Mandibular Length Research Articles

Morphometric measurements of mandible to determine stature and sex: A postmortem study

ObjectivesIdentification of humans has medicolegal relevance in civil issues involving property inheritance, marriage, contested sex, admission to educational institutions, and the disappearance of individuals. To determine the sex of human remains, forensic anthropologists usually use morphologic and metric approaches. This study was conducted to determine stature and sex according to mandibular dimensions in postmortem autopsy samples. MethodsA total of 150 mandibles from people 18–65 years of age were studied. Stature and sex were noted, and six mandibular measurements were taken with Vernier calipers, flexible measuring tape, a protractor, and a graduated autopsy table. Statistical analysis of the measured parameters was conducted in SPSS software. Statistical parameters, such as mean, standard deviation, Spearman's correlation coefficient, multiple linear regression, stepwise regression, and Mann–Whitney U test were analyzed. ResultsBicondylar width was the stature estimation predictor with the strongest correlation (r = 0.439). The other parameters significantly associated with stature were bigonial width (p = 0.000), mandibular angle (p = 0.004), and mandibular arch length (p = 0.000), according to Spearman's correlation coefficient. The mandibular angle had the greatest dimorphic statistical significance (p = 0.004) according to the Mann–Whitney U test. ConclusionBicondylar width may serve as a valuable tool for estimating stature, and mandibular angle can be used to identify sex. Our findings may help forensic anthropologists estimate stature and identify human remains.

Longitudinal changes of the natural craniofacial and dentoalveolar complex in the fourth decade of life

This study aimed to longitudinally examine the changes in craniofacial and dentoalveolar regions during the third and fourth decades of life. The data from this study constitute the cephalometric films and plaster models of 8 female and 8 male dental students or dentists. The mean chronological ages of the subjects at the first observation period was 22.09 years for females and 22.64 years for males. The material was collected over 3 intervals: 1985-1989, 1998-2000, and 2016-2017. The observation period was approximately 28 years. Acquired cephalometric recordings and dental models were assessed for subjects in their 20s (baseline), 30s, and 40s. Maxillary, mandibular, maxillomandibular, soft-tissue, and dentoalveolar cephalometric variables were measured with a cephalometric analysis software, and dental cast measurements were made with a digital caliper. Changes in the cephalometric films and dental casts were evaluated statistically. Statistical analysis showed that the length of the midfacial region increased with age. The height of the lower face increased significantly in females and the mandible can be seen mildly rotating to the posterior as it increased in length. The nose moved slightly forward and downward in males and females. Upper lip height was significantly increased in females; however, there was a significant reduction in upper lip thickness for males and females. Soft-tissue pogonion measurements showed a significant forward and downward chin movement in females. Overjet was significantly increased in females, whereas the mandibular arch length was significantly decreased for both sexes, although it was more prominent in females. There was a loss of space in the anterior segments of males and females, resulting in increased crowding. However, the loss of space was only significant in the mandible. We observed significant changes in skeletal, soft-tissue, and dentoalveolar variables of subjects in their third and fourth decades of life. The fact that many changes have occurred throughout this study demonstrates that the process of maturation and aging is ongoing.

Comparison of accuracy of panoramic radiograph and lateral cephalogram in determining linear mandibular measurements among orthodontic patients in tertiary dental care center of Kathmandu

Mandibular dimensions are one of the key parameters for planning the treatment by an Orthodontist. Lateral cephalograms are usually used to evaluate the skeletal relationship. However, due to the superimposition of both the sides, lateral cephalogram may not be reliable in measuring the right and left sides of the cranial landmarks. Panoramic radiography delivers a wide-ranging view of maxillofacial structures with comparatively lesser radiation exposure than other tools and superimposition of structures is less compared to lateral cephalogram image. OPG and lateral cephalograms of all the patients of age group 16-35 years attending Department of Orthodontics in Nepal Medical College from September 2022 to February 2023, having Angle’s Class I Molar relationship with minimum crowding was taken. Linear measurements (ramus height, total mandibular length and mandibular body length) were measured on OPG and Lateral cephalogram. The data was processed in SPSS version 17 for further analysis. There was no statistically significant difference in mean linear measurements between right and left sides on OPG (p-value 0.77, 0.49 and 0.59 respectively). But there was a statistically significant difference in mean linear measurements between both sides on OPG and lateral cephalograms (p-value <0.001). OPG can be used reliably to measure the mandibular length and ramus height of right and left side but comparison of mandibular length and ramus height between lateral cephalogram and OPG may not be reliable.

