:2 Herbst-Multibracket appliance (Herbst-MBA) treatment.

SUBJECTS AND METHODS

All Class II:2 patients who had started Herbst-MBA treatment at the study centre since 1986 were included. Study casts from before treatment, after Herbst-MBA treatment, and (if available) after ≥24 months of follow-up were evaluated using standard occlusal variables, the Peer Assessment Rating (PAR)-Index, and the Ahlgren-Scale.

RESULTS

During treatment, the pre-treatment PAR score was reduced from 23.6 ± 7.66 to 5.6 ± 3.85 (n = 192); during the follow-up period, a slight increase to 6.0 ± 3.60 occurred (n = 127). The percentage of patients who could be assigned to the PAR category 'greatly improved' was 30% after treatment and 33% after follow-up; only 1%, respectively, 2% had to be assigned to the category 'worse/no different'. The outcome ratings according to the Ahlgren-Scale revealed 20% excellent, 32% good, 46% acceptable, and 2% unsuccessful results.

LIMITATIONS

Retrospective study design with follow-up data not available from all subjects and no data from untreated controls.

CONCLUSIONS

Herbst-MBA is an efficient treatment approach in orthodontic care of Class II:2 malocclusions. High-quality results (mean/median PAR score: 5.6/5.0) with very good short-term stability (2.2 years' follow-up) were achieved. Unfortunately, no appropriate control group or groups, where other treatment approaches had been applied, exist.

Long-term stability of curve of Spee levelled with continuous archwires in subjects with different vertical patterns: a retrospective study

OBJECTIVES

The aim of the study was to evaluate the curve of Spee (COS) stability in patients treated with continuous archwires with different vertical patterns.

METHODS

The study sample consisted of 60 patients (28 males, 32 females; mean age 19.8 ± 1.4 years) presenting with COS depth of at least2 mm at baseline. For each subject, lateral cephalograms and dental casts were available before treatment (T1), at the end of orthodontic therapy (T2), and 2 years after the end of treatment (T3). All subjects were divided into three groups according to vertical facial patterns. Cephalometric parameters were used to evaluate the dental movements after treatment. COS depth was measured on digital casts. Mean differences between vertical facial subgroups were contrasted by means of analysis of variance test (P < 0.01).

RESULTS

In low-angle subjects, COS levelling occurred through advancement and intrusion of lower incisors, whereas in high-angle patients, the COS was flattened through extrusion and uprighting of lower posterior teeth. In the low-angle group, a significant relapse of lower incisors inclination was observed. Differently, the high-angle group exhibited a greater stability of COS obtained by stable extrusion of posterior teeth.

CONCLUSIONS

The long-term instability of flared incisors determined the relapse of overbite and COS depth in the low-angle group.

[Long-term stability and relapse of deep bite correction: a systematic review]

INTRODUCTION

 Deep overbite is one of the most common malocclusions and is the most difficult to treat successfully. The real challenge remains the stability of long-term deep overbite correction. A search through the scientific literature revealed only one systematic review on this subject. Given the recent publications on the stability of deep bite correction and the development of new processes designed to avoid relapse of these treatments, this one existing systematic review needs to be updated. The purpose of the present systematic review is to evaluate the long-term stability of deep overbite correction.

MATERIALS AND METHODS

 Electronic databases were searched and nonelectronic journals were manually explored for papers on long-term stability and relapse of deep overbite correction. Articles deemed appropriate for inclusion in this review were selected and analyzed. Their scientific quality was assessed and the data they contained were extracted and summarized.

RESULTS

 The rate of deep overbite relapse was 47.27%. Patients treated with the straight wire appliance showed a 67.74% relapse rate whereas those treated with the Ricketts biological progressive segmented mechanics appliance displayed a 30.38% rate. Subjects treated towards the end of adolescence presented a 14.3% rate of deep overbite relapse whereas those treated in their early teens or in adulthood had a deep overbite relapse rate of 30% and 30.8%, respectively. Intramuscular injections of botox helped obtain 100% stability in maxillofacial surgery to correct deep bite.

CONCLUSION

 Age at initiation of treatment and treatment technique are two factors impacting the long-term stability of deep overbite correction.

Mandibular alignment changes after full-fixed orthodontic treatment: a systematic review and meta-analysis

Background

Although post-treatment mandibular alignment has been extensively investigated, the findings remain controversial.

Objectives

The objective was to assess mandibular alignment changes, as measured by the irregularity index, of patients who underwent full-fixed orthodontic treatment and were followed up at least 1 year after retention.

