Lateral Mandibular Movements Research Articles

Temporomandibular joint biomechanics and equine incisor occlusal plane maintenance.

In equine dentistry, the physiological incisor occlusal surface is visually perceived as a plane with a distinct inclination to the head's coronal plane, extending rostro-ventrally to caudo-dorsally. To better understand the formation of this inclined plane and its connection to dental wear, we investigated the hypothesis that it arises from masticatory movements and the considerable distance between mandibular articular heads and the incisor occlusal surfaces, acting as the three points of support for the mandibles. Leveraging data from a large-scale clinical study involving static and dynamic orthodontic measurements in horses, we approximated the mandibular movement range where incisor occlusion and dental wear occur. By introducing and testing a segment coordinate system, we explored possible angular deviations from the occlusal plane caused by mandibular roll and pitch rotations during two lateral mandibular movement patterns, protrusion and retrusion. Theoretical biomechanical calculations and simulations confirmed the visual perception of the incisor occlusal surface as a plane. To further examine our assumptions, we employed a simple mechanical simulator to assess incisor normal occlusion and provoked malocclusions (diagonal, smile, and frown bite) by modifying temporomandibular joint (TMJ) movement patterns. The results from clinical investigations were corroborated by both the theoretical analysis and mechanical simulations, strengthening our understanding of the biomechanical basis behind the physiological incisor occlusal plane maintenance in horses. These findings have significant implications for equine dental health and contribute to a thorough understanding of TMJ dynamics.

Evaluation of the efficacy of manual soft tissue therapy and therapeutic exercises in patients with pain and limited mobility TMJ: a randomized control trial (RCT)

SummaryThe limited number of randomized controlled trials (RCTs) comparing the efficacy of soft tissue manual therapy and self-therapy interventions prompted the authors to focus on the analgesic and myorelaxant use of massage, post-isometric muscle relaxation (PIR) and therapeutic exercise in TMD patients.ObjectivesTo evaluate the effectiveness of soft tissue therapy and therapeutic exercises in female patients with pain, increased masseter muscle tension and limited mandibular mobility.Material and methodsThe study was conducted on a group of 82 women (G1) with the Ib disorder diagnosed in DC/TMD (Ib—myofascial pain with restricted mobility). The control group (G2) consisted of 104 women without diagnosed TMDs (normal reference values for TMJ ROM and masseter muscle sEMG bioelectric activity). Diagnostic procedures were performed in both groups (sEMG of the masseter muscles at baseline and during exercise, measurement of TMJ mobility, assessment of pain intensity—NRS scale). The G1 group was randomly divided into 3 therapeutic groups in which the therapy was carried out for 10 days: therapeutic exercises (TE), manual therapy – massage and therapeutic exercises (MTM_TE), manual therapy – PIR and therapeutic exercises (MTPIR_TE). Each time after therapy, the intensity of pain and TMJ mobility were assessed. Sealed, opaque envelopes were used for randomization. After 5 and 10 days of therapy, bilateral sEMG signals of the masseter muscles were acquired.ResultsMassage, PIR and self-therapy led to a decrease in sEMG at rest as well as in exercise. After day 6 of therapy, the groups obtained a significant difference (p = 0.0001). Each of the proposed forms of therapy showed a minimal clinically significant difference (MID) in the sEMG parameter at the endpoint, with the most considerable difference in the MTM_TE group. The forms of MT used were effective in reducing the patients’ pain intensity; however, a significant difference between therapies occurred after 4 treatments (p = 0.0001). Analyzing the MID between methods, it was observed that self-therapy had an analgesic effect only after 8 treatments, while PIR after 3 and massage after 1 treatment. After day 7, the mean pain score in the MTM_TE group was 0.889 and in the TMPIR_TE group was 3.44 on the NRS scale. In terms of MMO, a significant difference was obtained between monotherapy and each form of TM, i.e. massage (p = 0.0001) and PIR (p = 0.0001). Analyzing mandibular lateral movements, the authors got a significant difference in the proposed MT forms, of which massage treatments exceeded the effectiveness of PIR.ConclusionsSoft tissue manual therapy and therapeutic exercise are simple and safe interventions that can potentially benefit patients with myogenic TMDs, with massage showing better analgesic effects than PIR.