Comparison of Computed Tomography Assisted 3D Cephalometric Measurements in Straight Egyptian Arabian and Thoroughbred Horses.

Dental malocclusions are commonly encountered in horses. The objective of this study was to report the normal cephalometric values from skull computed tomography (CT) scans of adult Straight Egyptian Arabian (SEAR) and thoroughbred (TB) horses and to compare differences in the measurements between the two breeds. Standing skull CTs were performed on 29 clinically normal adult horses (15 SEAR; 14 TB) and cephalometric measurements were taken. All 9 cephalometric measurements, as well as the interincisal angle, were found to be significantly greater in TB than SEAR (P < 0.05). TB were found to have significantly greater facial line: mandibular length (FL/ML) ratios compared to SEAR (P = 0.002) whereas for the maxillary cheek teeth length: ethmoidal line ratio (Mxa/EtL), SEAR were found to have significantly greater values than TB (P = 0.0007). SEAR cephalometric measurements, as well as certain ratios, differ significantly from TB and could have an impact on the development of dental malocclusions in this breed. Further investigation is needed to ascertain whether these cephalometric differences between the two breeds predispose the SEAR to the development of dental malocclusions.

Local injection of abaloparatide promotes mandibular condyle lengthening in adolescent rats via enhancing chondrogenesis and ossification.

Mandibular condylar hypoplasia negatively affects patient's facial appearance and dentofacial function. To investigate the effect of local injection of the drug abaloparatide (ABL), an analogue of parathyroid hormone related protein (PTHrP), on promoting lengthening of the mandibular condyle. Thirty adolescent male Sprague-Dawley rats were randomly divided into two groups, which received the injection of ABL or normal saline (the control) every 3 days in the temporomandibular joint (TMJ) cavity. Cone-beam computed tomography and immunohistochemistry assays were performed at 2, 4 and 6 weeks since the injection. Mandibular condylar chondrocytes (MCC) and pre-osteoblasts were treated with ABL or PBS, followed by the CCK-8 detection, IC50, real-time PCR assay, Western Blot and immunofluorescence staining. In vivo, compared with the control, the ABL group significantly increased the mandibular condylar process length (by 1.34 ± 0.59 mm at 6 weeks), the thickness of the cartilage layer, and enhanced the matrix synthesis. The ABL group had significant up-regulation of SOX 9, COL II, PTHrP and PTH1R, down-regulation of COL X in the cartilage, up-regulation of RUNX 2, and unchanged osteoclastogenesis in the subchondral bone. In vitro, the intra-TMJ injection of ABL promoted the MCC proliferation, with up-regulated expression of chondrogenic genes, and enhanced osteogenic differentiation of the pre-osteoblasts. Intra-TMJ injection of abaloparatide promotes mandibular condyle lengthening in the adolescent rats via enhancing chondrogenesis in the mandibular condylar cartilage and ossification in the subchondral bone.

Reliability and Accuracy of Tweed’s Triangle, Mandibular Length &amp; Corpus Size on Lateral 2D Cephalogram and 3D CBCT Scan

Reliability and Accuracy of Tweed’s Triangle, Mandibular Length &amp; Corpus Size on Lateral 2D Cephalogram and 3D CBCT Scan

Analysis of the Facial Measurements and Dental Arch Dimensions for the Construction of Dental Prostheses among Adult Yemenis.