Search methods

MEDLINE, EMBASE, and Cochrane library, in addition, the reference lists of included studies, were screened. The search was conducted up to April 2018.

Selection criteria

The study designs included both interventional and observational studies of orthodontic patients who received either extraction or non-extraction treatment.

Data collection and analysis

The interventional studies were assessed using the Cochrane Collaboration’s risk of bias assessment tool. The quality of the observational studies was evaluated using National Institution of Health quality assessment tools. The first two authors independently applied the eligibility criteria, extracted the data, and assessed the risk of bias. Any conflicts were resolved with consensus discussion with the third author.

Results

The search retrieved 11 326 articles, 170 of which were assessed for eligibility. There were 44 studies included in the qualitative assessments and 30 in the meta-analyses. The studies included 1 randomized control trial (RCT) and 43 observational studies. The RCT was judged to have a high risk of bias and all of the observational studies had either fair or poor quality. The meta-analysis was based on studies judged to be of fair quality, including a total of 1859 patients. All meta-analyses were performed using random-effect models. The standardized mean difference between post-treatment and post-retention irregularity was 1.22 (95% CI, 1.04–1.40) and 0.85 (95% CI, 0.63–1.07) after extraction and non-extraction treatments, respectively. There was a substantial heterogeneity for the extraction (I2 = 75.2%) and non-extraction (I2 = 70.1%) studies. The follow-up duration (1–10 versus 10–20 years) explained 33% of the heterogeneity, with longer follow-up studies showing more irregularity.

Limitations

The quality of evidence provided by the studies was low. There was a risk of publication bias, and the search was limited to English language.

Conclusions and implications

Post-treatment mandibular irregularity increases are limited. Irregularity increases are slightly greater in patients treated with mandibular premolars extractions, and in patients followed up over longer periods of time.

Registration

The study protocol was not registered.

Combined orthodontic-orthopedic treatment of an adolescent Class II Division 2 patient with extreme deepbite using the Forsus Fatigue Resistant Device

Class II Division 2 malocclusion is often characterized by severe, traumatic deepbite with lingually inclined and overerupted incisors. Combined orthodontic-orthopedic treatment of this malocclusion is a challenging issue for orthodontists. This case report describes the combined orthodontic-orthopedic treatment of an adolescent Class II Division 2 patient with an extreme deepbite and a retrognathic mandible using the Forsus Fatigue Resistant Device.

Dental arch changes in postretention in Class II division 1 extraction cases

OBJECTIVE

The purpose of this study is to evaluate the postretention stability of the dental arches in Class II division 1 patients treated with four bicuspid extractions and the edgewise technique.

MATERIALS AND METHODS

A digital caliper was used to analyze the dental casts from 29 Class II division 1 malocclusion patients with skeletal type II (14 males, 15 females; ages ranging from 10.2-18.0 years), treated with four bicuspid extractions and the edgewise technique. Intercanine width, intermolar width, arch length, irregularity index, overjet and overbite were evaluated at three times: pretreatment (T1), posttreatment (T2) and postretention (T3) (mean: 4.15 years). Student's t-tests were used to compare the pretreatment-posttreatment, posttreatment-postretention and pretreatment-postretention. Significance was determined at P<0.05.

RESULTS

The results of the study are listed as: (1) The upper and lower intercanine widths significantly increased (P<0.05) between T1-T2 and decreased between T2-T3. However, no significant changes were observed between T1-T3; (2) The upper and lower intermolar widths significantly decreased (P<0.05) between T1-T2, between T2-T3 and between T1-T3, except for the upper intermolar width between T2-T3 which showed no significant change; (3) The upper and lower arch lengths significantly decreased (P<0.05) at posttreatment and postretention due to the closure of extraction spaces. Both the upper and lower arch lengths significantly decreased between T1-T2, T2-T3, and T1-T3, except for the upper arch length between T2-T3, which showed no significant change; (4) The irregularity index was significantly improved after treatment. However, there was a slight increase in incisor irregularity at postretention. At postretention, 75.86% of the patients had mild crowding, 20.68% had moderate crowding, 3.48% had severe crowding; (5) The overjet and overbite significantly decreased (P<0.05) between T1-T2 and increased between T2-T3.

CONCLUSION

The changes in the dental arches were small at postretention with a tendency to return towards their original position. The overall stability of Class II division 1 extraction cases is relatively good.

