[Growth disturbances of the temporomandibular joint: causes, diagnosis and treatment]. / Groeistoornissen van het kaakgewricht: oorzaken, diagnose en behandeling.

Growth disturbances of the temporomandibular Joint are characterized by mandibular asymmetry, sometimes with secondary maxillar disturbances. Although the clinical symptoms are sometimes quite severe, patients usually have no pain. There are several growth disturbances, but in this article we discuss three particular causes of facial asymmetry, namely hemimandibular growth defects; overdevelopment, underdevelopment and neoplasms of the mandibular joint. Hemimandibular overdevelopment (hyperplasia) is a growth disorder characterized by progressive asymmetry of the mandibula. Hemimandibular hypoplasia, on the other hand, is a growth disorder involving underdevelopment of the condyle mandibulae due to impingement of the growth center and ankylosing. A pronounced asymmetrical face can cause aesthetic problems and always requires diagnostics, because in addition to the hyperplasia and hypoplasia mentioned above, other causes can explain the asymmetry such as, for example, an osteoarthritis or even a tumor emanating from the base of the skull, mandibula or soft tissues.

[Internal derangements of the temporomandibular joint]. / Internal derangements van het kaakgewricht.

An internal derangement of the temporomandibular joint is described as a deviation in the position or shape of the joint tissues. Such a change is only functionally manifest if it interferes with smooth movements of the jaw joint. There are a number of internal derangements associated with jaw movements in which popping jaw joint sounds can occur. Examples are an anteriorly or posteriorly displaced disc and hypermobility of the condylar head. Although most internal derangements are harmless and only cause minor discomfort to patients, disc displacements can in some cases develop into a clinical problem, for example when there is a limitation of mouth opening (so-called closed lock) or an inability to close the mouth (so-called open lock). Most patients with these conditions do not require any or only conservative treatment.

[Deep Margin Elevations, clinical considerations]. / Deep Margin Elevations in de praktijk.

Subgingival restorations are problematic due to reduced visibility at the preparation margins, humidity (saliva, crevicular fluid and/or blood), problems with taking impressions (digital or analogue) and problems with the application of a rubber dam. Solutions, such as the use of a surgical microscope, retraction cord and Teflon tape, are available. Since modern dentistry largely relies upon adhesive techniques with hydrophobic materials, these require a clean and dry working area. One solution is to place the preparation margin supragingivally. This can be done in three ways: a local build-up using a direct composite restoration, a surgical clinical crown lengthening or an extrusion (orthodontic or surgical). Since in practice only a small part is usually located subgingivally, placing a direct composite restoration is often sufficient. The term Deep Margin Elevation is generally used in the international English-language literature for this approach. If the area located subgingivally is larger, then techniques like crown lengthening and extrusion might be better.

[Surgical extrusion, an alternative to a dental implant?] / Chirurgische extrusie, een alternatief voor een tandheelkundig implantaat?

Unfortunately, accidents do happen. Dentoalveolar injury to the front teeth resulting from trauma can sometimes be so problematic that an (adhesive) restoration seems almost impossible to make, let alone saving the tooth. In this contribution the case of a 17-year-old patient whose upper incisor suffered severe dentoalveolar trauma in a traffic accident is presented. His upper incisor was fractured deeply subgingivally, at bone level, and at first glance, appeared to be lost. Surgical extrusion, however, in this patient represents a full alternative to a prosthetic solution, such as a dental implant.

Arthrocentesis versus non-surgical intervention as initial treatment for temporomandibular joint arthralgia: a randomized controlled trial with long-term follow-up.

