Vertical skeletal changes after extraction and non-extraction treatment in matched class I patients identified by a discriminant analysis: cephalometric appraisal and Procrustes superimposition

Effect of four premolar extractions on the vertical dimension of the face : A retrospective cephalometric study

PURPOSE

Adequate control of the vertical dimension is of great importance in orthodontic treatment. Although existing evidence is very limited, extraction of four premolars is thought to contribute towards improved control of anterior facial height compared with non-extraction treatment protocols. Thus, the aim of this retrospective cohort study was to compare the effect of fixed-appliance treatment with extraction of four premolars to non-extraction treatment on the skeletal vertical dimension.

METHODS

A consecutive sample of 76 children with skeletal hyperdivergence (49% male; mean age 11.9 years) was divided into two groups for treatment with either non-extraction (n = 31) or extraction of four premolars (n = 45). Baseline characteristics were comparable: overjet 5.1 ± 2.5 mm, overbite 2.4 ± 1.9 mm, ANB angle 4.6 ± 2.3°, and SN-ML angle 40.2 ± 3.5°. Patients were treated with standard edgewise fixed appliances with closing loops/sliding mechanics. Vertical skeletal and dental outcomes were measured on lateral cephalograms before and after treatment. Data were analyzed with linear regression at 5%.

RESULTS

Compared to non-extraction treatment, treatment with premolar extractions had no significant effect on the SN-ML angle (difference (Δ) = 0.07°; 95% confidence interval -0.90 to 1.01°; P = 0.88). Statistically significant changes between the extraction and non-extraction groups were only found for the parameters SNA (Δ -1.47°; P = 0.003), ANB (Δ -1.17°; P = 0.004), SN-OP (Δ -1.48°; P = 0.04), and L1-ML (Δ -6.39°; P < 0.001).

CONCLUSION

Orthodontic treatment of children with skeletal hyperdivergence using systematic extraction of four premolars had minimal effects on the vertical facial dimension compared to non-extraction treatment.

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.

Hard and soft tissue shape variation and changes in Class II division 1 malocclusion during orthodontic treatment: a geometric morphometric analysis

BACKGROUND

This study aims to determine the hard and soft tissue shape variation and its changes in Class II division 1 malocclusion before and after orthodontic treatment using Geometric Morphometric Analysis.

METHODS

This retrospective study included 141 pre-treatment and near-end treatment lateral cephalometric radiographs of Class II division 1 malocclusion patients aged 16-40 years with a skeletal II pattern (ANB > 4o). 32 landmarks in Cartesian coordinates were created and identified using MorphoJ software to establish a shape analysis.

RESULTS

The vertical dimensions (hypodivergent to hyperdivergent facial profiles) showed the largest variation in the general shape of hard and soft tissue, followed by the anteroposterior dimensions (mild to severe skeletal II patterns). Variations of lip shape (long to short), lip protuberance (everted to inverted), and nasolabial angle (obtuse to acute) were present. Orthodontic treatment affected the shape of the hard and soft tissue significantly (p < 0.0001). T2 showed significant uprighting of upper incisors (17.5o) and lower incisors (3.7o), improved NLA (8o), an increase in upper lip thickness (1.5 mm), and a reduction in lower lip thickness (0.7 mm) (p < 0.05).

CONCLUSION

Vertical and anteroposterior shape variations were found. Orthodontic treatment had an impact on both hard and soft tissue shapes. Hence, understanding both the hard and soft tissue shape variations and the orthodontic treatment changes is crucial for an accurate diagnosis and treatment plan to achieve a successful outcome and excellent patient satisfaction.

Effect of socioeconomic and malocclusion-related factors on duration of orthodontic treatment by fixed appliance: A retrospective study

OBJECTIVES

The aims of this study were to evaluate the effect of related factors that influence orthodontic treatment time and to identify the predictors of orthodontic treatment duration in a Chinese population.

MATERIALS AND METHODS

Information for 29 sociodemographic, malocclusion and orthodontic treatment characteristics was collected. Patients were divided into two groups: the duration ≤24 months group and duration >24 months group. The treatment dates of the initial visit and end of orthodontic treatment were obtained to calculate duration. The data were subjected to univariate and multivariate logistic regression modelling to quantify the association between characteristics and the treatment duration; odds ratios (ORs) and 95% confidence intervals (95% CIs) are reported.

