Extraction frequencies at a university orthodontic clinic in the 21st century: Demographic and diagnostic factors affecting the likelihood of extraction

Long-term relapse of anterior teeth in orthodontic patients treated with and without premolar extractions using a 3-dimensional surface mesh analysis

INTRODUCTION

The study evaluated the long-term postretention changes in patients with borderline crowding treated with and without premolar extractions using 3-dimensional surface registration analyses and 2-dimensional (2D) conventional measurements.

METHODS

The study sample comprised 29 nonextraction patients (nonextraction group [NG]) and 33 extractions (extraction group [EG]). Cephalometric radiographs and dental models of the included patients were used from pretreatment, posttreatment, and postretention. Retention durations were 3.76 ± 1.26 years and 4.52 ± 1.94 years in the NG and EG, respectively. The postretention follow-up period was 17.06 ± 5.83 years for the EG and 14.30 ± 5.70 years for the NG, with similar long-term observations. Maxillary and mandibular superimpositions were performed using 3-dimensional digital scans of the dental models and commercial software. In addition, conventional 2D model measurements and the irregularity index were also assessed.

RESULTS

The investigated parameters regarding the surface changes showed nonsignificant differences (P >0.05) between the 2 groups in the maxillary and mandibular anterior 6 teeth, except for the under tolerance value (the percentage of mesh points that is less than the lower tolerance limit) in mandibular surface registrations (P <0.044). In both groups, the maxillary and mandibular irregularity index and maxillary and mandibular intercanine distances showed significant relapses (P <0.05).

CONCLUSIONS

Comparable surface change outcomes were observed in the NGs and EGs. However, the percentage of meshes exceeding the negative threshold value (-1 mm) of the mandibular dentition in the NG exceeded the EG, indicating more significant lingual movement and relapse of the incisors. In addition, the 2D conventional linear relapse measurements were well below the 3.5 mm threshold value reported in the literature. This finding indicated that both treatment approaches provide acceptable long-term stability in borderline patients when similar retention regimens are employed.

Changes in alveolar bone remodeling after maxillary anterior retraction using fixed appliances with different periodontal conditions: A retrospective study based on cone-beam computed tomography

INTRODUCTION

This study aimed to compare changes in maxillary anterior alveolar bone remodeling and complication rates in adult patients with different periodontal conditions after maxillary anterior tooth retraction using fixed appliances. In addition, this study analyzed potential factors affecting alveolar bone thickness in patients with periodontitis.

METHODS

A total of 55 adult patients (mean age, 23.53 ± 4.55 years) with Angle Class I or II Division 1 malocclusion with maxillary protrusion were recruited and categorized into the healthy control group (n = 23), stage I periodontitis (P-I) group (n = 17), and stage II periodontitis (P-II) group (n = 15). The maxillary anterior teeth were retracted using a fixed appliance. Cone-beam computed tomography was used to measure the thickness, height, and density of the alveolar bone in the maxillary anterior region before (T1) and after (T2) treatment. The incidences of bone dehiscence and fenestration were documented. Statistical analysis was conducted to evaluate intergroup and intragroup differences. Clinical and cephalometric data were collected to identify factors affecting the changes in alveolar bone thickness using multivariate linear regression analysis.

RESULTS

The labial alveolar bone thickness increased significantly after treatment in all groups, but no differences were observed among the groups. In contrast, the palatal alveolar bone thickness decreased, particularly in the P-I and P-II groups, at the midroot and apical levels (P <0.05). A significant decrease in alveolar bone height was observed in the P-I and P-II groups (P <0.05). The incidence of palatal bone dehiscence was higher in the P-II (84.44%) and P-I (69.61%) groups. Multivariate linear regression analyses revealed that sex, treatment duration, periodontal treatment, changes in tooth inclination, and initial thickness significantly affected palatal alveolar bone thickness changes in patients with periodontitis.

CONCLUSIONS

After retraction of the maxillary anterior teeth with a fixed appliance, the labial alveolar bone of the maxillary anterior teeth thickened, whereas the palatal bone exhibited thinning in adults with periodontitis. The reduction in palatal bone height was more significant in this population than in healthy subjects, along with a higher incidence of palatal bone dehiscence. Bone morphology must be carefully assessed, considering these relevant factors before and during orthodontic treatment.

Factors Influencing the Choice of Conservative and Surgical Procedures in Dental Patients from Poland: A Single-Center Retrospective Analysis

Background/Objectives: Oral health behaviors can be shaped by various factors, both global (such as the COVID-19 pandemic) and individual (e.g., gender, age). This retrospective study aims to assess the factors influencing the choice between conservative and surgical dental procedures among patients based on the example of the university specialized center in Poznan. Methods: We explored the patient dataset from the University Center of Dentistry and Specialized Medicine (Poznan, Poland), covering the period from 1 January 2017 to 31 December 2023. A total of 182,654 medical records were analyzed, focusing on procedures such as restorations, endodontic interventions, and extractions. Multivariate logistic regression and multidimensional correspondence analyses were employed to assess the impact of demographic factors (age and gender) and tooth-specific characteristics on clinical decisions. Results: Females, particularly younger, were more likely to choose restorative procedures, while males, especially those over 50, predominantly underwent surgical procedures. Endodontic treatments were most common in males aged 18-30, primarily for maxillary anterior teeth and premolars. Molar extractions, especially in the mandible, were the most frequent surgical procedure. Maxillary teeth, particularly canines and premolars, were more likely to be treated conservatively. Conclusions: Economic factors, limited treatment access, and variations in patient preference influenced the observed patterns. Despite a national trend toward increased conservative treatments, disparities persisted based on age, gender, and tooth type. These findings emphasize the need for targeted prevention strategies and equitable access to advanced dental care.

Evaluation of angular and positional changes of maxillary third molars following premolar extraction, molar distalization, and non-extraction treatments

BACKGROUND

To compare the effects of first premolar extraction, molar distalization, and non-extraction treatments on the angulation and vertical positions of maxillary second molars (MxM2s) and maxillary third molars (MxM3s). To our knowledge, this is the first study to compare the effects of three different treatment types on MxM3 simultaneously.

METHODS

Initial (T0) and final (T1) panoramic radiographs of three different patient groups were analyzed: first premolar extraction group (n = 26 patients, 52 MxM2, 52 MxM3), molar distalization group (n = 20 patients, 40 MxM2, 40 MxM3), and non-extraction group (n = 31 patients, 62 MxM2, 62 MxM3). Descriptive data, including growth pattern, crowding, overjet, overbite, and maxillary incisor inclination, were recorded. Angular changes of maxillary third molars (MxM3) relative to the Interorbital Plane (IOP) and Palatal Plane (PP), as well as changes in inclination and vertical position according to Archer's classification, were also documented. Differences between T0 and T1 within the same group were assessed using the paired sample t-test and Wilcoxon signed-rank test. Comparisons between groups were evaluated with one-way analysis of variance (ANOVA) and Kruskal-Wallis H test. The threshold for statistical significance was set at p < .05.

RESULTS

IOP and PP values of MxM2 and MxM3 showed significant improvement in the extraction group (EG)(p < .001). The improvement in MxM3 IOP and PP values was not significant in the distalization group (DG)(p = .196 and p = .544, respectively). According to Archer's classification, within-group comparisons revealed that the inclination and vertical position of MxM3 showed significant improvement in the EG, DG, and non-extraction groups (NEG)(inclination: p < .001 in EG, p = .032 in DG, p = .024 in NEG; vertical position: p < .001 in EG, p = .048 in DG, p < .001 in NEG). In between-group comparisons, the most significant improvement was observed in the EG. The number of MxM3 with vertical positions in Stages 1 and 2 at T1 were 19 in EG, 3 in DG, and 10 in NEG.

CONCLUSION

Premolar extraction has a positive effect on the angular and positional changes of MxM2 and MxM3. The changes in the inclination and vertical position of MxM3 between NEG and DG were not statistically significant.

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.