To investigate the dental arch dimension (width, length, and height) and facial measurements including inner-canthal width (ICW), bizygomatic width (BZW), inter-alar width (IAW), and mouth width (MW), and to assess the correlation between these facial measurements and dental arch width (canine width [CW], inter-first premolar width [I1PW], and inter-first molar width [I1MW]), to establish a preliminary reference for artificial teeth selection in Yemeni adult. The study included 80 individuals (40 males and 40 females) with symmetrical faces and normal class I occlusion ranging in age from 20 to 35. Maxillary and mandibular stone casts were made for each individual. The dimensions of dental casts and facial measurements, including ICW, BZW, IAW, and MW, were assessed using a digital caliper. The collected data were analyzed by using the SPSS software program. The descriptive statistics for each measurement were made. Differences between males and females were tested using an independent-sample t-test with p-values below 0.05 considered significant. Pearson correlation coefficient between facial measurements and dental arch width was also done. Most dental arch dimensions and facial measurements exhibited larger mean values in the male than in the female group, with the greatest significant difference in the maxillary dental arch width and the lowest in mandibular dental arch length. A highly significant correlation is observed between ICW and maxillary canine width (CW) (r = 0.318, p = 0.004). In contrast, no significant correlation between dental arch width and BZW, IAW, and MW is shown. Within this study's limitations, the ICW can determine the ideal dimension of the artificial teeth in the anterior maxillary arch. While the other facial parameters, including BZW, IAW, and MW, cannot be used for artificial teeth selection in Yemeni populations. The findings of this study established a reference database of facial measurements and their correlation to dental arch and teeth width in Yemeni populations. So, it can be implemented in artificial teeth and dental prostheses design and construction.

Relationship between vertical facial morphology and dental arch measurements in class II malocclusion: a retrospective study.

To evaluate the relationship between dental arch measurements and the vertical facial pattern determined in skeletal Class II untreated patients. Lateral cephalograms and plaster models were obtained from 124 untreated female adults (average age: 17.6 ± 3.8 years). Class I (CI), Class II Division 1 (CII/1) and Class II Division 2 (CII/2) malocclusions were divided into three subgroups according to their vertical morphology as hypodivergent, normodivergent and hyperdivergent. The multivariate variance analysis (MANOVA) method was used in the comparison of measurement values according to vertical and sagittal morphology. The relationship between both A point-Nasion-B point (ANB) and Frankfurt-mandibular plane (FMA) angles and dental arch measurements was examined by Pearson correlation analysis. The significance level was received as p < 0.05. While vertical morphology has a statistically significant effect on mandibular arch length, sagittal morphology affects maxillary arch depth. The parameters influenced by both morphologies are maxillary and mandibular arch length, as well as maxillary intermolar width. The mandibular arch length was significantly shorter in hyperdivergent-CII-2 malocclusion (50.5 ± 7.4 mm). Larger values were obtained in both mandibular arch length and maxillary arch depth measurements in CII-1 malocclusion compared to CII-2 malocclusion. The maxillary intermolar width was significantly shorter in hypodivergent-CII-1 malocclusion (46.8 ± 3.4 mm), while it was higher in hypodivergent-CI malocclusion (51.1 ± 3.4 mm). The maxillary arch length was the lowest in hyperdivergent-CI malocclusion (63.1 ± 13.3 mm) and the highest in hypodivergent-CI malocclusion (72.8 ± 7.6 mm). Additionally, a positive but weak correlation was found between ANB and FMA angles. Dental arch measurements have been found to be affected by both vertical facial morphology and skeletal sagittal relationship. A positive correlation was found between ANB and FMA angles.

Risk factors for orthodontic fixed retention failure: A retrospective controlled study.

