Deep Overbite Research Articles

CBCT analysis of mandibular position and bilateral symmetry in adult female patients with a deep overbite before and after flat bite plate treatment: a retrospective study.

To determine whether three-dimensional measurements can assess symmetry and mandibular position with greater accuracy than traditional two-dimensional measurements. Mimics 19 software was used for three-dimensional measurements of 20 adult female patients' cone-beam computed tomography with deep overbite before and after flat bite plate treatment. Differences in mandible position and bilateral symmetry were assessed using the paired t test. Three-dimensional measurements showed that the condylar distance in the pogonion-Frankfort horizontal, pogonion-coronal, right and left gonion-coronal planes was significantly higher after flat bite plate treatment. However, flat bite treatment did not affect the distance between the vertex of the condyles and the gonion of each measurement reference plane. After flat bite plate treatment, the mandibles of adult female patients had rotated backward and downward, with the condyle as the centre; the chin had been backward. Bilateral symmetry remained unchanged. Flat bite plate treatment in adult female patients resulted in a downward and downward rotation of the mandible, with the condyle as the centre, chin backward, and no significant change in bilateral symmetry.

The prevalence of malocclusion and oral health-related quality of life among 12- and 15-year-old schoolchildren in Shanghai, China: a cross-sectional study

BackgroundMalocclusion is one of the three major oral diseases and may cause deterioration in oral health-related quality of life (OHRQoL). This study aims to determine the prevalence of malocclusion by gender and its impact on quality of life among 12- and 15-year-old children in Shanghai.MethodsThis study summarizes the data obtained in the Shanghai Oral Health Epidemiological Survey conducted in 2019. Random cluster sampling was used to select students in Shanghai. A total of 1591 12-year-old children and 747 15-year-old children were included. Each student underwent an oral examination and completed a questionnaire. The Index of Complexity, Outcome and Need (ICON) was adopted to measure the objective severity of malocclusion and Child Oral Health Impact Profile (COHIP) was applied to evaluate quality of life of schoolchildren. Comparisons of COHIP scores were performed among different treatment needs and difficulties by t-test and analysis of variance (ANOVA).ResultsNo significant difference was found between genders except that the prevalence of deep overbite in 12-year-old boys (1.11 ± 0.95) was significantly higher than that in girls (0.93 ± 0.88) while the prevalence of crossbite among 12-year-old girls (26%) is significantly higher than boys (20%). Malocclusion in 15-year-old children was descended compared with 12-year-old. 15-year-old students demonstrates larger impact of malocclusion on oral health than 12-year-old group except self-image. Health impacts (COHIP) increase significantly as the malocclusion becomes severer except self-image in 12-year-old group.ConclusionsIn Shanghai, the severity of malocclusion in 15-year-old children was less than 12-year-old children. Malocclusion has greater influence on oral health of 15-year-old children than 12-year-old children. Severer malocclusion generally correlates with higher level of oral health impacts in schoolchildren.

Evaluation of anterior teeth crown-root morphology and alveolar bone structure in patients with closed deep overbite using cone beam computed tomography

This retrospective study used cone-beam computed tomography to investigated the crown-root morphology and alveolar bone structure in incisors region in subjects with closed deep overbite and comparison the difference between gender and age. The CBCT images for 40 subjects (group C) with Angle II division 2 were selected from patients of the HeFei Stomatological Hospital from November 2023 to March 2024.20 individual normal occlusion subjects (group A),20 patients with Angle II division 1(group B) were included. The crown-root ratio of the maxillary and mandibular anterior teeth, crown-root angle and alveolar bone structure were measured on the CBCT images, the data were statistically analyzed. In addition to mandibular lateral incisor, the crown-root ratio of maxillary and mandibular anterior teeth in the Class II division 2 group was higher than that in the individual normal occlusion group and the Class II division 1 (P < 0. 05). The crown-root angle of maxillary anterior teeth in the Class II division 2 group was smaller than that in the individual normal occlusion group and the Class II division 1 (P < 0. 05). The alveolar bone thickness of the maxillary central incisor was comparatively smaller, while the alveolar bone height was relatively higher in the Class II division 2 group. Age and gender were associated with change in root lengths and crown-root angle for the Class II division 2 group (P < 0. 05). Patients with closed deep overbite malocclusion exhibit a significant difference compared to the controls for most measurements. The patients presenting with Class II division 2 malocclusion exhibit excessive inward positioning of the anterior teeth, resulting in evident crown-root angle, a large crown-root ratio, and minimal labial alveolar bone. In order to keep the tooth movement within the safe range of alveolar bone movement, it is necessary to strictly control the torque and use appropriate orthodontic force to reduce the risk of bone fenestration, bone dehiscence, gingival recession and root resorption.