Treatment of Adults with Anterior Mandibular Teeth Crowding: Reliability of Little's Irregularity Index

The attempt of this article was to assess reliability of Little's Irregularity Index (LII) as for stability of the treatment outcomes in adults with crowded mandibular incisors. LII was measured on a digital cast prior to an orthodontic treatment (T1) of the 302 patients thus allowing us to establish the treatment plan, which called for (a) expansion (group 1), interproximal stripping (group 2), or extraction of one of the mandibular incisors. LII was measured after debonding (T2) and a year after retention (T3). Treatment resulted in significant reduction of LII values after treatment, in T1-T2 period in all groups. As for T2-T3 period it brought significant but clinically irrelevant relapse that occurred in groups 1 and 2; group 3 presented with insignificant improvement of occlusion. Conclusively, 30 years after introducing LII it has been a reliable parameter that allows selection of optimal treatment methods, provided that the appropriate ranges of values displaying dentoalveolar discrepancy are obeyed, namely, (1) up to 3 mm: expansion, (2) from 3 to 5 mm: interproximal enamel reduction, and (3) above 5 mm: extraction.

Stability of Class II fixed functional appliance therapy--a systematic review and meta-analysis

OBJECTIVES

To systematically search for scientific evidence concerning the stability of treatment (Tx) results achieved by means of Class II fixed functional appliance therapy and to assess possible differences between appliances.

SEARCH METHODS

An electronic search of databases and orthodontic journals was carried out (until December 2013), with supplemental hand searching. In addition to the names of all identified appliances, the term fixed functional was used in combination with each of the following search terms: long-term, post-Tx, relapse, retention, stability.

SELECTION CRITERIA

To be included in the review, the articles had to contain clear data on: Class II Tx with a fixed functional appliance (>5 patients), post-Tx period ≥ 1 year, assessment of ANB angle, Wits appraisal, molar relationship, soft-tissue profile convexity excluding the nose, overjet and/or overbite.

DATA COLLECTION AND ANALYSIS

The literature search revealed 20 scientific investigations which corresponded to only two of the 76 identified appliances (Herbst and Twin Force Bite Corrector). As only one publication was found for the Twin Force Bite Corrector, a meta-analysis could only be performed for Herbst Tx. The data were extracted, pooled and weighted according to the number of patients in each study.

RESULTS

The mean values for post-Tx relapse (percentages relative to the Tx changes) were: ANB angle 0.2 degrees (12.4 per cent), Wits appraisal 0.5mm (19.5 per cent), sagittal molar relationship 1.2mm/0.1 cusp widths (21.8 per cent /6.5 per cent); soft-tissue profile convexity excluding nose less than 0.1 degrees (1.0 per cent), overjet 1.8mm (26.2 per cent), overbite Class II:1 1.4mm (44.7 per cent), overbite Class II:2 1.0mm (22.2 per cent).

CONCLUSIONS

The scientific evidence concerning the stability of Tx results is inexistent for most fixed functional appliances for Class II correction except for Herbst appliance Tx. Even if the evidence level of most included studies is rather low, good dentoskeletal stability without clinically relevant changes was found for most variables.

Extraction treatment of a class II division 2 malocclusion with mandibular posterior discrepancy and changes in stomatognathic function

This case report describes the successful extraction treatment of a Class II division 2 malocclusion with mandibular posterior discrepancy and a congenitally missing maxillary lateral incisor on the left side. The posterior space in the mandibular arch was small, and the mandibular second molars were impacted, with distal tipping. The discrepancies in the maxillary and mandibular arches were resolved by extraction of the maxillary lateral incisor on the right side and the mandibular second premolars on both sides. The mesial movement of the mandibular first molars occurred appropriately, with the second molars moving into an upright position. A lip bumper was used with a preadjusted edgewise appliance in the maxillary dentition to reinforce molar anchorage and labial movement of the retroclined incisors. Despite the extraction treatment, a deep bite could be corrected without aggravation as a result of the lip bumper and utility arch in the mandibular dentition. Thus, an Angle Class I molar relationship and an ideal overbite were achieved. The occlusal contact area and masticatory muscle activities during maximum clenching increased after treatment. The maximum closing velocity and the maximum gape during chewing increased, and the chewing pattern changed from the chopping to grinding type. The findings in the present case suggest that the correction of a deep bite might be effective for improving stomatognathic function.