: To investigate the potential correlation between fixed orthodontic retention failure and several patient- and treatment-related factors. : Patients finishing treatment with fixed appliances between 2016 and 2017 were retrospectively included in this study. Those not showing fixed retention failure were considered as control group. Patients with fixed retention failure were considered as the experimental group. Additionally, patients with failure of fixed retainers in the period of June 2019 to March 2021 were prospectively identified and included in the experimental group. The location of the first retention failure, sex, pretreatment dental occlusion, facial characteristics, posttreatment dental occlusion, treatment approach and presence of oral habits were compared between groups before and after treatment separately by using a Fisher exact test and a Mann-Whitney U test. : 206 patients with fixed retention failure were included, 169 in the mandibular and 74 in the maxillary jaws. Significant correlations were observed between retention failure in the mandibular jaws and mandibular arch length discrepancy (P = 0.010), post-treatment growth pattern (P = 0.041), nail biting (P < 0.001) and abnormal tongue function (P = 0.002). Retention failure in the maxillary jaws was more frequent in patients with IPR in the mandibular jaws (P = 0.005) and abnormal tongue function (P = 0.021). : This study suggests a correlation between fixed retention failure and parafunctional habits, such as nail biting and abnormal tongue function. Prospective studies with larger study populations could further confirm these results.

Short- and Long-Term Prediction of the Post-Pubertal Mandibular Length and Y-Axis in Females Utilizing Machine Learning.

The aim of this study was to create a novel machine learning (ML) algorithm for predicting the post-pubertal mandibular length and Y-axis in females. Cephalometric data from 176 females with Angle Class I occlusion were used to train and test seven ML algorithms. For all ML methods tested, the mean absolute errors (MAEs) for the 2-year prediction ranged from 2.78 to 5.40 mm and 0.88 to 1.48 degrees, respectively. For the 4-year prediction, MAEs of mandibular length and Y-axis ranged from 3.21 to 4.00 mm and 1.19 to 5.12 degrees, respectively. The most predictive factors for post-pubertal mandibular length were mandibular length at previous timepoints, age, sagittal positions of the maxillary and mandibular skeletal bases, mandibular plane angle, and anterior and posterior face heights. The most predictive factors for post-pubertal Y-axis were Y-axis at previous timepoints, mandibular plane angle, and sagittal positions of the maxillary and mandibular skeletal bases. ML methods were identified as capable of predicting mandibular length within 3 mm and Y-axis within 1 degree. Compared to each other, all of the ML algorithms were similarly accurate, with the exception of multilayer perceptron regressor.

Effects of headgear timing on dental arch changes from 7 to 18 years of age: a follow-up study.

Dental arch effects after cervical headgear (CHG) treatment have been researched from several different perspectives. However, the long-term effects of CHG timing are still unknown. To analyse the long-term effects of CHG timing on dental arches. A total of 67 children with Angle Class II malocclusion comprised the study group in this trial. The participants were randomized into two equal-sized groups. In the early group (EG, n = 33), treatment was started after the eruption of the first upper molars. In the later-timed group (LG, n = 34), treatment was started 18 months later compared with the early group. Long-term effects were measured from dental casts taken at five time points between 7 and 18 years of age. The total maxillary dental arch length was achieved earlier, the gained length persisted better in the long term, and significantly more space was achieved in EG compared with LG (P = .048). The intermolar width in the maxillary dental arch was more stable and was reached earlier in EG compared with LG (P = .002). The results showed that in terms of total mandibular arch length increases, EG males benefited the most and LG females the least from CHG treatment (P = .031). Both genders benefited from earlier CHG treatment. The maxillary dental arches remained longer, and the final width was gained earlier in EG compared with LG.

Prediction of Pubertal Mandibular Growth in Males with Class II Malocclusion by Utilizing Machine Learning.