Comparison between effects of reverse curve of Spee nickel titanium archwire and stainless steel archwires with and without torque on the lower incisors in deep overbite treatment: a randomized control study.

To compare the effect between three different reverse curve of Spee (RCOS) archwires: 0.016 × 0.022-inch Nickel-Titanium and 0.019 × 0.025-inch stainless steel (SS) with and without crown labial torque (CLT) on lower incisors during deep overbite treatment. Eighty subjects with deep overbite were randomly divided into three groups: the first group (mean age: 20.5 years) received SS RCOS with CLT, the second group (mean age: 19.4 years) was treated with 0.019 × 0.025-inch SS RCOS with zero CLT, the third group (mean age: 18.2 years) was treated with rocking-chair nickel-titanium (NiTi) 0.016 × 0.022-inch with RCOS. Two lateral cephalometric images were taken for each patient, one after alignment and the second after deep bite correction. These images were superimposed using the corpus axis to study the lower incisor horizontal and vertical changes. The lower incisor angular change was significantly smaller in Group II (-0.3°) compared to Group I (4.8°) and Group III (6.0°, P ≤ .001). Lower incisor anterior movement was reduced in Group II compared to Group I (P = .014) and Group III (P = .008). Group III showed significantly more downward movement of the lower Incisors (P ≤ .001). The three groups showed comparable amounts of true intrusion (1 mm, P = .536). 0.016 × 0.022-inch NiTi and 0.019 × 0.025-inch SS with crown labial torque RCOS archwires resulted in similar proclination and forward movement of the lower incisors. Removal of anterior crown labial torque from the 0.019 × 0.025-inch SS RCOS archwire prevents lower incisor proclination and forward movement.

Prevalence of Malocclusion among School aged Children and Adolescents in Kabul, Afghanistan

One of the major public health concerns is the prevalence of malocclusion among school-aged children. Malaligned teeth and incorrect jaw posture are referred to as malocclusion, and they can cause a number of functional and cosmetic problems. The aim of this study was to investigate the prevalence of malocclusion in school-aged children and adolescents in Kabul, Afghanistan. This descriptive cross-sectional study was conducted at the Faculty of Dentistry, Kabul University of Medical Sciences “Abu Ali Ibn Sina” (KUMS). The data were collected from High schools in Kabul, Afghanistan during 2019 and 2020. A sample of 479 children and adolescents, 236 females (49.3%) and 243 males (50.7%) 8-18 years old (mean age 14.16±2.8) were randomly selected from four high schools of different districts of Kabul city. We used the angle classification for sagittal plane malocclusion; open bite and deep bite for vertical plane malocclusions; cross bites for transverse plane malocclusion; midline diastema, spacing and crowding show the tooth material and arch length discrepancies. This study demonstrated that only 41 (8.6%) of subjects had normal occlusion while 92.4% of subjects had different types of malocclusions. Class I malocclusion was found in 275 subjects ( (57.4%, class II Division 1 in 63 subjects (13.1%), Class II Division 2 in 64 subjects (13.4%), Class III malocclusion in 36 subjects (7.5%), moreover, crowding in 183 (38.2%), spacing in 79 (16.5%), midline diastema in 54 (11.3%), crossbite in 77 subjects (16.1%), open bite in 23 subjects (4.8%) and deep overbite in 44 subjects (9.2%) were found. According to Angle’s classification of malocclusion class I malocclusion was the most prevalent malocclusion and class III was the least prevalent malocclusion in school-aged children and adolescents in Kabul city.