Efficacy of Arthrocentesis with and Without Sodium Hyaluronate Injection for Temporomandibular Joint Disorders: A Comparative Study.

To evaluate the efficacy of arthrocentesis with and without sodium hyaluronate injection for internal derangement of temporomandibular joint. Patients with clinically and radiographically confirmed cases of temporomandibular joint disorders were enrolled for this study. 20 patients were randomly allocated into two groups for arthrocentesis of TMJ with 10 patients in each group. In group 1, patients were treated with TMJ arthrocentesis followed by sodium hyaluronate injection, and in group 2, patients were treated with arthrocentesis alone. All the patients were treated under local anaesthesia. The patients were followed up at 1st week, 2nd week, 4th week and 12th week post operatively for maximum mouth opening, lateral mandibular movements, pain at rest and on mastication and the subjective efficacy of the treatment. By the end of twelfth week follow up, the mean mouth opening showed significant improvement in group 1, the right and left lateral movements showed better results in group 1 than in group 2, pain at rest and pain on mastication were mild in both the groups with subjective efficacy good in group 1 and moderate in group 2. This study suggested that TMJ arthrocentesis with sodium hyaluronate injection had better clinical outcome compared to TMJ arthrocentesis alone for TMJ disorders.

Remodeling dental anatomy vs sham therapy for chronic temporomandibular disorders. A placebo-controlled randomized clinical trial

BackgroundEvidence regarding the etiology or effective treatments for chronic orofacial pain, the majority diagnosed as temporomandibular disorder (TMD), is limited. PurposeTo investigate whether occlusal equilibration therapy (ET) and decreasing the (higher) angle of the lateral guidance on the nonworking-side leads to a reduction in chronic TMDs intensity. MethodsIt was conducted a randomized, explanatory, single blind with blinded assessment, placebo-controlled trial with strong protection against bias involving patients with chronic TMDs. Participants were randomly assigned to receive equilibration therapy or sham therapy. ET in this study consisted of minimal invasive occlusal remodeling to obtain balanced occlusion with reduction of the steeper angle of lateral mandibular movement with respect to the Frankfort plane. The primary outcome was a change in the pain intensity score (on a 0–10 point scale, with 0 indicating no pain and 10 the worst possible pain) at month 6. Secondary outcomes include maximum unassisted mouth opening and psychological distress. ResultsA total of 77 participants underwent randomization, 39 of whom received ET and 38 sham therapy. The trial was stopped early for efficacy, according to preestablished rules when 67 participants (n = 34, n = 33, respectively) had completed the analysis. At month 6, the mean unadjusted pain intensity score was 2.1 in the ET and 3.6 in the sham therapy group (adjusted mean difference, −1.54; 95% confidence interval [CI] −0.5 to −2.6; P = 0.004; ANCOVA model). The mean increase in maximum unassisted mouth opening (main secondary outcome) was significantly higher in the real therapy group (adjusted mean difference 3.1 mm, 95% CI 0.5–5.7, p = 0.02). ConclusionET significantly reduced the intensity of facial pain associated with chronic TMDs and increased maximum unassisted mouth opening, as compared with sham therapy, over the course of 6 months. There were no serious adverse events.Funded by the Instituto de Salud Carlos III from the Ministry of Science and Innovation of the Government of Spain and European Regional Development Fund, Grant nº PI11/02507; “una manera de hacer Europa”.

3D-printed temporomandibular joint-mandible combined prosthesis: A prospective study.

The study aimed to introduce and evaluate a new customized temporomandibular joint-mandible combined prosthesis with 3D printing fabrication. This was a prospective study including patients with temporomandibular joint-mandible combined lesions. A 3D-printed customized temporomandibular joint-mandible combined prosthesis was implanted to repair the joint and jaw defect. Clinical follow-up and radiographic examinations were taken to assess the clinical efficacy. The assessment indices were compared by the Wilcoxon signed rank test. Eight patients were treated with the combined prosthesis and included in this study. All prostheses were accurately positioned and fixed without wound infection, prosthesis exposure, displacement, loosening, or fracture. All cases had no mass recurrence at the last follow-up point. Pain, diet, mandibular function, lateral mandibular movement to the diseased side, and maximal interincisal opening showed significant improvements at every follow-up point and went to a stable condition at 6 months after the operation. But the lateral movement to the non-operated side was still limited following surgery. The 3D-printed combined prosthesis may be an alternative to other well-established reconstructions for temporomandibular joint and mandible defects.