Second molar eruption disturbances in borderline extraction orthodontic patients

INTRODUCTION

Nonextraction treatment is associated with a greater prevalence of third molar impactions, whereas data on second molars are lacking. This study investigated whether there is a difference in the prevalence of second molar eruption disturbances when crowding is treated with or without extractions.

METHODS

Patients were grouped by maxillary and mandibular crowding, including mild crowding (<5 mm) without extractions, borderline crowding (5-9 mm) without extractions, and borderline crowding with extractions. The 535 evaluated arches were from 346 patients aged 10-15 years with unerupted second molars at treatment start. The frequency and severity of second molar eruption disturbances were scored in final records using a severity classification based on a modified Archer system, a hybrid Archer Pell-Gregory system, and a partial impaction scale. Pretreatment panoramic radiographs were scored for impaction-risk indicators. Fisher exact test was used.

RESULTS

In the maxilla, 20.0% of nonextraction patients with borderline crowding had second molar eruption disturbances compared to 5.2% of extraction patients with borderline crowding (P = 0.010). In the mandible, 27.6% of nonextraction borderline crowding patients had second molar eruption disturbances compared to 7.1% of extraction patients with borderline crowding (P = 0.006). There was no difference in the frequency of eruption disturbances between mild crowding without extractions and borderline crowding without extractions. The prevalence of impactions was higher in the maxilla when molars were apically positioned and in the mandible when molars were mesially angulated or had insufficient space pretreatment.

CONCLUSIONS

In patients with borderline crowding, extraction treatment reduces the risk of second molar eruption disturbances; however, nonextraction treatment does not increase the risk when compared with patients with mild crowding. When considering extractions for crowding, providers should evaluate second molar impaction-risk indicators on pretreatment radiographs.

Evaluation of four machine learning methods in predicting orthodontic extraction decision from clinical examination data and analysis of feature contribution

Introduction

The study aims to predict tooth extraction decision based on four machine learning methods and analyze the feature contribution, so as to shed light on the important basis for experts of tooth extraction planning, providing reference for orthodontic treatment planning.

Methods

This study collected clinical information of 192 patients with malocclusion diagnosis and treatment plans. This study used four machine learning strategies, including decision tree, random forest, support vector machine (SVM) and multilayer perceptron (MLP) to predict orthodontic extraction decisions on clinical examination data acquired during initial consultant containing Angle classification, skeletal classification, maxillary and mandibular crowding, overjet, overbite, upper and lower incisor inclination, vertical growth pattern, lateral facial profile. Among them, 30% of the samples were randomly selected as testing sets. We used five-fold cross-validation to evaluate the generalization performance of the model and avoid over-fitting. The accuracy of the four models was calculated for the training set and cross-validation set. The confusion matrix was plotted for the testing set, and 6 indicators were calculated to evaluate the performance of the model. For the decision tree and random forest models, we observed the feature contribution.

Results

The accuracy of the four models in the training set ranges from 82% to 90%, and in the cross-validation set, the decision tree and random forest had higher accuracy. In the confusion matrix analysis, decision tree tops the four models with highest accuracy, specificity, precision and F1-score and the other three models tended to classify too many samples as extraction cases. In the feature contribution analysis, crowding, lateral facial profile, and lower incisor inclination ranked at the top in the decision tree model.

Conclusion

Among the machine learning models that only use clinical data for tooth extraction prediction, decision tree has the best overall performance. For tooth extraction decisions, specifically, crowding, lateral facial profile, and lower incisor inclination have the greatest contribution.

Risk factors for gingival invagination: A retrospective study

AIM

This study aimed to identify the risk factors for gingival invagination during orthodontic treatment after premolar extraction.

MATERIALS AND METHODS

The medical records of 135 patients who had undergone interdental space closure after premolar extraction were collected, and cone beam computed tomography was performed to determine the presence of gingival invagination. The risk factors were examined using mixed-effects models and generalized propensity score weighting (GPSW) to develop a predictive model.

RESULTS

Univariate analysis revealed that the extraction site, buccal bone thickness 4 mm apical to the cemento-enamel junction (MB1), mid-root buccal bone thickness (MB2) and vertical skeletal relationships were related to gingival invagination (p < .05). Furthermore, a subsequent multivariable mixed-effects model analysis indicated a significantly increased risk of gingival invagination at MB1 < 1 mm (p < .001; odds ratio [ORMB1≤0.5mm] = 29.304; 95% confidence interval [CI]: 8.986-93.807; OR0.5

CONCLUSIONS

The risk of gingival invagination is higher in patients with MB1 < 1 mm and in normodivergent or hyperdivergent patients.

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Key Words

• gingiva
• orthodontics
• periodontal diseases
• risk factors
• tooth extraction

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MESH Headings

• Humans
• Female
• Retrospective Studies
• Male
• Risk Factors
• Cone-Beam Computed Tomography
• Bicuspid/diagnostic imaging
• Adult
• Gingival Diseases/etiology
• Adolescent
• Tooth Extraction/adverse effects
• Young Adult

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Grants

• 2022Z02 Applied Basic Research Program, Affiliated Stomatological Hospital of Southwest Medical University
• 2023ZYD0112 Centralized Guided Local Science and Technology Development Project

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Affiliation(s)

M Han Department of Orthodontics, The Affiliated Stomatological Hospital, Southwest Medical University, Luzhou, China
S H Li Department of Orthodontics, The Affiliated Stomatological Hospital, Southwest Medical University, Luzhou, China
Y Yao Department of Orthodontics, The Affiliated Stomatological Hospital, Southwest Medical University, Luzhou, China
Yijiao Zhao The Center of Digital Dentistry, Faculty of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, China
L P You Department of Orthodontics, The Affiliated Stomatological Hospital, Southwest Medical University, Luzhou, China
Q Zheng Department of Orthodontics, The Affiliated Stomatological Hospital, Southwest Medical University, Luzhou, China
X M Xu Department of Orthodontics, The Affiliated Stomatological Hospital, Southwest Medical University, Luzhou, China

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Collaborators Collapse

Effectiveness of Machine Learning in Predicting Orthodontic Tooth Extractions: A Multi-Institutional Study

The study aimed to evaluate the effectiveness of machine learning in predicting whether orthodontic patients would require extraction or non-extraction treatment using data from two university datasets. A total of 1135 patients, with 297 from University 1 and 838 from University 2, were included during consecutive enrollment periods. The study identified 20 inputs including 9 clinical features and 11 cephalometric measurements based on previous research. Random forest (RF) models were used to make predictions for both institutions. The performance of each model was assessed using sensitivity (SEN), specificity (SPE), accuracy (ACC), and feature ranking. The model trained on the combined data from two universities demonstrated the highest performance, achieving 50% sensitivity, 97% specificity, and 85% accuracy. When cross-predicting, where the University 1 (U1) model was applied to the University 2 (U2) data and vice versa, there was a slight decrease in performance metrics (ranging from 0% to 20%). Maxillary and mandibular crowding were identified as the most significant features influencing extraction decisions in both institutions. This study is among the first to utilize datasets from two United States institutions, marking progress toward developing an artificial intelligence model to support orthodontists in clinical practice.

Evaluating color change and hydrogen peroxide penetration in human and bovine teeth through in-office bleaching procedures

OBJECTIVE

Assess color alteration and hydrogen peroxide (HP) penetration in human and bovine teeth using various in-office bleaching protocols with different application times.

MATERIALS AND METHODS

Thirty healthy human premolars and 30 healthy bovine incisors were divided into five groups and subjected to different bleaching protocols: 2 × 15 min, 1 × 30 min, 2 × 20 min, or 1 × 40 min, with a control group for each tooth type. All teeth were treated with 35% HP gel. Color alteration was measured using digital spectrophotometry before and 1 week after bleaching. HP concentration within the pulp was determined via UV-Vis spectrophotometry. Statistical analysis included one-way ANOVA, Tukey's, and Dunnett's tests (α = 0.05).

