Mandibular Position Research Articles

Cone-Beam Computed Tomography Assessment of Bifid and Trifid Mandibular Canals: A Cross-Sectional Study

The exact knowledge of the mandibular canal position is fundamental in oral surgery and implantology. Clinicians have to be extremely cautious when operating in close proximity to this structure in order to avoid damaging the neurovascular bundle. Several anatomical variations of the mandibular canal have been described in the literature, such as bifid or trifid structures. The use of cone-beam computed tomography (CBCT) offers a detailed representation of the inferior alveolar nerve path, albeit with some difficulties of identification when dental implants or metal prosthesis are present. The aim of this study is to retrospectively evaluate the prevalence and location of bifid/trifid mandibular canals (BMC/TMC) by CBCT in Italian patients. The screening phase involved 584 patients, only 238 enrolled (97 men; 141 women), with an average age of 51 ± 17.20. A total of 36 patients (15.25%) showed at least one bifid mandibular canal; only 2 patients (0.84%) showed a trifid mandibular canal. Overall, 12 patients (5.04%) presented this variation bilaterally. There was no association with the sex of the enrolled sample. In conclusion, the presence of BMCs and TMCs may be considered as a risk factor for the onset of neurovascular complications. Being aware of changes in the mandibular canal helps clinicians to prevent inferior alveolar nerve impairments that may occur during oral surgery and implantology.

Factors influencing the perception of profile beauty in Class III dental compensation: A comparative cross-sectional study according to three categories of assessors

The main objective of this study was to evaluate the different factors influencing the perception of female profile facial beauty in Class III patients with protruded mandible that can be treated with orthodontic dental compensation: (1)severity of the protrusion, (2) the upper incisors inclination and (3) the presence of jawlines. The secondary objective was to determine if the rater's gender and profession played a role in the assessment of the preferred profile. A normal and smiling photographs of a female subject with normal facial and skeletal profile criteria were digitally manipulated to obtain 3 different mandibular sagittal positions: 0mm, +4mm and +8mm. Each position of the chin was evaluated with the presence or not of jawlines. In the smiling profiles, the same chin modifications were scored, and the maxillary incisor inclination was changed from 0 to +10 degrees with 5 degrees increments. A total of 320 raters (107 dentists, 103 orthodontists and 110 laypeople) scored the attractiveness of the different images using a Visual Analogue Scale. The limit of statistical significance wasP<0.05. Generalized estimating equation (GEE) models were conducted to assess the predictors of variations in ratings within each set of photos, as well as the interactions of predictors where adjusted odds ratios (aOR) and their 95% confidence intervals were calculated and reported. In the profiles without a smile, image +4mm chin (Class III treated by compensation) and image +8-mm mandible (Class III not treated) were selected as the most and least attractive images, respectively, by almost all groups with no difference. The presence of jawlines has a positive role in facial attractiveness. In the smiling profiles, all the examiners showed a preference for image +4-mm chin and a slight protrusion of maxillary incisors (+5 degrees). No significant difference was found between genders in this study. Class III treated by compensation (+4mm) are more attractive than non-treated Class III (+8mm) by almost all groups with no difference. The presence of jawlines has a positive role in facial attractiveness. In the smiling profiles, all the examiners showed a preference for image +4-mm chin and a slight protrusion of maxillary incisors (+5 degrees). Orthodontists older than 50 years old are aware of the difficulty to treat a skeletal Class III and tend to accept it due to their long career experience. No significant difference was found between genders in this study.

