Skeletal, dentoalveolar and soft tissue changes after stabilization splint treatment for patients with temporomandibular joint disorders.

BACKGROUND: Temporomandibular disorder (TMD) is a grouping of heterogeneous disorders with multifactorial origins. Stabilization splints (SS) have demonstrated an acceptable treatment effect in TMD. The possible changes at the skeletal, dental, and soft tissue levels need to be addressed to evaluate the benefit/risk ratio of this therapeutic procedure. Accordingly, this study aimed to three­dimensionally evaluate skeletal, dentoalveolar and soft tissue changes after SS treatment for patients with TMD. METHODS: This retrospective study included 74 adult patients with myofascial and/or intra-articular disorders (25 males and 49 females), with an average age of 22.88 ± 4.8 years, who underwent SS treatment. Pre- and post-treatment Cone beam computed tomography were analysed using Invivo 6.0.3 software. The primary outcome was the vertical skeletal and dentoalveolar changes, while the secondary outcomes were the anteroposterior skeletal, dentoalveolar and soft tissue changes. Paired t-test and Wilcoxon rank sum test were used for statistical analyses. RESULTS: For the primary outcome; skeletally, there was a significant increase in mandibular plane inclination (difference: 0.82°±1.37), decrease facial height ratio (difference: 0.45%±1.07) and at the dentoalveolar level, the inclination of the functional (FOP-SN, FOP-FH) and bisecting (BOP-SN, BOP-FH) occlusal planes exhibited a significant increase too (difference: 0.38 ± 1.43°, 0.49 ± 1.62°, 0.44 ± 1.29° and 0.41 ± 1.17°, respectively) and also a decrease in the overbite (difference: -0.54 ± 0.83). For the secondary outcomes; there was a significant decrease in mandibular position (SNB) (difference: 1.60 ± 1.36°) and increase in the overjet (difference: 0.93 ± 1.04, p < 0.001) and a significant lower lip retrusion (difference: 0.33 ± 1.01 mm p < 0.01), was observed too. CONCLUSIONS: SS therapy resulted in significant vertical skeletal and dentoalveolar changes that were manifested mainly by facial height ratio, mandibular and occlusal plane changes, and to a lesser extent, significant anteroposterior skeletal, dentoalveolar, and soft tissue changes in the form of mandibular position, increased overjet and a more retrusive lower lip. These changes should be considered during patients' selection prior to initiating SS therapy.

Long-term skeletodental changes with early and late treatment using modified C-palatal plates in hyperdivergent Class II adolescents.

OBJECTIVES: To compare skeletodental changes between early and late treatment groups using modified C-palatal plates (MCPP) and long-term retention outcomes in hyperdivergent Class II adolescents. MATERIALS AND METHODS: Seventy-one hyperdivergent Class II patients were divided into four groups according to treatment modality and treatment timing: group 1, early treatment with MCPP (n = 16; 9.9 ± 0.9 years); group 2, late treatment with MCPP (n = 19; 12.3 ± 0.8 years); group 3, early treatment with headgear (HG; n = 18; 9.6 ± 0.8 years); and group 4, late treatment with HG (n = 18; 12.1 ± 1.2 years). Lateral cephalograms were taken and skeletal and dental variables were measured. For statistical analysis, paired t-tests, independent t-tests, and multiple regression were performed. RESULTS: The early MCPP group showed a more significant decrease in mandibular plane angle than the late MCPP group did, and vertical control was more efficient in the early group than in the late group. In the MCPP groups, both FMA and SN-GoGn were increased with late treatment but decreased with early treatment, and the difference was statistically significant (P < .01). The early-treatment MCPP group had a significant decrease in SN-GoGn of 0.6° compared with an increase of 1.7° in the early treatment HG group (P < .01). Posttreatment stability of both the early and late MCPP groups was maintained in long-term retention. CONCLUSIONS: Early MCPP showed more significant vertical control than late MCPP. However, there was no difference in long-term stability between early and late groups.

Effects of eruption guidance appliance in the early treatment of Class III malocclusion.

