Treatment and postretention changes in dental arch width dimensions--a long-term evaluation of influencing cofactors

Predictors for long-term relapse of orthodontic treatment in patients with cleft lip and palate. A clinical follow-up study

OBJECTIVES

To identify predictors for long-term relapse of orthodontic therapy in patients with cleft lip and palate (CLP).

MATERIALS AND METHODS

Patients with uni- and bilateral non-syndromal CLP were followed up at least two years after completion of their orthodontic therapy. Plaster casts of the start of treatment (T1), after completion of treatment (T2), and at follow-up (T3) were measured using the modified Huddart Bodenham Index. Characteristics of multidisciplinary therapy were taken from the patient files. Potentially influencing factors of relapse were investigated using logistic regression analyses and Spearman correlations.

RESULTS

In total 58.07% of the included 31 patients showed a stable treatment outcome at follow-up after an average of 6.9 years. Even if relapse occurred, 61.54% of these patients still showed improvement regarding their occlusion compared to baseline. Predictors for the occurrence of relapse were the severity of dysgnathia at baseline (p = 0.039) and the extent of therapeutic change (p = 0.041). The extent of therapeutic change was additionally a predictor for the extent of post-therapeutic relapse (ρ = 0.425; p = 0.019).

CONCLUSIONS

Patients with CLP benefit from their orthodontic therapy in the long term despite an increased tendency to relapse.

CLINICAL RELEVANCE

Results of this long-term study could be used to adapt the treatment concept for patients with CLP and reinforce the significance of a patient-centered orthodontic treatment concept for affected patients.

A Comparative Analysis of Arch Widths in Class I and Class II Malocclusion: Extraction vs. Non-extraction Treatment

INTRODUCTION

This study aimed to assess and compare dental arch widths in the anterior and posterior regions among patients undergoing extraction and non-extraction treatments for Class I and Class II malocclusions.

MATERIALS AND METHODOLOGY

A total of 40 patients were selected, with 10 in each of the categorized groups based on malocclusion type and treatment status. Dental arch widths were meticulously measured using a digital Vernier caliper at the canine and molar regions to ensure precise data collection.

RESULTS

Statistically significant differences were noted when comparing mean inter-canine and molar widths between pre- and post-treatment periods among extraction cases in Class I malocclusion (p < 0.001). Conversely, there were no significant changes observed in arch widths among non-extraction cases in Class I malocclusion. Similarly, significant changes were observed in both extraction and non-extraction cases of Class II malocclusion when comparing mean inter-canine and molar widths between pre- and post-treatment periods (p < 0.05).

CONCLUSION

After treatment, both Class I and Class II extraction cases showed an increase in inter-canine arch width, while intermolar arch width remained unchanged, suggesting that the treatment did not significantly alter the buccal corridor. Additionally, there were no notable changes in inter-canine arch widths between pre- and post-treatment in Class I non-extraction cases. However, the Class II non-extraction group exhibited increased upper and lower inter-canine arch widths after treatment.

Scan Aided Dental Arch Width Prediction via Internationally Recognized Formulas and Indices in a Sample of Kurdish Population/Iraq

Background: Numerous studies have investigated the applicability of Pont's index using a variety of selection criteria. The morphology of teeth and the shapes of the face are significantly influenced by racial, cultural, and environmental factors, so the current study focused on these demographics. Methods: This study is a retrospective study and included one hundred intraoral scanned images selected from patients seeking orthodontic treatment. Medit design software was used to obtain the real measurements and compare them to the predicted values from Pont's index. Paired t tests were used to test the validity of Pont's index, and regression equations were advocated to predict the inter-molar, inter-premolar, and anterior arch widths via SPSS version 25. Results: There were significant differences between the real anterior, inter-premolar, and inter-molar widths and the predicted values obtained from Pont's index, and there were weak positive correlations between the real values and the predicted values from Pont's index. Conclusions: Pont's index is not reliable to predict the arch widths for the Kurdish population, and new formulas are advocated. Hence, space analysis, malocclusion treatment, and arch expansion therapy should all take into account these results. Therefore, the derived equations may have further positive effects on diagnoses and treatment preparation.