Interventions for managing relapse of the lower front teeth after orthodontic treatment

BACKGROUND

Orthodontic relapse can be defined as the tendency for teeth to return to their pre-treatment position, and this occurs especially in lower front teeth (lower canines and lower incisors). Retention, to maintain the position of corrected teeth, has become one of the most important phases of orthodontic treatment. However, 10 years after the completion of orthodontic treatment, only 30% to 50% of orthodontic patients effectively retain the satisfactory alignment initially obtained. After 20 years, satisfactory alignment reduces to 10%. When relapse occurs, simple effective strategies are required to effectively manage the problem. The periodontal, physiological or psychological conditions may be different from those before orthodontic treatment, so re-treatment methods may also need to be different.

OBJECTIVES

To assess the effects of interventions used to manage relapse of the lower front teeth after first fixed orthodontic treatment.

SEARCH METHODS

The following electronic databases were searched: the Cochrane Oral Health Group Trials Register (to 9 November 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 10), MEDLINE via OVID (1950 to 9 November 2012), EMBASE via OVID (1980 to 9 November 2012). There were no restrictions regarding language or date of publication. A thorough handsearch was done in relation to the following journals: American Journal of Orthodontics and Dentofacial Orthopedics (1970 to 9 November 2012), Angle Orthodontist (1978 to 9 November 2012), European Journal of Orthodontics (1979 to 9 November 2012), Journal of Orthodontics (1978 to 9 November 2012), Chinese Journal of Stomatology (1953 to 9 November 2012), West China Journal of Stomatology (1983 to 9 November 2012), Chinese Journal of Dental Materials and Devices (1992 to 9 November 2012) and Chinese Journal of Orthodontics (1994 to 9 November 2012).

SELECTION CRITERIA

We would have included randomised controlled trials (RCTs) which compared any of the following: fixed options (including labial braces, lingual braces and fixed lingual wire), removable options (including Hawley's retainer with active components such as Hawley's retainer with spring elastomeric module, Bloore removable aligner and any other modifications on the Hawley's retainer to correct the lower front teeth, and invisible removable aligners such as Invisalign and Clearstep) and no active treatment for the management of relapsed lower front teeth after orthodontic treatment. We excluded RCTs of participants with craniofacial deformities/syndromes or serious skeletal deformities who received prior surgical/surgical orthodontic treatment.

DATA COLLECTION AND ANALYSIS

Two review authors, independently and in duplicate, assessed the results of the searches to identify studies for inclusion. The Cochrane Collaboration statistical guidelines were to be followed for data synthesis.

MAIN RESULTS

We did not identify any RCTs which met the inclusion criteria for this review.

AUTHORS' CONCLUSIONS

This review has revealed that there was no evidence from RCTs to show that one intervention was superior to another to manage the relapse of the alignment of lower front teeth using any method or index, aesthetic assessment by participants and practitioners, treatment time, patient's discomfort, quality of life, cost-benefit considerations, stability of the correction, and side effects including pain, gingivitis, enamel decalcification and root resorption. There is an urgent need for RCTs in this area to identify the most effective and safe method for managing the relapse of alignment of the lower front teeth.

Stability of molar relationship after non-extraction Class II malocclusion treatment

OBJECTIVE

This study aimed to evaluate the stability of molar relationship after non-extraction treatment of Class II malocclusion.

METHODS

The sample comprised 39 subjects (16 females, 23 males) with initial Class II malocclusion treated with no extractions, using fixed appliances. Mean age at the beginning of treatment was 12.94 years, at the end of treatment was 15.14 years and at post-retention stage was 21.18 years. Mean treatment time was 2.19 years and mean time of post-treatment evaluation was 6.12 years. To verify the influence of the severity of initial Class II molar relationship in stability of molar relationship, the sample was divided into two groups, one presenting a ½-cusp or ¾-cusp Class II molar relationship, and the other with full-cusp Class II molar relationship. In dental casts from initial, final and post-retention stages, molar, first and second premolars and canine relationships were measured. Data obtained were analyzed by dependent ANOVA, Tukey and Pearson's correlation tests, as well as independent t test between the two groups divided by severity of initial molar relationship.

RESULTS

There was a non-statistically significant 0.12-mm relapse of molar relationship. The initial severity of Class II molar relationship was not correlated to relapse in the post-retention period. When compared, the two groups showed no difference in relapse of molar relationship.

CONCLUSIONS

It was concluded that correction of Class II molar relationship is stable and initial severity does not influence relapse of molar relationship.