RESULTS

All groups exhibited significant color alteration, with no statistically differences among them (p > 0.05). However, significant differences were observed when compared with their respective control groups (p < 0.05). HP penetration into the pulp was evident in all bleached teeth compared to the control groups (p < 0.05), with the 2 × 20 group showing the highest HP levels within the pulp cavity, irrespective of tooth type (p < 0.05).

CONCLUSION

A simplified 1 × 30-min protocol can be recommended as it effectively maintains color alteration and HP penetration, irrespective of whether human or bovine teeth.

CLINICAL SIGNIFICANCE

This study suggests that an in-office dental bleaching protocol using a 1 × 30-min session is recommended, as it ensures both effective color change and no increase in the amount of HP penetration.

Is the third molar the most frequently extracted tooth? A population-based study utilizing dental panoramic radiographs in adults

OBJECTIVES

The study aimed to examine the authenticity of the often-mentioned statement that the third molar is the most frequently extracted tooth. This finding has not been shown previously in a large population-based sample.

MATERIALS AND METHODS

Data comprised a nationally representative sample of 6082 panoramic radiographs taken from adults in the cross-sectional Health 2000 Survey. From the radiographs, all missing teeth were recorded. Information on congenital agenesis of individual teeth was retrieved from two published meta-analyses. Primary outcome was the frequency of missing teeth by tooth type. Explanatory variables were age, sex, and the jaw (maxilla/mandible). Statistical analyses included χ2 test and binomial logistic regression.

RESULTS

Mean age of participants (46% men, 54% women) was 53 years (SD 14.6; range 30‒97 years). Missing teeth occurred more often in women than in men (P < 0.001). The third molar was most frequently missing and the canine least frequently. In the maxilla and mandible, the third molar was missing more often than each of the other tooth types up to the age of 80 years (P < 0.01).

CONCLUSIONS

When considering the rates of congenital agenesis of individual teeth, it is concluded that the third molar remained the most common tooth extracted up till the age of 80 years.

CLINICAL RELEVANCE

The third molar is the most common target for extraction, but also the most common tooth associated with malpractice claims, and therefore, calls for skills, adequate equipment, and other resources for a successful extraction.

AI in Orthodontics: Revolutionizing Diagnostics and Treatment Planning-A Comprehensive Review

The advent of artificial intelligence (AI) in medicine has transformed various medical specialties, including orthodontics. AI has shown promising results in enhancing the accuracy of diagnoses, treatment planning, and predicting treatment outcomes. Its usage in orthodontic practices worldwide has increased with the availability of various AI applications and tools. This review explores the principles of AI, its applications in orthodontics, and its implementation in clinical practice. A comprehensive literature review was conducted, focusing on AI applications in dental diagnostics, cephalometric evaluation, skeletal age determination, temporomandibular joint (TMJ) evaluation, decision making, and patient telemonitoring. Due to study heterogeneity, no meta-analysis was possible. AI has demonstrated high efficacy in all these areas, but variations in performance and the need for manual supervision suggest caution in clinical settings. The complexity and unpredictability of AI algorithms call for cautious implementation and regular manual validation. Continuous AI learning, proper governance, and addressing privacy and ethical concerns are crucial for successful integration into orthodontic practice.

Statistical Study Concerning Extraction and Non-Extraction Methods in Orthodontic Treatments

INTRODUCTION

The need to extract permanent teeth for the correction of dento-maxillary anomalies remains even today a controversy in orthodontic therapy. The purpose of this study was to assess the orthodontist's point of view on the extraction and non-extraction methods used in orthodontic treatments, regarding clinical experience.

MATERIAL AND METHODS

A de novo conceived questionnaire was elaborated by means of Google Forms and it comprised 22 questions regarding gender, age, different proprieties and aspects of both extraction and non-extraction methods and the percentage of treated patients who developed an increase in dental sensitivity and caries activity following the therapeutic stripping procedure.

RESULTS

204 orthodontists answered the questionnaire. The respondents chose dental stripping (IPR-interproximal reduction) as the most used non-extraction method in their orthodontic practice with 34,3%, followed by over-expansion and dental stripping 24%. The probability that females will try to avoid dental extractions is 1.888 times higher compared to males. The association is statistically significant (p-value 0.0336). 70,1% of clinicians state that they use dental stripping as a non-extraction method to gain space even when there is NO Bolton discrepancy. In Class III cases, for reducing crowding and correcting the dental relations, 65.2% of doctors opt for dental stripping, while 34.8% do not avoid the extraction of a lower incisor.

CONCLUSIONS

Among the non-extraction methods for creating space, the most used by the surveyed orthodontists was dental stripping IPR. Tooth extraction remains a solution used by orthodontists for treating dentomaxillary disharmonies with crowding.

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.

A machine learning model for orthodontic extraction/non-extraction decision in a racially and ethnically diverse patient population

INTRODUCTION

The purpose of the present study was to create a machine learning (ML) algorithm with the ability to predict the extraction/non-extraction decision in a racially and ethnically diverse sample.

METHODS

Data was gathered from the records of 393 patients (200 non-extraction and 193 extraction) from a racially and ethnically diverse population. Four ML models (logistic regression [LR], random forest [RF], support vector machine [SVM], and neural network [NN]) were trained on a training set (70% of samples) and then tested on the remaining samples (30%). The accuracy and precision of the ML model predictions were calculated using the area under the curve (AUC) of the receiver operating characteristics (ROC) curve. The proportion of correct extraction/non-extraction decisions was also calculated.

RESULTS

The LR, SVM, and NN models performed best, with an AUC of the ROC of 91.0%, 92.5%, and 92.3%, respectively. The overall proportion of correct decisions was 82%, 76%, 83%, and 81% for the LR, RF, SVM, and NN models, respectively. The features found to be most helpful to the ML algorithms in making their decisions were maxillary crowding/spacing, L1-NB (mm), U1-NA (mm), PFH:AFH, and SN-MP(̊), although many other features contributed significantly.

CONCLUSIONS

ML models can predict the extraction decision in a racially and ethnically diverse patient population with a high degree of accuracy and precision. Crowding, sagittal, and vertical characteristics all featured prominently in the hierarchy of components most influential to the ML decision-making process.

Evaluation of the relationship between incisor torque and profile aesthetics in patients having orthodontic extractions compared to non-extractions

OBJECTIVE

The aim of the present study was to evaluate the relationship between soft tissues aesthetics and incisor torque, as well as the effect of crowding, anchorage, and extraction pattern, in adult patients treated without extraction or with two or four extractions.

MATERIALS AND METHODS

Seventy-seven subjects with permanent dentition were selected retrospectively. Among these, 24 patients were treated with four extractions, 24 with two extractions and 29 without extractions. Lateral cephalograms and photographies taken before (T0) and after (T1) treatment were retrieved. The amount of crowding and the type of anchorage were recorded, and a cephalometric analysis was performed. A one-way ANOVA was used to compare the variables within and between groups. Linear regressions were performed to evaluate the effect of different predictors on soft tissues variables at T1.

RESULTS

The statistical analysis showed no differences within and between groups for soft tissue aesthetics. A significant reduction of the angle obtained from the intersection of Frankfurt plane and mandibular plane was observed in the four-extractions group, and a significant proclination of the lower incisors was observed in the two-extraction group. Linear regressions revealed that the change in soft tissue profile aesthetics was affected by the type of anchorage and the two-extractions pattern.

CONCLUSIONS

Similar soft tissue aesthetics were observed after treatment in the three groups, despite the presence of some skeletal and dental differences.

CLINICAL RELEVANCE

A well-controlled incisor torque helps to preserve soft tissues aesthetics. The type of anchorage could influence soft tissues.

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.

Genetics of three-dimensional tooth inclination and angulation in orthodontic patients with Class I Occlusion: A cross-sectional study

PURPOSE

This cross-sectional study aimed to utilize quantitative polymerase chain reaction (qPCR) to investigate the influence of genetic variance over teeth inclination and angulation in orthodontic patients with Class I occlusion.

