Arch-width and perimeter changes in patients with borderline Class I malocclusion treated with extractions or without extractions with air-rotor stripping

Comparative assessment of the clinical outcomes of clear aligners compared to fixed appliance in class II malocclusion

OBJECTIVE

This study compared clinical outcomes between aligners and fixed appliances in class II adolescent patients.

MATERIALS AND METHODS

Records of 31 aligners and 35 fixed class II patients, aged 13.5 ± 1.6 years were compared. Class II elastics was the mechanism employed for correcting the malocclusion. DI scores were used to compare initial complexity, and the PAR index scores were used to compare the clinical outcomes. Data on demographics, treatment and finishing durations, number of visits and refinements, duration of class II correction, and changes in the IMPA were collected.

RESULTS

The mean pre-, post-treatment, and overall reduction in PAR index scores between the groups were not significantly different (P > 0.05). The clear aligners group had significantly shorter treatment duration (20.0 ± 11.6 months) than the fixed group (27.4 ± 9.1 months) (P < 0.001). The number of visits for the aligners' group was significantly less (12.7 ± 6.2) than in the fixed group (17.8 ± 5.8) (P < 0.001). Duration for class II correction was significantly shorter for clear aligners (13.3 ± 10.0 months) compared to the fixed group (17.4 ± 9.0 months) (P = 0.026). A smaller post-treatment change in IMPA (2 ± 6°) was detected in the aligners group compared to the fixed group (5 ± 6°) (P < 0.05).

CONCLUSIONS

Treatment outcomes for aligners in class II adolescent patients were comparable to those achieved in fixed appliances. Shorter treatment and class II correction durations, fewer visits, and better control for the IMPA were noticed in the aligners' group.

CLINICAL RELEVANCE

Treating class II adolescent patients with aligners seems promising and demands shorter treatment time and fewer visits.

Evaluation of different machine learning algorithms for extraction decision in orthodontic treatment

INTRODUCTION

The extraction decision significantly affects the treatment process and outcome. Therefore, it is crucial to make this decision with a more objective and standardized method. The objectives of this study were (1) to identify the best-performing model among seven machine learning (ML) models, which will standardize the extraction decision and serve as a guide for inexperienced clinicians, and (2) to determine the important variables for the extraction decision.

METHODS

This study included 1000 patients who received orthodontic treatment with or without extraction (500 extraction and 500 non-extraction). The success criteria of the study were the decisions made by the four experienced orthodontists. Seven ML models were trained using 36 variables; including demographic information, cephalometric and model measurements. First, the extraction decision was performed, and then the extraction type was identified. Accuracy and area under the curve (AUC) of the receiver operating characteristics (ROC) curve were used to measure the success of ML models.

RESULTS

The Stacking Classifier model, which consists of Gradient Boosted Trees, Support Vector Machine, and Random Forest models, showed the highest performance in extraction decision with 91.2% AUC. The most important features determining extraction decision were maxillary and mandibular arch length discrepancy, Wits Appraisal, and ANS-Me length. Likewise, the Stacking Classifier showed the highest performance with 76.3% accuracy in extraction type decisions. The most important variables for the extraction type decision were mandibular arch length discrepancy, Class I molar relationship, cephalometric overbite, Wits Appraisal, and L1-NB distance.

CONCLUSION

The Stacking Classifier model exhibited the best performance for the extraction decision. While ML models showed a high performance in extraction decision, they could not able to achieve the same level of performance in extraction type decision.

The Role of Interproximal Reduction (IPR) in Clear Aligner Therapy: A Critical Analysis of Indications, Techniques, and Outcomes

Interproximal reduction (IPR) has become a standard practice in orthodontic treatment, particularly in the clear aligner therapy. It became an integral part of the digital plan when using clear aligners. Given the irreversible nature of IPR, precise planning and performance is essential. This article aims to analyze and summarize the existing literature on IPR in the context of clear aligners. The goal is to help clinicians to gain essential knowledge for safely and effectively navigating IPR. The review critically examines different perspectives found in the literature, covering indications, methods, and outcomes. Topics exploring the impact of IPR on treatment outcomes include space gaining, addressing tooth size discrepancies, tooth shape adjustments, resolving malocclusion, and enhancing aesthetics. Emphasizing precision of the procedure by the clinician and awareness of contraindications, the article also discusses the impact of IPR on patients. This includes considerations like increased pulp temperature, susceptibility to cavities due to changes in enamel roughness, effects on soft tissues, and post-IPR tooth sensitivity.