OBJECTIVES: To evaluate the dentoskeletal effects and effectiveness of the eruption guidance appliance in Class III patients in the mixed dentition. MATERIALS AND METHODS: The experimental group comprised 22 patients with Class III malocclusion and anterior cross-bite (12 males, 10 females, mean age 7.63 ± 0.96 years) treated with the eruption guidance appliance over a mean period of 1.72 ± 0.48 years. The control group comprised 22 untreated subjects (12 males, 10 females, mean age 7.21 ± 0.60 years) with Class III malocclusion. Lateral cephalometric radiographs were obtained at pretreatment (T1) and posttreatment (T2). Intergroup comparisons were performed with Mann-Whitney and t-tests (P < .05). RESULTS: In the experimental and control groups, the anteroposterior relationship between the maxilla and mandible (ANB angle) remained stable during the treatment period (T1 to T2). The mandibular plane angle decreased in the experimental group and increased in the control group. In the experimental group, the lower anterior face height increase and maxillary molar vertical development were significantly smaller compared to controls. Positive overjet was achieved in 54% of the experimental group. CONCLUSIONS: The eruption guidance appliance produced no change in the skeletal anteroposterior relationship. The anterior cross-bite/edge-to-edge relationship was corrected in only about half of the treated subjects.

Functional therapy and adenotonsillectomy clinical trial for class II malocclusion (FACT-II): protocol for a randomised controlled trial.

INTRODUCTION: Class II malocclusion with mandibular retrognathia is a common complication of paediatric obstructive sleep apnoea (OSA), often accompanied by transverse maxillary deficiency. In early orthodontic treatment, a twin block (TB) is a regular functional appliance for correcting this malocclusion. For paediatric OSA, the most common risk factor is adenotonsillar hypertrophy (AHT). Untreated AHT may lead to the persistence and worsening of obstructive sleep-disordered breathing traits, including habitual mouth breathing. Additionally, the clockwise mandibular rotation associated with AHT-induced pharyngeal crowding can undermine the effectiveness and stability of TB treatment. Adenotonsillectomy (T&A) is currently the first-line treatment for paediatric OSA. This proposed trial will investigate the impact of T&A surgery timing on the efficacy and stability of TB functional treatment in children with class II mandibular retrognathia and ATH. METHODS AND ANALYSIS: This will be a single-centre, parallel-group, superiority randomised controlled trial with participants randomised to intervention (T&A followed by TB treatment) or control arms (TB treatment followed by T&A) in a 1:1 ratio. A total of 40 patients aged 8-14 years, diagnosed with class II mandibular retrognathia and co-existing ATH-induced OSA, and indicated for both T&A surgery and TB treatment, will be recruited at the School and Hospital of Stomatology, Wuhan University. The primary outcomes will be the changes in the apnoea-hypopnoea index and the point A-nasion-point B angle from baseline to postorthodontic treatment between the two groups. Secondary outcomes will include other dental, skeletal, upper airway and soft tissue changes, as well as subjective sleep-related and oral-related quality of life. Outcome changes within each group and between groups will be analysed. ETHICS AND DISSEMINATION: This study is approved by the Ethics Committee of the School and Hospital of Stomatology, Wuhan University (no. 2022-D07). The research findings will be faithfully disseminated through scientific conferences or published articles. TRIAL REGISTRATION NUMBER: ChiCTR2200061703 (https://www.chictr.org.cn).

Prevalence of malocclusion and oral health-related factors among pre-school children in Northern Albania.

The aim of the present study was to investigate prevalence and association between malocclusion and caries among pre-school children aged 4-6 years frequenting public kindergartens in Shkodër, the largest city in North Albania. The sample for this descriptive and cross-sectional study included 389 pre-school children aged 4-6 years frequenting 20 public kindergartens in Shkodër, the largest city in North Albania. The participants were divided into two groups according to their caries experience evaluated, as determined by decayed-missing-filled index dmf (World Health Organization criteria) score. Those with dmf score of zero were considered to be free of caries. The prevalence of children with at least one malocclusion trait was 89%. The prevalence of caries was 66% (mean dmf score: 3.63). Increased overbite (43%), followed by increased overjet, were the most prevalent malocclusion traits observed in children with a dmf of zero. Among children with caries, the most prevalent trait was increased overjet (42%) and increased overbite. Almost half of the entire study population had a straight terminal plane and class I canine relationship. There was a similar prevalence of bilateral crossbite. Significant changes (p = 0.008) were observed between the groups with regards to the absence of spacing in the maxillary anterior region. Regression analysis further revealed that children with an absence of maxillary spacing were 2.564-fold more likely to have caries; those with a deepbite were 0.814-fold more likely to have caries. More than half of the children had caries. Increased overjet, overbite, crossbite and maxillary crowding were malocclusion traits observed in the population included in this study. A positive association was identified between maxillary crowding, deepbite and caries. The association between malocclusion and caries, highlights the necessity for an increased awareness of these two conditions that are commonly found among children of pre-school age.