Long-term stability of surgical orthodontic treatment for patients with asymmetric mandibular prognathism: a retrospective comparison study on surgical methods

ABSTRACT Purpose To consider long-term postoperative stability, and its contributing factors in surgical orthodontic treatment for asymmetric mandibular prognathism by comparing a sagittal split ramus osteotomy (SSRO) and a combination of Le Fort I osteotomy and SSRO. Materials and Methods Patients with asymmetric mandibular prognathism had undergone SSRO (14 patients; one-jaw surgery group) or a combination of Le Fort I osteotomy and SSRO (15 patients; two-jaw surgery group) were enrolled. Cephalometric analyses were performed at five time points: initial visit (T0), pre-surgery (T1), several months after surgery (T2), start of retention (T3) and more than 5 years after surgery (T4). Factors were evaluated by measuring two groups at each time point, comparing changes in measurements during each time period, correlating mandibular changes between each period, and correlating changes in lower first molar and ramus inclination with T2-T4 measurements. Results The two-jaw surgery group had significantly smaller transverse changes of menton (Me) at T3–T4 and T2–T4 compared to the one-jaw surgery group. In the one-jaw surgery group, transverse changes in Me at T2–T4 were positively correlated with changes in transverse inclination of mandibular ramus at the deviated side observed at T1–T2. Vertical change of pogonion at T2–T4 was positively correlated with change in bucco-lingual inclination of lower first molar at T0–T1. Conclusions Two-jaw surgery is suggested to be more effective than one-jaw surgery in achieving long-term stability of mandibular position in the transverse and anteroposterior dimensions after surgical orthodontic treatment for asymmetric mandibular prognathism. Long-term follow-up is necessary to monitor potential mandibular relapse.

Effect of maxillary impaction on mandibular surgical accuracy in virtually-planned orthognathic surgery: A retrospective study

Although surgical accuracy has been evaluated in bi-maxillary procedures, few studies have investigated the relationship between maxillary and mandibular accuracy. The present study evaluated the effect of maxillary impaction accuracy on mandibular surgical outcome.This cohort study analyzed skeletal class III patients who underwent planned maxillary impaction in bi-maxillary surgery. The primary predictor was the difference between the virtual plan and surgical outcome in the maxilla, as determined by three-dimensional (3D) and vertical differences. The secondary predictors were the planned 3D distances in the maxilla and mandible. The primary outcome was mandibular surgical accuracy, defined as the difference between the planned and actual outcomes, calculated as 3D Euclidean distance.The study included 73 patients. Increased differences between the planned and actual outcomes in the maxilla were associated with increased differences in the mandible. The post-operative position of the mandible was closer to the planned position when the position of the impacted maxilla was superior than when it was inferior to the planned position.Moving the maxilla closer to the planned position resulted in a more accurate mandibular position. These findings suggest that careful surgical procedures are needed to avoid inferior positioning of the maxilla during maxillary impaction surgery.

Clinical and Radiological Characterization of the Long-Term Association between Unaffected/Minimally Affected Implants and History of Severe Periodontitis: A Retrospective Study.

The objectives of this research were to compare, retrospectively, the clinical and radiographic modifications of periodontal parameters and peri-implant conditions and to analyze the relationship between the changes in periodontal parameters and peri-implant conditions over a mean follow-up period of 7.6 years in a treated population with progressive/uncontrolled periodontitis and at least one unaffected/minimally affected implant. Nineteen partially edentulous patients having 77 implants inserted, with a mean age of 54.84 ± 7.60 years, were matched for age, gender, compliance, smoking status, general health, and implant characteristics. Periodontal parameters were evaluated in the remaining teeth. Means per teeth and implants were used when making comparisons. Statistically significant differences were observed between baseline and final examination in teeth for tPPD, tCAL and MBL. Furthermore, at 7.6 years, statistically significant differences existed between implants and teeth with regard to iCAL and tCAL (p = 0.03). Multiple regression analyses were performed and revealed a significant association regarding iPPD and CBL with smoking and periodontal diagnosis. In addition, FMBS was significantly associated with CBL. Unaffected/minimally affected implants were found more frequently in the posterior mandible, with longer lengths (>10 mm) and small diameters (<4 mm), including in screwed multi-unit bridges. The study results appear to reflect minimally affected mean crestal bone-level loss around implants in comparison to the marginal bone-level loss around teeth when exposed to uncontrolled severe periodontal disease over a mean period of observation of 7.6 years, while the unaffected/minimally affected implants seemed to benefit from a combination of clinical factors, including posterior mandibular position, smaller diameters, and screwed multi-unit restorations.