Relapse of incisor crowding: a visit to the Prince of Salina

The management of the retention period after comprehensive orthodontic treatment is of great importance, as a primary goal of clinician. Considerable controversy still surrounds the problem of stability after the retention period. Many studies analyze factors associated to the presence of crowding or incisor irregularity and find predictive features on its relapse. Most studies have reported little o no correlation between the treatment changes in the biological parameters - clinical, biometric (irregularity index, intermolar width, intercanine width, arch length, overjet, overbite), or cephalometric variables- that ocurred and the posttretament and postretention changes that may predict their future development. This article provides a bibliographical overview on the relapse of dental alignment in treated cases. In a brief historical introduction, the first studies on the long-term stability of orthodontic results are analysed. The article then goes on to assess studies that focus attention on anteroinferior alignment before finally studying relapse of upper crowding. It concludes by making some final comments in the light of the bibliography provided and the differents schools regarding retention needs and methods.

A restorative approach to the clinical and aesthetic management of adult patients with Class II division 2 incisor malocclusions

A Class II division 2 incisor malocclusion may be a cause of aesthetic and/or functional concern for some affected patients. Their particular concerns may include dark spaces around the misaligned teeth or uneven gingival contours. Orthodontic and/or orthognathic treatment can address some of these problems but frequently involves lengthy and expensive treatment in the adult dentition. Sadly, such treatment often produces an unstable result, with significant drawbacks such as the requirement for long-term retention. This article aims to describe alternative strategies for managing patients with this incisor malocclusion.

CLINICAL RELEVANCE

This paper outlines a quicker, pragmatic and minimally destructive restorative treatment alternative to conventional orthodontic treatment and the associated long-term retention.

Stability of deep-bite correction: A systematic review

OBJECTIVES

Deep bite occurs in about 15% to 20% of the US population. Currently, it is unknown which types of correction are most efficient or stable. The purpose of this systematic review was to investigate factors related to stability of deep-bite correction.

MATERIALS AND METHODS

An electronic search of 4 databases was performed from January 1, 1966 to June 27, 2012. Studies were considered for inclusion if they reported on deep bite samples that underwent orthodontic treatment in the permanent dentition. Records were required at the initial, posttreatment, and 1-year posttreatment times. Hand searching of reference lists of the included studies was performed. Data were abstracted using custom forms, and risk of bias was assessed using a modified Newcastle-Ottawa Scale.

RESULTS

Twenty-six studies met the inclusion criteria. Most were case series, with considerable potential for bias. The significant heterogeneity of the studies precluded meta-analyses, and only descriptive statistics and stratified comparisons were reported. On average, patients underwent significant overbite improvement during treatment, and most of the correction was maintained long-term. Across all studies, the mean initial overbite, posttreatment overbite, and long-term overbite were 5.3, 2.6, and 3.4 mm, respectively. Initial severity appeared to be related to long-term stability. However, this relationship was difficult to isolate from other factors. The length of follow-up did not appear to be related to the amount of relapse.

CONCLUSIONS

Although the quality of the current evidence is not high, patients with deep-bite malocclusion appear to undergo relatively successful treatment, and most of the correction appears to be stable.

Relapse of orthodontically corrected deepbites in accordance with growth pattern

INTRODUCTION

A common orthodontic problem is a deep overbite malocclusion. Because of its high relapse tendency, it is also one of the most challenging problems to treat. To minimize relapse, the morphologic characteristics of patients need to be considered. The aim of this study was to compare deepbite relapse in 3 groups of patients categorized by vertical growth type.

METHODS

The total sample included 60 patients treated at the University of Washington in Seattle, all with initial overbites greater than 50%. Data were collected from casts and cephalometric radiographs at 3 time points: pretreatment, posttreatment, and 10 years postretention. A mixed-effects model (analysis of variance) and post-hoc t tests were used for the statistical evaluations.

RESULTS

The high-angle subjects showed the least deepbite relapse (0.1 ± 1.1 mm), whereas the low-angle (1.2 ± 0.9 mm) and the normal-angle (1.4 ± 1.3 mm) subjects had statistically significant relapses P <0.001. This overbite relapse might be partially due to changes in the mandibular and interincisal angles, which were also observed in these 2 groups.

CONCLUSIONS

High-angle subjects tend to relapse less in overbite than do low-angle and normal-angle subjects in the long term.

Long-term development of malocclusion traits in orthodontically treated and untreated subjects

INTRODUCTION

The purposes of this study were to analyze long-term changes in malocclusion traits and to compare the development in orthodontically treated and untreated subjects.

METHODS

The sample comprised 308 adolescents in the intermediate, late mixed, or early permanent dentition who were examined clinically at the ages of 8 to 17 years and again 25 years later. The treated subgroup of 58 subjects had received orthodontic treatment with fixed or removable appliances or both. All subjects had a full complement of teeth, except a subgroup of 19 who had premolar extractions as a part of their orthodontic treatment plan.