MATERIALS AND METHODS

DNA was extracted from adolescent patients seeking orthodontic treatment in a single institution (from July 2018 to April 2020), who had CBCTs taken as part of initial standardized records. Patients had permanent dentition, Class I skeletal and dental classifications, with normal vertical and transverse skeletal dimensions, normal incisors inclination, no to mild crowding or spacing. qPCR was performed using genetic markers for candidate genes EPB41, TGFβ3, GHR and PAX9. Three-dimensional teeth inclinations (TI) and angulations (TA) were evaluated using Invivo6 software and correlated with genotypes. Reliability of TI and TA was assessed using intraclass correlation coefficients (ICC). Mixed models and multiple linear regression analyses were used to assess the association between each single nucleotide polymorphisms (SNP) with tooth inclination (TI) and with tooth angulation (TA). The results were evaluated at the significance level of P<0.05.

RESULTS

Twenty four adolescent patients with mean age of 13.4±2.4 years were included in the study. ICC showed adequate intra-examiner reliability for TI and TA (0.806<r<0.988, P<0.001). Multiple linear regression analysis showed a significant association between TI and homozygous-T polymorphism for PAX9 (P=0.028) and homozygous-G polymorphism for GHR (P=0.028). Also, a significant association between TA and homozygous-A polymorphism for EPB41 (P=0.019) and homozygous-G polymorphism for GHR (P=0.001) was evident.

CONCLUSIONS

Autosomal recessive patterns of inheritance for PAX9 and GHR with TI and for EPB41 and GHR with TA were shown. This study offers insight toward the hierarchical nature of epigenetic interactions between heredity and the environment in determining the three-dimensional positions of teeth in orthodontic patients with Class I occlusion.

A qualitative evaluation of attitudes toward extractions among primary care orthodontists in Great Britain

INTRODUCTION

The need to extract permanent teeth as part of orthodontic treatment has been keenly debated over many decades. Changes in the frequency of extraction have been well documented; however, we continue to lack an understanding of what influences clinicians' decisions regarding extracting permanent teeth.

METHODS

Purposive sampling was undertaken to obtain representative views from primary care practitioners across Great Britain with a range of experience representing genders and wide geographic distribution. Twenty participants (9 female, 11 male) took part in in-depth, qualitative, 1-to-1 interviews based on a piloted topic guide. Interviews were conducted via video conferencing software with audio recording and verbatim transcription. Thematic analysis was performed with discussion and agreement to identify the main themes.

RESULTS

Five main themes were identified: (1) patient-related factors, such as age and features of the malocclusion, (2) operator factors, including the level of experience, (3) setting, with regard to geographic location and method of remuneration, (4) mechanical approaches, including variations in appliance systems; and (5) self-directed ongoing education, including both formal continuing professional development and informal learning from peers. These factors acted as barriers, enablers, or both in relation to nonextraction treatment.

CONCLUSIONS

Five key influences on extraction decisions among orthodontists in Great Britain were identified. Extraction choices appear to be influenced by various interrelated factors, evolving over time and with increased experience.

Detailed Correlation between Central Incisor Movement and Alveolar Bone Resorption in Adults with Orthodontic Premolar Extraction Treatment: A Retrospective Cohort CBCT Study

Background: This study aims to explore the detailed correlation between the movement of maxillary and mandibular central incisors and alveolar bone resorption in adults who had orthodontic premolar extraction treatment. Methods: A total of 63 adult patients (mean age, 24.41 years) who received orthodontic treatment with the extraction of four first premolars were included in this study. CBCT images were obtained before and after treatment. Three-dimensional evaluations of the movement of 252 central incisors (126 maxillary and 126 mandibular incisors) and alveolar bone changes were conducted. Four points were used to describe the incisor movement: C (cusp point), R (root apex point), M (mid-point of root neck), and L (labial cementoenamel junction point). The thickness of labial and palatal alveolar bone was assessed at the crestal, mid-root, and apical levels of incisors. The results were analyzed with Spearman’s correlation and multilinear regression. Results: Matching the measurements of central incisor movement and alveolar bone resorption, significant correlations could be observed. For maxillary central incisors, the labial alveolar bone resorption at the crestal level was correlated with the movement of Point L (r = 0.290, p < 0.05), and the labial alveolar bone resorption at the apical level was correlated with Point M (r = 0.387, p < 0.05). For mandibular central incisors, the labial alveolar bone resorption at the apical level was correlated with the movement of Point M (r = 0.493, p < 0.05) and R (r = 0.498, p < 0.01); the palatal alveolar bone resorption at the mid-root level with Point M (r = -0.170, p < 0.01); and the palatal alveolar bone resorption at the apical level with Point R (r = 0.177, p < 0.01). Conclusions: This study investigated the concrete correlations between central incisor movement and alveolar bone resorption in adults after orthodontic treatment with premolar extraction. It is potentially helpful for orthodontists to have a relatively accurate prediction of alveolar bone resorption based on the specific movements of central incisors and to reduce the risk of alveolar bone resorption by better adjusting the three-dimensional movement types of incisors.

Non-extraction orthodontic treatment for severe dental crowding using miniscrew-assisted rapid maxillary expansion

Malocclusion is caused by an incorrect relationship between the teeth and jaws, which leads to an abnormal variation of normal occlusion. Crowding is an increasingly common type of malocclusion caused by a discrepancy in tooth-jaw size that leads to twisted and misaligned teeth. Two methods to treat this malalignment are tooth material reduction and arch width expansion. Of these two treatment options, the latter is preferred because it enables orthodontists to avoid extractions and increase the dental arch perimeter by widening the jaws; this resolves crowding and accommodates existing teeth. This case report describes a unique approach in the treatment of a patient with severe crowding by an orthopaedic widening of the dental arches using a skeletally anchored rapid palatal expander. Under favorable circumstances, this approach can serve as a robust method to treat patients with severe crowding and may be used as an alternative to extraction.

Accuracy of artificial intelligence for tooth extraction decision-making in orthodontics: a systematic review and meta-analysis

OBJECTIVE

This study aimed to analyze the accuracy of artificial intelligence (AI) for orthodontic tooth extraction decision-making.

MATERIALS AND METHODS

PubMed/MEDLINE, EMBASE, LILACS, Web of Science, Scopus, LIVIVO, Computers & Applied Science, ACM Digital Library, Compendex, and gray literature (OpenGrey, ProQuest, and Google Scholar) were electronically searched. Three independent reviewers selected the studies and extracted and analyzed the data. Risk of bias, methodological quality, and certainty of evidence were assessed by QUADAS-2, checklist for AI research, and GRADE, respectively.

RESULTS

The search identified 1810 studies. After 2 phases of selection, six studies were included, showing an unclear risk of bias of patient selection. Two studies showed a high risk of bias in the index test, while two others presented an unclear risk of bias in the diagnostic test. Data were pooled in a random model and yielded an accuracy value of 0.87 (95% CI = 0.75-0.96) for all studies, 0.89 (95% CI = 0.70-1.00) for multilayer perceptron, and 0.88 (95% CI = 0.73-0.98) for back propagation models. Sensitivity, specificity, and area under the curve of the multilayer perceptron model yielded 0.84 (95% CI = 0.58-1.00), 0.89 (95% CI = 0.74-0.98), and 0.92 (95% CI = 0.72-1.00) scores, respectively. Sagittal discrepancy, upper crowding, and protrusion showed the highest ranks weighted in the models.

CONCLUSIONS

Orthodontic tooth extraction decision-making using AI presented promising accuracy but should be considered with caution due to the very low certainty of evidence.

CLINICAL RELEVANCE

AI models for tooth extraction decision in orthodontics cannot yet be considered a substitute for a final human decision.

Incidence and clinical risk factors associated with the development of labial protuberances after orthodontic treatment

INTRODUCTION

Distinct, irregular, and hard, nodular labial protuberances (LPs) that were due to differential alveolar bone modeling can be noted on the labial gingival surface of the incisors after orthodontic treatment. Clinically, LPs cause patient discomfort and esthetic issues, but information on this phenomenon is limited. This study aimed to evaluate the incidence of LPs and demonstrate the etiology and clinical risk factors associated with this phenomenon.