Risk factors observed in 2-dimensional radiographs for permanent injury of the inferior alveolar nerve after removal of mandibular third molars: a case-control study

To assess whether differences exist in signs observed in 2D radiographs of mandibular third molars between a case group of patients with and a control group without permanent sensory disturbance of the inferior alveolar nerve (IAN) after removal. Three observers blinded to patient status assessed radiographs from the case group (n=162) and the control group (n=172). Two new signs, craniocaudal relation of the roots and the mandibular canal and position of the canal over the roots; and 4 "classic" signs, interruption of the white borders of the canal, darkening of the roots, narrowing of the canal lumen, and diversion of the canal over the roots were registered. Chi-square tests assessed differences in distribution of radiographic signs between the groups. Odds ratios expressed the association between radiographic signs and permanent sensory disturbance. Inter- and intraobserver reliability values were calculated. We found significantly more teeth with roots positioned inferiorly to the canal borders (P<0.001; OR 4.1-5.3) and with the canal superimposed over the upper or middle third of the roots (P<0.001; OR 2.6-3.9) in the case group than in the control group. Inter- and intraobserver reproducibility was excellent for roots inferior to the canal borders and fair to good for canal superimposition. Two radiographic signs are valid predictors of permanent sensory disturbance of the IAN in 2D radiographs.

Relationship between Mandibular Condyle Position and Pain in Patients with Disc Displacement with Reduction: A Retrospective Study

Objective: This study aimed to compare the condyle position of the temporomandibular joint (TMJ) in patients with disc displacement with reduction (DDWR) between with and without arthralgia using cone-beam computed tomography (CBCT). Methods: A total of 39 adult patients were examined retrospectively and were divided into three groups: 14 patients (21 joints) with TMJ DDWR and arthralgia, 14 patients (14 joints) with TMJ DDWR without arthralgia, and 11 asymptomatic patients (22 joints). Joint space measurements and condyle position were assessed using sagittal and coronal CBCT images. The radiographic data were correlated between the subgroups. One-Way ANOVA test was used for the analysis of normally distributed data, Kruskal Walis H test was used for non-normally distributed data in comparisons between three or more groups. The relationship between categorical data was examined with Chi-Square analysis. A descriptive statistical method (Mean, Median, Standard Deviation, Minimum-Maximum) was used while evaluating the study data. The confidence interval was set at 0.05 Results: There was no significant difference in age and gender between subgroups. The mean posterior and lateral joint space distance was found significantly higher in the painful DDWR group than in the painless DDWR group, and the incidence of anterior condylar position was significantly higher in the painful DDWR group than in the control group and painless DDWR group respectively. However, there was no significant difference in mediolateral condyle position variables among subgroups. Conclusion: Anterior condyle position may be correlated with pain in disc displacement disorders.

Treatment of Class II Malocclusion in the Growing Patient: Early or Late?