Noninvasive conservative management of anterior open bite treated with TADs versus clear aligner therapy.

OBJECTIVES: Anterior open bite can be treated non-surgically via molar intrusion using temporary skeletal devices (TAD). Clear aligner therapy (CAT) is recognized as a viable therapeutic modality for non-extraction treatment of adults with mild open bite. This study aimed to compare the treatment effect and mechanisms of open bite closure between patients treated with braces and TADs double arch intrusion and those treated with CAT. Treatment success at T3 was based on 1- positive overbite on ceph; 2- Change in the vertical dimension 3- post treatment POSI score equal to zero. MATERIAL AND METHODS: The TAD group includes 18 consecutively treated patients from the main author. The CAT group consisted of 16 selected patients from three different orthodontists. The observation time points were as follows: pretreatment (T1), end of molar intrusion and positive overbite achieved (T2), end of treatment (T3), at least 6-month follow-up (T4). Treatment changes were assessed by cephalometric analysis and frontal intraoral photo. RESULTS: At the end of treatment, 100% of the patient of the TAD group and 78,6% of the CAT group had a posi score of 0. The TAD group showed a significant reduction in vertical measurements (SN-MPA: -1,55° ± 0.41, LAFH: -3,05 ± 0.51 mm, U6-PP: -1.48 ± 0.30 mm), but the CAT group did not have significant changes for these variables. Both groups had significant increases in overbite from T1 to T3 (TAD: 4,32 ± 0,5 mm; CAT: 2,33 ± 0.56 mm), and overbite remained stable at T4. The CAT group did not have a significant upper molar intrusion, but a significant extrusion of 1.22 ± 0.42 mm of the lower incisor occurred. CONCLUSION: The TAD group achieved bite closure by upper molar intrusion, lower molar and incisors vertical control, and mandibular plane counterclockwise rotation, resulting in an improved AP and vertical relationship. The CAT group achieved bite closure through the lower incisor extrusion without significant change in the vertical dimension. CLINICAL RELEVANCE: This study provides relevant information about the skeletal and dental changes of open bite treatment with TADs double arch intrusion. The comparison with a control group treated with CAT confirms known information.

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

BACKGROUND: Refinements 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. METHODS: This 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. RESULTS: The 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. CONCLUSIONS: The most overbite correction occurs during the 1st set of aligners, and refinement treatment does not significantly improve the deep bite correction.

Occlusal characteristics in modern humans with tooth agenesis.

Non-syndromic permanent tooth agenesis affects a significant proportion of the population, especially if third molars are considered. Although tooth agenesis has been linked to a smaller craniofacial size, reduced facial convexity and a shorter skeletal face, the occlusal characteristics of individuals with tooth agenesis remain largely unexplored. Therefore, this study investigated potential associations between tooth agenesis and metric occlusal traits in 806 individuals (491 with 4.1 missing teeth per subject, including third molars, and 315 without any tooth agenesis). Dentoskeletal morphology was defined through anatomical landmarks on pre-treatment cephalometric radiographs. Multivariate regression models, adjusted for sex and age, showed that tooth agenesis was significantly associated with a reduced overjet, an increased interincisal angle, and shorter upper and lower dental arch lengths, but not with overbite. Moreover, apart from reduced tooth length and dentoalveolar effects, as the number of missing teeth increased the upper front teeth were progressively retruded according to the craniofacial complex and to the face. Thus, tooth agenesis has a substantial influence on dental and occlusal characteristics, as well as on the sagittal position and inclination of anterior teeth. These findings emphasize the necessity for personalized, multidisciplinary approaches in individuals with multiple agenesis to successfully meet treatment goals.

Biomechanical analysis of total arch maxillary distalization using infrazygomatic crest miniscrews: a finite element analysis study.