MARPE as an adjunct to orthodontic treatment

Introduction:

Miniscrew or microimplant-assisted rapid palatal expansion (MARPE) devices are used to achieve a skeletal expansion of the palate and to increase the arch perimeter.

Objective:

To describe the treatment of a 23-year-old woman with an Angle Class II, division 1 malocclusion with constricted maxillary and mandibular arches.

Case report:

The patient’s main complaint was mandibular anterior crowding. The treatment plan included expansion of the mandibular arch concurrent with maxillary expansion, using a MARPE appliance in combination with a full-fixed appliance to align and level the crowded mandibular teeth, along with miniscrews as anchorage for the maxillary teeth and for distalization of the molars and premolars. A successful non-extraction orthodontic treatment was accomplished after 28 months, and the occlusion and teeth alignment, as well as facial goals, were resolved in a clinically satisfactory manner.

Conclusion:

The treatment objectives were met, and the outcome of the expansion of the maxillary arch with a MARPE appliance as an adjunct to a fixed appliance was considered a success. An esthetic, functional, and stable result after a 1-year follow-up was achieved and was satisfactory to the patient.

Clinical effects with customized brackets and CAD/CAM technology: a prospective controlled study

OBJECTIVE

Nowadays, CAD/CAM technologies enrich orthodontics in several ways. While they are commonly used for diagnoses and treatment planning, they can also be applied to create individualized bracket systems. The purpose of this prospective quasi-randomized study was to evaluate the clinical efficiency of a customized bracket system and its comparison with directly bonded conventional self-ligating bracket treatment.

MATERIALS AND METHODS

Altogether 38 patients were separated into two groups, treated either with direct bonded self-ligating brackets (Damon, Ormco, USA) or with indirect bonded customized CAD/CAM brackets (Insignia™, Ormco, USA). Overall treatment time, number of treatment appointments, number of lost or repositioned brackets, number of arch wires and wire bends, Little Irregularity Index, cephalometric analyses and ABO scores were compared. Superimpositions of the virtual set-ups and the treatment results of the CAD/CAM group were performed to evaluate the clinical realization of the treatment planning.

RESULTS

No differences between both treatment groups were found concerning overall treatment time, number of appointments and number of archwire bends. Bonding failures occurred more often using the CAD/CAM system. Indirectly bonded brackets did not have to be repositioned as often as directly bonded brackets. Treatment results with both systems were similar concerning their effects on the reduction of ABO scores. The number of used archwires was higher in the CAD/CAM group. Treatment with both systems led to further proclination of the incisors. Proclination in the lower jaw was greater than proclination in the upper jaw, and there was a statistically significant difference between the two treatment systems. Comparing the treatment results with the virtual set-ups, mesial positions were met best, followed by vertical positions. Transversal positions showed the greatest discrepancies. Concerning angles, values of angulation showed greatest accordance to the virtual set-up, while values of inclinations showed greatest discrepancies.

CONCLUSION

In comparison with a direct bonded self-ligating bracket system the use of indirect bonded customized CAD/CAM brackets showed only minor influence on treatment efficiency and treatment outcomes. Transversal expansion, deep bite correction, expression of torque and anchorage loss remain challenges in the treatment with straight-wire appliances. Trial registration DRKS, DRKS00024350. Registered 15 February 2021, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00024350 .

Relapse 1 week after bracket removal: a 3D superimpositional analysis

OBJECTIVES

To measure tooth movement 1 week post-treatment and assess potential correlation with changes invoked during treatment.

SUBJECTS AND METHODS

Thirty-eight patients were recruited (19 males, 19 females). Polyvinyl siloxane impressions were taken after bracket debonding (T1) and 1 week later (T2) and digitally scanned. During this period no retention was used. The digital casts were superimposed on structures of the hard palate. Translation and rotation of the first molars, canines, and central incisors were recorded. Additionally, movement of these teeth was assessed from the beginning (T0) until the end of treatment (T1). The correlation between the post-treatment relapse (T1-T2) and tooth movement during treatment (T0-T1) was investigated via the Spearman correlation coefficient.