Assessment of interproximal enamel reduction planned by the digital set-up of a customized lingual orthodontic appliance: A comparison cohort study

Objectives

Interproximal enamel reduction (IER), commonly known as stripping, is a frequently used technique in orthodontic treatment to address issues related to arch length discrepancies and tooth size discrepancies (TSD). The use of digital set-up allows for precise prediction of the amount of IER required. TSD occurs when the sizes of maxillary and mandibular teeth are not in proportion to each other. This study aims to evaluate and compare the suggested IER values generated by the digital set-up of a customized lingual orthodontic appliance in both upper and lower arches, across sextants, and among different teeth concerning TSD.

Materials and methods

We analyzed suggested IER values from 809 cases. The statistical analysis was divided into two parts: part 1 focused on the number of stripped surfaces, and part 2 assessed the quantity of enamel removed. Comparisons were made between upper and lower arches, sextants, and teeth using the Friedman test, followed by pairwise Wilcoxon tests with Bonferroni correction.

Results

The study found that mandibular and frontal stripping were more frequently suggested than maxillary and posterior stripping. Lower canines were the teeth most commonly recommended for stripping, followed by upper incisors.

Conclusion

Within the scope and limits of this cohort study, we conclude that, in general, more IER is required in the mandible as compared to the maxilla. Particularly in the anterior sextants, IER might be necessary to achieve optimal alignment and occlusion.

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.

Effects of interproximal enamel reduction techniques used for orthodontics: A systematic review

This systematic review aimed to determine the effects of the interproximal enamel reduction (IPR) techniques used in orthodontics. Six databases were searched: PubMed, Scopus, Web of Science, Dentistry & Oral Sciences Source, ScienceDirect and Clinical Trials. Grey literature was sourced from Google Scholar. The risk of bias was assessed by Risk of Bias 2, Newcastle-Ottawa Scale and Robins-I depending on the design of the evaluated study. Additionally, the quality of the included studies was determined using Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. This systematic review included randomized clinical trials, non-randomized clinical trials and observational studies with a control group that reported the effects of IPR for orthodontic purposes on the teeth and periodontium. Case reports, and in vitro and in vivo studies were excluded. Eight clinical studies match the eligibility criteria. As a result, no demineralization of the enamel, no increase in caries incidence, no periodontal changes or dental sensitivity was found after IPR. Also, considering the duration of orthodontic treatment, IPR resulted in a quicker technique than dental extractions. At the risk-of-bias assessment, all observational studies showed low risk, the non-randomized clinical trial had a critical bias, and all randomized clinical trials exhibited some concerns. The overall quality of the studies was found to be between low and very low. After the analysis of the data from included studies, it was concluded that the IPR procedures could be useful to treat dental crowding in orthodontic clinical practice without negative effects. However, more randomized controlled clinical trials with a longer follow-up time and high-quality studies are required to generate robust statements.

Orthodontic treatment for crowded teeth in children

BACKGROUND

Crowded teeth develop when there is not enough space in the jaws into which the teeth can erupt. Crowding can affect baby teeth (deciduous dentititon), adult teeth (permanent dentition), or both, and is a common reason for referral to an orthodontist. Crowded teeth can affect a child's self-esteem and quality of life. Early loss of baby teeth as a result of tooth decay or trauma, can lead to crowded permanent teeth. Crowding tends to increase with age, especially in the lower jaw.

OBJECTIVES

To assess the effects of orthodontic intervention for preventing or correcting crowded teeth in children. To test the null hypothesis that there are no differences in outcomes between different orthodontic interventions for preventing or correcting crowded teeth in children.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched four bibliographic databases up to 11 January 2021 and used additional search methods to identify published, unpublished and ongoing studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that evaluated any active interventions to prevent or correct dental crowding in children and adolescents, such as orthodontic braces or extractions, compared to no or delayed treatment, placebo treatment or another active intervention. The studies had to include at least 80% of participants aged 16 years and under.

