Overjet, overbite, and anterior crowding relapses in extraction and nonextraction patients, and their correlations

Comparative Assessment of Relapse Following Fixed Orthodontic Treatment in Patients Treated With and Without Extraction: A Systematic Review and Meta-Analysis

The present systematic review aimed to evaluate and compare the post-treatment relapse of overjet, overbite, and mandibular incisor crowding in patients treated with extraction and non-extraction orthodontic approaches and to assess the influence of treatment modality on long-term stability. The review was conducted following PRISMA guidelines. Data were extracted from 10 studies, including retrospective and longitudinal designs, with a total of 720 participants. The primary outcome measures included overjet, overbite, and Little's Irregularity Index. Standardized mean difference (SMD) was used as the summary statistic to compare extraction and non-extraction groups. The risk of bias was assessed using the ROBINS-I tool. The meta-analysis revealed no statistically significant differences in relapse between extraction and non-extraction groups for overjet (SMD: 0.52, 95% CI: -0.18 to 1.23, p>0.05), overbite (SMD: 0.41, 95% CI: -0.11 to 0.93, p>0.05), and incisor irregularity index (SMD: 0.71, 95% CI: -0 to 1.23, p>0.05). Funnel plots indicated no significant publication bias. Risk of bias assessment showed moderate concerns in confounding and participant selection across several studies, while bias due to missing data was notable in longer follow-up studies. The findings suggest that both extraction and non-extraction treatment approaches exhibit similar post-treatment relapse rates for overjet, overbite, and incisor irregularity. The choice of treatment should be based on clinical considerations along with concerns of long-term stability. Further high-quality randomized controlled trials are required to strengthen the evidence.

Comparison of aging of nonextraction treated and normal untreated occlusions: 40-year follow up

The objective of this study was to compare the aging changes of the dental arches in patients treated without extractions and untreated normal occlusion subjects after a four-decade follow-up. This retrospective study evaluated two groups: The Treated Group (Group T) comprised 16 patients (6 male; 10 female) presenting with Class I or Class II malocclusions treated orthodontically without extractions. Dental models were evaluated 3 stages: T1 (pretreatment, 13.20 years), T2 (posttreatment, 15.07 years) and T3 (long-term posttreatment, 50.32 years). The Untreated Group (Group UT) consisted of 22 untreated normal occlusion individuals. The dental casts were evaluated at the ages of 13.32 (T1), 17.82 (T2) and 60.95 years (T3). The dental casts were digitized and the irregularity index, intercanine, interpremolar and intermolar widths, overjet and overbite, arch length and perimeter were measured. Intergroup comparisons were performed with independent t tests (P < 0.05). From T1 to T2, the treated group showed maxillary and mandibular crowding and overjet decrease and a maxillary interpremolar and intermolar width increase compared to the untreated group. From T2 to T3, a greater maxillary and mandibular crowding increase and a greater arch length decrease were observed in the treated group compared to the normal occlusion subjects. Overbite increased in the treated group and decreased in the untreated group. The maturational changes of treated patients were different from untreated normal occlusion subjects. Relapse might have contributed for the greater changes observed in incisor crowding and arch length observed in orthodontically treated patients. The aging changes of untreated normal occlusions and nonextraction treated patients, after a four-decade follow-up, proved to be different, indicating that relapse of orthodontic treatment played a role in aging changes of treated patients.

Alveolar bone remodelling and stability of mandibular incisors in adult patients after orthodontic treatment with premolar extractions: A prospective follow-up study

OBJECTIVE

To evaluate alveolar bone remodelling and stability of mandibular incisors in adult orthodontic extraction patients.