AIM: To evaluate the maxillary incisors and canine's immediate movement tendency using three different power arms (PA) height levels during total arch maxillary distalization supported on infrazygomatic crest (IZC) miniscrews according to finite element analysis (FEA). METHODS: Three finite element models of the maxilla were developed based on CBCT imaging of a teenage male patient presenting a Class II Division 1 malocclusion in the early permanent dentition. Maxillary complex, periodontium, orthodontic accessories, IZC miniscrews and an orthodontic wire were digitally created. The PAs were placed between canines and lateral incisors and projected at 4, 7, and 10 mm height distances. After that, distalization forces were simulated between PA and IZC miniscrews. RESULTS: The anterior teeth deformation produced in the FEA models was assessed according to a Von Mises equivalent. The stress was measured, revealing tendencies of initial maxillary teeth movement. No differences were found between the right and left sides. However, there was a significant difference among models in the under-stress areas, especially the apical and cervical root areas of the maxillary anterior teeth. More significant extrusion and lingual tipping of incisors were observed with the 4 mm power arm compared to the 7 mm and 10 mm ones. The 10 mm power arm did not show any tendency for extrusion of maxillary central incisors but a tendency for buccal tipping and intrusion of lateral incisors. CONCLUSION: The maxillary incisors and canines have different immediate movement tendencies according to the height of the anterior point of the en-masse distalization force application. Based on the PA height increase, a change from lingual to buccal tipping and less extrusion tendency was observed for the incisors, while the lingual tipping and extrusion trend for canines increased.

Evaluation of the effect of extraction in comparison to distalization on the maxillary third molars in class II malocclusion: a retrospective study.

OBJECTIVE: To compare the effects of first premolar extraction versus distalization on the vertical position and mesiodistal angulation of maxillary third molars (MxM3) in adolescent class II patients. METHODS: The panoramic x-rays (OPGs) of 200 adolescent class II patients with developing MxM3s were screened. The chosen sample consisted of 2 groups: Group 1 (Distalization) comprising 48 MxM3s, and Group 2 (Extraction) comprising 50 MxM3s. The pre- and post-treatment OPGs were traced to detect the mesiodistal angulation changes of the second molars (MxM2) and MxM3s. RESULTS: The angulation and vertical position of the MxM3s at T0 & T1 were also evaluated using Archer's classification. The distalization group presented a non-significant decrease in the mean angulation of MxM2 and MxM3 (-2.4o & -4.5o uprighting respectively). In the extraction group, both MxM2 and MxM3 presented a highly significant decrease in the mean angulation (-10.5o & -11o uprighting respectively). The angulation and vertical position change of MxM3 significantly improved in the extraction group when compared to the distalization group (P < .001). CONCLUSION: Significant uprighting and occlusal positioning of the maxillary third molars occurred in the premolar extraction treatment group when compared to the distalization treatment group. The results of the current study highlight the importance of recognizing maxillary third molars during orthodontic treatment planning of Class II malocclusion cases.

Evaluation of mandibular motion in adolescents with skeletal class II division 1 malocclusion during mandibular advancement using clear functional aligners: a prospective study.

BACKGROUND: This study aimed to evaluate the characteristics of mandibular protrusive condylar trajectory in adolescents with skeletal Class II Division 1 malocclusion and the changes of condylar trajectory during mandibular advancement (MA) treatment using clear functional aligners. METHODS: This prospective study consisted of a cross-sectional study and a longitudinal study. In cross-sectional study, sixty-one adolescents were divided into two groups: Class I (n = 30) and Class II Division 1 (n = 31). The condylar trajectory was measured and compared using the Mann-Whitney U test. The longitudinal study was the MA treatment group using clear functional aligner and consisted of 16 participants from Class II Division 1group. The condylar trajectory was collected at three-time points: pre-treatment (T1), during MA treatment at approximately 3 months (T2, 105.6 days average), and at the end of MA treatment (T3, 237.6 days average). The changes at T1, T2, and T3, as well as the symmetry between the left and right condyles across all groups, were examined using the Wilcoxon paired test. RESULTS: A greater increase in the anteroposterior displacement and space displacement during protrusive movements was observed in the Class II Division 1 group compared with that in the Class I group, with a large difference being observed in the left and right condylar movements. The condylar anteroposterior displacement and space displacement decreased significantly at T2 and increased significantly at T3; however, no significant difference was observed between T1 and T3. A significant difference was observed between the condylar movement on the left and right sides at T1; however, no significant difference was observed at T2 and T3. CONCLUSIONS: Adolescents with Class II Division 1 malocclusion had higher protrusive capacity than those with Class I. Moreover, their left and right condylar motion was more asymmetric. The range of condyle motion decreased first and then increased during MA therapy, and the left and right condyle movement became more symmetrical, which may be the adaptive response of neuromuscular function to the changes in jaw position.