DATA COLLECTION AND ANALYSIS

Two review authors, independently and in duplicate, extracted information regarding methods, participants, interventions, outcomes, harms and results. We resolved any disagreements by liaising with a third review author. We used the Cochrane risk of bias tool to assess the risk of bias in the studies. We calculated mean differences (MDs) with 95% confidence intervals (CI) for continuous data and odds ratios (ORs) with 95% CIs for dichotomous data. We undertook meta-analysis when studies of similar comparisons reported comparable outcome measures, using the random-effects model. We used the I² statistic as a measure of statistical heterogeneity.

MAIN RESULTS

Our search identified 24 RCTs that included 1512 participants, 1314 of whom were included in analyses. We assessed 23 studies as being at high risk of bias and one as unclear.  The studies investigated 17 comparisons. Twenty studies evaluated fixed appliances and auxiliaries (lower lingual arch, lower lip bumper, brackets, archwires, lacebacks, headgear and adjunctive vibrational appliances); two studies evaluated removable appliances and auxiliaries (Schwarz appliance, eruption guidance appliance); and two studies evaluated dental extractions (lower deciduous canines or third molars). The evidence should be interpreted cautiously as it is of very low certainty. Most interventions were evaluated by a single study. Fixed appliances and auxiliaries One study found that use of a lip bumper may reduce crowding in the early permanent dentition (MD -4.39 mm, 95% CI -5.07 to -3.71; 34 participants). One study evaluated lower lingual arch but did not measure amount of crowding. One study concluded that coaxial nickel-titanium (NiTi) archwires may cause more tooth movement in the lower arch than single-stranded NiTi archwires (MD 6.77 mm, 95% CI 5.55 to 7.99; 24 participants). Another study, comparing copper NiTi versus NiTi archwires, found NiTi to be more effective for reducing crowding (MD 0.49 mm, 95% CI 0.35 to 0.63, 66 participants). Single studies did not show evidence of one type of archwire being better than another for Titinol versus Nitinol; nickel-titanium versus stainless steel or multistrand stainless steel; and multistranded stainless steel versus stainless steel.  Nor did single studies find evidence of a difference in amount of crowding between self-ligating and conventional brackets, active and passive self-ligating brackets, lacebacks added to fixed appliances versus fixed appliances alone, or cervical pull headgear versus minor interceptive procedures. Meta-analysis of two studies showed no evidence that adding vibrational appliances to fixed appliances reduces crowding at 8 to 10 weeks (MD 0.24 mm, 95% CI -0.81 to 1.30; 119 participants). Removable appliances and auxiliaries One study found use of the Schwarz appliance may be effective at treating dental crowding in the lower arch (MD -2.14 mm, 95% CI -2.79 to -1.49; 28 participants). Another study found an eruption guidance appliance may reduce the number of children with crowded teeth after one year of treatment (OR 0.19, 95% CI 0.05 to 0.68; 46 participants); however, this may have been due to an increase in lower incisor proclination in the treated group. Whether these gains were maintained in the longer term was not assessed. Dental extractions One study found that extracting children's lower deciduous canines had more effect on crowding after one year than no treatment (MD -4.76 mm, 95 CI -6.24 to -3.28; 83 participants), but this was alongside a reduction in arch length. One study found that extracting wisdom teeth did not seem to reduce crowding any more than leaving them in the mouth (MD -0.30 mm, 95% CI -1.30 to 0.70; 77 participants).

AUTHORS' CONCLUSIONS

Most interventions were assessed by single, small studies. We found very low-certainty evidence that lip bumper, used in the mixed dentition, may be effective for preventing crowding in the early permanent dentition, and a Schwarz appliance may reduce crowding in the lower arch. We also found very low-certainty evidence that coaxial NiTi may be better at reducing crowding than single-stranded NiTi, and that NiTi may be better than copper NiTi. As the current evidence is of very low certainty, our findings may change with future research.