Arthrocentesis for arthralgia of the temporomandibular joint (TMJ) is often only indicated when conservative, non-surgical interventions have failed. However, performing arthrocentesis as initial therapy may facilitate earlier and better recuperation of the joint. The aim of this study was to assess the efficacy of this therapy with a long-term follow-up. Eighty-four patients were randomly allocated to receive either arthrocentesis as initial treatment (n = 41) or non-surgical intervention (n = 43). Pain (100-mm visual analogue scale, VAS) and mandibular function impairment questionnaire scores (MFIQ, 0-100) were recorded at 3, 12, and 26 weeks, and ≥ 5 years (median 6.2, interquartile range 5.6-7.4 years). Univariable analyses were performed and linear mixed-effect models were constructed. Patients in the arthrocentesis group experienced significantly lower TMJ arthralgia compared to those treated non-surgically (pain during movement: -10.23 mm (95% confidence interval -17.86; -2.60); pain at rest: - 8.39 mm (95% confidence interval -13.70; -3.08)), while mandibular function remained similar in the two groups (MFIQ -2.41 (95% confidence interval -8.61; 3.78)). Of the final sample, 10 patients (10/39, 26%) in the non-surgical intervention group and two patients (2/34, 6%) in the arthrocentesis group received additional treatment during follow-up. Thus, initial treatment with arthrocentesis reduced TMJ arthralgia more efficaciously than non-surgical intervention in the long term, while maintaining similar mandibular function.

Arthrocentesis as initial treatment for temporomandibular joint arthropathy: a randomized controlled trial.

OBJECTIVE: To determine the effectiveness of arthrocentesis compared to conservative treatment as initial treatment with regard to temporomandibular joint pain and mandibular movement. PATIENTS AND METHODS: In this randomized controlled trial, 80 patients with arthralgia of the TMJ (classified according to the Research Diagnostic Criteria for Temporomandibular Disorders) were randomly assigned to one of the two treatment groups. One group received arthrocentesis as initial treatment (n = 40), the other group received conventional treatment including soft diet, physical treatment and occlusal splint therapy (n = 40). Follow-up was after 3, 12 and 26 weeks post treatment. Prior to treatment, and at every follow-up assessment, pain intensity was measured (VAS 0-100 mm at rest, and VAS 0-100 mm during movement) and maximum mouth opening (MMO) (mm interincisor distance). Furthermore patients were asked to fill out several surveys concerning the impact of mandibular impairment on their daily life, and psychosocial aspects. RESULTS: After 26 weeks, the TMJ pain (mm VAS at rest, and mm VAS during movement) had declined comparably in both groups (arthrocentesis n = 36; conservative treatment n = 36) and MMO (mm interincisor distance) had slightly improved. GEE models showed significant differences between arthrocentesis as initial treatment and conservative treatment, indicating that the arthrocentesis group improved more rapidly with regard to TMJ pain (VAS at rest p = 0.008; regression coefficient ß = -8.90 (95% confidence interval -15.50, -2.31), VAS during movement p = 0.003; regression coefficient ß = -10.76 (95% confidence interval -17.75, -3.77)) and MMO (p = 0.045; regression coefficient ß = -2.70 (95% confidence interval -5.35, -0.06)) compared to conservative treatment. CONCLUSIONS: Arthrocentesis as initial treatment reduces pain and functional impairment more rapidly compared to conservative treatment. However, after 26 weeks, both treatment modalities achieved comparable outcomes. TRIAL REGISTRATION NUMBER: www.trialregister.nl: NTR1505.

Randomized trial on the effectiveness of dexamethasone in TMJ arthrocentesis.

The aim of this study was to compare the effectiveness of dexamethasone administration following arthrocentesis of the temporomandibular joint (TMJ) with a placebo (saline). Twenty-eight participants with TMJ arthralgia were randomly assigned to two groups of a parallel double-blind RCT. In both groups, an arthrocentesis procedure was carried out. In one group, the procedure was followed by the administration of a single-dose intra-articular dexamethasone. In the other group, saline was administered as a control. Follow-up visits were scheduled after 1, 3, and 24 weeks. During each visit, TMJ pain (on a 100-mm VAS) and jaw stiffness (mouth opening in mm) were scored. In the statistical analysis, generalized estimating equation (GEE) models showed no differences between the two study groups, although pain and jaw stiffness were both reduced over 24 weeks. In conclusion, intra-articular dexamethasone following arthrocentesis did not improve the procedure's effect in patients presenting with TMJ arthralgia (ClinicalTrials.gov number CT01275014).

Guided bone regeneration in rat mandibular defects using resorbable poly(trimethylene carbonate) barrier membranes.