The aim of this paper is to evaluate several factors that can improve the efficacy of Class II treatment in the growing patient with mandibular skeletal retrusion. Previous research has shown that functional appliances are most effective in altering short-and long-term mandibular growth and mandibular sagittal position if active treatment includes the pubertal growth spurt. If functional jaw orthopedic treatment is initiated in the prepubertal growth period, the positive occlusal changes are primarily dentoalveolar in nature. The staging of the maturation level of the cervical vertebrae (CVM method) has proven effective in differentiating the stages of maturation.The second factor, typically not considered routinely during the decision-making process, is the responsiveness of a specific patient to the prescribed treatment. Not all patients respond to the same treatment in the same manner. One way of predicting individual patient responsiveness is to evaluate mandibular morphology at puberty. Good responders to functional jaw orthopedics for Class II malocclusion with mandibular retrusion are characterized by a small mandibular angle (Co-Go-Me). Poor responders have larger mandibular angles.The third issue that is addressed is the question of whether an early phase of treatment is necessary in a Class II patient with mandibular skeletal retrusion. The most frequently seen deficiency in the early mixed dentition is narrowness of the maxilla. A measurement of transpalatal width between the closest points between the maxillary first permanent molars of 35-39 mm usually indicates that there is enough arch perimeter to accommodate teeth of normal size. If transpalatal width is constricted, an acrylic splint expander or a banded expander can be used to widen the maxilla. A removable lower Schwarz expander also can be used to gain a modest amount of lower arch perimeter while uprighting the lower posterior teeth. Rapid maxillary expansion in the early mixed dentition can help in improving Class II malocclusion as a side-effect, both skeletally and dentally.

Orthognathic surgery effects on temporomandibular joint compressive stresses.

This study tested orthognathic surgery effects on temporomandibular joint (TMJ) compressive stresses. Pre- (T1) and post-surgery (T2) cone-beam computed tomography images were collected from consenting subjects aged ≥15 years. Anatomical data were used to measure surgical changes in anteroposterior mandibular position and occlusal plane angle (FH-OP), estimate condylar loading areas (mm2 ) and calculate T1 and T2 TMJ and jaw muscle forces (N) during canine biting via numerical modelling. Analysis of covariance tested for sex and biting angle differences in T2 - T1 TMJ compressive stresses (TMJ force/loading area, MPa). Principal component analyses identified jaw muscle forces that accounted for changes in T2 - T1 TMJ loads. Regression analyses tested the correlations between surgical changes in mandibular position, FH-OP, TMJ loads and muscle forces. Of 148 cases screened, 28 females and 16 males provided complete records. Condylar loading areas were significantly smaller (P = .024) for females vs males (124 ± 5 vs 144 ± 7 mm2 ). T2 - T1 differences in TMJ compressive stresses varied by surgical change, biting angle and sex. Overall, the largest increases in TMJ compressive stresses post-surgery were for females with mandibular setbacks where FH-OP angle decreased. T2 - T1 changes in jaw muscle forces had moderate (ipsilateral, λ = 4.59; η2 = 0.071) to large (contralateral, λ = 1.49; η2 = 0.31) effects on TMJ loads. T2 - T1 differences in TMJ compressive stresses during canine biting were affected by surgical changes in mandibular position and occlusal plane angle, biting angle and sex. Surgical changes altered jaw muscle forces for the same biting conditions and, thus, affected TMJ loads and compressive stresses.

Improved Super-elastic Ti-Ni Alloy Wire for Nonsurgical Treatment of Skeletal Class III Malocclusion Combined with Anterior Crowding and Anterior Crossbite Case

The article reported the use of improved super-elastic Ti-Ni alloy wire (ISW), which was developed by Tokyo Medical and Dental University, to correct a case of skeletal Class III malocclusion combined with anterior crowding and anterior crossbite. An 18-year-old male with a chief complaint of poor dental alignment and protruded lower incisors showed up in our clinic for treatment. Clinical examination revealed skeletal Class III facial profile. Anterior crowding and anterior crossbite could be also noted. Because the patient refused orthognathic surgery, we tried camouflage orthodontic treatment. First, we used ISW crossbite arch to eliminate the anterior interference in order to observe the change of the mandibular position. After that, we use ISW multiloop edgewise arch wire (MEAW) technique and intermaxillary elastics to achieve midline correction and adequate overjet with the bite raising process. The treatment was finished with the improvement of facial appearance and a stable occlusion.

Correlation between Temporomandibular Disorders (TMD) and Posture Evaluated trough the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD): A Systematic Review with Meta-Analysis.