Extraction or Nonextraction in Orthodontic Cases: A Review

Orthodontic treatment helps bring teeth in alignment. There is always debate whether tooth should be extracted or not for treating crowding. The present article highlights various advantages and disadvantages of extraction.

Comparative evaluation of soft tissue changes in Class I borderline patients treated with extraction and nonextraction modalities

Objective:

To compare soft tissue changes in Class I borderline cases treated with extraction and nonextraction modalities.

Methods:

A parent sample of 150 patients with Class I dental and skeletal malocclusion (89 patients treated with premolar extraction and 61 patients without extraction) was randomly selected and subjected to discriminant analysis which identified the borderline sample of 44 patients (22 extraction and 22 nonextraction patients). Pretreatment and post-treatment cephalograms of the borderline subsample were analyzed using 22 soft tissue parameters.

Results:

Upper and lower lips were more retracted and thickness of the upper lip increased more in the borderline extraction cases (p < 0.01). The nasolabial angle became more obtuse and the interlabial gap was reduced in the borderline extraction cases (p < 0.01). Lower lip, interlabial gap and nasolabial angle showed no changes in the borderline nonextraction cases.

Conclusion:

The soft tissue parameters which can be used as guideline in decision making to choose either extraction or nonextraction in Class I borderline cases are upper and lower lip protrusion in relation to the E-plane and Sn-Pg' line, lower lip protrusion in relation to the true vertical line (TVL), upper lip thickness, nasolabial angle and interlabial gap.

Arch-width changes in extraction vs nonextraction treatments in matched Class I borderline malocclusions

INTRODUCTION

The aims of this study were to identify a sample of borderline Class I extraction and nonextraction patients and to investigate posttreatment changes in arch-width and perimeter measurements.

METHODS

A parent sample of 580 Class I patients was subjected to discriminant analysis, and a borderline subsample of 62 patients, 31 treated with extraction of 4 first premolars and 31 treated without extractions, was obtained. The patients' plaster casts were digitally scanned, and the maxillary and mandibular intercanine and intermolar widths and perimeters were assessed.

RESULTS

The extraction group showed increases in maxillary and mandibular intercanine widths (P <0.001) and decreases in mandibular intermolar width and in maxillary and mandibular perimeters (P <0.001). The nonextraction group showed increases in all 4 arch-width measurements (P ≤0.003), whereas the maxillary and mandibular perimeters were maintained. The posttreatment differences between the 2 groups showed significant differences in the maxillary (P <0.001) and mandibular intermolar widths (P <0.001). Also, the comparison of the arch perimeters between the 2 treatment groups showed adjusted differences of -8.51 mm (P <0.001) and -8.44 mm (P <0.001) for the maxillary and mandibular arches, respectively. The intercanine widths showed no changes between the 2 treatment groups.

CONCLUSIONS

Borderline Class I patients treated with extraction of 4 first premolars had decreased maxillary and mandibular intermolar and perimeter measurements compared with nonextraction patients. The maxillary and mandibular intercanine widths showed no significant difference between the 2 treatment groups.

Arch width changes in patients with Class II division 1 malocclusion treated with maxillary first premolar extraction and non-extraction method

Background

The aim of this study was to determine arch width changes during maxillary first premolars extraction and non-extraction treatment in patients with Class II division 1 malocclusion.

Material and Methods

Dental casts of 91 Class II division 1 patients (36 males and 55 females) were evaluated. The minimum age of the subjects at the beginning of treatment was above 16 years. 48 patients were treated with extraction of the maxillary first premolars and 43 patients were treated without extraction. Pre- and post-treatment maxillary and mandibular inter-canine and inter-molar arch widths were measured.

Results

At the end of treatment, maxillary and mandibular inter-canine widths of both groups increased significantly. The maxillary inter-molar width decreased in the extraction group and increased in the non-extraction group. The mandibular inter-molar width increased significantly in both groups. No significant differences were observed between males and females.

