Comparative prospective study on splint therapy of anterior disc displacement without reduction.

A prospective randomized study was carried out to compare the therapeutic success of two different types of splint in patients with painful anterior disc displacement of the temporomandibular joint. The patients in Group I (n = 20) received stabilization splint therapy and the patients in Group II (n = 20) pivot splint therapy. Clinical investigation of the craniomandibular system was performed before and 1, 2 and 3 months after therapy and this was accompanied by subjective evaluation by the patients of their symptoms, using a validated questionnaire with visual analogue scales (VAS). There was a significant increase in maximum jaw opening and a significant reduction in subjective pain in both groups during the course of therapy (Wilcoxon test, P < 0.05). Active jaw opening increased by a mean of 8.05 mm in the group of patients treated with a stabilization splint (Group I). The comparable figure with pivot splint therapy (Group II) was 8.26 mm. The VAS scale value in Group I was reduced by 30.54 units and in Group II by 39.36 scale units. However, neither of these differences between the groups was statistically significant (Mann-WhitneyU-test, P > 0.05). It can be concluded that both types of splint provided effective therapy in patients with anterior disc displacement.

Elongated styloid process: when is it really elongated?

OBJECTIVE: The styloid process (SP) is often denoted as elongated when it is longer than 30 mm or 33 mm. These dimensions, based on early reports, do not respect the natural variation of the SP. The aim of this study is to investigate the natural variation of the length of the SP. Knowing this variation is a prerequisite for consistent terminology in anatomy and anthropology; it is essential for the classification of the SP as elongated on panoramic radiographs (PRs). MATERIALS AND METHODS: 1000 consecutive PRs of a normal population were retrieved from inactive files at the Dental School of the Hannover Medical University. Measurements of the length of the SPs were made directly on the radiographs from the caudal margin of the tympanic plate to the tip of the SP. RESULTS: On 521 of the 1000 PRs the length of the SP could be measured at least on one side. As there was no significant difference between distributions on the left and right side, both sides were combined to give a total of 837 measurements. The median was 28.0 mm, the interquartile range was from 23.0 mm to 36.0 mm. The distribution depends significantly on age and gender. The 90th percentile varies between 42 mm for women under 35 years and 49 mm for men aged over 35 years. CONCLUSIONS: The medians in our sample correspond to the thresholds for elongated SP quoted in the literature. Our results show that these thresholds are too low, since they are exceeded in 50% of normal patients. We propose that the SP should be considered to be elongated only if its length exceeds 45 mm, which corresponds to the average of the 90th percentiles for different sex and age groups.

Comorbidity of internal derangement of the temporomandibular joint and silent dysfunction of the cervical spine.

The aim of this evaluation was to examine correlations between internal derangement of the temporomandibular joint (TMJ) and cervical spine disorder (CSD). A prospective controlled clinical study was carried out. Thirty patients with signs and symptoms of internal derangement but without any subjective neck problems and 30 age- and gender-matched control subjects without signs and symptoms of internal derangement were examined. The investigation of the temporomandibular system was carried out using a 'Craniomandibular Index'. Afterwards an examiner-blinded manual medical investigation of the craniocervical system was performed. This included muscle palpation of the cervical spine and shoulder girdle as well as passive movement tests of the cervical spine, to detect restrictions in the range of movement as well as segmental intervertebral dysfunction. The internal derangement of the TMJ was significantly associated with 'silent' CSD (t-test, P < 0.05). Patients with raised muscle tenderness of the temporomandibular system exhibited significantly more often pain on pressure of the neck muscles than patients without muscle tenderness of the temporomandibular system (t-test, P < 0.05). As a result of the present study, for patients with internal derangement of the TMJ an additional examination of the craniocervical system should be recommended.

[Styloid process: radiograph and craniomandibular dysfunction (CMD)]. / Processus styloideus: Röntgenbild und cranio-mandibuläre Dysfunktion (CMD).

The aim of the study was to investigate the suitability of orthopantomograms for measuring the length of the styloid process (SP), and to determine the frequency of elongated SP in patients with craniomandibular dysfunction (CMD). For 350 patients, two ortho-pantomograms were available, produced by a SIEMENS Orthophos 5 using programs P1 and P6, respectively, plus a craniomandibular function index. The SP length measurements from the orthopantomograms and the palpation findings were correlated. In 34,7% of the 700 orthopantomograms the SP was measurable. The mean length was determined to be 29.1 mm in OPT1 films on both sides. In the OPT6 films the length values were 30.1 mm on the right, and 30.4 mm on the left side. In CMD patients there was no evidence of the SP causing the complaints. Two conclusions can be made: For epidemiologic studies on the length of the styloid process, the orthopantomogram is of limited use. In CMD patients the elongated styloid process is of negligible importance as a cause of complaints.