Malocclusion in deciduous dentition: a cross-sectional study in a Portuguese preschool population

PurposeTo determine the prevalence of malocclusion in Portuguese preschool children, to characterise occlusion in the deciduous dentition, and to study the relationship between malocclusion, sex, and age.MethodsThis cross-sectional study included 3–6 years old children, from 25 randomly selected kindergartens from the Lisbon district. Data were collected through an oral examination. Malocclusion was defined as the presence of any type of occlusion anomaly (anterior crossbite, edge-to-edge, increased overjet, open bite, deep overbite, posterior crossbite, scissor bite), spacing anomaly (crowding), or dentition anomaly (supernumerary teeth, agenesis, malformations). Canine class, terminal plane of the deciduous second molars and type of Baume arch were also recorded. Statistical analysis included descriptive and chi-squared test (α = 0.05).ResultsThe sample included 426 children with a global prevalence of malocclusion of 60.6%. Occlusion anomalies were the most prevalent (59.2%), the most frequent being deep overbite (27%), increased overjet (22.1%) and posterior crossbite (14.1%). Crowding had a prevalence of 1.6% and agenesis of 1.4%. Class I canine (57.3%), straight second molar terminal plane (60.1%) and type I Baume arch (53.3%) were the most common. The mean overjet was 2.6 mm (sd = 2.1) and the mean overbite was 2.2 mm (sd = 2.1). Age was associated with the presence of occlusion anomalies (p = 0.03), and increased overjet prevalence was found to be higher in girls (p = 0.03).ConclusionsThe prevalence of malocclusion was high, with occlusion anomalies being the most prevalent. It is important to identify modifiable risk factors associated with malocclusion to prevent this condition in both the deciduous and permanent dentitions.

Deep overbite reduction in adolescent patients treated with Invisalign: A retrospective analysis

Data regarding the efficacy of deep overbite correction with clear aligner therapy in adolescent patients are lacking. This study aimed to investigate the efficacy of deep overbite reduction in adolescent patients treated with Invisalign (Align Technology, San Jose, Calif) aligners. This retrospective study investigated a sample of 102 patients aged 10-17 years from a large database. All patients had completed wear of a prescribed series of Invisalign aligners with planned overbite reduction on a nonextraction basis. The predicted, pretreatment, and posttreatment overbite measurement values were obtained from Align Technology's ClinCheck digital facility. Linear modeling, with Bland-Altman plots, was used to compare the effect of age, the use of bite ramps, and the adoption of the eighth-generational (G8) protocol on the difference between predicted and achieved overbite measurements. A total of 102 patients with a mean ± standard deviation age of 13.94 ± 1.53 years satisfied the selection criteria. A mean ± standard deviation of 41.38 ± 30.43% of the predicted overbite reduction was achieved. There were no differences in the predictability of overbite reduction between patients who were aged<14 years or those aged 14-17 years (P= 0.73), between patients prescribed and not prescribed bite ramps (P= 0.25), or between patients prescribed the G8 protocol and not prescribed the G8 protocol (P= 0.65). The average achieved overbite was less than half of what was planned by the orthodontists via the ClinCheck facility. The age grouping, the provision of bite ramps, and the G8 protocol appear to have little influence on the efficacy of overbite reduction in adolescent patients.

Impact of Invisalign® first system on molar width and incisor torque in malocclusion during the mixed dentition period.

In orthodontic treatment of patients during the mixed dentition period, arch expansion and opening deep overbite are one of the objectives to achieve proper alignment of the teeth and correction of sagittal and vertical discrepancies. However, the expected outcomes of most therapeutic regimens are not clear, making it impossible to standardize early treatment effects. Therefore, this study was designed to evaluate the impact of the Invisalign® First System on the dental arch circumference and incisor inclination in patients during the mixed dentition period. A total of 21 children during the mixed dentition period (10 females and 11 males, with an average age of 8.76 years) were included in this study. The patients received non-extraction treatment through Invisalign® First System clear aligners, and no other auxiliary devices were used except Invisalign® accessories. Subsequently, the cooperation degree of patients during treatment and the oral measurement parameters at the beginning (T1) and the end (T2) of treatment were collected. All patients showed moderate/good cooperation degree during treatment. Besides, horizontal width of the maxillary first molar increased significantly; the designed arch expansion was 4.1 mm (±1.4 mm), while the actual arch expansion was 3.0 mm (±1.7 mm). Furthermore, the torque expression rate of upper anterior teeth reached 56.53%. Invisalign® First System clear aligners can effectively correct the teeth of patients during the mixed dentition period, widen the circumference of dental arch, and control the torque of incisors.