Temporomandibular disorders (TMDs) are a series of disorders that affect the muscles and joint. Symptoms include joint pain, muscle pain, and limitation of mouth opening. One of several multifactorial diseases, temporomandibular dysfunction has mostly been linked to five etiological factors: occlusion, trauma, severe pain stimuli, parafunctional activities, and psychological elements, including stress, anxiety, and depression. The position of the human body as it is displayed in space is referred to as posture. Several nerve pathways regulate posture, and through ligaments, TMD and posture affect each other. The purpose of this study is to evaluate the possible correlation between posture and TMD through a meta-analysis of the literature; Methods: A literature search was performed on PubMed, Lilacs, and Web of science, and articles published from 2000 to 31 December 2022 were considered, according to the keywords entered. The term "temporomandibular disorders" has been combined with "posture", using the Boolean connector AND; Results: At the end of the research, 896 studies were identified from the search conducted on the 3 engines. Only three were chosen to draw up the present systematic study summarizing the article's main findings. The meta-analysis showed through forest plot analysis a correlation between posture and TMD Conclusions: This literature meta-analysis showed a correlation between posture and TMD. Nerve pathways probably regulate both body posture and mandibular posture. Further clinical studies will be needed to confirm this hypothesis and to indicate the main conclusions or interpretations.

Early Treatment of a Class III Patient with Chincup: A Case Report

Class III malocclusions are usually related to growth and mandibular posture. The mixed dentition stage of development may provide a useful opportunity to embark upon orthodontic therapy to correct a Class III malocclusion. Chin cap is a useful appliance in growingpatients that exhibit mandibular prognathis. This case report aim to describe an early treatment of a Class III malocclusion by using a chincup. This case report presents a 9 year-old girl with a functional Class III malocclusion and anterior crossbite. She has treated by using chincup for 10 months. The occlusion was elevated with a maxillary appliance, and the maxilla was freed from the restriction of the mandible. In this way, the maxilla was able to continue its development and the growth of the mandible was limited by chincup. Anterior cross-bite was corrected and a positive overjet were achieved. Facial profile was improved. While posterior rotation of the mandible was expected with the effect of the chincup, SN-GoGn angle didn’t change in this case. At the end of treatment, a class I relationship and a smooth soft tissue profile were obtained.

Average Three-Dimensional Skeletofacial Model as a Template for Bone Repositioning during Virtual Orthognathic Surgery.

Virtual planning has revolutionized orthognathic surgery. This study presents a computer-assisted method for constructing average three-dimensional skeletofacial models that can be applied as templates for surgical planning for maxillomandibular repositioning. The authors used the images of 60 individuals (30 women and 30 men) who had never undergone orthognathic surgery to construct an average three-dimensional skeletofacial model for male participants and one for female participants. The authors validated the accuracy of the newly developed skeletofacial models by comparing their images with 30 surgical simulation images (ie, skulls) that had been created using three-dimensional cephalometric normative data. The comparison was conducted by superimposing surgical simulation images created using the authors' models with the previously created images to analyze their differences, particularly differences in the jawbone position. For all participants, the authors compared the jaw position in the surgical simulation images created using the authors' average three-dimensional skeletofacial models with that in the images created using three-dimensional cephalometric normative data. The results revealed that the planned maxillary and mandibular positions were similar in both images and that the differences between all facial landmarks were less than 1 mm, except for one dental position. Most studies have reported less than 2 mm to be the success criterion for the distance difference between planned and outcome images; thus, the authors' data indicate high consistency between the images in terms of jawbone position. The authors' average three-dimensional skeletofacial models provide an innovative template-assisted orthognathic surgery planning modality that can enhance the fully digital workflow for virtual orthognathic surgical planning. Therapeutic, V.