A retrospective study evaluating the influence of Class III correction appliances on the sagittal pharyngeal airway dimension.

The aim of this study was to compare the effects of Class III correction appliances including the Facemask (FM), and the new non-compliance fixed functional appliances such as the Reversed Forsus Fatigue Resistant Device (FRD), as well as the CS-2000 (CS), on the sagittal pharyngeal airway dimension (SPAD). Pre-treatment and post-treatment lateral cephalograms of 45 patients who underwent Class III appliance treatment, using either FM, Reversed FRD, or CS were collected from the files of treated patients. SPAD changes were evaluated in each group, and comparisons were conducted between the three study groups. Additionally, sagittal and vertical skeletal measurements were conducted. The FM, the Reversed FRD, and the CS, were found to generate a significant increase in the SPAD, with the Reversed FRD contributing to the most significant change at the OPAA (116.80 ± 26.36 mm2). All three appliances elicited significant antero-posterior changes in the SNA°, SNB°, and ANB°, also with the greatest intermaxillary change documented with the employment of the Reversed FRD (ANB° = 3.33 ± 0.82°). As for the vertical dimension, the FM, the Reversed FRD, and the CS elicited significant FMA° increases, with the greatest change attributed to the FM (FMA° = 2.32 ± 0.97°). Therefore, the three tested Class III corrective appliances generated significant SPAD, antero-posterior, and vertical changes. However, the Revered FRD showed a superior impact in increasing the SPAD at the OPAA level and in eliciting significant intermaxillary changes.

Evaluation of digital and manual orthodontic diagnostic setups in non-extraction cases using ABO model grading system: an in-vitro study.

BACKGROUND: To evaluate the outcome quality of manual and digital orthodontic diagnostic setups in non-extraction cases according to the American Board of Orthodontics model grading system and to calculate the laboratory time needed for orthodontic diagnostic setup construction. METHODS: The sample consisted of 60 pretreatment models of non-extraction orthodontic cases with age ranges of 18-30. The study models were duplicated and scanned with 3Shape R-750 scanner. Digital and manual diagnostic setups were constructed according to their respective treatment plans. Digital diagnostic setups were 3D printed and then both manual and digital setups were assessed using the modified American Board of Orthodontics Cast Radiograph evaluation score (ABO CRE), which includes alignment, marginal ridge, buccolingual inclination, occlusal contacts, occlusal relationships, interproximal contacts, and overjet. The laboratory time needed for orthodontic setups was measured in minutes. RESULTS: The total ABO CRE score of the digital diagnostic setup group (5.93 ± 2.74) was significantly lower than that of the manual diagnostic setup group (13.08 ± 3.25). The manual diagnostic setup had significantly larger scores in marginal ridge, overjet, overbite, buccolingual inclination, occlusal relationship, and total scores (P < 0.01). However, the digital diagnostic setup had a statistically larger occlusal contacts score than the manual diagnostic setup (P < 0.01). There was no significant difference between the alignment and the interproximal contacts scores in either group. The manual diagnostic setup needed significantly longer laboratory time (187.8 ± 14.22) than the digital setup (93.08 ± 12.65) (P < 0.01). Comparison between broken teeth was performed by using the chi-square test which found no significant difference between different tooth types. CONCLUSIONS: Digital diagnostic setup is a reliable tool for orthodontic diagnostic setup construction providing excellent quality setup models. Manual diagnostic setup is time consuming with a technique-sensitive laboratory procedure.

Impact of molar teeth distalization by clear aligners on maxillary alveolar bone thickness and root resorption: a three­dimensional study.

OBJECTIVE: This study aimed to evaluate the impact of molar teeth distalization movement by clear aligners on changes in the alveolar bone thickness and orthodontically induced inflammatory root resorption (OIIRR) in maxillary molars using conebeam computed tomography (CBCT). MATERIALS AND METHODS: Three-dimensional CBCT scans of 35 adult patients (one hundred forty maxillary molars) with pre-designed selection criteria and a mean age of 24.4 ± 7.1 years were included. The measured parameters, including alveolar bone thickness for maxillary molars and root resorption (OIIRR), were analyzed using pre-and post-treatment CBCT (T0 and T1, respectively) with Invivo 6.0 software. RESULT: Post-treatment, relevant statistically significant changes included deposition of bone in the average palatal surface of the 1st molars. The reduction of bone was seen in the average buccal surface of the first molars and both surfaces of the second molars. Regarding root length after treatment, the average maxillary 1st molar roots showed significant OIIRR (p < 0.001). CONCLUSION: Clear aligner treatment could effectively reduce the incidence of alveolar bone thickness reduction and OIIRR in treating Class II malocclusions compared to conventional braces, as shown in previous studies. This research will aid in fully grasping the benefits of clear aligners.