MATERIALS AND METHODS

Cone-beam computed tomography images of 25 adult patients undergoing extraction were collected before orthodontic treatment (T1), after orthodontic treatment (T2), and after at least 1 year of retention (T3). The labial and lingual alveolar bone heights (ABH), thickness (ABT), and tooth movement of the mandibular incisors were measured during the retraction (T2-T1) and retention (T3-T2) periods. According to the tooth movement during the retention period, the mandibular incisors were further divided into stable and unstable groups, and the correlation between L1-BMe and stability was evaluated.

RESULTS

The labial and lingual ABHs significantly increased after orthodontic treatment and decreased during the retention period. The lingual ABH was 7.36 ± 2.27 mm at T2 and 5.37 ± 1.98 mm at T3, indicating a great bone remodelling capacity. The labial ABT exhibited a significant increase during orthodontic treatment and a slight decrease during the retention period, while the lingual ABT showed an opposite trend. During the retention period, the root apex moved labially into the alveolar bone housing. L1-BMe significantly increased during orthodontic treatment and decreased during the retention period. Compared to the stable group, lingual ABH and L1-BMe at T2 was significantly higher, and lingual ABT was smaller in the unstable group.

CONCLUSION

Post-treatment lingual alveolar bone defects of the mandibular incisors could recover to some extent during the retention period. There was a negative correlation between post-treatment L1-BMe and mandibular incisor stability.

Extraction vs nonextraction orthodontic treatment: a systematic review and meta-analysis

OBJECTIVES

To compare four first premolar extraction and nonextraction treatment effects on intra-arch width, profile, treatment duration, occlusal outcomes, smile aesthetics and stability.

MATERIALS AND METHODS

An electronic search of the literature to June 2, 2023 was conducted using health science databases, with additional search of gray literature, unpublished material, and hand searching, for studies reporting nonsurgical patients with fixed appliances regarding sixteen sub-outcomes. Data extraction used customized forms, quality assessed with ROBINS-I (Risk Of Bias In Non-randomized Studies-of Interventions) and Cochrane RoB 2 (risk-of-bias) tool. GRADE (Grading of Recommendations Assessment, Development and Evaluation) assessed certainty of evidence.

RESULTS

Thirty (29 retrospective studies, 1 randomized controlled trial) studies were included. Random-effect meta-analysis (95% CI) demonstrated maxillary (MD: -2.03 mm; [-2.97, -1.09]; P < .0001) and mandibular inter-first molar width decrease (MD: -2.00 mm; [-2.71, -1.30]; P < .00001) with four first premolar extraction; mandibular intercanine width increase (MD: 0.68 mm; [0.36, 0.99]; P < .0001) and shorter treatment duration (MD: 0.36 years; [0.10, 0.62]; P = .007) in the nonextraction group. Narrative synthesis included three and five studies for upper and lower lip-E plane, respectively. For American Board of Orthodontics Objective Grading System and maxillary/mandibular anterior alignment (Little's irregularity index), each included two studies with inconclusive evidence. There were no eligible studies for UK Peer Assessment Rating (PAR) score. Class I subgroup/sensitivity analyses favored the same results. Prediction interval indicated no significant difference for all outcomes.

CONCLUSIONS

Four first premolar extraction results in maxillary and mandibular inter-first molar width decrease and retraction of upper/lower lips. Nonextraction treatment results in mandibular intercanine width increase and shorter treatment duration. There was no significant difference between the two groups regarding maxillary intercanine width, US PAR score, and posttreatment smile esthetics. Further high-quality focused research is recommended.

Long-term stability of mandibular incisor alignment in patients treated nonextraction with or without interproximal enamel reduction

INTRODUCTION

This study aimed to compare long-term mandibular incisor stability in nongrowing patients with moderate crowding treated nonextraction with and without interproximal enamel reduction (IPR).