Relationship between the Mandibular Condyle Position and the Bite Force in the People with Normal Temporomandibular Joint

Statement of the Problem. The mandibular condyle position is important in temporomandibular joint (TMJ) disorders. The bite force is a mechanical force that may affect the condylar position. Purpose. To investigate the relationship between condylar position in the glenoid fossa and maximum bite force in adults with normal temporomandibular joint. Materials and Methods. In this cross-sectional study, 23 subjects (21 females and 2 males; mean age 38.88 ± 11.7 years) with 41 joints participated. Right and left joints were examined using cone-beam computed tomography. Maximum bite force was measured using the strain gauge transducer in the regions of right molar, left molar, and incisors. Pearson correlation coefficient, paired sample t-test, and binary logistic regression were employed for analysis. Results. The mean maximum bite force was 169.09 ± 87.7 N. The most common position of the condyle was anterior (n = 36) and inferior (n = 31). The mean of mandibular condyle joint spaces for right and left sides were not statistically significant ( P &gt; 0.05 ). There were no relationships between the condylar positions and the mean maximum bite force ( P &gt; 0.05 ). Conclusion. The condylar positions in the glenoid fossa are not related to the bite force in the people with normal temporomandibular joint.

Evaluation of Local Application of Glucosamine Sulfate and Chondroitin Sulfate on Temporomandibular Joint Response and Alleviation of Pain and Tension During the Functional Treatment of Skeletal Class II Patients: A Randomized Control Clinical Trial.

This study was conducted to assess the effects of applying a gel ofcombined glucosamine sulfate and chondroitin sulfate on the temporomandibular joint (TMJ) area in patients with skeletal Class II malocclusion treated by removable functionalappliances in terms of TMJ internal proportions, levels of pain, and tension. The study included 36 patients aged 10-13 years with skeletal Class II malocclusion due to retrusion of the mandible characterized by:4-8 degrees of the sagittal skeletal discrepancy (ANB) angle,4-7 mm of overjet,72-76 degrees of the sagittal mandibular positioning (SNB) angle, and a bone maturity stage locatedat pubertal growth spurt. Patients were distributed to the experimental group (Twin-Block appliance + Jointance®gel)or thecontrol group (conventional treatment with the Twin-Block appliance). An allocation ratio of 1:1 was employed. Pre- and post-treatment digital lateral cephalometric radiograms were taken, and the TMJ joint spaces were measured using the Viewbox software (dHAL Software, Kifissia, Greece). The pain and discomfort levels were evaluated using a questionnaire with a four-point Likert scale at three assessment times. The anterior and posterior glenoid and anterior condylar distances to the pterygoid vertical (PTV) reference planesignificantly decreased after treatment (p<.001), and the anterior joint space decreased significantly (p<.001). In contrast, the superior distance of the condyle to the Frankfort horizontal reference planeincreased significantly after treatment, and the same results were found for the posterior and superior joint spaces (p<.05). There were no significant differences between the two groups in the evaluatedlinear variables. No significant differences were found when comparing pain and tension levels between the two groups at each assessment time. A gradual decrease in pain and tension levels was observed between the three evaluation times in both groups. A combinationof glucosamine sulfate and chondroitin sulfate did not affect the temporomandibular joint spaces, pain, and tension levelsin patients with skeletal Class II malocclusions treated by removable functional appliances.

Use of a novel body mandibular plane (mental foramen-protuberance menti) in analyzing mandibular asymmetry compared with conventional border mandibular plane.

To compare a novel body mandibular horizontal plane (mental foramen-protuberance menti; Body-MHP) with the conventional border mandibular horizontal plane (gonion-menton [Me]; Border-MHP) to assess mandibular body inclination and dental compensation of skeletal Class III patients with and without facial asymmetry. Retrospective data obtained from diagnostic cone-beam computed tomography of 90 skeletal Class III patients (mean age, 21.67 ± 2.93 years; range, 15.0-30.6 years) were divided into symmetry (n = 30) and asymmetry groups (n = 60). The asymmetry group was subdivided into roll (n = 30) and non-roll types (n = 30). The differences in body inclination and dental measurements (distance and angle) according to two mandibular planes (Body-MHP and Border-MHP) were assessed in the groups and subgroups. Mandibular body inclinations relative to the Body-MHP were not different in the roll-type asymmetric mandible between the sides, while those relative to the Border-MHP were different (P < .001). For the mandibular first molar positions relative to the Border-MHP, the differences in vertical distance between the sides were undermeasured and the inclination differences were overmeasured when compared relative to the Body-MHP. The Body-MHP demonstrated better bilateral similarity in body inclination compared with the Border-MHP in patients with roll-type facial asymmetry. The novel body mandibular plane ensures an accurate diagnosis for tooth movement and jaw surgery, particularly in the roll-type asymmetric mandible.