Selective grinding and neuro-occlusal rehabilitation

The characteristics of the modern human diet do not favour normal tooth wear. This lack of evolution of the occlusal morphology will be responsible for limitations in mandibular lateral movements and masticatory work. When masticatory impotence is detected, artificial wear of the cuspid reliefs should be performed as soon as possible. These grindings, called selective by Pedro Planas, make it possible to free the mandibular lateral movements and to rehabilitate the masticatory function. Physiological, unilateral and alternating chewing function allows for «happy growth» of the jaws and maintenance of a healthy masticatory system.

Arthrogryposis multiplex congenita with maxillofacial involvement: a case report

BackgroundArthrogryposis multiplex congenita is a rare condition that mainly involves the lower limbs, characterized by severe joint deformity and contracture, muscular atrophy, and functional impairment. Its clinical manifestations are heterogenous and may involve the maxillofacial district as well.Case presentationThis case report describes a 20-year-old patient with arthrogryposis multiplex congenita with skeletal crossbite, facial asymmetry, reduced mouth opening and absence of lateral mandibular movement on the left side. After clinical evaluation, the following exams were required: postero-anterior cephalometric tracing, head and neck electromyography, computerized axiography, computed tomography scan, and maxillofacial magnetic resonance imaging. Orthognathodontic evaluation indicated skeletal asymmetry, reduced condylar movements on the left side and abnormally low electromyography activity of the masticatory muscles on the left side. Computed tomography and magnetic resonance imaging revealed unilateral left mandibular hypoplasia, hypotrophy, and fatty infiltration of masticatory muscles on the left side, as well as immobility of the left condyle during mouth opening, and hypoplasia of the left articular disk, which was however not displaced. Surgery was not indicated and conservative orthognathodontic treatment with function generating bite was suggested to balance the occlusal plane, as well as stretching exercises.ConclusionsA rare case of arthrogryposis multiplex congenita with maxillofacial involvement illustrates that a patient-centred, multidisciplinary approach with accurate diagnosis is required to formulate the best treatment plan. Because of the considerable damage to the masticatory muscles, conservative orthognathodontic therapy may be the best treatment option.

Familial Marcus Gunn phenomenon without ptosis in resting position in 2 successive generations: a case report and review of literature

Background: Marcus Gunn syndrome is a rare congenital disorder. The major symptom is unilateral blepharoptosis during mandibular masticating movements and ptosis; although cases with the absence of the ptosis symptom in resting position, even rarer, were also recorded. The aim of this article was to present two cases of familial Marcus Gunn Jaw-Winking Synkinesis (MGJWS) without ptosis in two successive generations. Case Presentation: Upon routine examination, the 41-year-old female patient was diagnosed with MGJWS, with the synkinetic movement of the upper left eyelid only observed during the downward, forward, and lateral mandibular movements. Ptosis was not observed in the resting position. The patient’s 12-year-old daughter, who did not have any significant medical history, was also diagnosed with MGJWS, with the same symptoms. No surgical or conservative intervention was performed on the patients, and they are currently under regular follow-up. Conclusion: The absence of the ptosis symptom might make the diagnosis of MGJWS a challenge. The synkinetic movement being observed during masticatory movements presents a diagnostic opportunity for the dental clinician and surgeon since it will be observed during a routine temporomandibular joint examination. Thus, the authors think that it is important for dental clinicians and surgeons to be informed about the syndrome.

Does Orthodontic Treatment Change the Preferred Chewing Side of Patients with Malocclusion?