RESULTS

The prevalence of maxillary overjet was significantly reduced in the untreated group and the treated subgroups. The prevalence of distal molar occlusion was significantly reduced in the subgroup treated without extractions. Comparison of treated and untreated groups in terms of changes over time showed that development was significantly more favorable in all treatment categories regarding maxillary overjet, and in the nonextraction category regarding distal molar occlusion. Subjects treated without extractions had less favorable development than did untreated subjects regarding molar crossbite.

CONCLUSIONS

The long-term benefit of orthodontic treatment, with or without extractions, was confirmed regarding maxillary overjet, and the lasting effect of nonextraction treatment was confirmed regarding the distal molar relationship. The pattern of changes in treated and untreated subjects indicated that long-term development and individual variation can to some extent conceal the effects of a brief orthodontic intervention.

Relationship between initial crowding and interproximal force during retention phase

This study investigated the change in interproximal force (IPF) in mandibular anterior teeth during retention and the relationship between the irregularity index before orthodontic treatment and the IPF. The effect that an erupting third molar had on IPF was also examined. Forty treated patients (40 with extraction of four bicuspids) were followed for 18 months during the retention phase. The irregularity index was determined from initial plaster casts. The total IPF was determined by measuring the interdental frictional forces at the mandibular anterior teeth by withdrawing a metal strip. The total IPF increased during the retention phase until 18 months, and there was a positive correlation between the irregularity index and total IPF 6 to 18 months after active treatment. An erupting third molar did not affect the total IPF. An increase in the total IPF may be an indication of relapse in mandibular anterior crowding. In conclusion, orthodontists should pay special attention to potential relapse in the lower anterior teeth 6 months after active treatment in cases with severe anterior crowding before treatment.

Post-treatment occlusal changes in Class II division 2 subjects treated with the Herbst appliance

The aim of this retrospective study was to analyse and compare the post-treatment occlusal changes of Class II division 2 treatment with the Herbst appliance in early adolescent, late adolescent, and adult subjects. The subjects were 37 Class II division 2 patients (19 females and 18 males) treated at the Orthodontic Department, University of Giessen, Germany. All were in the late mixed or permanent dentition and exhibited a Class II molar relationship > or =0.5 cusp width (CW) bilaterally or > or =1.0 CW unilaterally, an overbite (OB) >3.0 mm, and two upper central incisors retroclined. The subjects were divided into three skeletal maturity groups based on evaluation of hand wrist radiographs: early adolescent (n = 10, stages MP3-E to MP3-FG at start of treatment, age range: 11.3-13.2 years), late adolescent (n = 14, stages MP3-G to MP3-I at start of treatment, age range: 14.1-16.4 years), and adult (n = 13, stages R-I to R-J at the start of treatment, age range: 16.3-25.6 years). Study casts from before treatment (T1), after Herbst-Tip-Edge-Multibracket appliance treatment (T2), and after an average retention time of 27 months (T3) were analysed. Statistical analysis was undertaken using t-tests for paired and unpaired samples. For the whole sample, the molar relationship at T3 was stable in 82.4 per cent, the canine relationship in 82.9 per cent, and OB in 75.7 per cent of the cases. In the different skeletal maturity groups, the stability of the molars, canines, and overbite was as follows: early adolescents: 95.0, 100.0, and 70.0 per cent, respectively; late adolescents: 92.9, 74.1, and 85.7 per cent, respectively; and adults 61.5, 80.8, 69.2 per cent, respectively. Occlusal correction of Class II division 2 malocclusions with Herbst treatment was relatively stable 2 years post-treatment. The outcome of treatment of adolescents was more stable than that of adults.

Mini-implants for en masse intrusion of maxillary anterior teeth in a severe Class II division 2 malocclusion

This case report describes the treatment of a 16-year-old post pubertal male patient with a severe Class II division 2 malocclusion and 100% deep bite. In the first phase of treatment, a 'Jones-Jig' molar distalization appliance was used to distalize the maxillary molars by more than 6 mm, to achieve a Class I molar relation. In the second phase of treatment, mini-implants were inserted between the roots of the maxillary lateral incisor and canine to intrude all the maxillary anterior teeth en masse in a single step. Four millimetres of intrusion was achieved. The implants remained stable throughout treatment. In the mandibular arch the incisors were proclined to alleviate the severe crowding. Good overjet and overbite was achieved and has been maintained one year after completion of active orthodontic treatment.