A three-dimensional investigation of mandibular deviation in patients with mandibular prognathism

BackgroundCraniofacial disharmony in cases of jaw deformity associated with abnormal lateral deviation of the jaw mostly involves both the maxilla and mandible. However, it has been still difficult to capture the jaw deviation aspect in a 3-dimensional and quantitative techniques. In this study, we focused on 3-dimensional mandibular morphology and position of the condylar head in relation to the base of the skull in patients with mandibular prognathism, one of the most common jaw deformities. We used cluster analysis to quantify and classify deviation and clarified its characteristics. We also investigated the degree of correlation between those findings and menton (Me) deviation measured on frontal cephalograms, which is a conventional indicator of jaw deformity.ResultsFindings obtained from 100 patients (35 men, 65 women) were classified into the following three groups based on mandibular morphology and condylar position relative to the skull base. Then, reclassification using these parameters enabled classification of cluster analysis findings into seven groups based on abnormal jaw deviation characteristics. Comparison among these seven groups showed that the classification criteria were ramus height, mandibular body length, distance from the gonion to the apex of the coronoid process, and the lateral and vertical positions of the mandible. Weak correlation was also found between Me deviation on frontal cephalograms and each of the above parameters measured on 3D images.ConclusionsFocusing on mandibular morphology and condylar position relative to the skull base in patients with mandibular prognathism, we used cluster analysis to quantify and classify jaw deviation. The present results showed that the 3D characteristics of the mandible based on mandibular morphology and condylar position relative to the skull base can be classified into seven groups. Further, we clarified that Me deviation on frontal cephalograms, which has been used to date, is inadequate for capturing jaw deviation characteristics.

Effect of Mandibular Third Molar Presence and Position on the Risk of Mandibular Angle Fracture

Background: Mandibular third molar presence and position may have an effect on the risk of mandibular angle fracture.&#x0D; Objective: The purpose of the present study was to see the effect of mandibular third molar presence and position on the risk of mandibular angle fracture.&#x0D; Methodology: This cross-sectional study was conducted in four centers in Bangladesh from July 2009 to June 2010 for a period of one year. The mandibular angle fractured patients were selected for the study. The medical records and panoramic radiographs of patients with mandibular angle fracture were examined. The presence or absence and degree of impaction of the mandibular third molars were assessed for each patient and related to the occurrence of fracture of the mandibular angle. Data were also collected for age, sex, mechanism of injury, number and location of mandibular angle fractures.&#x0D; Results: A total number of 100 patients with mandibular angle fracture were analyzed. The mean age is 44.36±21.9 years. Among 100 cases, 75 cases had lower third molars and 25 cases had without lower third molars. Within the 75 patients, 64 cases had impacted third molars while 11 cases had erupted third molars. Among the impacted group, 64.1% cases were mesioangular, 15.6% cases were horizontal, 12.5% cases were distoangular and 7.8% cases were vertical.&#x0D; Conclusion: In conclusion mandibular angle that contains an impacted lower third molar is more susceptible to fracture when exposed to trauma than an angle without lower third molar.&#x0D; Journal of National Institute of Neurosciences Bangladesh, July 2022;8(2):181-184