Characteristics Of Occlusion In Primary Dentition And Its Relationship With Caries In Preschool Children In Aydın

Objective: The purpose of this study was to determine the clinical characteristics of occlusion in primary dentition and examine its relationship to caries experience in preschoolers in Aydın, TÜRKİYE. Materials and methods: The study was conducted among 962 children aged 3–5 years from preschoolers in a cross-sectional design. The clinical features were evaluated according to Björk et al and the caries examination was carried out with dft index. Results: The most common type of terminal plane relationship was flush type (46.7%) and primary canine relationship was Class I (69.6%). The most common type of irregularity was the prevalence of deep overbite (55.7%) followed by midline deviation (15.8%). Approximately half of the children (51.2%) had at least one carious tooth but caries experience was not related with any of the occlusal irregularities. Conclusion: Occlusal characteristics of the preschool children were defined and no relationship was found between these features and gender or caries experience.

Prevalence of Malocclusion Traits in Primary Dentition, 2010-2024: A Systematic Review.

The present review was aimed to describe the prevalence and the regional distribution of malocclusion among preschool children worldwide. Two independent reviewers performed a systematic literature search to identify English publications from January 2010 to May 2024 using PubMed, ISI Web of Science and Embase. Search MeSH key words were "malocclusion", "primary dentition" and "child, preschool". The reporting quality was assessed by the modified Newcastle-Ottawa Quality Assessment Scale. We identified 2599 publications and recruited 47 articles. Fourteen of the included studies were conducted in Asia, four in Europe, twenty-eight in South America and one in Africa. The prevalence of malocclusion ranged from 28.4% to 83.9%, and half of the reported prevalences were higher than 50%. The highest percentage was in Asia (61.81%), followed by Europe (61.50%), South America (52.69%) and Africa (32.50%). Statistically significant differences existed in deep overbite, anterior open bite, posterior crossbite, edge-to-edge incisor relationship and distal step between continents (p < 0.05). Europe showed the highest prevalence (33.08%) of deep overbite. Africa showed the highest prevalence (18.60%) of anterior open bite. Europe showed the highest prevalence (15.38%) of posterior crossbite. The most common malocclusion traits were increased overjet and deep overbite. To conclude, malocclusion remained prevalent in the primary dentition and varied between countries.

The clinical study and multi-factor analysis of temporomandibular joint disorder induced by tooth extraction

BackgroundTemporomandibular joint disorder (TMD) is a common complication of tooth extraction. The pathogenesis of TMD is not clear, and its incidence has not been controlled effectively. Some studies have shown that tooth extraction can induce temporomandibular joint disorder, but the specific factors still need further study. Methods536 patients of tooth extraction were included in our hospital from January 2018 to December 2022. According to whether TMD occurred after tooth extraction, the patients were divided into experimental group and control group.Gender, age, tooth position, tooth type, hammer, tooth extraction time, bruxism, deep overbite and overjet were compared between the two groups. ResultsTMD occurred in 44 patients (8.2%) after tooth extraction. Univariate analysis and logistic regression analysis showed that TMD after tooth extraction was related to the position of tooth extraction (upper or lower jaw), type of tooth extraction (molar or non-molar, deep overbite or overjet (P < 0.05), but not to gender, age, hammer, extraction time and bruxism (P > 0.05). ConclusionMandibular, molar, deep overbite and overjet are the risk factors for TMD after tooth extraction. The corresponding treatment plan should be adopted according to different clinical manifestations and diagnosis. Meanwhile, minimally invasive tooth extraction should be carried out during tooth extraction for minimizing the damage to the temporomandibular joint and preventing the occurrence of TMD.

Influence of Different Jumping Gaps on Socket-Shield Technology: Three-Dimensional Finite Element Analysis

Socket-shield technique expands the indications for immediate implant placement and effectively maintains the contour of the labial bone. However, due to its relatively high incidence of complications, the technique has not become routine. Understanding the biomechanical characteristics among different structures in socket-shield technique has clinical significance. In this study, finite element analysis was conducted to investigate the biomechanical correlations with the exposure, migration and fracture of the root shield. Seven three-dimensional finite element models were constructed with jumping gaps of 0[Formula: see text]mm, 0.5[Formula: see text]mm, 1[Formula: see text]mm, 1.5[Formula: see text]mm, 2[Formula: see text]mm, 2.5[Formula: see text]mm and 3[Formula: see text]mm, respectively. The results illustrate deep overbite loading induces unfavorable biomechanical reactions in various structures in socket-shield technique. For normal occlusion, the jumping gap that is too small leads to stress exceeding the yield strength of the root shield and comparatively large displacement in the root shield, possibly causing fracture and migration of the root shield. The jumping gap that is too large causes micro-damages to the cortical bone around the implant, potentially leading to cortical bone resorption and exposure of the root shield. Therefore, the technique should be avoided in patients with deep overbite loading, and the jumping gap of 1.5–2[Formula: see text]mm may be a suitable choice.