Whether orthodontic treatment can change the preferred chewing side (PCS) is unknown. This study examined (1) if the PCS changes after orthodontic treatment and (2) which factors contribute to this change. Two hundred fifty patients who visited the orthodontic clinic at Tokyo Medical and Dental University Hospital between 2017 and 2020 were included in the study. Mandibular kinesiograph (MKG) was taken at pre- and post-treatment, and PCS was determined. Patients who showed a change in PCS to the opposite side and those who showed no change in PCS at post-treatment were pooled into the PCS-changed and PCS-unchanged groups, respectively. The demographic, clinical, and cephalometric parameters were compared between the groups. Significant factors associated with changes in were of age < 20 years at the beginning of orthodontic treatment (odds ratio (OR), 2.00), maximum lateral mandibular movement to PCS ≥ 10.0 mm at pre-treatment (OR, 6.51), and change in occlusal canting of ≥1.0° (OR, 2.72). The predicted probability of change in PCS was 13.2%, 36.0%, and 67.5% for no factor, one factor, and two factors associated with PCS change, respectively. Orthodontic treatment may change PCS due to patient age, maximum lateral mandibular movement to PCS, and change in occlusal canting.

Mandibular lateral movements of orthognathic patient by Four-Dimensional JAW motion system

To compare the maximum lateral movements between the control group and group of patients before and after combined orthodontic and orthognathic treatment based on a four-dimensional jaw motion system. This study included ten patients before and after combined orthodontic and orthognathic surgery treatment and ten controls. The mandibular left and right lateral movements were tracked, visualized, and analyzed using Planmeca four-dimensional jaw motion system. A t-test was used to compare the means between the groups. The average maximum of lateral movement in the control group was on the left side 12.8 mm and on right 14.15 mm. The number of lateral movements in the orthognathic group was on the left side 9.24 mm and on right 8.44 mm before treatment and after treatment on the left side was 8.99 mm and on the right side was 8.26 mm. There was no statistical difference between groups at p<0.05; p=0.30. Only the right lateral movement was statistically significant (p=0.02) comparing the control to the orthognathic group before the surgery. This short research showed that there was a slight reduction in the lateral movements in the group of orthognathic patients after treatment but with no statistical difference. The statistically significant difference was of the right lateral movement comparing the control to the orthognathic group before the surgery. Further research is needed to demonstrate if there can be some improvement of lateral movements in the orthognathic patient after surgery.

Pattern of occlusal contacts in eccentric position of mandible in dental students

Introduction: Canine protection and group function are the two stand out occlusal schemes observed during laterotrusive movement of the mandible. The study aims to evaluate the frequency of these occlusal schemes in Nepalese dental students. Materials and methods: A cross-sectional study was conducted among dental students in People’s Dental College and Hospital, Kathmandu, Nepal after the ethical approval from PDCH-IRC. Sixty four undergraduate students aged 21-30 years, were examined for the occlusal contact patterns in lateral mandibular movements using 12μm shim stock. The data were analyzed using SPSS software (version 21) Result: On 1mm laterotrusive position on mandible, 43 subjects (67%) showed group function, 15 subjects (24%) canine guided and 6 subjects (9%) non specified occlusion. On 3mm laterotrusive movement, 31(48%) subjects showed group function and 27 subjects (42%) showed canine guided occlusal scheme. The most frequent mediotrusive contact was the second molar followed by the first molars during both 1mm and in 3mm excursion Conclusion: Majority of occlusal schemes of the study population were group function followed by canine protection and non specified occlusion. Canine protected occlusion scheme was increased on 3mm lateral excursion. Most of mediotrusive side contact seen on 2nd molar on 1mm.

The Effect of 660-nm Low Level Laser Therapy on Mandibular Lateral Movement After Orthognathic Surgery