The present study evaluates a new synthetic degradable barrier membrane based on poly(trimethylene carbonate) (PTMC) for use in guided bone regeneration. A collagen membrane and an expanded polytetrafluoroethylene (e-PTFE) membrane served as reference materials. In 192 male Sprague-Dawley rats, a standardized 5.0mm circular defect was created in the left mandibular angle. New bone formation was demonstrated by post mortem micro-radiography, micro-computed tomography imaging and histological analysis. Four groups (control, PTMC, collagen, e-PTFE) were evaluated at three time intervals (2, 4 and 12 weeks). In the membrane groups the defects were covered; in the control group the defects were left uncovered. Data were analysed using a multiple regression model. In contrast to uncovered mandibular defects, substantial bone healing was observed in defects covered with a barrier membrane. In the latter case, the formation of bone was progressive over 12 weeks. No statistically significant differences between the amount of new bone formed under the PTMC membranes and the amount of bone formed under the collagen and e-PTFE membranes were observed. Therefore, it can be concluded that PTMC membranes are well suited for use in guided bone regeneration.

Long-term oral-appliance therapy in obstructive sleep apnea: a cephalometric study of craniofacial changes.

OBJECTIVES: The aim of this randomized controlled study was to cephalometrically assess possible changes in craniofacial morphology associated with long-term use of an adjustable oral-appliance compared with continuous positive airway pressure (CPAP) in patients with the obstructive sleep apnea/hypopnea syndrome (OSAHS). In addition, we wanted to study the relationship between these possible changes and the degree of mandibular protrusion associated with oral-appliance therapy. METHODS: Fifty-one patients were randomized to oral-appliance therapy and 52 patients to CPAP therapy. At baseline and after follow-up (2.3±0.2 years), a lateral cephalogram of all patients was made in maximum intercuspation to determine relevant cephalometric variables. Both baseline and follow-up cephalograms were traced digitally whereupon cephalometric variables were compared. Changes in craniofacial morphology between the oral-appliance- and CPAP group were evaluated with a linear regression analysis. RESULTS: Compared with CPAP, long-term use of an oral-appliance resulted in small but significant (dental) changes. Overbite and overjet decreased, 1.0 (±1.5)mm and 1.7 (±1.6)mm, respectively. Furthermore we found a retroclination (-2.0 (±2.8)°) of the upper incisors and a proclination (3.7 (±5.4)°) of the lower incisors. Moreover, the lower- and total anterior facial height increased significantly, 0.8 (±1.5)mm and 0.9 (±1.4)mm, respectively. No changes in skeletal variables were found. Linear regression analysis revealed that the decrease in overbite was associated with the mean mandibular protrusion during follow-up (B=-0.029, SE=0.014, p<0.05). CONCLUSIONS: Oral-appliance therapy should be considered as a life long treatment, and there is a risk of craniofacial changes to occur. Therefore, patients treated with an oral-appliance, need a thorough follow-up by a dentist or dental-specialist experienced in the field of dental sleep medicine.

[Pain on mandibular movements]. / Pijn bij bewegingen van de onderkaak.

Pain or fatigue in the masticatory muscles or pain in the temporomandibular joints are well-known complaints. Diagnosing these complaints, that have a relation with mandibular movements, can be challenging since they can arise from the teeth and surrounding tissues, the temporomandibular joints or other musculoskeletal structures. Also referred pains are a common finding in this area. Pain history and clinical examination are crucial for a comprehensive diagnosis. Besides the disorders underlying the pain (so called axis I), the impact of the pain on the patient's physical and psychosocial functioning can play an important role in the diagnosis (axis II).

[Occupational differentiation in dentistry 3. Hypermobility of the temporomandibular joint and condylar position at maximal mouth opening]. / Beroepsdifferentiatie in de tandheelkunde 3. Hypermobiliteit van het kaakgewricht en de positie van het caput mandibulae bij maximale mondopening.