The goal of this study was to create a novel machine learning (ML) model that can predict the magnitude and direction of pubertal mandibular growth in males with Class II malocclusion. Lateral cephalometric radiographs of 123 males at three time points (T1: 12; T2: 14; T3: 16 years old) were collected from an online database of longitudinal growth studies. Each radiograph was traced, and seven different ML models were trained using 38 data points obtained from 92 subjects. Thirty-one subjects were used as the test group to predict the post-pubertal mandibular length and y-axis, using input data from T1 and T2 combined (2 year prediction), and T1 alone (4 year prediction). Mean absolute errors (MAEs) were used to evaluate the accuracy of each model. For all ML methods tested using the 2 year prediction, the MAEs for post-pubertal mandibular length ranged from 2.11-6.07 mm to 0.85-2.74° for the y-axis. For all ML methods tested with 4 year prediction, the MAEs for post-pubertal mandibular length ranged from 2.32-5.28 mm to 1.25-1.72° for the y-axis. Besides its initial length, the most predictive factors for mandibular length were found to be chronological age, upper and lower face heights, upper and lower incisor positions, and inclinations. For the y-axis, the most predictive factors were found to be y-axis at earlier time points, SN-MP, SN-Pog, SNB, and SNA. Although the potential of ML techniques to accurately forecast future mandibular growth in Class II cases is promising, a requirement for more substantial sample sizes exists to further enhance the precision of these predictions.

Fixed Functional Appliance Therapy With and Without Skeletal Anchorage in Class II Malocclusion: A Systematic Review of Randomized Controlled Trials

Background: For its synergistic effects in producing skeletal changes as well as to lessen the proclination of the lower incisors, which is a common negative result of mandibular advancement, fixed functional appliances with skeletal anchorage have recently been used. Aim: Objective was to evaluate the skeletal and dentoalveolar effects with fixed functional appliances with and without skeletal anchorage. Methods: Electronic database search and manual search were performed up to 2021, April in four databases namely The Cochrane Library, PubMed, Lilac, and Google Scholar. RCTs that employed the use of fixed functional appliances in Class II malocclusion with and without skeletal anchoring were collected. Two co-authors independently extracted the data, and a pre-designed template was followed during the data extraction process. Data including inclusion and exclusion criteria; study design, the year of publication; age and gender of the patients; type of fixed functional device; stage of skeletal maturation; size and site of mini-implant or miniplate placement, amount of force applied in grams or Newtons; method of study outcome assessment (2D or 3D); and follow up were collected. The skeletal and dentoalveolar parameters were extracted. Results: The risk of bias was evaluated, and the SMD and 95% confidence intervals (CIs) were also calculated. Four RCTs were evaluated for qualitative and quantitative analysis. The review involved data of 179 Class II individuals. The results of a random-effects meta-analysis showed that the SNB differed significantly from the control group (SMD = 0.50 (95% CI –1.55 to –0.10)). No significant differences noted between the two groups in terms of lower incisor inclination and mandibular length changes [SMD = –0.04 (95% CI −2.06 to 1.98) and –1.33 (95% CI −3.28 to 0.62), respectively]. The studies under this were not able to provide enough data to draw any conclusions about the effects of using skeletal anchorage with FFA. Conclusion: According to the evidence that is currently available, using FFA coupled with skeletal anchorage does not appear to have any superior skeletal effects than those without skeletal anchorage.

Skeletal structure of asymmetric mandibular prognathism and retrognathism

BackgroundThis study aimed to compare the skeletal structures between mandibular prognathism and retrognathism among patients with facial asymmetry.ResultsPatients who had mandibular asymmetry with retrognathism (Group A) in The Netherlands were compared with those with deviated mandibular prognathism (Group B) in Korea. All the data were obtained from 3D-reformatted cone-beam computed tomography images from each institute. The right and left condylar heads were located more posteriorly, inferiorly, and medially in Group B than in Group A. The deviated side of Group A and the contralateral side of Group B showed similar condylar width and height, ramus-proper height, and ramus height. Interestingly, there were no inter-group differences in the ramus-proper heights. Asymmetric mandibular body length was the most significantly correlated with chin asymmetry in retrognathic asymmetry patients whereas asymmetric elongation of condylar process was the most important factor for chin asymmetry in deviated mandibular prognathism.ConclusionConsidering the 3D positional difference of gonion and large individual variations of frontal ramal inclination, significant structural deformation in deviated mandibular prognathism need to be considered in asymmetric prognathism patients. Therefore, Individually planned surgical procedures that also correct the malpositioning of the mandibular ramus are recommended especially in patients with asymmetric prognathism.