RESULTS

Of 2120 patients, 704 patients (mean age, 15.9 ± 6.0 years) were included. Age, extraction, Bolton ratio (overall), rotated teeth, overjet and crowding (lower arch) were predictors for duration. The nomogram based on predictive factors exhibited strong discrimination ability, with concordance indices of 0.755 (95% CI = 0.712-0.798) in the training cohort model and 0.717 (95% CI = 0.647-0.787) in the validation cohort model. The calibration curves for the training and validation cohorts showed that the probabilities of the nomogram agreed well with actual probabilities.

CONCLUSIONS

Young age, non-extraction and severe crowding (lower arch) can increase the chance of durations of ≤24 months. Rotated teeth, excessive overjet and Bolton ratio (overall) can increase the chance of durations of >24 months.

Skeletal and soft-tissue changes in humans with untreated normal occlusion throughout lifetime: a systematic review

Age-related skeletal and soft-tissue changes are important in orthodontics, especially due to the increase of adult patients seeking treatment. The aim of this study is to assess the available evidence regarding age-related skeletal and soft-tissue changes in untreated Angle Class I. Articles studying skeletal and soft-tissue changes in orthodontically untreated subjects with Angle Class I and comparing them between age groups were included. Studies focusing on a single age group or in languages other than English were excluded. Risk of bias was assessed with both the MINORS and ROBINS-I tools. 50 studies were included, showing high methodological heterogeneity and a lack of information in subjects over 60 years old. In subjects with Angle Class I, the mandibular plane inclination was reported to reduce from 7 and 20 years old, while the anterior and posterior facial height continue to increase in late adult life. The anterior cranial base length increases until 20 years old, afterwards decreasing slowly until late adulthood. Nasal width increases and the nasolabial angle decreases during adolescence. Upper lip length and lower lip length increase from 6 to 18 years along with retrusion of the lips in late adulthood. Age-related skeletal and soft-tissue changes are documented in the literature from childhood until the fifth decade of life, but studies mostly focus on subjects until 20 years old. Changes after the second decade of life are studied only for the vertical and sagittal dimensions. No changes are reported in the transversal dimension beyond 15 years for neither skeletal nor soft tissues. Well-designed, long-term prospective cohort studies considering all three dimensions of skeletal and soft tissues are needed for confirmation of these findings (PROSPERO: CRD42020203206).

Palatal shape covariation in extraction versus nonextraction borderline patients: A geometric morphometric study

INTRODUCTION

This study aimed to evaluate changes in palatal shape after orthodontic treatment from a borderline sample of extraction and nonextraction patients with a Class I relationship.

METHODS

A borderline sample regarding premolar extractions was obtained through discriminant analysis and comprised 30 nonextraction and 23 extraction patients. The digital dental casts of these patients were digitized with 3 curves and 239 landmarks placed on the hard palate. Procrustes superimposition and principal component analysis were implemented to assess group shape variability patterns.

RESULTS

The success of the discriminant analysis in identifying a borderline sample regarding the extraction modality was validated using geometric morphometrics. Concerning palatal shape, no sexual dimorphism was found (P = 0.78). The first 6 principal components that were statistically significant accounted for 79.2% of the total shape variance. Palatal changes were 61% more pronounced in the extraction group, which exhibited a decrease in palatal length (P = 0.02; 10,000 permutations). In contrast, the nonextraction group showed an increase in the palatal width (P <0.001; 10,000 permutations). Intergroup comparisons indicated that the nonextraction group exhibited longer palates, whereas the extraction group exhibited higher palates (P = 0.02; 10,000 permutations).

CONCLUSIONS

Considerable changes in palatal shape were seen for the nonextraction and extraction treatment group, with the latter exhibiting more pronounced changes, mainly in terms of palatal length. Further investigations are needed to clarify the clinical significance of the palatal shape changes in borderline patients after extraction and nonextraction treatment.

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.

Analysis of canine retraction and anchorage loss in different facial types with and without piezocision: a split-mouth-design, randomized clinical trial

OBJECTIVES

To investigate canine retraction (CR) and anchorage loss (AL) among average facial height (AFH) and high facial height subjects (HFH) with or without piezocision surgery (PS).