Evaluation of Mandibular Projection in Class II Division 2 Subjects Following Orthodontic Treatment Using Clear Aligners.

The purpose of this study was to evaluate the mandibular growth and/or projection following maxillary incisor proclination, overbite correction, and maxillary dentoalveolar expansion without the use of any class II mechanics, in growing class II division 2 patients treated with clear aligners. Before and after treatment cone-beam computed tomographic (CBCT) generated lateral and posteroanterior cephalograms of thirty-two patients with skeletal class II division 2, 16 in the treatment group and 16 in the untreated group, were reviewed to evaluate treatment-related changes. Upper incisors were proclined and protruded, as well as upper arch expansion and overbite correction were performed as part of their regular treatment. Cephalometric analysis was performed to evaluate skeletal and dental changes. Unpaired statistical t-tests were performed to determine if significant skeletal class II correction was achieved in the treatment group. In the treatment group, after treatment, the upper incisors became more proclined and protruded, and the inter-molar width increased while the overbite was reduced compared to the control group. An increase in skeletal mandibular growth and forward projection was also observed, thus contributing to an improvement of the sagittal skeletal relationship as evidenced by ANB and Wits values compared to the control group. A combination of upper incisor proclination, correction of deep overbite, and maxillary dentoalveolar expansion using clear aligners appears to contribute to an improvement of the skeletal class II relationship in growing patients with class II division 2. This study shows that unlocking the mandible by correcting a deep overbite, proclining upper incisors, and expanding the upper arch in growing class II division 2 patients can improve skeletal class II using clear aligners. How to cite this article: Mirzasoleiman P, El-Bialy T, Wiltshire WA, et al. Evaluation of Mandibular Projection in Class II Division 2 Subjects Following Orthodontic Treatment Using Clear Aligners. J Contemp Dent Pract 2024;25(4):295-302.

A longitudinal study of the probability of developing malocclusion in children using a Bayesian analysis

This study evaluated the probability of developing malocclusions in mixed dentition. A longitudinal study was conducted with 598 children (aged 5 years) in deciduous dentition. The children were followed for 3 years until mixed dentition (aged 8 years). Overjet, overbite, and transversal relations were evaluated. Bayesian models were used to analyze the data and estimate the parameters. The parameter θ was used for the distributions, indicating the probability of presenting a given condition with a credibility index (ICr) of 95%. After 3 years of follow-up, 121 children were reevaluated. The results showed that children have a high probability of malocclusion in mixed dentition. There was a higher probability of developing an increased overjet in the mixed dentition of 20.5% (ICr 95%, 13.6-28.4) to 48.3% (ICr 95%, 39.1-57.7) and a higher probability of having a normal overbite in the deciduous dentition and a lower probability in the mixed dentition (ICr 95%, 9.2-21.3). Considering the probabilistic model of Bayesian analysis, children with normal overjet in the deciduous dentition may show an increased overjet in the mixed dentition. Concerning overbite, children may present an anterior open bite during the transition between deciduous and mixed dentition, as well as self-correction of deep overbite in mixed dentition. Furthermore, they may present a posterior crossbite during the mixed dentition when there is a normal transverse relationship in the deciduous dentition.

Two simple yet efficient biomechanics for correction of retroclined maxillary central incisors

Angle’s class II division 2 malocclusion is characterized by retroclined maxillary central incisors and increased overbite. The first step in the treatment of such cases involves the correction of incisor inclination and their intrusion. Conventional techniques for intrusion are taxing on the anchor teeth like molars and adjacent teeth like lateral incisors. Appropriate biomechanical use of temporary anchorage devices (TADS) will enable the clinician to avoid undesirable tooth movements. The following are two cases in which simple and efficient biomechanics have been performed with the use of TADS for the correction of incisor inclination and deep overbite. The case-specific use of single vs two mini implants as well as round vs rectangular wire for intrusion and proclination of central incisors has also been explained.