The Correlation between Quantitative Cervical Vertebral Maturation and Mandibular Dimensions in Children Aged 8-16 Years: A Cross-Sectional Analytical Study

Background: During growth modification, the mandible plays a crucial role in functional orthopaedic treatment. To maximize the efficacy and efficiency of functional appliance therapy, one must know when to initiate treatment. To maximize the efficacy and efficiency of functional appliance therapy, one must know when to initiate treatment. To accurately determine when to initiate functional appliance therapy, the contemporary maturity indicators utilised are subjective with poor reproducibility and validity. Quantitative cervical vertebral maturity indicators are quantitative with good reproducibility. Objective: To determine the correlation between quantitative cervical vertebral maturation and mandibular dimensional changes in 8–18-year-old growing children. Material and Method: In this prospective cross-sectional analytical study, 164 samples were employed with an age range of 8–18 years. Samples were divided into four groups as per the quantitative cervical vertebral maturity indicator. Pubertal staging was analysed utilising the Li Chang, et al. method on a lateral cephalometric radiograph, and mandibular dimensions were measured as the total mandibular length of a condylon-gnathion line, the height of the mandibular ramus from the condylon-gonion intersection line, and the length of the mandibular body from the gonion intersection-gnathion line. Statistical Analysis: The data obtained was analyzed using Statistical Package for the Social Sciences (SPSS) software; descriptive statistics, student t test and bivariant analysis were applied. Results: The mean total mandibular length was seen at its maximum in periods of high acceleration velocity. Intergroup analysis shows significant differences between the groups, and there is a strong correlation between maturational stage and mandibular dimensional change. Conclusions: During functional orthopaedic treatment planning, the mandible can be utilised as a skeletal maturity indicator.

Long-Term Outcomes and Growth Analysis of Costochondral Grafts for Hemifacial Microsomia: 24-Year Experience of a Single Surgeon.

Costochondral grafts (CCGs) can be used in mandibular reconstruction of Kaban-Pruzansky IIB/III hemifacial microsomia (HFM). Their growth is variable, occasionally necessitating secondary surgery. This study examined one surgeon's 24-year experience to better quantify long-term outcomes and surgical care required in CCG reconstruction of HFM mandibles. Serial 3-dimensional computed tomography scans, from preoperative to most recent, were analyzed in patients with a minimum of 4 years of clinical follow-up after CCG reconstruction. Graft/ramus height, length, volume, bilateral mandibular body length, and chin deviation were measured. Changes in measurements were analyzed preoperatively, immediately postoperatively, at the most recent imaging before secondary surgery, and at the most recent imaging overall. Growth rates per measure were calculated using scans after CCG but before secondary surgery. Thirteen patients were analyzed. Median (SD) clinical follow-up was 10.0 (5.1) years. One patient developed temporomandibular joint ankylosis secondary to stacked-graft malposition, which was repaired without further complications. CCG reconstruction led to immediate improvement in graft/ramus height ( P = 0.03), length ( P = 0.002), and volumetric symmetry ( P = 0.02). No difference was found between graft and native ramus height ( P = 0.4) or length measures ( P = 0.5), whereas graft volume and the affected mandibular body grew significantly more slowly. According to the latest imaging, 63% of patients required secondary surgery, including distraction osteogenesis or orthognathic surgery, due to differential graft or hemimandible growth behavior. Based on the most recent clinical follow-up, this proportion increased to 93%. CCGs provide significant short-term mandibular and facial symmetry improvement in HFM IIB/III. Long-term analysis reveals frequent undergrowth requiring secondary intervention to promote and maintain symmetry. Therapeutic, IV.