METHODS

Differential alveolar bone modeling was defined as present (+) when ≥1 distinct LPs (diameter >1 mm) developed after orthodontic treatment by comparing pretreatment and posttreatment intraoral photographs and casts of an orthodontic patient cohort treated with fixed appliances (n = 872). The incidence rate, affected sites, and their association with age, sex, and orthodontic treatment modalities were evaluated.

RESULTS

The incidence rate of differential alveolar bone modeling among orthodontic patients was 3.2% (28 out of 872). The maxillary lateral incisor region was the most frequently affected site. Males (vs females) (odds ratio, 2.56 [95% confidence interval, 1.155-5.604]), adults (aged ≥ 20 years) (vs teens) (12.84 [3.003-54.866]), and those who had orthodontic extraction (vs nonextraction) (11.60 [3.434-39.156]) demonstrated significantly higher odds of developing LPs after orthodontic treatment (P <0.05).

CONCLUSIONS

The incidence rate of the development of notable LPs after orthodontic treatment was 3.2%. Adult males and those who undergo orthodontic extraction have a higher risk of developing LPs. Clinicians should be aware that distinct LPs may develop when large amounts of incisal retraction are planned in adults.

Clinical Potential of Dental Pulp Stem Cells in Pulp Regeneration: Current Endodontic Progress and Future Perspectives

Dental caries is a common disease that not only destroys the rigid structure of the teeth but also causes pulp necrosis in severe cases. Once pulp necrosis has occurred, the most common treatment is to remove the damaged pulp tissue, leading to a loss of tooth vitality and increased tooth fragility. Dental pulp stem cells (DPSCs) isolated from pulp tissue exhibit mesenchymal stem cell-like characteristics and are considered ideal candidates for regenerating damaged dental pulp tissue owing to their multipotency, high proliferation rate, and viability after cryopreservation. Importantly, DPSCs do not elicit an allogeneic immune response because they are non-immunogenic and exhibit potent immunosuppressive properties. Here, we provide an up-to-date review of the clinical applicability and potential of DPSCs, as well as emerging trends in the regeneration of damaged pulp tissue. In addition, we suggest the possibility of using DPSCs as a resource for allogeneic transplantation and provide a perspective for their clinical application in pulp regeneration.

Use of automated artificial intelligence to predict the need for orthodontic extractions

Objective

To develop and explore the usefulness of an artificial intelligence system for the prediction of the need for dental extractions during orthodontic treatments based on gender, model variables, and cephalometric records.

Methods

The gender, model variables, and radiographic records of 214 patients were obtained from an anonymized data bank containing 314 cases treated by two experienced orthodontists. The data were processed using an automated machine learning software (Auto-WEKA) and used to predict the need for extractions.

Results

By generating and comparing several prediction models, an accuracy of 93.9% was achieved for determining whether extraction is required or not based on the model and radiographic data. When only model variables were used, an accuracy of 87.4% was attained, whereas a 72.7% accuracy was achieved if only cephalometric information was used.

Conclusions

The use of an automated machine learning system allows the generation of orthodontic extraction prediction models. The accuracy of the optimal extraction prediction models increases with the combination of model and cephalometric data for the analytical process.

Extraction vs. Nonextraction on Soft-Tissue Profile Change in Patients with Malocclusion: A Systematic Review and Meta-Analysis

Objectives

We aimed to summarize the current evidence regarding the impact of extraction vs. nonextraction in orthodontic treatment on patients' soft-tissue profile with malocclusion.

Methods

Between April 30^th and November 30^th, 2020, we searched PubMed and SCOPUS for published papers from inception to November 2020 using "orthodontic," "extraction," "nonextraction," and "Malocclusion." Included studies were summarized, and relevant data were extracted and analyzed using Review Manager 5.4.

Results

Pooled data from four controlled trials demonstrated a nonsignificant difference between extraction and nonextraction in terms of SNA (MD = 0.50, 95% CI: -0.37, 1.38; p = 0.26), SNB (MD = 0.11, 95% CI: -1.23, 1.44; p = 0.88), FMA (MD = 1.82, 95% CI: -2.39, 6.02; p = 0.40), IMPA (MD = 0.06, 95% CI: -8.83, -8.94; p = 0.99), overjet (MD = -1.47, 95% CI: -6.21, 3.26; p = 0.54), and overbite (MD = 0.50, 95% CI: -1.40, 2.40; p = 0.60). On the other hand, the extraction method significantly increased the ANB compared with the nonextraction group (MD = 0.78, 95% CI: 0.25, 1.31; p = 0.004).

Conclusion

The current evidence demonstrated that nonextraction protocols for orthodontic treatment are a safe and effective alternative to extraction protocols; individually tailored treatment strategies should be applied. More randomized controlled trials are critically needed to safely make an evidence-based treatment conclusion.

Machine learning from clinical data sets of a contemporary decision for orthodontic tooth extraction

OBJECTIVE

To examine the robustness of the published machine learning models in the prediction of extraction vs non-extraction for a diverse US sample population seen by multiple providers.

SETTING AND SAMPLE POPULATION

Diverse group of 838 patients (208 extraction, 630 non-extraction) were consecutively enrolled.

MATERIALS AND METHODS

Two sets of input features (117 and 22) including clinical and cephalometric variables were identified based on previous studies. Random forest (RF) and multilayer perception (MLP) models were trained using these feature sets on the sample population and evaluated using measures including accuracy (ACC) and balanced accuracy (BA). A technique to identify incongruent data was used to explore underlying characteristics of the data set and split all samples into 2 groups (G1 and G2) for further model training.

RESULTS

Performance of the models (75%-79% ACC and 72%-76% BA) on the total sample population was lower than in previous research. Models were retrained and evaluated using G1 and G2 separately, and individual group MLP models yielded improved accuracy for G1 (96% ACC and 94% BA) and G2 (88% ACC and 85% BA). RF feature ranking showed differences between top features for G1 (maxillary crowding, mandibular crowding and L1-NB) and G2 (age, mandibular crowding and lower lip to E-plane).

CONCLUSIONS

An incongruent data pattern exists in a consecutively enrolled patient population. Future work with incongruent data segregation and advanced artificial intelligence algorithms is needed to improve the generalization ability to make it ready to support clinical decision-making.

A conservative approach for an adult patient with a fractured tooth and crowding: Autotransplantation at the fracture site

Autotransplantation of a mature premolar in adults can be a treatment of choice for tooth replacement when combined with well-planned orthodontic treatment. This case report describes the successful treatment of a 39-year-old patient with severe crowding and a hopelessly fractured tooth on the maxillary left side. Maxillary dental crowding was relieved by extraction of a premolar on the right side, and this extracted tooth was autotransplanted to replace the fractured tooth. A mandibular incisor was extracted to correct anterior crossbite. The total treatment period was 20 months. The treatment results showed a good long-term prognosis after transplantation of a mature premolar with normal surrounding alveolar bone level for over 6 years of follow-up. Occlusion and periodontal health were excellent in the long term.

Predictors of orthodontic treatment conclusion: A historical cohort study

INTRODUCTION

The study investigated which patient and orthodontic treatment factors act as predictors for the conclusion of the ongoing treatment in a dental clinic of a specialization program in Orthodontics.

METHODS

Data were collected from the records of patients treated from 1997 to 2015. Potential predictors for treatment conclusion were investigated: patient-related factors (PRFs) and treatment-related factors (TRFs). PRFs were sex, age, face balance, Angle malocclusion classification, open bite, denture, facial pattern, facial profile, buccal corridor, crossbite, maxillary deficiency, and sagittal mandibular behavior; and TRFs were therapeutic approaches, treatment modality, extractions, and Bolton discrepancy. The initial and final treatment dates were collected. Descriptive data analysis, univariate, and multivariate logistic regression were performed (5% significance).