RESULTS

Relapse was detected and reflected changes in tooth position during treatment. For the first molars (right, left) the correlation between treatment and post-treatment tooth movement was evident in the transverse direction (r = -0.38, P = 0.020; r = -0.32, P = 0.052), tipping (r = -0.40, P = 0.015; r = -0.34, P = 0.034) and the antero-posterior direction (r = -0.31, P = 0.061; r = -0.36, P = 0.027); for the canines (right and left), as rotation around their long axis (r = -0.55, P = 0.003; r = -0.58, P = 0.002); for central incisors (right and left) in the antero-posterior direction (r = -0.55, P = 0.000; r = -0.48, P = 0.03), transverse direction (r = -0.43, P = 0.07; r = -0.32, P = 0.047), and rotation around their long axis (r = -0.53, P = 0.001; r = -0.28, P = 0.089).

CONCLUSIONS

Post-treatment changes in tooth position were mostly related to tooth movement during treatment. The reported correlations may help clinicians predict short-term relapse, evaluate long-term retention need, and design individualized retention schemes.

Anterior tooth alignment and arch dimensions changes: 37-year follow-up in patients treated with and without premolar extraction

INTRODUCTION

The objective of this research was to evaluate the anterior tooth alignment and dental arch dimension changes after orthodontic treatments with and without premolar extractions in the long-term.

METHODS

Fifty-seven patients with Class I and Class II malocclusion were divided into 2 groups. Group 1 included 16 patients treated with nonextraction therapy, with mean initial (T1), final (T2), and long-term follow-up (T3) ages of 13.20 years, 15.07 years, and 50.32 years, respectively. The mean treatment (T2 - T1) and long-term follow-up (T3 - T2) times were 1.86 years and 35.25 years, respectively. Group 2 included 41 patients treated with extraction of 4 first premolars, with T1, T2, and T3 ages of 13.31 years, 15.63 years, and 53.60 years, respectively. The mean treatment and long-term follow-up times were 2.32 years and 37.96 years, respectively. The mean retention time was 2.26 years for both groups. The dental casts were obtained and digitized at T1, T2, and T3 stages. The following measurements were obtained: Little irregularity index, arch length, perimeter, and intercanine, interpremolar, and intermolar widths. Intragroup and intergroup comparisons were performed with repeated measures analysis of variance and t tests, respectively.

RESULTS

Anterior tooth irregularity index increased at T3 in both groups. In addition, all arch dimensions, except the intercanine width, were significantly smaller in the extraction group at T3. Both groups showed similar arch dimension changes at T3, except for the mandibular arch perimeter. The percentage of mandibular anterior tooth alignment change was significantly greater in the nonextraction than in the extraction group.

CONCLUSIONS

There was no difference in the changes of anterior alignment and transverse arch dimensions in patients treated with and without premolar extraction at T3, but the percentage of mandibular anterior tooth alignment changes was higher in the nonextraction than in the extraction patients at T3. The mandibular arch perimeter showed more of a decrease at T3 in extraction patients.

Nonextraction Management of Severely Malaligned and Constricted Upper Arch

This case report presents the treatment of a 12-year-old female with a severely crowded upper arch, severely palatally displaced upper premolars and lateral incisors, large midline diastema, lower midline deviation to the right, class III dental and skeletal relationships due to mild maxillary deficiency, retroclined lower incisors, straight profile, and retrusive lips. A nonextraction treatment approach is described, in which the upper and lower arches were expanded to their original three dimensions using a trihelix expander, a lip bumper appliance, and a fixed orthodontic appliance. Retention was also planned in accordance with the original malocclusion, which inclued a full-time-wear upper wraparound retainer, upper and lower anterior fixed lingual retainers, upper frenectomy, and fibrotomy for rotated teeth. Conclusion. Severe malalignment of teeth does not necessarily require extraction treatment. Gaining space is an art that requires a proper assessment of the anteroposterior and transverse dimensions of alveolar arches, lip prominence, and postorthodontic stability.

Effects of Three Different Orthodontic Treatment Methods on the Stability of Mandibular Incisor Alignment

OBJECTIVE

To compare the effects of extraction, non-extraction and air-rotor stripping treatments on mandibular dental arch dimensions, lower incisor positions and evaluate their effects on the stability of the treatment.

