Evaluation of new injection and cavity preparation model in local anesthesia teaching.

The aim of this study was to evaluate a recently developed preclinical injection and cavity preparation model in local anesthesia. Thirty-three dental students administered an inferior alveolar nerve block injection in the model, followed by preparation on a tooth. The injection was evaluated by three observers, and the feedback from the model was registered. After completion of the practical session, the opinion of the dental students was explored with a ten-item questionnaire. Thirty dental students (91 percent) performed the injection correctly according to the feedback of the model, and twenty-eight students (85 percent) did so according to the expert opinion. The agreement between feedback from the training model and the expert opinion was high. The students were very satisfied with the opportunity to practice with the training model, as indicated by the high scores on each item of the questionnaire. These results suggest that use of this preclinical training model in anesthesia teaching may have beneficial effects on the administration of local anesthetics by dental students.

Failure to detect an association between aggressive periodontitis and the prevalence of herpesviruses.

BACKGROUND: Herpes simplex virus type 1 (HSV-1), human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) have been suspected to play a causal role in periodontitis pathogenesis. The aim of this study was to determine the prevalence of these viruses in subgingival plaque samples of Caucasian patients with generalized aggressive periodontitis compared to periodontally healthy controls. METHODS: A total of 65 patients with aggressive periodontitis and 65 unmatched controls from Germany were investigated in the study. Subgingival plaque samples were analysed for the presence of HSV-1, EBV and HCMV by quantitative real-time polymerase chain reaction assays. Viral antibody titres were determined quantitatively by immunosorbent assays. RESULTS: DNA of HSV-1 and HCMV were detected in 1.5% of the patients and controls, whereas EBV DNA was present in 10.8% and 13.9% respectively. Detection rates of serum IgG against HSV-1 (76.1% versus 73.9%), EBV (98.5% versus 96.9%), HCMV (47.7% versus 46.2%) and IgM levels against HSV-1 (6.2% versus 1.5%), EBV (0% versus 0%), HCMV (0% versus 1.5%) did not significantly differ between patients and controls. CONCLUSION: The data of our study do not suggest any contribution of HSV-1, EBV or HCMV to aggressive periodontitis in a German population. Ethnic and methodological aspects might have caused conflicting results of previous studies.

Verification of nerve integrity after surgical intervention using quantitative sensory testing.

PURPOSE: The aim of this study was to apply a standardized Quantitative Sensory Testing (QST) approach in patients to investigate whether oral surgery can lead to sensory changes, even if the patients do not report any sensory disturbances. Furthermore, this study determines the degree and duration of possible neuronal hyperexcitability due to local inflammatory trauma after oral surgery. PATIENTS AND METHODS: Orofacial sensory functions were investigated by psychophysical means in 60 patients (30 male, 30 female) in innervation areas of infraorbital nerves, mental nerves and lingual nerves after different interventions in oral surgery. The patients were tested 1 week, 4 weeks, 7 weeks, and 10 weeks postoperatively. As controls for bilateral sensory changes after unilateral surgery, tests were additionally performed in 20 volunteers who did not have any dental restorations. RESULTS: No differences were found between the control group and the control side of the patients. Although not 1 of the patients reported paresthesia or other sensory changes postoperatively, QST detected significant differences between the control and the test side in the mental and lingual regions. Test sides were significantly less sensitive for thermal parameters (cold, warm, and heat). No differences were found in the infraorbital region. Patients showed significantly decreased pain pressure thresholds on the operated side. QST monitored recovery over time in all patients. CONCLUSIONS: The results show that oral surgery can lead to sensory deficits in the mental and lingual region, even if the patients do not notice any sensory disturbances. The applied QST battery is a useful tool to investigate trigeminal nerve function in the early postoperative period. In light of the increasing forensic implication, this tool can serve to objectify clinical findings.

In vitro study of adhesive polymethylmethacrylate bone cement bonding to cortical bone in maxillofacial surgery.

PURPOSE: In the treatment of midface fractures, the fragments are immobilized using screws and plates for osteosynthesis until reunion has occurred. This method involves drilling holes for the insertion of the screws, which can be associated with additional fracturing of the corresponding bone owing to the complex architecture and thin layers of facial bone. To alleviate this problem, new adhesive techniques for fixing the plates for osteosynthesis have been investigated, mitigating the detrimental effects of screw hole drilling. In the present experimental study, the strength of this adhesive bond and its resistance to hydrolysis were investigated. MATERIALS AND METHODS: To determine the adhesive bonding strength, a tension test was implemented. Osteosynthesis plates with screw holes 1.3 mm in diameter were fixed to cortical bone samples of bovine femur using ultraviolet (UV) light-curing polymethylmethacrylate bone cement. To facilitate bonding, the surface of the bone was conditioned with an amphiphilic bonding agent before cementing. UV light curing was implemented using either a conventional UV unit, such as is used in dentistry, or with a specialized UV unit with a limited emission spectrum but high luminosity. Reference control samples were prepared without application of the bone bonding agent. After this procedure, the samples were stored for 1 to 7 days at 37°C submerged in 0.9% saline solution before being subjected to the tension test. RESULTS: Without the bone bonding agent, the bonding strength was 0.2 MPa. The primary average bonding strength at day 0 was 8.5 MPa when cured with the conventional UV unit and 14 MPa for the samples cured with the specialized UV unit. An almost constant average bond strength of 8 and 16 MPa was noted for all samples stored up to 7 days after curing with the conventional and specialized UV unit, respectively. CONCLUSION: With the development of a new bone bonding agent, a method is now available to promote the bonding between the hydrophilic bone surface and the hydrophobic polymethylmethacrylate bone cement by creating an interlayer that is beneficial for adhesion. In the present in vitro study, the strength of this bond and its resistance to hydrolysis were investigated. This new method could have clinical bearing in cases in which conventional fixation with screws and plates is limited, such as can occur in comminuted fractures. The observed average bonding strengths of 8 to 16 MPa support the implementation of this technique in nonload-bearing regions such as the midface, facilitating immobilization until the bone reunion is complete.

Cerebral activations resulting from virtual dental treatment.

Pain, and anxiety of pain, for some people are serious problems in dental treatment. It is a common practical experience that even entering a dental surgery office, or the sound of a dental drill, may evoke vegetative correlates of toothache without any underlying disease. This everyday phenomenon suggests the hypothesis of a corresponding activation of pain-related brain areas by virtual dental treatment. Twenty healthy subjects viewed two different video clips presenting a dental treatment from the first-person perspective (simulation movie) and a moving hand holding an electrical toothbrush (control movie). Using functional magnetic resonance imaging, the cerebral hemodynamic responses that occurred during simulation and control movies were compared. Virtual dental treatment was associated with increased activity in pain-related brain areas such as the cingulate cortex, the insula, and primary and secondary somatosensory cortexes (SI, SII). The brain activation pattern indicates not only affective-motivational but also sensory-discriminative pain components during virtual dental treatment in all volunteers. Volunteers with a higher level of dental anxiety showed stronger activation of SI and SII. This may be a result of their higher anticipation of pain.