Long-term results of telescopic crown retained dentures--a retrospective study.

The clinical data for 250 telescopic crown retained dentures involving 617 abutment teeth preparations were collected and analysed in a retrospective study to ascertain the survival rate of the dentures and their abutment teeth. During the study period 10.6% of the abutment teeth had to be extracted. An increased number of telescopic crowns significantly improved the longevity of the prostheses and their associated abutment teeth in most denture designs, but this was not found to be the case with bilateral free-end saddle designs without an anterior bounded saddle. The use of more than four abutment teeth did not result in a higher survival rate.

Placement of the preparation line and periodontal health--a prospective 2-year clinical study.

The aim of this prospective clinical 2-year study was to determine whether the placement of the proximal margins of crowns within the zone of the biologic width results in periodontal alterations. In 41 patients, 116 prepared teeth as well as 82 unrestored, healthy contralateral teeth were examined. The following indices were determined before as well as 3, 6, 12, and 24 months after preparation: hygiene index, papillary bleeding index (PBI), and probing depth. After preparation, the distance between the restoration margins and the alveolar crest was measured with a modified periodontal probe on both proximal aspects of each tooth. These values were classified into 3 groups: I = < or = 1 mm between crown margin and alveolar crest, II = 1 to 2 mm, and III = > 2 mm. In addition, radiographs were taken directly after cementation of each restoration and after 12 and 24 months. The hygiene index did not significantly vary during the investigation, but PBI increased in all groups. The highest PBI increase was found in group I; in this group, the most significant increase was found between 3 and 6 months after preparation. The mean probing depth only increased in group I during the first 3 months after preparation on the mesial aspects. Only minor changes were found on the distal aspects of the teeth in group I and on all aspects in groups II and III. No alterations of the bone levels were diagnosed on the radiographs. These results indicate that the location of the restoration margins within the zone of the biologic width may impair the periodontal health of restored teeth.

The human mandibular intercondylar angle measured by computed tomography.

In axial computed tomography it is possible to measure the intercondylar angle at the intersection of the longitudinal axes of the condyles. Published values range from 131 to 165 degrees. This angle was determined here in two groups of patients with (n = 22) and without (n = 12) temporomandibular joint dysfunction. A third group of children (n = 12) aged 4-9 years was included to investigate any age-related change in the angle. In the group of healthy individuals, a range of 105 to 165 degrees was found, with a mean intercondylar angle of 139 degrees. In the group with temporomandibular joint dysfunction the mean angle was 143 degrees with a range from 85 to 170 degrees. No statistically significant relation could be shown between intercondylar angle and joint dysfunction. In the group of children the mean angle was 138 degrees with values ranging from 90 to 180 degrees. No significant differences could be demonstrated among the groups. The absolute value of the intercondylar angle seems to be independent of factors such as sex, age and functional disorders of the joint.

Surface quality achieved by polishing and by varnishing of temporary crown and fixed partial denture resins.

STATEMENT OF PROBLEM: Studies have suggested that coating a temporary restoration with varnish material could replace time-consuming polishing procedures needed for achieving an optimally smooth surface. PURPOSE: This study examined the surface roughness of acrylic resins after having been polished or coated with different varnish materials. MATERIAL AND METHODS: A total of 360 cylindrical specimens were fabricated from 9 brands of resin. One surface on each specimen was machined flat and subsequently either polished with rubber polishers or coated with 1 of 9 varnishes. Selected specimens were subjected to thermal cycling (5 degrees C to 55 degrees C, 2000 cycles). Surface quality was assessed by means of a profilometer and by SEM examination. RESULTS: Polished specimens had average surface roughness values (Ra) of 0.8 microm; differences in roughness between materials were small, but statistically significant. Type of coating had a significant influence on surface quality. Depending on the combination of materials used, the coating produced both smoother and rougher surfaces than polishing (0.4 microm < Ra < 4.6 microm). Five coatings were deemed not to be clinically applicable because of poor wetting properties. Thermal cycling did not significantly influence surface quality, but caused minute cracks in the cyanoacrylate coating. CONCLUSION: In regard to surface quality and applicability, the use of varnishes on temporary restorations is not advisable.