MATERIALS AND METHODS

This was a split-mouth, randomized clinical trial. Twenty-three females (aged 19.05 ± 2.95 years) who presented with Class II division I malocclusion requiring bilateral maxillary extraction and who fulfilled eligibility criteria were included and categorized into two groups: AFH (12 participants) and HFH (11 participants). Atraumatic extractions were performed 10 weeks following bonding. Before space closure, impressions were taken to fabricate models, which were scanned to generate digital models. Each participant had PS on the randomly assigned side. Space closure was undertaken using 100-g nickel-titanium coil closing springs on 0.019 × 0.025-inch stainless steel archwire. Digital models were collected 6 and 12 weeks post-PS. They were superimposed using reliable reference points and a region of interest on the palate, and crown movements were analyzed in three dimensions.

RESULTS

Three months post-PS, intergroup comparisons showed that rates of CR for control sides (mean = 1.88 ± 0.83 mm for AFH, mean = 1.76 ± 0.62 mm for HFH) and intervention sides (mean = 1.48 ± 0.74 mm for AFH, mean = 1.40 ± 0.85 mm for HFH) were not significantly different. AL was not significantly different (P > .05) between groups.

CONCLUSION

Regardless of whether the patient underwent PS, CR and AL rates for AFH and HFH patients were not significantly different.

Vertical Skeletal Changes after Extraction and Nonextraction Orthodontic Treatment

OBJECTIVES

 Due to the constant battle regarding the controversial topic of orthodontic extraction, this study aims to assess the changes in vertical dimensions of patients treated with premolar extractions compared with nonextraction orthodontic patients.

MATERIALS AND METHODS

 A sample of 60 borderline patients were recruited and divided into extraction and nonextraction groups. Eleven pretreatment cephalometric measurements were recorded using WebCeph and patients were followed-up until the completion of treatment.

STATISTICAL ANALYSIS

 Intragroup and intergroup comparisons were made using paired t-test and two-sample independent t-test, respectively. The joint significance of differences was measured using F-tests.

RESULTS

 The intragroup comparison revealed that in the extraction group, the vertical dimension was significantly increased posttreatment for four cephalometric measurements, that is, mandibular plane angle (p < 0.05), palatal plane angle (p < 0.05), Frankfort mandibular plane angle (p < 0.05), and y-axis (p < 0.05). In the comparison of the posttreatment values of both groups, the mean differences of the posttreatment values for sella nasion (SN)-gonion (Go)-gnathion (Gn) angle (p = 0.008), the total anterior (p = 0.050), and lower anterior facial heights (AFH; p = 0.011) were significantly higher. At the same time, the Jarabak ratio was significantly (p = 0.006) lower in the extraction group than in the nonextraction group.

CONCLUSION

 The increase in vertical dimension is significantly higher in the extraction group than in the nonextraction group which indicates a significant impact of orthodontic extraction on the vertical dimensions.

Three-dimensional soft tissue changes in orthodontic extraction and non-extraction patients: A prospective study

OBJECTIVES

To assess the soft tissue changes in orthodontic extraction and non-extraction patients on 3D stereophotogrammetric images.

SETTING AND SAMPLE

23 extraction (22.2 ± 9.2 years) and 23 non-extraction (20.3 ± 11.1 years) consecutive patients were enrolled at the Sections of Orthodontics at Aarhus University and at University of Naples Federico II.

METHODS

All patients had a first 3D image taken after bonding of brackets on the upper incisors (T0), and a second 3D image (T1) after space closure in the extraction group or at insertion of the first SS or TMA rectangular wire in the non-extraction group. The 3D images were captured with 3dMDFace System and analysed with 3dMDVultus Software. After placing 19 landmarks, 15 measurements were obtained. Intragroup changes were analysed with paired t-test and intergroup changes with unpaired t-test (P < .05).

RESULTS

Superimpositions of the 3D images at T0 and T1 visualized with colour-coded maps showed that soft tissue changes primarily happened in the perioral area in both groups. The Nasolabial angle increased significantly in the extraction group (3°± 4.1, P = .002), while it decreased in the non-extraction group (-1.5°± 5.5°, P = .002). There was a significant difference between the two groups (4.4°, P = .004).

CONCLUSIONS

3D comparison of the soft tissues in the extraction and non-extraction groups showed statistically significant, but clinically limited differences in the perioral area. The Nasolabial angle was significantly larger at T1 in the extraction group compared with the non-extraction group.

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.

First premolar extractions in an adolescent presenting a Class I biprotrusion malocclusion with skeletal Class II: A case report

This case report shows the orthodontic treatment of four first premolar extractions of a 14-year-old teenager presenting a dental Class I malocclusion with a severe retrognathic mandible. It reflects conflicting views on objectives between the orthodontist who takes into account the facial balance and the patient who only desires a tooth alignment.

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.