METHODS

Forty-two nongrowing patients with Class I dental and skeletal malocclusion with moderate crowding were divided into 2 groups with an equal number of patients depending on whether IPR was used (IPR group) or not (non-IPR group) during treatment. All patients were treated by the same practitioner and used thermoplastic retainers full-time for 12 ± 1 months at the end of the active treatment. Changes in Peer Assessment Rating scores, Little's irregularity index (LII), intercanine width (ICW), and mandibular incisor inclination (IMPA and L1-NB°) were evaluated using pretreatment, posttreatment, and 8 ± 1 years postretention dental models and lateral cephalograms.

RESULTS

At the end of the treatment, Peer Assessment Rating scores and LII decreased, and ICW, IMPA, and L1-NB° increased significantly (P <0.001) in both groups. At the end of the postretention period, in both groups, LII increased, and ICW decreased significantly (P <0.001) compared with posttreatment values, whereas IMPA and L1-NB remained stable. When treatment changes were compared, increases in ICW, IMPA, and L1-NB were significantly (P <0.001) higher in the non-IPR group. When postretention changes were compared, the only significant difference between 2 groups was observed in ICW. The decrease in ICW was significantly higher in the non-IPR group.

CONCLUSIONS

Long-term stability of mandibular incisor alignment in Class I nongrowing patients with moderate crowding treated nonextraction with and without IPR was similar.

The influence of 3x3 bonded retainer on anterior crowding relapse in mandibular incisor extraction cases

Objective:

To evaluate the 3x3 bonded retainer influence on the mandibular anterior crowding in cases treated with mandibular incisor extraction

Methods:

The sample comprised pretreatment, posttreatment and follow-up orthodontic records of 16 subjects (10 females and 6 males) with Class I malocclusion treated with extraction of a single mandibular incisor. The mean ages (± SD) at pretreatment, posttreatment and follow-up evaluation were 23.45 ± 9.14 years, 25.50 ± 8.95 years and 30.11 ± 8.59 years, respectively. The mean (± SD) treatment time and posttreatment evaluation time were 2.05 ± 0.45 years and 4.60 ± 1.85 years , respectively. Little irregularity index and interdental widths were evaluated using dental casts. The sample was divided into two subgroups, according to the presence of the 3x3 bonded retainer at follow-up.

Results:

The subgroup without 3x3 bonded retainer presented a greater relapse at the follow-up, when compared to 3x3 bonded retainer subgroup.

Conclusion:

There was a significant relapse in cases treated with mandibular incisor extraction at follow-up. The subgroup without 3x3 bonded retainer showed a significant relapse at the follow-up when compared to the retainer group.

Occlusal changes in orthodontically treated subjects 40 years after treatment and comparison with untreated control subjects

INTRODUCTION

The objective of this study was to compare the aging changes of the dental arches in orthodontically treated and untreated subjects after a 4-decade follow-up period.

METHODS

This retrospective study analyzed 2 groups. The treated group comprised 29 patients (11 male, 18 female) presenting with Class I or Class II malocclusions orthodontically treated with extractions of 4 first premolars. Dental models taken at pretreatment (12.84 years), posttreatment (14.95 years), and long-term posttreatment (51.37 years) were evaluated. The untreated (control) group consisted of 22 untreated patients with dental models taken at 13.32, 17.82, and 60.95 years of age. The dental models were digitized, and the following variables were evaluated: Little irregularity index, intercanine, interpremolar and intermolar widths, arch length, arch perimeter, overjet, and overbite. Interphase comparison of the treated group was performed with repeated measures analysis of variance and Tukey tests. Intergroup comparisons were performed using t tests (P <0.05).

RESULTS

Crowding was corrected with treatment but relapsed significantly in the long term. Intercanine width increased with treatment and decreased in the long term. Interpremolar and intermolar widths, arch perimeter, and length decreased with treatment and continued to decrease long-term posttreatment. Overjet and overbite were corrected with treatment and remained stable in the long term. From posttreatment to long-term posttreatment, a greater crowding increase was observed in the treated group than in the untreated group. The treated group demonstrated a greater decrease in mandibular intercanine and maxillary and mandibular interpremolar widths than the untreated sample. Overbite increased in the treated group and decreased in the untreated group. The multiple regression analysis showed that previous 4-premolar extractions orthodontic treatment is significantly associated with anterior crowding in the long term.