RESULTS

Of the 903 records, 561 patients were included in the study. It was demonstrated that starting the treatment at a young age (PRF) and the presence of crossbite (TRF) are predictive factors for the treatment conclusion. A vertical facial pattern (dolichofacial or brachyfacial) and a greater number of extractions for orthodontic reasons may contribute positively to the conclusion of the treatment. The frequency of treatment inconclusion was higher during the first 2 years of treatment (more than 50% of the patients that initiated the treatment).

CONCLUSIONS

Young age at the beginning of treatment and the presence of crossbite malocclusion can increase the chance of treatment conclusion.

Frequency of premolar teeth extractions for orthodontic treatment

It is of interest to evaluate the frequency of premolar extractions during orthodontic treatment in patients reporting to the Saveetha dental hospital in Chennai from 2019-2020. We used the records from 987 patients who underwent orthodontic treatment from June 2019 to March 2020 in a dental hospital for this analysis. Digital case records of patients who underwent therapeutic extractions of premolars were isolated. A sample dataset of 340 case records were selected for this study. Data shows that 34.4% of subjects underwent premolar extractions amongst a total of 987 subjects who underwent orthodontic treatment. 89.4% of patients were Angle's Class I malocclusion patients, and the rest were Class II patients. However, no premolar extractions were done in Class III patients. Data also shows that 67.1% of subjects underwent all 4 first premolar extractions and 13.2% underwent only upper first premolar extractions. Thus, a significant association was found between Type of Malocclusion and the Type of premolar extractions with p < 0.05. Moreover, only 34.4% of patients underwent premolar extractions and the majority of them underwent all 4 first premolar extractions.

Current status of clinical orthodontics in European and American countries

Current status of clinical orthodontics in European and American countries was examined by means of a questionnaire survey through internet. In the European and American countries, most popular technique in daily orthodontic practice is preadjusted straight wire edgewise technique. In major developed countries in Europe and America, the treatment fee is considerably high, whereas the fee is relatively low in the countries under development and/or after economic crisis. Rate of non-extraction treatment among all the cases treated with multi-bracket appliances is significantly higher in Europe and America than in Asia except in a few countries. In the European and American countries, treatment system for jaw deformity patients is well developed with higher availability of the social health insurance than in Asia. The maximum CLP prevalence of 0.200 is found in Germany and Austria and the mean is around 0.140 or one to 700 births. In general, CLP treatment is covered by social health insurance in European and American countries. In Europe and America, lingual orthodontic technique has not become popular because patients never want to hide orthodontic appliance. Higher cost of lingual appliance and lack in information and technical skills may be the reasons of less frequent use of lingual appliance. Many interviewees replied that usage of TADs has not become so popular in USA and Canada as compared to that in Asia. In another word, the initial fascination with TADs wore off and are now used in selected patients as needed. This may be due to more harmonious maxillofacial structure with longer and wider dentitions in Caucasians which also results in higher rate of non-extraction treatment with multibracket appliances in European and American countries.

Influence of orthodontic treatment with premolar extraction on the spatial position of maxillary third molars in adult patients: a retrospective cohort cone-bean computed tomography study

Background

Based on low-dose radiation Cone-bean computed tomography (CBCT) images, This study aims to establish a space coordinate system, which offers more precise and comparable evaluation on changes of maxillary third molars influenced by orthodontic treatment with premolar extraction in adults. The system suggests promising application prospect in future studies related to CBCT superimposition and evaluation for its feasibility and efficiency.

Methods

Forty-nine maxillary third molars from 27 patients (mean age, 20.78 years) were included. CBCT images were obtained before and after orthodontic treatment with premolars extracted (mean treatment duration, 31.47 months). The changes in the position, angulation, and rotation of the third molars were evaluated with a space coordinate system using four landmarks: anterior nasal spine (ANS), posterior nasal spine (PNS), left and right orbitales.

Results

After orthodontic treatment, the third molars moved forward (adjusted mean, 1.44 mm) (p < 0.001) and downward (adjusted mean, 2.87 mm) (p < 0.001) accompanied by outward rotation of the crowns (adjusted mean, 5.38°) (p = 0.001), while changes in angulation were insignificant.

Conclusions

This was the first study to systematically investigate the spatial position change of maxillary third molars in adult patients who received orthodontic treatment with premolar extraction. During the process, maxillary third molars moved downward and forward accompanied by outward rotation of the crowns. Orthodontists should take tooth movement potential into consideration when making extraction plans.

Pretreatment dentoskeletal comparison between individuals treated with extractions in the 1970s and in the new millennium

OBJECTIVE

This retrospective study aimed to compare the occlusal and dentoskeletal initial features of patients treated with four first premolar extractions in the 1970s and after 2000.

MATERIALS AND METHODS

Group 70' was composed by 30 subjects with Class I malocclusion (mean age of 12.8 years, 10 male, 20 female) treated in the 1970s with four first premolar extractions and comprehensive orthodontic treatment. Group NM comprised 30 subjects with Class I malocclusion (mean age of 13.4 years, 13 male, 17 female) treated in the new millennium, similarly to Group 70'. Initial dental models and lateral cephalograms were digitized and measured using OrthoAnalyzerTM 3D software and Dolphin Imaging 11.0 software, respectively. Initial occlusal and dentoskeletal features were analyzed and compared. Intergroup comparison was performed using t tests (p < 0.05). Holm-Bonferroni correction for multiple comparison was applied.

RESULTS

Group NM showed significantly greater maxillary and mandibular effective lengths and greater maxillary and mandibular incisor protrusion in comparison with Group 70'. Group NM presented a significantly greater lower anterior facial height. Group NM also showed significantly smaller nasolabial angle and protruded inferior lip.

CONCLUSION

Patients with Class I malocclusion treated with four first premolar extractions in the new millennium present a greater degree of dental and labial protrusion, increased lower anterior facial height, and more acute nasolabial angle compared with patients treated similarly in the 1970s. Greater dental and labial protrusion determines first premolar extractions in the new millennium.

CLINICAL RELEVANCE

Despite the decrease of tooth extraction frequency, four first premolar extractions may be justified in cases with severe dental and skeletal protrusions.

Is periodontal phenotype modification therapy beneficial for patients receiving orthodontic treatment? An American Academy of Periodontology best evidence review

BACKGROUND

Orthodontic treatment can greatly impact the periodontium, especially in dentitions with a thin periodontal phenotype. Orthodontic tooth movement can result into iatrogenic sequelae to these vulnerable anatomic conditions, such as development and exacerbation of bony dehiscence or fenestration defects, which can manifest loss of periodontal support and gingival recession (GR). This systematic review aimed to investigate whether periodontal phenotype modification therapy (PhMT) involving hard tissue augmentation (PhMT-b) or soft tissue augmentation (PhMT-s) has clinical benefits for patients undergoing orthodontic treatment.

METHODS

An electronic search was performed in two major databases for journals published in English language from January 1975 to January 2019 and a hand search of printed journals was also performed to identify human clinical trials reporting clinical and radiographic outcomes of patients receiving orthodontic treatment with or without hard and soft tissue augmentation procedures. Data were extracted and organized into tables for qualitative assessment.

RESULTS

Eight studies were identified evaluating the outcomes of PhMT in patients undergoing orthodontic therapy. Six studies evaluated patients receiving PhMT-b via corticotomy-assisted orthodontic therapy (CAOT) and simultaneous bone augmentation while the other two received PhMT-s before tooth movement. No studies investigated PhMT-b alone without CAOT and most studies focused on the mandibular anterior decompensation movements. There was high heterogeneity in the study design and inconsistency of the reported outcomes; therefore, a meta-analysis was not performed. Evidence at this moment supports CAOT with hard tissue augmentation accelerated tooth movement. However, only two studies provided direct comparison to support that CAOT with PhMT-b reduced the overall treatment time compared with conventional orthodontic treatment. No periodontal complications or evidence of severe root resorption were reported for both groups. Four studies provided radiographic assessment of the PhMT-b and demonstrated increased radiographic density or thicker facial bone after the treatment. Two studies reported an expanded tooth movement. One study reported an increase in keratinized tissue width post-CAOT plus PhMT-b, while another study with a 10-year follow-up showed a lower degree of relapse using the mandibular irregularity index when compared with conventional tooth movement alone. Two studies examined the effect of PhMT-s before orthodontic treatment. Unfortunately, no conclusions can be drawn because of the limited number of studies with contradicting outcomes.