STUDY DESIGN

The sample consisted of 44 patients with Class I malocclusion and moderate crowding including 15 patients treated with extraction, 13 with air-rotor stripping (ARS), and 16 with non-extraction treatment. The records were taken at pretreatment (T0), end of active orthodontic treatment (T1), minimum 3 years post-treatment (T2). The model and cephalometric measurements were evaluated. For statistical analyses ANOVA and Welch test was applied.

RESULTS

At post-retention period Little's irregularity indices were increased to 1.96 mm, 2.38 mm and 3.59 mm for extraction, ARS and non-extraction groups respectively (p<0.05). At T1-T2, intercanine widths were decreased significantly at all groups (p<0.05). The arch length and arch depth decreased significantly at extraction group (p<0.05) from T0 to T1 and remained the same at T2 (p>0.05). The lower incisors were retroclined with treatment and slightly proclined at post-retention period in extraction group. In ARS and non-extraction group, lower incisors proclined with treatment and remained the same at post-retention.

CONCLUSION

At all groups the irregularity indices relapsed but did not return to pretreatment values. Although significant increase at intercanine width was only observed in non-extraction treatment, at post-retention phase, intercanine widths were significantly decreased at all groups. The changes at lower incisor inclinations relapsed slightly in extraction group but remained the same in the other groups.

Stability of orthodontic treatment outcome in relation to retention status: An 8-year follow-up

INTRODUCTION

Our aim was to evaluate the stability of orthodontic treatment outcome and retention status 7 or more years after active treatment in relation to posttreatment or postretention time, type of retention appliance, and duration of retainer use.

METHODS

The subjects were former patients who completed orthodontic treatment with fixed appliances from 2000 to 2007. The pretreatment eligibility criteria were anterior crowding of 4 mm or more in the maxilla or the mandible and Angle Class I or Class II sagittal molar relationship. Acceptable pretreatment and posttreatment dental casts were required. A total of 67 patients participated, 24 men and 43 women, with a mean age of 24.7 years (range, 20.0-50.0 years). All participants had a follow-up clinical examination, which included impressions for follow-up casts, and each completed a questionnaire. Data were obtained from pretreatment, posttreatment, and follow-up (T2) casts as well as from the patients' dental records. Treatment stability was evaluated with the peer assessment rating (PAR) index and Little's irregularity index.

RESULTS

The participation rate was 64%. The average posttreatment time was 8.5 years (range, 7.0-11.0). All participants had received a retainer in the mandible, maxilla, or both after active treatment. At T2, the PAR score showed a mean relapse of 14%. The majority (78%) of participants still had a fixed retainer at T2 (retainer group), and 22% had been out of retention for at least 1 year (postretention group). The relapse according to the PAR did not differ significantly between participants with and without a retainer at T2. From posttreatment to T2, the irregularity of the mandibular incisors increased almost 3 times more in participants with no retainer in the mandible compared with those with an intact retainer at T2 (P = 0.001). In the maxilla, no corresponding difference was found.

CONCLUSIONS

Our results suggest that occlusal relapse can be expected after active orthodontic treatment irrespective of long-term use of fixed retainers. Fixed canine-to-canine retainers seem effective to maintain mandibular incisor alignment, whereas in the maxilla a fixed retainer may not make any difference in the long term.

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.

A 22-year follow-up of the nonsurgical expansion of maxillary and mandibular arches in a young adult: Are the outcomes stable, relapsed, or unstable with aging?

Adult maxillary and mandible arch expansion without a surgical approach can be uncertain when long-term stability is considered. This case report describes the treatment of a 19-year-old woman with an Angle Class I malocclusion with constricted maxillary and mandibular arches. The patient's main complaint was mandibular anterior crowding. The treatment plan included expansion of the mandibular arch concurrent with semirapid maxillary expansion. An edgewise appliance was used to adjust the final occlusion. Smile esthetics and dental alignment were improved without straightening the profile. This outcome was followed up with serial dental casts for 22 years after treatment. At the end of that period, the occlusion and tooth alignment were clinically satisfactory, further supported by mandibular fixed retention. However, the transverse widths were continuously and gradually reduced over time, superposing orthodontic transverse relapse and natural arch constriction caused by aging.