CONCLUSIONS

In the long-term, the treated patients showed relapse of crowding and a decrease in arch form. Long-term changes of treated patients were different from untreated subjects. Relapse might have contributed to greater changes in incisor crowding and arch widths observed in the treated patients.

Stability of maxillary interincisor diastema closure after extraction orthodontic treatment

OBJECTIVES

To evaluate the stability of maxillary interincisor diastema closure and the relationship between space relapse and interincisor diastema width, overjet, overbite, angulations between adjacent maxillary anterior teeth and presence of intermaxillary osseous cleft after orthodontic treatment with extractions.

MATERIALS AND METHODS

Twenty-four individuals with a maxillary interincisor diastema pretreatment, treated with maxillary first premolar extractions were evaluated. Dental casts and panoramic radiographs taken at pretreatment (T1), posttreatment (T2), and posttreatment follow-up (T3) were assessed. Periapical radiographs at T1 and T2 were also evaluated. Diastema relapse was assumed when T3-T2 interincisor space change was greater than zero. Diastema relapse was considered clinically significant when it was at least 0.50 mm. Data were analyzed using repeated-measures analysis of variance followed by post hoc Tukey tests or Friedman followed by Wilcoxon tests. T-test or Mann-Whitney U-test, Pearson correlation coefficient, and multiple linear regression analyses were also performed.

RESULTS

No statistically significant relapse of maxillary interincisor diastemas was found. The percentage of clinically significant relapse of the maxillary interincisor diastemas was 27.78%. Specifically, for the interincisor midline diastema, it was 8.33%.

CONCLUSIONS

Maxillary interincisor diastema closure showed no statistically significant relapse after orthodontic treatment with premolar extractions. Clinically significant stability for maxillary interincisor diastema closure was 72.22% and, specifically, for interincisor midline diastema closure, it was 91.67%.

Long-Term Outcomes of Nonextraction Treatment in a Patient with Severe Mandibular Crowding

OBJECTIVE

To describe a clinical case with a severe mandibular crowding treated without extraction and showing a long-term outcome.

METHODS

A 14-year-old boy in permanent dentition showed a class I molar and cuspid relationship, a severe deep bite of 8 mm, a constricted V-shaped upper arch with moderate crowding, and a severe crowding of about 12 mm in the lower arch. The panoramic X-ray showed an impacted upper right canine. The treatment started with the placement of a transpalatal bar and 0.022 × 0.028 in standard edgewise appliances in the upper arch and a lip bumper bonded on the second lower molars. Initial leveling of the teeth was accomplished with light Australian round wires. Finishing was then performed with rectangular wires. The phase with fixed appliances lasted 2 years and 9 months, and the patient was motivated and cooperative throughout the treatment, although with poor oral hygiene. The patient was treated without extractions.

RESULTS

The space was gained with the first and second upper molar derotations using the transpalatal bar and the gingival lip bumper in the lower arch. The upper right canine was well positioned, and the maxillary arch form was improved. The severe lower crowding was completely corrected, and a good overbite was achieved.

CONCLUSION

A conservative, nonextraction treatment approach for this patient with class I malocclusion with severe mandibular crowding was effective, and the results have remained stable after a long-term follow-up (10 years).