Three dimensional evaluation of the skeletal and temporomandibular joint changes following stabilization splint therapy in patients with temporomandibular joint disorders and mandibular deviation: a retrospective study

BackgroundThree-dimensional (3D) detailed evaluations of the mandibular mediolateral position, mandibular condylar position, and temporomandibular joint (TMJ) spaces following stabilization splints (SS) therapy in patients with temporomandibular joint disorders (TMD) and mandibular deviation (MD) have not been reported in the available literature. Accordingly, this study aimed to three-dimensionally analyze the skeletal and bony temporomandibular joint changes following stabilization splint therapy in adult patients with temporomandibular joint disorders and mandibular deviation.MethodsThis study is a retrospective clinical study that enrolled 26 adult patients with TMD and MD with a mean age of 24.86 years. The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) was used to diagnose TMD. SS was adjusted weekly until occlusal contact stabilization occurred, and then adjusted monthly, patients were instructed to wear it at night for at least 10 h. The SS was removed after the elimination of TMD symptoms (TMJ/muscle pain on palpation, muscle spasm, and clicking) and having both condyles completely seated in a musculoskeletally stable position. Pre- and post-therapeutic Cone Beam Computed Tomography (CBCT) was analyzed. Mandibular mediolateral position, TMJ spaces, and mandibular condyle position were analyzed three-dimensionally using Mimics 21.0 software. Paired t-test or Wilcoxon rank-sum test was performed, and the significance level was considered at P < 0.05.ResultsThe treatment period with SS therapy was 10.07 ± 3.1 months. The deviated chin was improved in 69.23% of the sample; the range of improvement was > 0 mm ≤ 3.9 mm. The mandibular rotation was significantly decreased from 3.58 ± 2.02° to 3.17 ± 1.60. The deviated side’s superior and posterior joint TMJ spaces were significantly increased from 2.49 ± 0.88 mm and 1.25 ± 0.79 mm to 2.98 ± 1.02 mm and 1.86 ± 0.72 mm, respectively. The value of the difference from the bilateral condyle head position to the X and Z axes significantly decreased from 2.50 ± 1.56 mm and 2.30 ± 1.57 mm to 1.64 ± 1.58 mm and 1.82 ± 1.11 mm, respectively.ConclusionThe main positional effect of the stabilization splint treatment in TMD patients with MD includes considerable correction of mandibular deviation, improving facial asymmetry, and moving the condyle into a stable condylar position; these were done by promoting the mandible to rotate around the Z (roll) and Y (yaw) axes and by forward, downward, and outward condylar movement on the deviated side, respectively.

Bone thickness and height of the buccal shelf area and the mandibular canal position for miniscrew insertion in patients with different vertical facial patterns, age, and sex.

The objectives of this article were the following: (1) to analyze bone thickness and height (BTH) of the buccal shelf area (BS) quantitatively in four different potentially eligible sites for miniscrew insertion; (2) to compare and contrast BTH and the changes in spatial position of the inferior alveolar nerve canal (IANC); and (3) to assess differences with age among vertical facial patterns (hypodivergent, normodivergent, and hyperdivergent) and well as by sex. Cone-beam computed tomography scans of 205 individuals (110 women and 95 men) were divided into groups according to age, vertical facial pattern, and sex. The BTH of the BS and the BTH to the IANC were measured in the mesial and distal roots of the first and second molars. BTH progressively increased in a posterior direction (P < .001), while BTH to the IANC increased and decreased (P < .001) for thickness and height, respectively, in the same direction in all age groups, for the three different vertical facial patterns, and in both sexes. Women showed significantly less BTH to the IANC (P < .002). Hypodivergent patients had greater BTH (P < .024) and a smaller bone height to the IANC (P < .018) only in the first molar region. Patients over 40 years of age had lower bone height in the second molar area (P < .003). The ideal place for BS miniscrew insertion is the region of the distal root of the second molars, regardless of facial pattern, sex, and age. The BS in women has less BTH and less BTH to the IANC.