CONCLUSIONS

Within the limited studies included in this systematic review, PhMT-b via particulate bone grafting together with CAOT may provide clinical benefits such as modifying periodontal phenotype, maintaining or enhancing facial bone thickness, accelerating tooth movement, expanding the scope of safe tooth movement for patients undergoing orthodontic tooth movement. The benefits of PhMT-s alone for orthodontic treatment remain undetermined due to limited studies available. However, PhMT-b appears promising and with many potential benefits for patients undergoing orthodontic tooth movement. There is a need for a higher quality of randomized controlled trials or case control studies with longer follow-up to investigate the effects of different grafting materials and surgical sites other than mandibular anterior region.

Effects of bicuspid extractions and incisor retraction on upper airway of Asian adults and late adolescents: A systematic review

OBJECTIVES

This systematic review aimed to assess the effects of bicuspid extractions and incisor retraction on airway dimension, hyoid position and breathing of adults and late adolescents.

METHODS

The review was conducted according to PRISMA guidelines. Eight databases including PubMed, EMBASE, Web of Science and Scopus were searched to August 2018. Minimum age of participants was 16 years. The intervention was dual-arch bicuspid extractions with incisor retraction. Outcomes were airway dimension, hyoid position and breathing assessment.

RESULTS

All nine publications meeting inclusion criteria were from Asia. They were divided into three Asian subregions. All East Asian lateral cephalometric studies reported anteroposterior airway narrowing at the oropharynx and sometimes the hypopharynx. However, the narrowing was small, comparable to measurement errors, and highly variable. Two out of three East Asian computed tomography (CT) studies described reductions in airway dimensions. The single functional breathing study showed increased simulated flow resistance after incisor retraction in East Asians. South Asian studies had mixed findings, with some reporting significant airway narrowing. The single study from West Asia found no significant airway or hyoid changes.

CONCLUSIONS

Airway response to bicuspid extractions and incisor retraction varied substantially when assessed with cephalometry. CT measurements present larger effect sizes and smaller variations, providing stronger evidence of airway narrowing. Orthodontic extractions for incisor retraction may be more frequently indicated in Asia, and East Asians seem particularly susceptible to airway narrowing and postero-inferior hyoid movement with incisor retraction. Better designed CT studies are needed for confirmation due to small effect size and large variability.

Does the time-point of orthodontic space closure initiation after tooth extraction affect the incidence of gingival cleft development? A randomized controlled clinical trial

Background

Gingival clefts (GCs) develop frequently during orthodontic space closure and may compromise the treatment outcome. This study assessed whether the time‐point of orthodontic space closure initiation, after permanent tooth extraction, affects the incidence of GC.

Methods

In 25 patients requiring bilateral premolar extraction because of orthodontic reasons, one premolar, chosen at random, was extracted 8 weeks before space closure initiation (“delayed movement,” DM), whereas the contralateral premolar was extracted 1 week before (“early movement,” EM) (“treatment group”). Presence or absence of GC after 3 and 6 months (“time‐point”) was recorded and any association with various parameters (i.e., treatment group, time‐point, gender, jaw, craniofacial growth, gingival biotype, buccal bone dehiscence after extraction, space closure) was statistically assessed.

Results

Twenty‐one patients contributing with 26 jaws were finally included in the analysis. Overall, GCs were frequent after 3 (DM: 53.9%; EM: 69.2%) and 6 months (DM: 76.9%; EM: 88.5%). EM (P = 0.014) and larger space closure within the study period (P = 0.001) resulted in a significantly higher incidence of GC. Further, there was a tendency for GC development in the presence of buccal bone dehiscence (P = 0.052) and thin gingival biotype (P = 0.054). “Fast movers” (herein cases with a tooth movement ≥1 mm per month) developed a GC in >90% of the cases already after 3 months. “Slow movers” developed a GC in 25% and 70% after 3 months and final evaluation, respectively.

Conclusions

GC development is a frequent finding during orthodontic space closure and seems to occur more frequently with early tooth movement initiation and in “fast movers.”

Which factors influence orthodontists in their decision to extract? A questionnaire survey

Background

To evaluate the relative influence of different criteria in the choice between extraction and nonextraction treatment in current orthodontics, and to assess how the percentage of extractions has evolved over time.

Material and Methods

Pre-treatment records (panoramic radiograph, lateral cephalogram, study casts and photographs) of fourteen cases in permanent dentition (adult or adolescent) with class I molar relationship and moderate anterior crowding were evaluated by 28 orthodontists. For each case, each orthodontist filled out a questionnaire reporting his treatment plan proposal (extraction or nonextraction) and the importance of specific parameters in his decision-making process, using categorical scales. Orthodontists practicing for more than 15 years were also asked to compare this decision with the one they would have taken at the beginning of their professional career.

Results

The two most important factors in the decision-making were the soft tissue profile and the amount of crowding. The least important factor was the presence of third molars. In cases of nonextraction treatment, the lack of space was managed mostly by dental expansion and stripping. Twenty percent of the case evaluations revealed extraction(s) decisions. Among the orthodontists practicing for more than 15 years, the current extraction rate reached 24%, whereas the same orthodontists reported they would have extracted in 39% of the cases in the past.

Conclusions

The present study suggests that soft tissue profile has a higher impact than traditional criteria such as cephalometric measurements in the extraction decision. This is associated with a decreased extractions rate compared to the past.

Key words:Orthodontics, extractions, survey, treatment planning.

Do premolar extractions necessarily result in a flat face? No, when properly indicated

The esthetic benefits are among the main goals of orthodontic treatment; therefore, tooth extractions have been avoided as a protocol for orthodontic treatment because they may impair the facial profile. The present article discusses aspects as the magnitude and response of soft tissue profile due to changes in incisor positioning, and the effect of different sequences of premolar extraction. One case report illustrates the subject, with favorable and stable esthetic and occlusal outcomes five years after orthodontic treatment with extraction of second premolars.

Extraction of premolars for orthodontic reasons on the decline? A cross-sectional survey of BOS members

OBJECTIVE

To obtain the opinion of British Orthodontic Society (BOS) members in relation to possible patterns of prescription of orthodontic extractions over the past 5-10 years and to relate any changes identified to treatment objectives, facial and smile aesthetics, and treatment strategies and adjuncts.

DESIGN

Cross-sectional questionnaire.

SETTING

On-line survey of BOS members.

METHODS

A 14-item on-line questionnaire was sent to orthodontic practitioners for completion. The questionnaire covered demographics, possible changes in frequency of prescribed extractions with specific information concerning the effect of patient age, and the influence of other factors including alternative approaches to space creation, evolving treatment mechanics, smile and facial aesthetics, and retention protocols.

RESULTS

Two hundred and eight responses were obtained with 95.6% (n = 199) reporting reduced extraction prescription over the last 5-10 years. Overall, 29.9% and 35.5% felt that their threshold for extractions had increased by more than 2 mm in adolescents and adults, respectively. Facial (n = 145; 69.7%) and smile (n = 127; 61.1%) aesthetics, and increased use of inter-proximal reduction (n =  102; 49%) were the factors most frequently reported as having either a moderate or major influence on this trend. Based on ordinal logistical regression analyses, no significant relationship was found between threshold for extractions and work setting (P =  0.675; O.R. 0.51; 95% CI: 0.39, 1.85) or level of orthodontic experience (P =  0.15; O.R. 1.02; 95% CI: 0.15, 1.05), although a higher threshold for extractions was more likely among users of conventional than self-ligating brackets (P =  0.001; O.R. 4.74; 95% CI: 1.95, 11.5).