Evaluation of the influence of mandibular third molars on mandibular anterior crowding relapse

Objective: To evaluate the influence of mandibular third molars on relapse of mandibular anterior crowding in orthodontically treated patients.Material and Methods: Sample included orthodontic records of 108 patients: Group 1: 72 patients (39 female; 33 male) with third molars present in the postretention evaluation stage. Group 2: 36 patients (18 female; 18 male) who did not present the third molars in the postretention evaluation stage. Panoramic radiographs and dental models were evaluated at three different stages: pre-treatment; posttreatment and postretention. Panoramic radiographs showed the presence or absence of third molars in the 3 evaluated stages and on the dental models, overbite and mandibular anterior crowding was measured by the Little Irregularity Index. For intergroup comparisons, t-tests and a multifactorial regression analysis were used.Results: There was no statistically significant difference in the relapse of mandibular anterior crowding among the groups with and without mandibular third molars at the postretention stage.Conclusion: The presence or absence of mandibular third molars did not influence the relapse of mandibular anterior crowding in orthodontically treated patients.

Tooth extractions in Orthodontics: first or second premolars?

Tooth crowding and protrusions demand rigorous attention during orthodontic planning that includes the extraction of first and second premolars. Some characteristics, such as dentoalveolar bone discrepancies, maxillomandibular relations, facial profile, skeletal maturation, dental asymmetries and patient cooperation, are important elements of an orthodontic diagnosis. This study discusses the options of treatments with extractions and describes the correction of a Class I malocclusion, bimaxillary protrusion, severe anterior crowding in both dental arches and tooth-size discrepancy, using first premolar extractions.

Liquid Chromatography Mass Spectrometry (LC-MS) analysis in determining the saliva protein of orthodontic patients during retention phase

Background

The biological responses involved during retention phase have been studied for many years but little is known about the effect of saliva proteome during retention phase of post-orthodontic treatment. This study aims to identify the protein profiles during retention phase in relation to biological processes involved by Liquid Chromatography Mass Spectrometry (LC-MS) approach.

Material and Methods

A total of 5 ml of unstimulated saliva was collected from each subject (10 non-orthodontic patients and 15 post-orthodontic patients with 6-months retention phase). Samples were then subjected to LC-MS analysis. The expressed proteins were identified and compared between groups. Incisor irregularity for both maxilla and mandible were determined with Little’s Irregularity Index at 6-months retention phase.

Results

146 proteins and 135 proteins were expressed in control and 6-months retention phase group respectively. 15 proteins were identified to be co-expressed between groups. Immune system process was only detected in 6-months retention phase group. Detected protein in immune system process was identified as Tyrosine-protein kinase Tec. Statistical significant of incisor irregularity was only found in mandible at 6-months retention phase.

Conclusions

Our study suggests that immune system process protein which is Tyrosine-protein kinase Tec could be used as biomarker for prediction of stability during retention phase of post-orthodontic treatment.

Key words:Orthodontics, proteomics, retention, LC-MS, saliva.

Candidate gene analyses of 3-dimensional dentoalveolar phenotypes in subjects with malocclusion

INTRODUCTION

Genetic studies of malocclusion etiology have identified 4 deleterious mutations in genes DUSP6,ARHGAP21, FGF23, and ADAMTS1 in familial Class III cases. Although these variants may have large impacts on Class III phenotypic expression, their low frequency (<1%) makes them unlikely to explain most malocclusions. Thus, much of the genetic variation underlying the dentofacial phenotypic variation associated with malocclusion remains unknown. In this study, we evaluated associations between common genetic variations in craniofacial candidate genes and 3-dimensional dentoalveolar phenotypes in patients with malocclusion.

METHODS

Pretreatment dental casts or cone-beam computed tomographic images from 300 healthy subjects were digitized with 48 landmarks. The 3-dimensional coordinate data were submitted to a geometric morphometric approach along with principal component analysis to generate continuous phenotypes including symmetric and asymmetric components of dentoalveolar shape variation, fluctuating asymmetry, and size. The subjects were genotyped for 222 single-nucleotide polymorphisms in 82 genes/loci, and phenotpye-genotype associations were tested via multivariate linear regression.