Influence of Invisalign precision bite ramp utilization on deep bite correction and root length in adults.

To assess the influence of Invisalign precision bite ramp use on skeletal deep overbite correction and root length and volume of maxillary anterior teeth. This was a retrospective study of 60 adults with skeletal deep overbite. Patients were divided into three groups: Invisalign (Align Technology, San Jose, Calif) with precision bite ramps (Invisalign with Bite Ramps [IBR] = 12), Invisalign with no bite ramps (INBR = 22), and full-fixed appliances (FFA = 26). Cone beam computed tomography records at T1 (pretreatment) and T2 (posttreatment) were used to measure eight skeletal, nine dental, and three soft-tissue cephalometric variables. Maxillary anterior teeth root length (mm), root volume (mm3), and percent root volume loss between T1 and T2 (%) were also recorded. Significant changes from T1 to T2 among the three groups were seen in ANB(o), lower face height (%), ODI (overbite depth indicator) (o), and U1-SN (o). Reduction in root length was significantly less (P < .001) in the INBR and IBR groups compared to the FFA group. Reduction in root volume and percent volume loss were significantly higher in the INBR group compared to the IBR group (P < .001), but the difference between the two Invisalign groups and the FFA group was not significant. Skeletal deep overbite correction using Invisalign with or without bite ramps is comparable to FFA. Reduction in root length was significantly less with Invisalign compared to FFA. Bite ramps influenced root volume and volume loss but not root length.

Does aligner refinement have the same efficiency in deep bite correction?: A retrospective study

BackgroundRefinements are very common in clear aligner treatments. The aim of this study is to assess whether the predictability of deep overbite correction is similar over several refinements using clear aligners (Invisalign, Align Technology, San Jose, Calif) and examine the accuracy of vertical movement and inclination change of individual teeth.MethodsThis retrospective study included 20 deep bite patients (7M and 13F; 32.63 ± 11.88 years old; an initial overbite of 5.09 ± 0.98 mm), consecutively treated from September 2016 and March 2023, who completed at least two sets of aligners, including refinements. The initial, predicted, and achieved models were exported from ClinCheck or OrthoCAD (Cadent Inc, Carlstadt, NJ) and superimposed via best-fit surface-based registration using SlicerCMF (version 4.9.0; cmf.slicer.org). We also examined 15 out of 20 patients who completed treatments. The overbite correction and changes in vertical movement and inclination for individual teeth were measured. Descriptive statistics and a paired t-test or Wilcoxon signed-rank test were performed. P < 0.05 was considered statistically significant.ResultsThe mean accuracy of overbite correction was 37.63% after 1st set, followed by 11.19%, 6.32%, and 13.80% (2nd-4th sets), respectively. There were statistically significant differences between the predicted and achieved vertical movements and inclination changes for all teeth for the 1st and 2nd sets. For the completed cases, the mean overbite correction was 38.54% compared to the initially planned overbite correction, which is similar to one of the 1st set. Still, the vertical movements and inclination changes of all teeth present statistically significant differences between the initially planned and finally achieved movements except for maxillary lateral incisor torque.ConclusionsThe most overbite correction occurs during the 1st set of aligners, and refinement treatment does not significantly improve the deep bite correction.

Cone-beam computed tomographic evaluation of mandibular incisor alveolar bone changes for the intrusion arch technique: A retrospective cohort research.

: Alveolar bone loss is a common adverse effect of intrusion treatment. Mandibular incisors are prone to dehiscence and fenestrations as they suffer from thinner alveolar bone thickness. : Thirty skeletal class II patients treated with mandibular intrusion arch therapy were included in this study. Lateral cephalograms and cone-beam computed tomography images were taken before treatment (T1) and immediately after intrusion arch removal (T2) to evaluate the tooth displacement and the alveolar bone changes. Pearson's and Spearman's correlation was used to identify risk factors of alveolar bone loss during the intrusion treatment. : Deep overbite was successfully corrected (P < 0.05), accompanied by mandibular incisor proclination (P < 0.05). There were no statistically significant change in the true incisor intrusion (P > 0.05). The labial and lingual vertical alveolar bone levels showed a significant decrease (P < 0.05). The alveolar bone is thinning in the labial crestal area and lingual apical area (P < 0.05); accompanied by thickening in the labial apical area (P < 0.05). Proclined incisors, non-extraction treatment, and increased A point-nasion-B point (ANB) degree were positively correlated with alveolar bone loss. : While the mandibular intrusion arch effectively corrected the deep overbite, it did cause some unwanted incisor labial tipping/flaring. During the intrusion treatment, the alveolar bone underwent corresponding changes, which was thinning in the labial crestal area and thickening in the labial apical area vice versa. And increased axis change of incisors, non-extraction treatment, and increased ANB were identified as risk factors for alveolar bone loss in patients with mandibular intrusion therapy.

