Analysis of supra- and subgingival long-term biofilm formation on orthodontic bands.

Insertion of fixed orthodontic appliances induces increased biofilm formation caused by a higher number of plaque-retentive sites. The purpose of the study was to perform a quantitative analysis of supra- and subgingival long-term biofilm formation on orthodontic bands. Ten patients (five females and five males, aged 18.3+/-5.4 years) who had received therapy with fixed orthodontic appliances for 24+/-9 months were enrolled in the study. Biofilm formation on 28 orthodontic bands was analyzed quantitatively with the Rutherford backscattering detection method, a scanning electron microscopy technique. The biofilm formation for the supra- and subgingival surfaces was calculated from the grey values. Statistical analysis was performed with a mixed model with the patient as the random factor. A P-value <0.05 was considered significant. A biofilm was found on 16.1+/-9.2 per cent of supragingival surfaces and on 3.6+/-4.4 per cent of subgingival surfaces. Differences in biofilm formation in supra- and subgingival surfaces were statistically significant (P<0.05) and formed a distinct demarcation line. Despite the presence of supragingival biofilm, no mature subgingival biofilm was found on the tested orthodontic bands.

Load-bearing capacity of direct four unit provisional composite bridges with fibre reinforcement.

The aim of the current in vitro study was to evaluate the load-bearing capacity of provisional four-unit bridges with and without two different types of glass-fibre reinforcement produced in a direct technique with a silicon template from the composite materials Protemp, Luxatemp and CronMix. From each composite material, 30 bridges were manufactured, 10 without fibre reinforcement, 10 with Stick/StickNet and 10 with everStick/everStickNet reinforcement. After artificial aging by thermocycling samples were cemented onto a master model and subjected to load testing in a universal testing machine. Mean force at fracture for the groups without fibre reinforcement varied from 486 to 612 N. Depending on the material combination, fibre reinforcement resulted in a slightly increased or a reduced mean load-bearing capacity, varying from 674 N for the combination of Protemp and Stick to 262 N for CronMix and everStick. Position of fibres within the resin pontic was found to have an important influence on load-bearing capacity of reinforced bridges. Scanning electron microscopic investigation showed good adhesion of everStick fibres to the pre-impregnation resin whereas bonding of Stick fibres to the embedding polymer was incomplete. In conclusion, fibre reinforcement with Stick or everStick did not improve the load-bearing capacity of direct provisional bridges made from Protemp, Luxatemp, or CronMix as the position of fibres could not be controlled during the direct manufacturing process. To increase the load-bearing capacity of the provisional bridges, an exact positioning of fibres at the tension side in the dental laboratory is necessary.

Short-term efficacy of physical therapy compared to splint therapy in treatment of arthrogenous TMD.

A prospective randomized study was carried out to evaluate the efficacy of physical therapy in addition to splint therapy on treatment outcome in patients with temporomandibular disorders (TMD) with respect to objective and subjective parameters. Twenty-six patients suffering from an arthrogenic TMD and exhibiting a painfully restricted jaw opening were randomized in two groups. Thirteen patients were treated solely with Michigan splint (group I), 13 patients received supplementary physical therapy (group II). Before treatment a clinical examination and electronic recording of jaw movements were performed and subjective pain level was evaluated by visual analogue scales. After 3 months of therapy maintenance of improvement was evaluated. Within treatment groups comparison of data before and after treatment was analysed using Wilcoxon test. Groups were compared by Mann-Withney-U test. A P-value < 0.05 was considered significant. Compared with the baseline, in both groups mandibular movement capacity increased significantly after treatment, whereas subjective pain decreased significantly (P < 0.05). Active jaw opening increased from 28.6 +/- 5.8 to 35.9 +/- 4.8 mm in group I and from 30.1 +/- 5.4 to 40.8 +/- 4.1 mm in group II. After therapy the difference of active jaw opening between groups was significant (P < 0.05). Physical therapy also gave a supplementary improvement of protrusive mandibular movement capacity during electronic registration and subjective pain level. For none of these parameters this difference between groups was significant. Physical therapy seems to have a positive effect on treatment outcome of patients with TMD.

Analysis of early biofilm formation on oral implants in man.