Introduction: Limited jaw motion is a common complication after orthognathic surgeries that can negatively affect the patients’ quality of life, thus it is required to be properly treated. Regarding the growing interests in laser application in density, we aimed to evaluate the effects of 660nm LLLT on mandibular lateral movements after orthognathic surgery. Materials and Methods: Twelve candidates of bimaxillary orthognathic surgery were included in a split-mouth, triple-blind phase 1 trial. On 1, 4, and 7 days after the surgery, a 660-nm diode low-level laser was applied to one facial side of patients, whereas the other side was kept untreated as placebo. Then, rightward and leftward mandibular movements from the maxillary midline were measured in millimeters (mm) on 2, 7, and 14 after the surgery. The measurements were then compared between the study groups using ANCOVA analysis. Results: Despite the constant improvement in mandibular lateral movements in both study groups, the rightward mandibular movements in LLLT group were significantly better than in placebo group on second (3.9 versus 3.2 mm, P = 0.015), seventh (5.6 versus 4.2 mm, P = 0.018), and 14th (7.1 versus 5.2 mm, P = 0.005) days after the surgery. Also, the leftward mandibular movements in LLLT group were significantly better than in placebo group on second (3.7 versus 2.1 mm, P = 0.021), seventh (4.9 versus 2.9 mm, P = 0.019), and 14th (6.7 versus 4.2 mm, P = 0.002) days after the surgery. Conclusion: LLLT can effectively improve both rightward and leftward movements of mandibular after an orthognathic surgery.

Effects of Different Therapeutic Modalities on the Clicking Sound and Quantitative Assessment of the Vertical and Lateral Mandibular Movements of Patients with Internal Derangements of the Temporomandibular Joint.

To compare the efficacy of low-dose laser therapy to that of conservative treatment using two different occlusal splints (stabilization and anterior repositioning splints) in patients with internal derangements of the temporomandibular joint (TMJ). The study population consisted of patients with disc displacement with reduction diagnosed according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I and Axis II. In addition, disc displacement with reduction was confirmed in all patients using TMJ ultrasonography. These tests were conducted for 6 months with an interim control in the third month. The "clicking" sound from the joint on opening and closing the mouth and the extent to which the mouth opened vertically and laterally were assessed. In all, 20 patients received low-dose laser therapy, 20 were treated with a stabilization splint, and 20 were treated with an anterior repositioning splint. In addition, 10 untreated patients were included as a patient control group, and a further 10 healthy subjects were included as a healthy control group. Changes in the condition were assessed based on the results of the RDC/TMD Axis II and with the use of an algometer. The anterior repositioning splint group showed improvement in the "clicking" sound during mouth opening. Lateral movement improved significantly in patients who received laser therapy. In the patient control group, the click disappeared during mouth opening, the algometrically determined pain improved, and the lateral movement increased. There were no statistically significant differences between groups in the improvement of vertical mouth movement or in the clicking sound during mouth closing. Each treatment modality applied in this study separately produced positive results for the clicking sound, restrictions in vertical and lateral movements, and reduction of the pressure pain threshold observed in cases of TMJ irregularity. The decision regarding which treatment modality should be employed can be made based on the patient's symptoms. However, this study also indicates that TMJ derangements can resolve spontaneously when left untreated.

Limited Mandibular Movements as a Consequence of Unilateral or Asymmetrical Temporomandibular Joint Involvement in Juvenile Idiopathic Arthritis Patients.

This study aimed to assess the asymmetry of the lower face and motor dysfunction of the masticatory system resulting from unilateral or asymmetrical bilateral temporomandibular joint (TMJ) involvement in juvenile idiopathic arthritis (JIA) patients. The study consisted of clinical examination and cone beam computed tomography (CBCT) of TMJs. Statistical analysis showed correlations between several factors: facial asymmetry and mandibular lateral deviation; the direction of mandibular deviation and the degree of radiological deformities in TMJs; the child’s age at the time of the onset and the range of lateral movement towards the healthy or less destructed joint. In addition, there was a significant difference in ranges of lateral movements; a significantly smaller range was observed for the joint with fewer condylar abnormalities compared to the range in the opposite direction. In JIA children, among the clinical markers of unilateral or asymmetrical TMJ involvement, the asymmetry of the lower face, deviation of the mandible on opening, and an uneven range of mandibular lateral movements deserve attention. The obtained results do not show a relationship between the degree of condylar changes and the asymmetry of the lower face and the presence and degree of mandibular motor dysfunction.