Hypermobility of the temporomandibular joint is only noted when it interferes with smooth mandibular movements. These interferences may result from a condylar dislocation beyond the temporal eminence at maximum mouth opening. Aim of this study was to test whether the condyle of a symptomatically hypermobile temporomandibular joint is positioned more anterosuperiorly to the temporal eminence at maximum mouth opening than a condyle without hypermobility. Nine persons with a hypermobile temporomandibular joint and 9 control persons participated. Diagnostics were based upon opto-electronic mandibular movement recordings. Condylar positions at maximum mouth opening were assessed by magnetic resonance imaging. A small significant difference in condylar position was found between groups. Condyles of persons with a hypermobile temporomandibular joint moved beyond the temporal eminence. However, this was also true for nearly half of the control persons. This suggests that condylar position alone is not a sufficient condition for symptomatic hypermobility of the temporomandibular joint. Maybe, symptoms of hypermobility only become apparent in combination with a particular line of action of the masticatory muscles.

Is condylar position a predictor for functional signs of TMJ hypermobility?

Temporomandibular joint (TMJ) hypermobility is noted only when it interferes with smooth mandibular movements. These interferences (viz. clicking sounds and jerky mandibular movements) result from condylar dislocation in front of the eminence at wide mouth opening, or alternatively in front of the articular disc (posterior disc displacement). The aim of this study was to test the hypothesis that condyles of hypermobile persons are positioned more anterosuperiorly to the crest of the eminence during maximum mouth opening than those of persons without TMJ hypermobility. Possible posterior disc displacement was also evaluated. Nine persons with symptomatic hypermobility and nine control persons free of internal derangements were included, their diagnoses being based upon opto-electronic movement recordings. Condylar positions during maximum mouth opening were analysed on magnetic resonance images with two slightly different methods, showing the degree to which the condyles are displaced around the eminence. No posterior disc displacements were found in any of the magnetic resonance images. After excluding an outlier and using both measurement methods, a small difference in condylar position was found between the two groups of subjects. The condyles of all hypermobile persons travelled beyond the eminence; however, so were the condyles of nearly half of the non-hypermobiles. The large overlap between both groups suggests that condylar position alone is not a good predictor for symptomatic TMJ hypermobility. It is probably the combination of condylar location in front of the eminence with a particular line of action of the masticatory muscles, which gives rise to functional signs of hypermobility.

Recognition of internal derangements.

One of the most common symptoms of temporomandibular disorders is an internal derangement (ID). The aim of this study was to test the inter-observer reliability of the recognition of IDs by means of auscultation, palpation or both. To that end, 120 women and 100 men were screened by two trained examiners for the presence of IDs. Anterior disc displacement was diagnosed in 14% of the cases and hypermobility in 12%. In 4% of the cases, the ID was classified as 'other'. The inter-rater reliability (Cohen's kappa) was moderate for the presence of an ID for all techniques, while for the classification into type, an almost perfect reliability was found for the combined technique. It was concluded that the type of ID can best be established with the combination of auscultation and palpation; for the establishment of an ID as such, any of the three techniques would suffice.

Variation in masticatory muscle activity during subsequent, submaximal clenching efforts.

In previous studies to the relative contribution of the jaw closing muscles to the maintenance of submaximal clenching levels, a considerable variation in the electromyography (EMG) activities of these muscles during subsequent efforts was found. In this study, it was examined to what extent this variation could be explained by coincidental variations in mandibular positioning. From seven healthy individuals, a total of 90 EMG sweeps was recorded: three conditions (intercuspal position and two types of stabilization appliances) x three clenching levels (10, 30 and 50% of maximum voluntary contraction level) x 10 repetitions. Mandibular position was monitored with a six degrees of freedom opto-electronic jaw movement recording system. Variations in mandibular positioning during subsequent, submaximal clenching efforts explained up to 25% of the variance in the indices that quantify the relative contribution of the jaw closing muscles to the total clenching effort (P=0.000; ANOVA). Only a weak dependency of positioning upon clenching condition was found whereas during higher clenching levels, the positioning effect tended to be smaller than during lower levels. In conclusion small, coincidental variations in mandibular positioning during subsequent clenching efforts partly explain the variance in EMG activity of jaw closing muscles, especially at lower clenching levels.