RESULTS

Principal component analysis of symmetric variation identified 4 components that explained 68% of the total variance and depicted anteroposterior, vertical, and transverse dentoalveolar discrepancies. Suggestive associations (P < 0.05) were identified with PITX2, SNAI3, 11q22.2-q22.3, 4p16.1, ISL1, and FGF8. Principal component analysis for asymmetric variations identified 4 components that explained 51% of the total variations and captured left-to-right discrepancies resulting in midline deviations, unilateral crossbites, and ectopic eruptions. Suggestive associations were found with TBX1AJUBA, SNAI3SATB2, TP63, and 1p22.1. Fluctuating asymmetry was associated with BMP3 and LATS1. Associations for SATB2 and BMP3 with asymmetric variations remained significant after the Bonferroni correction (P <0.00022). Suggestive associations were found for centroid size, a proxy for dentoalveolar size variation with 4p16.1 and SNAI1.

CONCLUSIONS

Specific genetic pathways associated with 3-dimensional dentoalveolar phenotypic variation in malocclusions were identified.

Smile esthetics: Evaluation of long-term changes in the transverse dimension

Objective

To analyze the long-term changes in maxillary arch widths and buccal corridor ratios in orthodontic patients treated with and without premolar extractions.

Methods

The study included 53 patients who were divided into the extraction (n = 28) and nonextraction (n = 25) groups. These patients had complete orthodontic records from the pretreatment (T1), posttreatment (T2), and postretention (T3) periods. Their mean retention and postretention times were 4 years 2 months and 17 years 8 months, respectively. Dental models and smiling photographs from all three periods were digitized to compare the changes in three dental arch width measurements and three buccal corridor ratios over time between the extraction and nonextraction groups. Data were analyzed using analysis of variance tests. Post-hoc multiple comparisons were made using Bonferroni correction.

Results

Soft-tissue extension during smiling increased with age in both groups. The maximum dental width to smile width ratio (MDW/SW) also showed a favorable increase with treatment in both groups (p < 0.05), and remained virtually stable at T3 (p > 0.05). According to the MDW/SW ratio, the mean difference in the buccal corridor space of the two groups was 2.4 ± 0.2% at T3. Additionally, no significant group × time interaction was found for any of the buccal corridor ratios studied.

Conclusions

Premolar extractions did not negatively affect transverse maxillary arch widths and buccal corridor ratios. The long-term outcome of orthodontic treatment was comparable between the study groups.

Effect of orthodontic treatment on the upper airway volume in adults

INTRODUCTION

The aim of this study was to examine the effects of orthodontic treatment with and without extractions on the anatomic characteristics of the upper airway in adults.

METHODS

For this retrospective study, the pretreatment and posttreatment cone-beam computed tomography scans of 74 adult patients meeting defined eligibility criteria were analyzed. Imaging software was used to segment and measure upper airway regions including the nasopharynx, the retropalatal, and retroglossal areas of the oropharynx, as well as the total airway. The Wilcoxon signed rank test was used to compare volumetric and minimal cross-sectional area changes from pretreatment to posttreatment.

RESULTS

The reliability values were high for all measurements, with intraclass correlation coefficients of 0.82 or greater. The volumetric treatment changes for the extraction and nonextraction groups were as follows: total airway, 1039.6 ± 3674.3 mm³ vs 1719.2 ± 4979.2 mm³; nasopharynx, 136.1 ± 1379.3 mm³ vs -36.5 ± 1139.8 mm³; retropalatal, 412.7 ± 3042.5 mm³ vs 399.3 ± 3294.6 mm³; and retroglossal, 412.5 ± 1503.2 mm³ vs 1109.3 ± 2328.6 mm³. The treatment changes in volume or minimal cross-sectional area for all airway regions examined were not significantly (P >0.05) different between the extraction and nonextraction groups.

CONCLUSIONS

Orthodontic treatment in adults does not cause clinically significant changes to the volume or the minimally constricted area of the upper airway. These results suggest that dental extractions in conjunction with orthodontic treatment have a negligible effect on the upper airway in adults.