Maxillary anterior alignment stability in Class I and Class II malocclusions treated with or without extraction

OBJECTIVE

To compare the postretention stability of maxillary incisors alignment in subjects with Class I and II malocclusion treated with or without extractions.

MATERIALS AND METHODS

The sample comprised 103 subjects with initial maxillary anterior irregularity greater than 3 mm and was divided into four groups: group 1 comprised 19 patients with Class I malocclusion treated with nonextraction (mean initial age = 13.06 years); group 2 comprised 19 patients with Class II malocclusion treated with nonextraction (mean initial age = 12.54 years); group 3 comprised 30 patients with Class I malocclusion treated with extractions (mean initial age = 13.16 years); group 4 comprised 35 patients with Class II malocclusion treated with extractions (mean initial age = 12.99 years). Dental casts were obtained at three different stages: pretreatment (T1), posttreatment (T2), and long-term posttreatment (T3). Maxillary incisor irregularity and arch dimensions were evaluated. Intergroup comparisons were performed by one-way analysis of variance followed by Tukey tests.

RESULTS

In the long-term posttreatment period, relapse of maxillary crowding and arch dimensions was similar in all groups.

CONCLUSION

Changes in maxillary anterior alignment in Class I and Class II malocclusions treated with nonextractions and with extractions were similar in the long-term posttreatment period.

The validity, reliability, and time requirement of study model analysis using cone-beam computed tomography-generated virtual study models

OBJECTIVES

To investigate the validity, reliability, and time spent to perform a full orthodontic study model analysis (SMA) on cone-beam computed tomography (CBCT)-generated dental models (Anatomodels) compared with conventional plaster models and a subset of extracted premolars.

SETTING AND SAMPLE POPULATION

A retrospective sample of 30 consecutive patient records with fully erupted permanent dentition, good-quality plaster study models, and CBCT scans. Twenty-two extracted premolars were available from eleven of these patients.

MATERIALS AND METHODS

Five evaluators participated in the inter-rater reliability study and one evaluator for the intrarater reliability and validity studies. Agreement was assessed by ICC and cross-tabulations, while mean differences were investigated using paired-sample t-tests and repeated-measures anova.

RESULTS

For all three modalities studied, intrarater reliability was excellent, inter-rater reliability was moderate to excellent, validity was poor to moderate, and performing SMA on Anatomodels took twice as long as on plaster.

CONCLUSIONS

Study model analysis using CBCT-generated study models was reliable but not always valid and required more time to perform when compared with plaster models.

Posttreatment and physiologic occlusal changes comparison

Objective:

To compare posttreatment and postretention occlusal changes with the physiologic occlusal changes caused by natural development of untreated subjects.

Materials and Methods:

The sample was divided into three groups. Group 1 comprised 97 subjects treated with four premolar extractions at a mean pretreatment (T0) age of 13.03 years, a mean posttreatment (T1, first observation) age of 15.12 years, and a mean postretention (T2, second observation) age of 20.52 years. The mean observation period (T2-T1) was 5.39 years. Group 2 comprised 58 subjects treated nonextraction at a mean pretreatment age of 12.83 years, a mean posttreatment age of 14.99 years, a mean postretention age of 20.22 years, and a mean observation period of 5.22 years. Group 3 comprised 114 untreated subjects at a mean age at T1 of 14.91 years and at T2 of 20.48 years. The mean observation period was 5.56 years. Dental casts were evaluated using the Peer Assessment Rating (PAR) index and the Little irregularity index in maxillary and mandibular arches. Changes in PAR and Little indexes were compared among the three groups by analysis of variance and Tukey tests.

Results:

Intergroup comparison showed that at T1 and T2 the treated groups presented smaller PAR and Little indexes than the untreated group. In the observation period, the treated groups showed greater increase in PAR and Little maxillary indexes than the untreated group. The extraction group showed a greater increase of the Little mandibular index than the untreated group.

Conclusions:

The treated groups showed more changes according to PAR and Little maxillary indexes than the untreated group. The posttreatment change of the mandibular anterior crowding of the treated extraction group was greater than the mandibular crowding caused by physiologic changes in the untreated group.