Assessing the Impact of Maxillomandibular Difference on the Success of Orthodontic Decompensation Preparation in Orthognathic Surgical Skeletal Class-III Patients

Background: Combined orthodontic-surgical treatment includes a thorough diagnosis and analysis of dental and facial deformities. Cephalometric analysis is a common tool for this, in which measurements of specific anatomical landmarks are performed. In order to achieve a successful surgery, orthodontic teeth preparation is mandatory, including dental decompensation before surgery. This should be planned and adequately executed to allow the surgeon to move the jaws to the correct ideal position. Aim: The current study aimed to check if the orthodontic decompensation amount is influenced and compromised by the maxillomandibular difference and if there is a correlation between the deformity’s severity and the orthodontist’s difficulty in achieving an accurate result in the orthodontic decompensation preparation. Methods: The study consisted of 50 pre-operational cephalometric radiographs of patients with Class-III (prognathic) deformity. The measurements included the angles of the upper incisor (U1) longitudinal axis to the Frankfort plane (FH) and palatal plane (PP), lower incisor (L1) longitudinal axis to the lower mandibular plane (MP), overjet (OJ), effective maxillary length, effective mandibular length, and the maxilla–mandibular difference (Diff); Pearson correlation coefficient was applied. Results: There was a significant correlation between the maxilla–mandibular difference and U1 to FH angle (r = 0.254, p = 0.037), U1 to PP angle (r = 0.447, p &lt; 0.001), OJ (r = (−0.426), p &lt; 0.001). There was no statistical significance for Diff and L1 to MP angle (p = 0.342). Conclusions: In Class-III patients, achieving adequate decompensation is more challenging with the maxillary incisors rather than with the mandibular incisors, especially in more severe cases.

Does the timing of treatment affect the clinical and psychological outcomes of Twin-block therapy?

This study is a multicenter, two-arm parallel randomized control trial carried out across 3 hospital orthodontic units. A total of 75 patients participated in the study, with 41 randomly allocated in an Immediate Treatment Group (ITG) and 34 randomly allocated into an 18-month delayed Later Treatment Group (LTG). The patients were aware as to which group they were being allocated, as were the clinicians. Both patient groups received the same twin block appliance for use during the study. The appliance was to be worn full time, including eating, but to be removed while participating in contact sports or swimming. Achieving an overjet reduction between 2-4 mm was defined as being the clinical endpoint. After this, the appliance was only worn at night up until the next data collection point, allowing an 18-month window to finish treatment. Blinded clinicians measured skeletal changes using lateral cephalograms and overjet change via study models. Psychological impact was measured using two questionnaires: Oral Aesthetic Subjective Impact Scale (OASIS) and the Oral Health Quality of Life (OHQL). Data was collected from when the patient first registered in the study (DC1), 18 months after registration (DC2) and 3 years after registration (DC3). In total, 41 boys and 34 girls were included in the study. Ages for the boys ranged from within 1 month of their 12th birthday to 13.5 years old. For the girls, the range was from within 1 month of their 11th birthday to 12.5 years old. Further inclusion criteria included a class II skeletal pattern and having an overjet of 7 mm+. Exclusion criteria included patients of non-white Caucasian origin, girls aged 12.5 years+ and boys aged 13.5 years+. Furthermore, patients with a history of cleft lip or palate, mandibular asymmetry, muscular dystrophy, general health precluding compliance with treatment, a medically diagnosed growth excess or deficiency, not dentally fit or having previously received orthodontic treatment were not included in the study. SPSS Version 25 software was used to undertake the data analysis. No formal statistical testing was undertaken. To analyze and compare the scores between the two groups, independent t-tests were used. All analysis was carried out at 0.05 level of significance. The reliability of the examining clinicians was assessed using Bland-Altman limits of agreement. As only the ITG were in treatment over the periods of DC1-DC2 a comparison of the clinical outcomes cannot be made. With regards to the psychological outcome, no statically significant impact was noted for the ITG when compared with the LTG, who had not started treatment (OASIS P = 0.53, OHQL P = 0.92). When comparing the treatment effects of twin block therapy for the ITG (DC1-DC2) and the LTG (DC2-DC3), study model overjet and cephalometric changes were not statistically significant with the exception of % lower facial height (which was deemed not to be clinically significant) and mandibular unit length. There was no statistical significance with regards to the psychological outcomes post treatment when comparing the groups (OASIS P = 0.30, OHQL P = 0.85) CONCLUSIONS: The findings of this study suggest that adolescents (with a mean age of 12 years 8 months for boys and 11 years 8 months for girls) will not be disadvantaged, either clinically or psychologically, by waiting 18 months for twin block therapy.