Conclusions

The results of this study indicated that there was a tendency for an increase in arch width during both the extraction and non-extraction treatment except maxillary inter-molar width in the extraction cases.

Key words:Dental arch, malocclusion, angle Class II, tooth movement, extraction.

Changes in mandibular incisor position and arch form resulting from Invisalign correction of the crowded dentition treated nonextraction

OBJECTIVE

To investigate changes in mandibular incisor position resulting from Invisalign correction of the crowded dentition without extraction.

MATERIALS AND METHODS

A retrospective chart review was completed on 61 adult White patients. Patients were categorized into three groups based on the value of pretreatment crowding of the lower dentition: 20 mild (2.0-3.9 mm), 22 moderate (4.0-5.9 mm), and 19 severe (>6.0 mm). Cephalometric radiographs were measured to determine lower incisor changes. Interproximal reduction and changes in arch width were also measured. Statistical evaluation of T0 and T1 values using paired t-tests and analysis of covariance were applied to evaluate mean value changes.

RESULTS

Lower incisor position and angulation changes were statistically significant in the severe crowding group. There were no statistically significant differences in lower incisor position between the mild and moderate crowding groups. There was a statistically significant increase in buccal expansion in each of the three groups.

CONCLUSIONS

Invisalign(®) treatment can successfully resolve mandibular arch crowding using a combination of buccal arch expansion, interproximal reduction, and lower incisor proclination. When there is <6 mm of crowding, lower incisor position remained relatively stable. The lower incisors proclined and protruded in the more severely crowded dentitions (>6 mm).

Interproximal wear versus incisors extraction to solve anterior lower crowding: a systematic review

OBJECTIVE

To determine by means of a systematic review the best treatment, whether interproximal wear or incisor extraction, to correct anterior lower crowding in Class I patients in permanent dentition.

METHODS

A literature review was conducted using MEDLINE, Scopus and Web of Science to retrieve studies published between January 1950 and October 2013. In selecting the sample, the following inclusion criteria were applied: studies involving interproximal wear and/or extraction of mandibular incisors, as well as Class I cases with anterior lower crowding in permanent dentition.

RESULTS

Out of a total of 943 articles found after excluding duplicates, 925 were excluded after abstract analysis. After full articles were read, 13 were excluded by the eligibility criteria and one due to methodological quality; therefore, only fours articles remained: two retrospective and two randomized prospective studies. Data were collected, analyzed and organized in tables.

CONCLUSION

Both interproximal wear and mandibular incisor extraction are effective in treating Class I malocclusion in permanent dentition with moderate anterior lower crowding and pleasant facial profile. There is scant evidence to determine the best treatment option for each case. Clinical decision should be made on an individual basis by taking into account dental characteristics, crowding, dental and oral health, patient's expectations and the use of set-up models.

Stability of changes in mandibular intermolar and intercuspid distances following orthodontic treatment

BACKGROUND

The aim of this study was to determine the pattern and amount of change exhibited in mandibular intercanine and intermolar width during treatment and assessing its stability1-3 years post-retention.

MATERIALS AND METHODS

The material consisted of 70 cases of which 20 cases were treated without extraction and 30 cases were treated with extraction, which were compared with 20 untreated cases which served as a control group. A series of three measurements were made for each case of the treated group: At the beginning of treatment, end of active treatment and 1-3 years post-retention; and for the control group: At 12, 15 and 18 years of age. The Wilcoxon signed ranks test was used to evaluate treatment changes in each group. The Kruskal-Wallis H test was used to compare the treatment changes between the 3 groups (α = 0.05). SPSS 16 software (SPSS Inc., Chicago, IL, USA) was used to evaluate the data.

RESULTS

Mean changes of intercanine width for three groups was -0.5 mm for control group, -0.26 mm for non-extraction group and +0.18 mm for extraction group. Intermolar width of the extraction group decreased significantly during treatment. In contrast to the extraction group, the control and non-extraction groups both demonstrated an increase in mean intermolar width which was 0.66 mm and 0.91 mm respectively.

CONCLUSION

It was concluded that although mean changes of intercanine and intermolar width were statistically significant but they were not perceptible clinically.