Effects of clear aligners on the vertical position of the molar teeth and the vertical and sagittal relationships of the face: a preliminary retrospective before-after clinical trial.

INTRODUCTION: Despite the popularity of clear aligners, their predictability has not been assessed adequately. Moreover, no study has investigated their effects on numerous dentomaxillary variables. Therefore, this study was conducted for the first time, assessing several new or controversial items. The aim of the study was to evaluate the effects of clear aligners on the vertical position of the molar teeth and the vertical and sagittal relationships of the face. METHODS: This preliminary retrospective before-after non-randomized clinical trial was performed on 168 observations of 84 patients (33.60±9.28 years, 54 females) treated with 0.75mm Invisalign appliances. Pretreatment and posttreatment values were measured for: mandibular plane angle, occlusal plane angle, Y-Axis, ANB, facial angle, lower anterior facial height, overbite, and the distances of the molars from the palate and mandibular plane were measured. The alterations in parameters caused by treatment (delta values) were calculated for each measurement. Effects of treatment and some parameters on delta values were analyzed statistically (α=0.05). RESULTS: Mean±SD of ΔMP-FH, ΔOP-FH, ΔY-Axis, ΔLAFH, ΔNPog-FH, ΔANB, ΔOverbite, ΔSNB, Δ6-PP, Δ7-PP, Δ6-MP, and Δ7-MP were respectively 0.11±1.61, 0.80±1.56, 0.15±1.18, 0.07±0.91, -0.22±1.25, 0.03±0.62, 0.04±1.15, -0.06±1.14, -0.36±0.94, -0.32±1.14, 0.19±0.96, 0.18±1.10. Only the alterations in OP-FH, 6-PP, and 7-PP were significant (P≤0.011). Age, sex, treatment duration, or pretreatment mandibular plane angle were not correlated with any delta values. However, the pretreatment occlusal plane angle was negatively correlated with ΔOP-FH and ΔY-Axis. Crowding was correlated negatively with ΔOP-FH and ΔY-Axis and positively with ΔNPog-FH. Overjet was negatively correlated with ΔANB and ΔOverbite (P≤0.035). CONCLUSIONS: Invisalign intruded first/second maxillary molars and increased the occlusal plane angle. Age, sex, and treatment duration were not correlated with post-treatment anatomic alterations.

Three-dimensional computed tomography analysis of airway volume in growing class II patients treated with Frankel II appliance.

OBJECTIVE: The purpose of this retrospective study was to assess the airway volume changes associated with the use of Frankel appliance (FR II) in Class II malocclusion patients using three-dimensional cone beam computed tomography (3D CBCT) imaging. MATERIALS AND METHODS: The sample consisted of 31 Class II malocclusion patients (mean age 9.24 ± 1.93 years old, 17 males (54.8%) and 14 females (45.2%)) treated with FR II appliance by the same orthodontist for an average of 9 months ± 20 days. CBCT images were taken before and after treatment and upper airway volume changes were measured using Dolphin 3D software version11.0 (Dolphin Imaging, Chatsworth, CA) and statistically compared. RESULTS: Airway volume of nasal cavity, nasopharynx, oropharynx, hypopharynx and the total airway volume significantly increased after the use of FR II appliance. In addition, significant increase was reported in maxillary base, inter-molar, inter-premolar and inter-canine width. Significant increase in soft tissue thickness was only recorded opposite to CV2. CONCLUSION: The use of the FR II appliance in growing subjects with Class II malocclusion led to a significant increase in the upper airway volume in addition to the anticipated dental and skeletal transverse expansion effects.

Comparison of Twin Block appliance and Herbst appliance in the treatment of Class II malocclusion among children: a meta-analysis.