Effects of different patterns of movement for correcting a deep curve of Spee with clear aligners on the anterior teeth: a finite element analysis

ObjectiveTo analyse the anterior teeth effects of clear aligners on five different patterns of mandibular molar movement and to define the most effective configuration to be implemented with clear aligners through finite element analysis.MethodsA three-dimensional mandibular model with a deep overbite in the mandible was constructed using cone beam computerized tomography (CBCT) data. The model included the mandibular dentition, mandibular periodontal ligaments, attachments, and aligners. Five models were created: (1) configuration A: second molar distalization (0.25 mm); (2) configuration B: second molar distalization (0.25 mm), first molar extrusion (0.15 mm); (3) configuration C: second molar distalization (0.25 mmm), first and second premolar extrusion(0.15 mm); (4) configuration D: second molar distalization (0.25 mm), first molar and first/second premolar extrusion(0.15 mm); and (5) configuration E: second molar distalization (0.25 mm), first molar and first/second premolar extrusion (0.15 mm), first molar and first/second premolar expansion (0.15 mm).ResultsIn all configurations, the anterior teeth exhibited labial tipping and the mandibular central incisor of configuration E showed the highest labial tipping. Configuration E demonstrated a relatively minor impact on mandibular molars distalization compared with configuration A. Configuration A showed the highest distal displacement value, and configuration E produced the lowest displacement value. Configuration E caused the highest periodontal ligament (PDL) pressure of the central and lateral incisors. The differences in the canines between configurations C and D,were not significant, and the stress distribution differed among the five groups.ConclusionsAll patterns utilizing clear aligners facilitated mandibular molar distalization. Extruding the premolars and second molar distalization at the same time had little impact on second molar distalization; When expansion and extrusion were simultaneously performed during the distalization of mandibular molars, our prime consideration was the alveolar bone on the labial side of the anterior teeth to prevent the occurrence of gingival recession, dehiscence, and fenestration. Due to the lack of consideration for periodontal tissues in this study, clinical protocols should be designed based on the periodontal status of the mandibular anterior teeth.

The second molar dilemma in orthodontics: to bond or not to bond?

To compare orthodontic treatment (OT) outcome in adolescents undergoing nonextraction fixed OT with or without bonding of second molars using the score of the American Board of Orthodontics Cast Radiograph Evaluation (C-R-Eval). This study included healthy adolescents with skeletal Class I or mild Class II/Class III malocclusion, normal or deep overbite (OB), and mild-to-moderate dental crowding (<5 mm) who underwent nonextraction fixed OT with ("bonded" group) or without ("not-bonded" group) bonding of second molars. Patient treatment records, pre- and posttreatment digital models, lateral cephalograms, and orthopantomograms were assessed. The evaluated outcomes included leveling of the curve of Spee (COS), OB, control of incisor mandibular plane angle (IMPA), number of emergency visits (related to poking wires and/or bracket failure of the terminal molar tubes), treatment duration, and C-R-Eval. Treatment variables were compared across time points and among groups. The sample included 30 patients (mean age 16.07 ± 1.80 years) in the bonded group and 32 patients (mean age 15.69 ± 1.86 years) in the not-bonded group. The mean overall C-R-Eval score was significantly higher (P < .001) in the not-bonded group (25.25 ± 3.98) than in the bonded group (17.70 ± 2.97). There were no significant differences in mean changes of COS, OB, IMPA, or treatment duration among groups. The mean number of emergency visits was significantly higher in the bonded (3.3 ± 0.6) than the not-bonded group (1.9 ± 0.4) (P < .001). Bonding of second molars enhances the outcome of nonextraction fixed OT as demonstrated by the C-R-Eval without increasing treatment duration, irrespective of more emergency visits.