Stability of upper incisor inclination changes in Class II division 2 patients

The aim of this study was to evaluate the changes in incisor inclination following orthodontic treatment in Class II division 2 patients, and to assess the long-term stability after retention. Dental casts and cephalograms of 61 Class II division 2 patients (31 males and 30 females, mean age 13.4 years) with a closed lip seal were available before (T1), at the end of treatment (T2), and 3.5 years (mean) post-treatment (T3). A method of measuring upper incisor inclination on dental casts was developed for the purpose of the investigation. This involved placing markers on the study casts and then taking radiographs which were measured to establish the upper incisor inclination. Statistical analysis of the data included the calculation of mean values, standard deviation, standard errors, and ranges for each variable. Spearman ranked correlation coefficients were computed for selected model variables and scattergrams plotted. To investigate the influence of the chosen retention therapy, a Mann-Whitney U-test was used. The mean change in incisor inclination during orthodontic treatment was 15.2 degrees. There was a mean relapse of 2.2 degrees between T2 and T3, but this was not considered clinically relevant. The amount of relapse was independent of the type of the retention appliance (Hawley type retainer or lingual retainer). The relationship between long-term stability of the incisor inclination and between the lip line relative to the upper incisors was also investigated, based on cephalometric data. A mean decrease in lip line height of 0.6 mm was seen at T2 and, although the observed change was statistically significant, it would not be clinically relevant.

Long-term follow-up of orthodontically treated deep bite patients

The aim of this study was to evaluate the long-term stability of corrected deep bite and mandibular anterior crowding in a sample of 62 subjects (30 patients and 32 controls). The patients began treatment at a mean age of 12.2 years (SD 1.56). The treatment consisted of non-extraction and fixed appliances in 23 subjects and functional appliances in seven. The treatment group was compared with the control group with normal molar occlusion, normal overjet and overbite, no crowding, and without an orthodontic treatment need. The registrations were made on four occasions: before treatment (T1), after treatment (T2), and at two long-term follow-ups (T3 and T4). Four registrations were also made in the control group. All measurements were undertaken on plaster models and lateral cephalograms. Treatment was found to have normalized the overbite and overjet and to have eliminated the space deficiency in the mandibular anterior region. At T4, there was a minor relapse in overbite in the treatment group (mean 0.8 mm). In the control group, the overbite underwent reverse development (bite opening by 0.7 mm) during the same period. The available mandibular incisor space, however, was -0.9 mm in the treatment group and -1.8 mm in the control group. The long-term stability of the treatment results was thus good.

A comparative study of cephalometric and arch width characteristics of Class II division 1 and division 2 malocclusions

The aim of this compound cephalometric and arch-width study was to determine any dental and/or skeletal differences between subjects with Class II division 1 and Class II division 2 malocclusions. The dento-skeletal characteristics of Class II subjects were evaluated using lateral cephalometric radiographs and dental casts of 90 untreated patients. The sample included 46 Class II division 1 patients (19 girls and 27 boys) with a mean age of 15.27 +/- 2.48 years, and 44 Class II division 2 patients (27 girls and 17 boys) with a mean age of 15.95 +/- 3.25 years. The intermolar, interpremolar and intercanine measurements were carried out on study models. The radiographs were digitized and processed using Dolphin Imaging software. In addition to standard descriptive statistical calculations, an independent samples t-test was carried out in order to compare the two groups. The non-parametric Mann-Whitney U test was utilized for the parameters for the data which were not normally distributed. The only statistically significant difference between the groups for the study model measurements was mandibular intercanine width. The cephalometric results revealed that SNB angle was responsible for the skeletal sagittal difference between the two groups. In addition, the Class II division 1 group had higher vertical proportions and the Class II division 2 group a more concave profile with a prominent chin. The sagittal skeletal pattern of Class II division 2 subjects was found to be very similar to the Class I skeletal relationship, with no evidence of any mandibular restriction.

Postretention changes in mandibular crowding: a review of the literature

Posttreatment stability is one of the challenges facing orthodontists today. Relapse of the mandibular anterior segment during the postretention period is perhaps the most predictable and frustrating of all orthodontic relapses. This type of relapse is sometimes erroneously construed as a sign of inappropriate treatment or evidence of misdiagnosis or incorrect mechanics. This article reviews mandibular incisor postretention stability outcomes in the setting of different treatment techniques and different ages of beginning orthodontic treatment. Mandibular incisor relapse is almost inevitable, regardless of orthodontic techniques and timing of orthodontic treatment. However, mandibular incisor relapse might be reduced when palatal expansion is combined with prolonged retention.