Several Variables Response to 2.2% Intra-Articular Injections of Hyaluronic Acid

Objectives of the research: to assess the effects of TMJ 2.2 hyaluronic acid injection on following TMJ pain, TMJ clicking, maximum opening capacity and lateral mandibular movements. This study include one hundred patients (77females and 23males) whom complain from clicking and pain at their TMJ with or without limitation of mandibular movements. The age ranged between 9-65 years old. Hyaluronic acid 2.2% were used for intra- articular injection unilaterally at the upper compartment of the most painful TMJ. Assessment of pain was done by using the visual analogue scale (0-10), the intensity of clicking was evaluated by stethoscope using basser clicking score, lateral movements were calculated by using ruler and recorded into special case sheet, and any complications that reported by the patients were recorded. These data were recorded before treatment and one, two, three weeks post injections, also one month after the last injection. SPSS (statistical package of social science) window 11.5 version was used for statistical investigation with chi square and paired T tests with P ≤ 0.001 as a significant value. The outcome of this study reveals that age cluster between (21-30) years was the most prevailing age, it signify (29%) of the entire trial, whereas the age group over 50 years was the least represented age group, it signify 7%, Female were presented in this study more often than males at a ratio of (3.3 -1). Regarding TMJ pain, there were significant differences (P≤ 0.001) before and after intra-articular drug administration. Significant differences P≤ 0.001were found in clicking scores means before and after intra-articular HA injections there were significant differences P≤ 0.001 in maximum opening capacity means before and after TMJ injections. There were significant differences in both lateral left and right movements means P ≤ 0.001 before and after TMJ injections of hyaluronic acid. This study conclude that HA 2.2% TMJ injection is an effective method in treating different TMJ diseases including temoporomandibular disorders, it reduce pain, clicking and improve mandibular motion, their effect persist even one month beyond last injection, it is effective, safe, painless, not costly, with no side effects like steroid, with no complications, usually no need to another drugs following injections like antibiotic and analgesic. We recommend that this modalities as the best treatment for TMDs. Also we conclude that females seek treatment more often than males at a ratio 3.3:1.

Horizontal change of philtrum after orthognathic surgery in patients with facial asymmetry

BackgroundSoft tissue asymmetry such as lip canting or deviation of the philtrum is an important influencing factor for unbalanced facial appearance. Lip canting could be improved by the correction of the occlusal canting or positional change of the mentum. Although there are many studies about changes of lip canting, however, postoperative changes of philtrum deviation have not been yet reported. In this study, we investigate the positional change of the philtrum after orthognathic surgery and influencing factors.MethodsPositional change of the philtrum was evaluated in 41 patients with facial asymmetry who underwent bimaxillary surgery, in relation to other anatomical soft tissue landmarks using a frontal clinical photo. The surgical movement of the maxillary and mandibular dental midline and canting were measured in postero-anterior cephalogram before and 1 day after surgery. The same procedure was repeated in patients with more than 1.5 mm perioperative change of the mandibular dental midline after bimaxillary surgery.ResultsMaxillary dental midline shifting and canting correction did not have a significant correlation with lateral movement of the philtrum midline. However, the mandibular shift had a statistically significant correlation with a lateral movement of the philtrum (p < 0.05) as well as other linear parameters and angle values.ConclusionThe horizontal change of the philtrum is influenced by lateral mandibular movement in patients with facial asymmetry, rather than maxillary lateral movement.

Evaluation of TMJ Functions after conservative Treatment of Unilateral Subcondylar Fracture

Aim: It is to assess TMJ functions after conservative treatment of unilateral subcondylar fractures. Subjects and Methods: A prospective study was conducted on 20 patients with unilateral mandibular subcondylar fracture undergoing nonsurgical treatment. Clinical and radiographic examinations were done prior to treatment and at 12-month follow up. Pain, perceived occlusion, mouth opening, protrusion, and horizontal movements of the mandible were evaluated by clinical examination. Radiologic evaluation was done using panoramic radiographs. Results: At 12-month follow-up, there was minimal pain in the temporomandibular joint region, there was an improvement in the perceived occlusion, without limited mouth opening. There was insignificant absolute difference between left and right lateral mandibular movements. The amount of increase in the protrusion of mandible was insignificant. On radiographic evaluation, mean ramus height pretreatment and 12 months post -treatment were 1.51+0.45 and 1.47+0.48, respectively. Conclusion: Unilateral subcondylar fractures of the mandible can be treated nonsurgically in patients with minimal occlusal discrepancies, adequate mouth opening, minimal displacement of condyle, and minimal ramus height shortening.