Effects of the amplitude threshold on the separability of neuropathic and myopathic from normal EMG using parameters of the turns/amplitude analysis.

OBJECTIVE: In this study, the relationship between the amplitude threshold used for the determination of the turns of the electromyographic (EMG) interference pattern and the parameters of the turns/amplitude analysis was examined. It was investigated whether the discrimination of myopathic and neuropathic from normal muscles could be optimized by an appropriate amplitude threshold. METHODS: The interference patterns of the tibialis anterior muscle of 15 patients with myopathies, 30 patients with neuropathies and 56 controls were recorded, using concentric needle electrodes. A computer program performed the Willison analysis, systematically varying the amplitude threshold between 10 microV and 200 microV. RESULTS: Amplitudes as well as the number of turns per second were non-linearly related to the amplitude threshold. The reduction of the amplitude threshold to 30 microV resulted in a clearly better separation of the distributions of the number of turns of neuropathic, myopathic and normal EMG, compared to the traditional threshold value of 100 microV. The distributions of amplitude values, however, were not affected. The distance between the turns parameter distributions of neuropathic patients and controls and between the distributions of myopathic patients and controls, expressed by the Kolmogoroff-Smirnov distance, had a maximum at 30 microV. CONCLUSIONS: For the turns/amplitude analysis of the tibialis anterior muscle an amplitude threshold of 30 microV should be selected.

Radiographic inspection of dental castings.

Underdimensioning may adversely affect the clinical use of a crown or bridge. Insufficient dimensions may be due to inadequate modelling or deficiencies caused by the casting process. The dimensions of cast objects are measured mechanically using a calliper. This method has often proved to be insufficient in detecting areas of too small dimensions. This paper presents a non-destructive method of inspecting dental castings using radiography. The occlusal thickness of a random sample of 150 crowns made during regular clinical treatment in our department was inspected mechanically and radiographically. We found that 19% of the crowns were only 0.1 mm thick or less at the thinnest spot, 18% were between 0.1 and 0.2 mm and 9% were between 0.2 and 0.3 mm. In comparison to mechanical examination, radiographic inspection usually showed smaller values.

[Studies on the effects of abutment position on the prognosis of endosseous implants]. / Untersuchungen zur Bedeutung der Pfeilergeometrie für die Prognose enossaler Implantate.

Although the use of osseointegrated Brånemark implants is associated with a high success rate, late losses of primarily osseointegrated implants have been observed again and again. In this study 50 patients were evaluated to clarify the effects of abutment position on late losses. The results have shown that implant position is less important for the loss of implants than other parameters such as healing disorders or poor oral hygiene.

[Examination of coordination of masseter muscle activity]. / Untersuchungen zur Koordination der Masseteraktivität.

The coordination of masseter muscle contraction is inseparably wrapped up in the occlusal elements. This study measured bilaterally the masseter muscle activity of 22 subjects without temporomandibular joint disease. The EMG recordings of the left and the right masseter muscles were repeated 20 times to test symmetry, reproducibility and appearance of silent periods. In 6 subjects the beginning of the muscle contraction showed laterality characteristics depending on handedness. The complex processes of recorded mandibular movements showed more biological variations than the recording patterns of occlusal indicator foils may disclose. That indicates the possibility of pseudocontact markings. The occluding surfaces therefore should allow free mandibular movements.

[Studies on the cybernetic aspects of occlusal splint therapy]. / Untersuchungen zu kybernetischen Aspekten der Schienentherapie.

This study was focussed on the effects of changes in interocclusal clearance on the activity of oral muscles. Two types of occlusal splints were incorporated in 20 subjects without TMJ-syndrome. Their muscle reactions were recorded electromyographically in the masseter muscle. The results show 5 groups of muscle reaction correlated with the mean postural face height. The changed height of the postural position has a significant influence on the control pattern of the masticatory system.

[Conservative treatment of perforated disks]. / Zur konservativen Therapie bei der Diskusperforation.

Stereognathographic recordings were taken of the mandibular movements of 11 patients who had undergone conservative treatment for unilateral disk perforation. The results showed a significant decrease in the condylar inclination angle of the affected joints. Based on these values the condylar inclinations were increased in a condyle positioning simulator (CPS). This allowed production of individually correct occlusal splints. In all cases studied this splinting therapy eliminated pain and crepitus.