Stability and relapse of maxillary anterior crowding treatment in class I and class II Division 1 malocclusions

INTRODUCTION

The maxillary anterior teeth are the most important to facial esthetics because they are the first to show on a smile. Therefore, stability of the maxillary anterior teeth alignment is an important issue. The objective of this study was to compare the stability of maxillary anterior tooth alignment in Class I and Class II Division 1 malocclusions.

METHODS

The sample comprised dental casts of 70 patients with Class I and Class II Division 1 malocclusions and a minimum of 3 mm of maxillary anterior crowding measured by an irregularity index. The patients were treated with extractions and evaluated at pretreatment and posttreatment and at least 5 years after treatment. The sample was divided into 3 groups: group 1, Class I malocclusion treated with 4 first premolar extractions comprising 30 subjects, with an initial age of 13.16 years and 8.59 mm of initial maxillary irregularity; group 2, Class II malocclusion treated with 4 first premolar extractions comprising 20 subjects, with an initial age of 12.95 years and 11.10 mm of maxillary irregularity; and group 3, Class II malocclusion treated with 2 first maxillary premolar extractions comprising 20 subjects, with an initial age of 13.09 years and 9.68 mm of maxillary irregularity.

RESULTS

The decrease in the maxillary irregularity index was significantly greater in group 2 than in group 1 during treatment. The stability of maxillary anterior alignment was 88.12% over the long term; 77% of the linear displacement of the anatomic contact points tended to return to their original positions.

CONCLUSIONS

Stability of maxillary anterior alignment between the 3 groups was similar. The stability of maxillary anterior alignment was high over the long term, but a high percentage of teeth tended to return to their original positions.

Long-term effectiveness of canine-to-canine bonded flexible spiral wire lingual retainers

INTRODUCTION

The flexible spiral wire (FSW) canine-to-canine lingual retainer bonded to all 6 anterior teeth is a frequently used type of mandibular fixed retainer. This study aimed to assess the long-term effectiveness of FSW canine-to-canine lingual retainers in maintaining the alignment of the mandibular anterior teeth after orthodontic treatment.

METHODS

The sample consisted of dental casts of 221 consecutively treated patients (75 girls, 146 boys) from the archives of the Department of Orthodontics and Craniofacial Biology, Radboud University Nijmegen Medical Center, The Netherlands, who received a FSW canine-to-canine lingual retainer bonded to all 6 anterior teeth after active orthodontic treatment. The casts were studied before treatment (Ts), immediately after treatment (T0), 2 years (T2), and 5 years (T5) posttreatment.

RESULTS

The main irregularity index decreased significantly from 5.40 mm (SD, 3.47) at Ts to 0.07 mm (SD, 0.23) at T0. At T5, the alignment of the mandibular anterior teeth was stable in 200 patients (90.5%); in 21 patients (9.5%), a mean increase of 0.81 mm (SD, 0.47) was observed. The increase of irregularity was strongly related to the bonding failures of the retainer. In 6 patients (2.7%), unexpected posttreatment complications (torque differences of the incisors, increased buccal canine inclination) were observed.

CONCLUSIONS

The FSW canine-to-canine lingual retainer is very effective in maintaining the alignment of the mandibular anterior region after active orthodontic treatment. However, regular checkups are necessary to determine bonding failures, posttreatment changes, and complications as early as possible.

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.

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.

Transverse implications of maxillary premolar extraction in Class III presurgical orthodontic treatment

INTRODUCTION

Maxillary premolars are often extracted to resolve incisor proclination in presurgical orthodontic treatment for severe skeletal Class III patients. The aim of this article was to compare arch-width changes and orthodontic tooth movements between maxillary premolar extraction and nonextraction modalities, and to provide an additional indication for presurgical maxillary premolar extraction according to the transverse dental arch characteristics of Class III surgical-orthodontic patients.

METHODS

Pretreatment and posttreatment dental casts of 55 adult Class III patients (24 nonextraction, 31 extraction) who underwent surgical-orthodontic treatment were collected. The changes in maxillary and mandibular dental arch widths were measured from the canines to the second molars. Orthodontic tooth movement was evaluated with an angulation-and-inclination measuring gauge.