Influence of restoration thickness on the stress distribution of ultrathin ceramic onlay rehabilitating canine guidance: a 3D-finite element analysis.

The rehabilitation of canine guidance can be performed with adhesive indirect materials, but can the restoration thickness be reduced without mechanical disadvantages? Thus the goal of this study was to analyze the stress of upper canines which received different thicknesses of ceramic fragments for the rehabilitation of the canine guidance using finite element analysis. A superior canine was modeled using a computer aided design software. The dental tissues were individually shaped containing enamel, dentin and periodontal ligament. The following three different ceramic fragment thicknesses were then implemented: 0.3, 0.7 and 1.5 mm. Lithium disilicate was chosen as the ceramic material. The solid geometries were exported to the analysis software. The materials were considered isotropic, homogeneous and linear. The set was submitted to efforts in the incisal third in the palatine face to analyze maximal principal stress, mimicking mandibular lateral movement. The applied load was 100N, and the fixation region was on the medullary bone. For restoration, the thinner the ceramic, the higher the stress concentration was; while for the adhesive surface of teeth, the thicker the ceramic, the higher the stress concentration. The smaller the ceramic thickness was, the lower stress concentration showed at the adhesive interface, while the stress concentration was higher on the restoration intaglio surface.

The importance of the posterior joint space for functional mandibular movements: A laboratory cross-sectional study.

BackgroundThe search for the ideal, healthy and reproducible position of the condyles is of utmost importance for dental diagnosis and treatment. Thus, the objective of this laboratory cross-sectional study was to verify the relationship between the posterior joint space and the mandibular lateral movements.Material and MethodsDental casts from 15 women and 15 men with normal mastication, 28 natural teeth and no history of temporomandibular disorders or pain, were fabricated and mounted on a fully adjustable articulator. From the maximum intercuspal position, condylar displacement was evaluated and measured on the working and nonworking sides during mandibular lateral movement, both to the right and left sides.ResultsThe correlation between the measures of interest was assessed with the Pearson correlation coefficient (α=.05). Condylar displacement on the working side and nonworking side condyle was 0.88±0.71 mm and 3.57±1.11 mm (right mandibular lateral movement); and 0.91±0.58 mm and 3.51±0.78mm (left mandibular lateral movement), respectively. No significant correlation in the condylar displacement between the working side condyles on the right and on the left sides was observed (r=.22; P=.248). The condylar poles of the articulator moved posteriorly, simulating the functional movements of the mandible during mastication. In all cases, condylar displacement during mandibular lateral movement both to the right and left occurred posteriorly on the working side condyle.ConclusionsThe condylar poles of the articulator moved posteriorly simulating the functional movements of the mandible during mastication. Moreover, left and right working condyles may require slightly different spaces to function, suggesting minor anatomical asymmetries. Key words:Mastication, dental occlusion, prosthodontics.

Mandibular Sub-Condylar Fractures Conservative Management - Advantages and Disadvantages: A Clinical Study

Background and objective: Mandibular fractures are the most frequent and sub condylar region is a common site of fracture. Proper management of sub condylar fracture is a matter of controversy. Improper management of sub condylar fracture can lead to impaired function and aesthetics. Hence a timely and appropriate management of sub condylar fracture is mandatory. Aim of the study was to evaluate the merits and demerits of conservative management of mandibular sub condylar fractures. Materials and methods: A total of 430 mandibular fractures were evaluated and out of this 107 had sub condylar fractures. In this study a clinical attempt was made to study comprehensively the conservative management of sub condylar fractures. The factors considered were age, sex, associated fractures of facial bones, treatment and complications. Results: Among 107 patients 85 males and 22 females had sub condylar fracture. Associated facial bone fractures were seen in 44 cases. There was no complication of ankyloses. Lateral mandibular movement was regained in 82.6% of cases and satisfactory occlusion achieved in all cases. Conclusion: Based on this study conservative management of mandibular sub condylar fracture gives good results in most of the cases if managed judiciously.