CONCLUSIONS

A reduced tendency to prescribe orthodontic extractions over the past 5-10 years among British Orthodontic Society members was identified. Comparative clinical research exploring the relative merits of extraction and non-extraction approaches could be timely.

Factors affecting treatment decisions for Class I malocclusions

INTRODUCTION

Orthodontic treatment planning requires skill and expertise with considerable practice variations. The aims of this study were to review retrospectively the pretreatment records of patients with Class I malocclusion and to identify variables that could play a role in the treatment decision.

METHODS

From the available records of 1500 orthdontic patients, the pretreatment records of 202 patients were selected at random. Inclusion and exclusion criteria were applied, and the surviving records were divided into extraction (n = 92) and nonextraction (n = 92) treatment groups. Skeletal, dental, and soft tissue measurements were obtained from pretreatment lateral cephalograms and dental casts of subjects with bilateral Class I molar relationships. Data were statistically analyzed by binary logistic regression tests.

RESULTS

The results showed that the variables of lower anterior facial height, E-plane to upper lip, and maxillary and mandibular incisor inclinations were significantly increased in the extraction group (P <0.05), whereas spacing in the mandibular arch and increased overbite were statistically significant in the nonextraction treatment group (P <0.05). According to the model, the odds of nonextraction treatment are 1.29 and 1.24 times that of extraction treatment for every 1-mm increase in overbite and spacing in the mandibular arch, respectively.

CONCLUSIONS

Vertical facial pattern, overbite, mandibular tooth size-arch length discrepancy, lip position, and maxillary and mandibular incisor inclinations are a few of the important variables that should not be overlooked when planning orthodontic treatment. The findings of this study could facilitate the treatment planning process for patients with Class I malocclusion.

Failure patterns of different bracket systems and their influence on treatment duration: A retrospective cohort study

OBJECTIVES

To compare the failure pattern of four different bracket types and to assess its effect on treatment duration.

MATERIALS AND METHODS

A total of 78 white patients (28 male, 50 female) with a mean age of 12.6 years were included in this retrospective cohort study and treated for a mean period of 30.6 months. The patients were treated in a private practice with stainless steel conventionally ligated brackets, ceramic conventionally ligated brackets, stainless steel self-ligating brackets, or nickel-free self-ligating brackets. The loss of at least one bracket during the course of treatment was analyzed with Cox proportional hazards survival analyses and generalized linear regression.

RESULTS

The overall bracket failure rate at the tooth level was 14.1% (217 brackets), with significant differences according to tooth type (between 8.0%-23.4%) and bracket type (between 11.2%-20.0%). After taking confounders into account, patients treated with ceramic brackets lost more brackets (hazard ratio = 1.62; 95% confidence interval = 1.14-2.29; P = .007) than patients with stainless steel brackets. On average, treatment time increased by 0.6 months (95% confidence interval = 0.21-1.05; P = .004) for each additional failed bracket.

CONCLUSIONS

Bracket failure was more often observed with ceramic brackets and was associated with increased treatment duration.

Soft tissue changes following extraction vs. nonextraction orthodontic fixed appliance treatment: a systematic review and meta-analysis

The aim of this systematic review was to assess the effect of systematic extraction protocols during orthodontic fixed appliance treatment on the soft tissue profile of human patients. Nine databases were searched until December 2016 for controlled clinical studies including premolar extraction or nonextraction treatment. After elimination of duplicate studies, data extraction, and risk-of-bias assessment according to the Cochrane guidelines, random-effects meta-analyses of mean differences (MD) or standardized mean differences (SMD) and their 95% CIs were performed, followed by subgroup, meta-regression, and sensitivity analyses. Extraction treatment was associated with increased lower lip retraction (24 studies; 1,456 patients; MD = 1.96 mm), upper lip retraction (21 studies; 1,149 patients; MD = 1.26 mm), nasolabial angle (21 studies; 1,089 patients; MD = 4.21°), soft-tissue profile convexity (six studies; 408 patients; MD = 1.24°), and profile pleasantness (three studies; 249 patients; SMD = 0.41). Patient age, extraction protocol, and amount of upper incisor retraction during treatment were significantly associated with the observed extraction effects, while the quality of evidence was very low in all cases due to risk of bias, baseline confounding, inconsistency, and imprecision. Although tooth extractions seem to affect patient profile, existing studies are heterogenous and no consistent predictions of profile response can be made.

Influence of orthodontic premolar extraction therapy on the eruption of the third molars: A systematic review of the literature

BACKGROUND

Through a systematic literature review, the authors assess the effect of premolar extractions on third-molar (M3) eruption considering eruption rate, retromolar space, and molar angulation.

TYPES OF STUDIES REVIEWED

The authors performed a systematic search using MEDLINE and Web of Science databases up through April 2017 to identify quality studies available comparing M3 eruption between a group with premolar extraction and a group without premolar extraction.

RESULTS

Twelve comparative retrospective cohort studies met all the inclusion criteria. The authors found in 5 studies comparing the rate of M3 eruption that there were significantly higher results in the group with extractions. They found in 5 studies comparing the evolution of the retromolar space significantly higher results in the group with extractions. Lastly, concerning the uprighting of the M3 during treatment, the authors found only 2 studies showing significant differences between the 2 groups, each time in favor of the group with extractions.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The dental literature on premolar extraction related to the eruption of the M3 is composed of average-quality retrospective studies. Premolar extraction significantly improves the chances of M3 eruption, but the level of evidence of comparative retrospective cohort studies is low. Clinicians must continue to rely on their judgment regarding premolar extraction on a case-by-case basis until the evidence is stronger. Retrospective studies with standardized protocols and more detailed methodologies are required to obtain higher levels of evidence.

Influence of clinicians' experience and gender on extraction decision in orthodontics

OBJECTIVE

To determine whether, in Class I borderline cases, experienced orthodontists choose nonextraction treatment more frequently than do orthodontists with less experience. A secondary aim was to evaluate whether clinicians' gender and place of education play a role in extraction decision making.

MATERIALS AND METHODS

An online survey was developed using three Class I borderline patient cases. The survey included questions about clinicians' demographics as well as questions about the selected cases. The survey was distributed to approximately 2000 clinicians through the American Association of Orthodontics.

RESULTS

Of the 253 responses collected, a trend was observed wherein clinicians with more than 15 years of experience preferred an extraction treatment option more frequently than did clinicians with less than 5 years of experience. There was no association between gender and place of education and the decision to extract in the selected borderline cases. Crowding, patient's profile, and mandibular incisor inclination were among the top three reasons chosen by clinicians for both the extraction and nonextraction treatment decisions.

CONCLUSIONS

A trend was observed in which clinicians with more experience chose an extraction treatment option more frequently in borderline cases than did those with less experience. Clinicians' gender did not play a role in extraction decision making.

Attitudes of orthodontists and laypersons towards tooth extractions and additional anchorage devices

Background

This study investigated the attitudes of orthodontists and laypersons towards the choice of extracting second premolars, rather than first premolars, based on tooth condition and the use of additional anchorage devices.

Methods

Questionnaires were sent to two groups: 324 orthodontists who were members of the Thai Association of Orthodontists, and 100 randomly selected Thai laypersons aged above 20 years and who were unrelated to the field of dentistry. Descriptive and chi-square statistics were used to analyze the data.

Results

Questionnaires were returned by 142 orthodontists (43.8%) and completed by 100 laypersons. The larger the size of the caries lesion in the maxillary second premolar was found, the more orthodontists and laypersons both chose to extract a carious maxillary second premolar instead of a healthy maxillary first premolar. For orthodontists, the use of mini-implant anchorage was significantly related to their extraction decision. Orthodontists who were familiar with mini-implants usage would choose to extract the second premolar at a lower size of extent of caries. Besides, when larger sizes of caries lesions in maxillary second premolars were considered, laypersons tended to have greater acceptance of the use of additional anchorage devices in order to keep the healthy maxillary first premolar.

Conclusions

In this study, tooth condition and the use of anchorage devices are currently the main considerations by both orthodontists and laypersons when selecting the teeth to be extracted for orthodontic treatment.