RESULTS

Statistical analyses showed that intermaxillary arch congruity was attributed mainly to maxillary arch-width changes. The arch-width changes could be interpreted as the result of inclination changes in both posterior dentitions. For the arch-width change, analysis of covariance (ANCOVA) showed a significant extraction effect: the premolar extraction group's ability to accommodate arch-width change was significantly greater than that of the nonextraction group.

CONCLUSIONS

The indications for maxillary premolar extraction in Class III presurgical orthodontic treatment might depend in part on the characteristics of the maxillary arch width and posterior teeth inclinations.

Correlation between mandibular incisor crown morphologic index and postretention stability

INTRODUCTION

Considering postretention stability as a result of successful orthodontic treatment, we aimed to verify the influence of mandibular-incisor-crown morphology in the relapse of mandibular anterior crowding.

METHODS

The sample comprised 56 white subjects of both sexes with Class I and Class II malocclusions at pretreatment, treated with extraction of 4 first premolars and edgewise mechanics. No patient underwent interproximal stripping during or after treatment. Mean pretreatment age was 13.23 years. Mean treatment time was 2.11 years, and mean posttreatment evaluation time was 5.12 years. Mandibular anterior crowding was measured with the Little irregularity index, and the mesiodistal and buccolingual proportion of the mandibular incisor crowns was measured with the Peck and Peck index. The measurements were obtained from dental casts at the pretreatment, posttreatment, and postretention stages. The Pearson correlation coefficient was calculated to determine the correlation between mandibular-incisor-crown morphology and the amount of postretention-crowding relapse.

RESULTS

The mandibular-incisor-crown morphologic index was not significantly correlated with the amount of mandibular-anterior-crowding relapse.

CONCLUSIONS

Mandibular-incisor-crown morphology is not correlated with the amount of mandibular-anterior-crowding relapse.

Stability of orthodontic treatment outcome: follow-up until 10 years postretention

Dental casts of 1016 patients were evaluated for the long-term treatment outcome using the Peer Assessment Rating (PAR) index. The PAR index was measured at the pretreatment stage (n = 1016), directly posttreatment (n = 783), postretention (n = 942), 2 years postretention (n = 781), 5 years postretention (n = 821), and 10 years postretention (n = 564). The mean absolute change as well as the percentage of change per year (relapse) related to the postretention stage was calculated. An analysis of variance was applied to compare the mean change in the PAR between cases with and without a fixed retainer at the postretention stage and up to 10 years postretention. Drop-out analysis showed that more Class II Division 2 cases were lost to follow-up than cases of other Angle classes. The results indicate that 67% of the achieved orthodontic treatment result was maintained 10 years postretention. About half of the total relapse (as measured with the PAR index) takes place in the first 2 years after retention. All occlusal traits relapsed gradually over time but remained stable from 5 years postretention with the exception of the lower anterior contact point displacement, which showed a fast and continuous increase even exceeding the initial score. The presence of a fixed retainer had a positive effect on the PAR score. In cases with fixed retention, the relapse was 3.6 PAR points less at 5 years postretention and 4.6 points less at 10 years postretention. The results of this type of studies enable clinicians to inform their patients about treatment limitations in order to better meet their expectations.

The role of extraction in stability of orthodontic treatment

Long-term postretention assessment of orthodontically treated cases has been of interest for 5 decades; however, extraction versus nonextraction follow-up studies are difficult to compare without regard to sample structure, therapy concept und different parameters. The results of selected studies- extraction of 1 or 2 incisors, of premolars and of second and third molars, early and late extraction therapy and serial extraction-showed that long-term postretention stability is not a realistic treatment goal. The Cologne long-term records allow optimistic prediction: relative stability has been found in the majority of former patients, irrespective of the kind of treatment and treatment time. Original anomaly, type (extraction/nonextraction) and amount of treatment, and end-of-treatment alignment were found to be major factors influencing dentoalveolar and skeletal post-treatment changes. The conclusion is that therapy-induced post-treatment changes can be reduced by having a treatment goal within the anatomic limits.