BACKGROUND: Our meta-analysis aimed to evaluate the efficacy of applying Herbst and Twin Block appliances in the treatment of Class II malocclusion among children. METHODS: Databases, including PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), China VIP Database (VIP), and Wanfang were thoroughly searched from inception to August 9, 2023. The outcomes included skeletal, dental, and soft tissue changes. The weighted mean difference (WMD) was used as the effect indicator, and the effect size was expressed with a 95% confidence interval (CI). The heterogeneity of each outcome effect size was tested, and the heterogeneity statistic I2 ≥ 50% was analyzed by the random-effect model, otherwise, the fixed-effect model was conducted. Sensitivity analysis was performed. RESULTS: A total of 12 studies involving 574 patients were included in this meta-analysis. Herbst appliance had a statistically significant increase in mandibular body length (WMD: 1.44, 95% CI: 0.93 to 1.96, P < 0.001) compared with the Twin Block appliance. More increases in angle and distance of L1 to mandibular plane (MP) were found in the Herbst appliance compared with the Twin Block appliance. Significant and greater improvements in molar relationship (WMD: 0.79, 95% CI: 0.28 to 1.29, P = 0.002), posterior facial height (WMD: -1.23, 95% CI: -2.08 to -0.38, P = 0.005), convexity angle (WMD: -1.89, 95% CI: -3.12 to -0.66, P = 0.003), and Sella-Nasion plane angle (U1 to SN) (WMD: 3.34, 95% CI: 2.25 to 4.43, P < 0.001) were achieved in the Twin Block appliance. Herbst and Twin Block appliances produced similar effects in the skeletal and dentoalveolar changes including Sella-Nasion-point A (SNA), Sella-Nasion-point B, point A-Nasion-point B (ANB), overjet, and overbite. CONCLUSION: As the findings revealed both Herbst and Twin Block appliances contributed successfully to the correction of Class II malocclusion. Compared with the Twin Block appliance, the Herbst appliance may have more advantages in mandibular bone movement. Twin Block therapy resulted in more improvement in the aesthetics of the face.

Comparison study of chewing efficiency in patients with different vertical skeletal patterns of Angle Class I and Angle Class II malocclusions.

OBJECTIVE: The purpose of this study was to analyze and compare the differences in chewing efficiency among patients with different vertical skeletal types of Angle Class I and Angle Class II malocclusions, to provide reference for orthodontic clinical practice. METHOD AND MATERIALS: Sample size estimation revealed a minimum of 53 for each class. Thus, a total of 108 patients with Angle Class I and Angle Class II malocclusions were selected. Lateral skull radiographs were taken, and head measurements were analyzed via geometric tracing software. Chewing efficiency was measured using the gravimetric method to compare between the two groups. The vertical skeletal pattern was classified via Steiner analysis. RESULTS: Significant statistical differences in chewing efficiency were observed between patients presenting with Angle Class I and Angle Class II malocclusions (P < .05). Additionally, significant differences in chewing efficiency were observed among patients with different vertical skeletal patterns (P < .05). Furthermore, a statistically significant difference in chewing efficiency was found between men and women (P < .05). CONCLUSIONS: Patients with Angle Class I malocclusions exhibited significantly higher chewing efficiency compared to those with Angle Class II malocclusions. Among patients with different vertical facial types, the chewing efficiency followed the order of low angle > normal angle > high angle. Moreover, men demonstrated a higher chewing efficiency than women.

Three-dimensional evaluation of condylar morphology after orthodontic treatment in adult patients with Class II malocclusion by cone-beam computed tomography.

BACKGROUND: The aim of this study was to evaluate the condylar morphological changes after orthodontic treatment in adult patients with Class II malocclusion using a Cone-beam computed tomography (CBCT). METHODS: Images of twenty-eight adult patients with Class II malocclusion who have no temporomandibular symptoms were involved in this study. To analyze the post-treatment changes in condylar morphology, mimics 17.0 software was used to measure several values and reconstruct the three-dimensional condyle, including height of the condyle, area and bone mineral density of the maximum axial and sagittal section, volume and bone mineral density of the three-dimensional condyle and condylar head before and after orthodontic treatment. Using SPSS 19.0 software package Paired t-test was applied for comparison of condylar morphology analysis between pre-treatment and post-treatment. RESULTS: Height of condylar head increase significant (P < .05). Bone mineral density showed a decrease in the maximum axial and sagittal section, three-dimensional condyle and condylar head (P < .01). Evaluation of volume revealed that volume of both condyle and condylar head decrease considerably (P < .05). No significant difference was detected in other values ((P > .05). CONCLUSION: Condylar volume decreased and height of condylar head have changed, so we speculated that adaptive bone remodeling of the condyle occurs.