Prediction of condylar movement envelope surface based on facial morphology

The present study aimed to predict the envelope surfaces from facial morphology. Condylar envelope surfaces for 34 healthy adults were formed and simplified as sagittal section curves. Cephalometric and maximum mandibular moving distances measurement were performed on the participants. There was no statistically significant difference (p = 0.763) between the left and right maximum lateral movements. There was a statistically significant difference in the mandibular body length between the sexes. The envelope surfaces were divided into type 1 with Hp2 ≥ 1/3 Hp1 and type 2 with Hp2 < 1/3 × Hp1. SNA and SNB for type 2 were significantly greater than those for type 1 (p < 0.001). Therefore, the participants were divided into four groups based on gender and envelope surface morphology. The curves could be fitted using the second-order Fourier function (R-square ≥0.95). Six facial parameters were selected and a matrix was used to map facial morphology to the envelope surface. Individual sagittal curves were predicted using the matrix and facial parameters, and the envelope surface was predicted using the curve and the condyle model. Deviation analysis for the predicted envelope surface using the actual envelope as a reference was carried out (root mean square = 0.9970 mm ± 0.2918 mm). This method may lay a foundation for the geometric design of artificial fossa components of temporomandibular joint replacement systems. It may improve prosthesis design without flexible tissue repair and guide the movement of the artificial joint head.

Anthropometric and Cephalometric Facial Characteristics of Adult Saudi Patients with Skeletal Class III Malocclusions

Abstract Objectives: We aimed to assess adult Saudi patients’ facial anthropometry and cephalometric characteristics with skeletal Class III malocclusions compared to Class I malocclusion patients. Materials and Methods: Our cross-sectional study included a review of the orthodontic records of 108 patients: 54 patients with skeletal Class III malocclusions and 54 patients with skeletal Class I malocclusions, equally distributed between males and females. Using anthropometric landmarks, seven angular and eight linear measurements were recorded and compared between Class III and Class I patients. In addition, we compared three horizontal facial proportions and three horizontal neoclassical canons between the two groups. Finally, we used Student’s t-tests to compare continuous variables and Chi-square tests for categorical variables. Results: Class III patients had significantly larger mandibular length, mandibular plane angle, mid- and lower-anterior face height, and posterior face height (P &lt; 0.05) compared to Class I patients. Class III patients had significantly proclined upper incisors, retroclined lower incisors, and an obtuse interincisal angle (P &lt; 0.05). The mouth: nose ratio differed significantly between skeletal Class III and I patients (P = 0.008). The orbital canon was valid in 14.8% of Class I and 9.3% of Class III patients, respectively. The orbitonasal proportion applied only to 31.5% and 20.4% of Class I and III patients, respectively. The naso-oral canon occurred in 18.5% and 1.9% of Class I and III patients, respectively. Conclusion: Saudis with Class III skeletal profiles have some distinctive Class III characteristics not observed in most other ethnic groups. The established horizontal facial proportions, neoclassical facial canons, and Class III skeletal profile did not apply to Saudis with skeletal Class I malocclusions, indicating that these proportions and characteristics may not be suitable as references when planning the surgical treatment for these patients.