Biofilm formation on oral implants can cause inflammation of peri-implant tissues, which endangers the long-term success of osseointegrated implants. It has been reported previously that implants revealing signs of peri-implantitis contain subgingival microbiota similar to those of natural teeth with periodontitis. The purpose of the first part of this study was an atraumatic, quantitative investigation of biofilm formation on oral implant abutments; the objective of the second part was to investigate whether Haemophilus actinomycetemcomitans and Porphyromonas gingivalis were present in the crevicular fluid around oral implants. Biofilm formation on 14 healing abutments, inserted for 14 days in 10 patients, was analysed quantitatively by use of secondary-electron and Rutherford-backscattering-detection methods. A 16S rRNA-based polymerase chain reaction detection method was used to detect the presence of H. actinomycetemcomitans and P. gingivalis in the crevicular fluid. For this investigation, samples of sulcus fluid were collected with sterile paper points at four measurement points per abutment. The difference between biofilm coverage of supragingival surfaces (17.5 +/- 18.3%) and subgingival surfaces (0.8 +/- 1.0%) was statistically significant (P < 0.05). By use of universal primers, bacteria were found in all the samples taken, although the two periodontal pathogens were not found in any of the samples. The absence of periodontal pathogens from the sulcus fluid during initial bacterial colonization, despite massive supragingival biofilm formation, substantiates the assumption that cellular adherence of peri-implant tissue by means of hemidesmosoma, actin filaments and microvilli reduces the risk of formation of anaerobic subgingival pockets.

Reproducibility of jaw movements in patients with craniomandibular disorders.

It has never been investigated, if mandibular movements of patients with craniomandibular disorders (CMD) result in a lower reproducibility of dynamic functional parameters which are used for the individual articulator setting. The aim of the present study was to compare the reproducibility of electronically registered functional parameters in patients with CMD and in a control group. Dynamic functional parameters were recorded in 30 patients and 30 volunteers with a computerized ultrasound system (ARCUSdigma). The whole registration was performed three times during one session and three times at a second session 1 week later. The horizontal condylar inclination in the patient group gave a standard deviation of 2.17 degrees +/- 0.95 degrees , indicating poorer reproducibility than in the volunteer group, for which the standard deviation was 1.37 degrees +/- 0.42 degrees . The reproducibility of measurements of the Bennett angle was also poorer in the patient group than in the volunteer group, with standard deviations of 1.70 degrees +/- 0.62 degrees and 1.22 degrees +/- 0.40 degrees , respectively. The standard deviations calculated for determination of incisal inclination during laterotrusion was 3.02 degrees +/- 1.49 degrees for patients and 2.30 degrees +/- 1.17 degrees for volunteers. The standard deviations for incisal inclination during protrusion was 2.02 degrees +/- 0.95 degrees for patients and 2.06 degrees +/- 1.82 degrees for volunteers. The reproducibility of measurement of horizontal condylar inclination, Bennett angle and incisal inclination during laterotrusion therefore showed significantly lower reproducibility in the patient group than in the volunteer group (P < 0.05). The overall reproducibility of the measurements was nevertheless good in both groups, with standard deviations under 3.1 degrees , so that an individual setting of an articulator seems useful even in patients with CMD.

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.

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.

In vitro study of enamel and dentin marginal integrity of composite and compomer restorations placed in primary teeth after diamond or Er:YAG laser cavity preparation.

PURPOSE: The aim of this in vitro study was to evaluate the effect of laser vs diamond instruments on Class II and Class V cavity margins in primary teeth with SEM after restoration with composite and compomer materials and subsequent thermocycling. MATERIALS AND METHODS: Class V cavities with margins completely located in enamel were prepared in 36 extracted primary teeth to examine the restoration-enamel interface. Eighteen cavities were prepared with an Er:YAG laser operated at 3 Hz, 300 mJ/pulse, and 18 with a spherical fine diamond bur. In 24 primary teeth, Class II cavities with cervical proximal margins located in dentin were prepared for examination of the restoration-dentin interface. All Class II cavities were prepared with a conventional cylindrical diamond bur. In 12 cavities, the margins located in dentin were conditioned with an Er:YAG laser (1 Hz, 100 mJ/pulse). All cavities were restored with a fine hybrid composite resin or a compomer material. RESULTS: SEM examination of Class V cavities after thermocycling (between 5 degrees C and 55 degrees C, 2500 cycles) revealed over 90% "perfect" margins in all composite fillings and in those compomer restorations applied after conventional preparation and acid etching. Compomer restorations placed without acid etching revealed a significantly superior marginal integrity in laser-prepared cavities (81% perfect margins) vs conventionally prepared cavities (60% perfect margins). SEM analysis of the dentinal margins of both compomer and composite restorations in Class II cavities showed mean percentages of perfect marginal adaptation ranging from only 13% to 66%. CONCLUSION: Er:YAG laser treatment can be recommended for composite restorations in Class V cavities in primary teeth. Compomer restorations can be placed after conventional preparation of Class V cavities and acid etching or after laser preparation. Dentin bonding in Class II cavities in primary teeth is not sufficient and cannot be improved with Er:YAG laser pretreatment.