Dental arch width in Class II Division 2 deep-bite malocclusion

A severe phenotype of Angle's Class II Division 2 (II/2) malocclusion with extremely deep overbite has been called cover-bite, or "Deckbiss" in its early German descriptions. This distinctive occlusal variation is characterized by skeletofacial hypodivergence, mandibular dentoalveolar retrusion, excessive bony chin projection, reduced mesiodistal tooth size, maxillary incisor retroclination, and at least 100% overbite, covering at least 1 mandibular incisor in occlusion. In this study, maxillary and mandibular dental arch widths measured at the first molars and the canines were recorded from dental casts of 23 subjects with II/2 cover-bite malocclusions. The data were compared with a control-reference sample of 46 orthodontic patients matched for age and gender. In the cover-bite group, the intermolar widths in both arches and the intercanine width in the maxilla were comparable with those in the control sample. However, mandibular intercanine width in the II/2 cover-bite group was significantly less than that of the controls (P =.01). These findings suggest that II/2 deep overbite malocclusion is characterized by normalized and relatively compatible transverse dimensions in the maxilla and in the mandibular posterior segments. The transverse underdevelopment that this study identified in the mandible from canine to canine is probably responsible for mandibular incisor compression and crowding--natural sequelae of the deep overbite in II/2 cover-bite. Thus, a reasonable orthodontic treatment plan for the mandibular dentoalveolar compensation often seen in II/2 deep-bite patients would be anterior expansion of the mandibular arch width, usually reducing the need for orthodontic tooth extractions and increasing the desirability of fixed retention.

The long-term benefits of orthodontic treatment

OBJECTIVE

This study aimed to evaluate post-treatment changes at least five years out of retention in a cohort of 100 consecutively started patients treated by a postgraduate student in a UK orthodontic department.

DESIGN

Analysis of study models using recognised occlusal indices. Setting Patients initially treated at Newcastle Dental Hospital were recalled for record collection.

MATERIALS AND METHODS

Study models and clinical photographs were taken for each patient attending for post-retention records. Weighted Peer Assessment Rating (PAR) Index and Index of Orthodontic Treatment Need (IOTN) scores were recorded for cases at the beginning, end and at least 5 years post-retention. Main outcome measures Post-treatment changes were evaluated using PAR Index and IOTN to evaluate extent and likelihood of change and to compare treatment modalities.

RESULTS

Seventy-eight patients attended for post-retention records. Overall PAR reduction immediately post-treatment was 68.6% and at a mean of 6.5 years post-retention was 55.5%. Dual arch fixed appliance treatments achieved the greatest reduction in PAR score, and maintained the reduction beyond the retention period better than other treatment modalities. Eighty-four per cent of the cohort still had some demonstrable improvement after a mean of 6.5 years post-retention. There was a residual need for treatment in 8% of cases on aesthetic grounds and in 24% of cases on dental health grounds.

CONCLUSIONS

Occlusal deterioration after orthodontic treatment is almost universal. Dual arch fixed appliance treatment provides the best post-treatment and post-retention result.

Nickel-titanium mandibular bonded lingual 3-3 retainer: for permanent retention and solving relapse of mandibular anterior crowding

An innovative technique that involves a nickel-titanium mandibular bonded lingual 3-3 retainer was used to treat relapse of mandibular anterior crowding. The purpose of this study was to demonstrate clinical procedures and to study the effects of a new mandibular bonded lingual 3-3 retainer on the mandibular dental arch. In 18 patients, changes in the irregularity index and in arch dimensions (intercanine width, arch length, and arch depth) were measured against the patients' mandibular dental casts, which were obtained at completion of the previous orthodontic treatment (T(0)). These measurements were taken at the beginning of retreatment (T(1)), and 2 (T(2)), 4 (T(3)), and 6 (T(4)) months after initiation of retreatment. During the period of relapse (T(0)-T(1)), the irregularity index increased from 1.3 to 3.5 mm and the mandibular arch dimensions decreased. Four months after a segment of.018-in nickel-titanium archwire was bonded lingually from canine to canine, the irregularity index decreased from 3.5 to 1.0 mm and the arch dimensions increased and recovered their original posttreatment dimensions. The nickel-titanium archwire was left in place for permanent retention after the period of retreatment. This simple technique effectively solved relapse of mandibular anterior crowding in 4 months. This mandibular bonded lingual 3-3 retainer could be used both actively, to re-treat mandibular anterior crowding without the use of lingual brackets, and passively, for maintenance as a bonded lingual retainer.