The obstructive sleep apnea syndrome is typically associated with conditions known to increase insulin resistance as hypertension, obesity, and diabetes. We investigated whether obstructive sleep apnea itself is an independent risk factor for increased insulin resistance and whether continuous positive airway pressure (CPAP) treatment improves insulin sensitivity. Forty patients (apnea-hypopnea index > 20) were treated with CPAP. Before, 2 days after, and after 3 months of effective CPAP treatment, hyperinsulinemic euglycemic clamp studies were performed. Insulin sensitivity significantly increased after 2 days (5.75 +/- 4.20 baseline versus 6.79 +/- 4.91 micromol/kg.min; p = 0.003) and remained stable after 3 months of treatment. The improvement in insulin sensitivity after 2 days was much greater in patients with a body mass index less than 30 kg/m2 than in more obese patients. The improved insulin sensitivity after 2 nights of treatment may reflect a decreasing sympathetic activity, indicating that sleep apnea is an independent risk factor for increased insulin resistance. The effect of CPAP on insulin sensitivity is smaller in obese patients than in nonobese patients, suggesting that in obese individuals insulin sensitivity is mainly determined by obesity and, to a smaller extent, by sleep apnea.

In a prospective study, 20 patients who underwent harvesting of chin grafts as outpatients, were followed up for 12 months (3 further patients with incomplete follow-up data were excluded from the study). Preoperatively and 7 days, 1, 3, 6 and 12 months postoperatively, follow-up data were assessed. Evaluation of the superficial sensory function of the inferior alveolar nerve was determined by the Pointed-Blunt Test and the Two-Point-Discrimination Test. Sensory disturbances were objectively assessed by testing thermal sensitivity with the "Pain and Thermal Sensitivity" Test (PATH Test). In addition, evaluation of the pulp sensitivity of teeth 35-45 was carried out by cold vitality testing. One week postoperatively, 8 patients were affected by superficial sensory impairment. 8 nerve territories showed hypoaesthetic reactions and 5 showed hyperaesthetic reactions. After 12 months, two patients still suffered from hypoaesthesia of one side of the chin. There was a statistically significant sensitivity impairment of the chin for all patients comparing the preoperative data of the Two-Point-Discrimination Test (left/right median: 8.17/8.17 mm, interquartile range (IQR) 1.00/2.00 mm) with the first postoperative measurement (left/right median 9.00/8.33 mm, IQR 1.67/2.66 mm). Comparing the latter to the last postoperative measurement there was significant tendency for regeneration of a nerve function (left/right median 8.00/7.84 mm, IQR 0.66/2.00 mm). In the PATH Test all hypoaesthetic areas could be identified by a reduction of thermal sensitivity. After the first postoperative examination 21.6% (n=38/176) of the examined teeth had lost their pulp sensitivity. After 12 postoperative months 11.4% (n=20/176) still did not react sensitively. Many of these were canines (n=8/20). Comparing the preoperative to the first postoperative examination, there was a significant reduction of pulp sensitivity. However, statistically significant recovery until the last postoperative follow-up could not be detected. The assessed data show that patients have to be informed extensively about disturbances of the inferior alveolar nerve function lasting longer than 12 months. Moreover, the loss of pulp sensitivity is a very frequent event which has always to be taken into account. Considering the high rate of complications with harvesting of chin grafts, more prospective trials should be done to find out whether there are other donor sites for autogenous bone which put less strain on patients.

The aim of the present study was to determine the correlation between the primary stability of dental implants placed in edentulous maxillae and mandibles, the bone mineral density and different histomorphometric parameters. After assessing the bone mineral density of the implant sites by computed tomography, 48 stepped cylinder screw implants were installed in four unfixed human maxillae and mandibles of recently deceased people who had bequeathed their bodies to the Anatomic Institute I of the University of Erlangen-Nuremberg for medical-scientific research. Peak insertion torque, Periotest values and resonance frequency analysis were assessed. Subsequently, histologic specimens were prepared, and bone-to-implant contact, the trabecular bone pattern factor (TBPf), the density of trabecular bone (BV/TV) and the height of the cortical passage of the implants were determined. The correlation between the different parameters was calculated statistically. The mean resonance frequency analysis values (maxilla 6130.4+/-363.2 Hz, mandible 6424.5+/-236.2 Hz) did not correlate with the Periotest measurements (maxilla 13.1+/-7.2, mandible -7.9+/-2.1) and peak insertion torque values (maxilla 23.8+/-2.2 N cm, mandible 45.0+/-7.9 N cm) (P=0.280 and 0.193, respectively). Again, no correlations could be found between the resonance frequency analysis, the bone mineral density (maxilla 259.2+/-124.8 mg/cm(3), mandible 349.8+/-113.3 mg/cm3), BV/TV (maxilla 19.7+/-8.8%, mandible 34.3+/-6.0%) and the TBPf (maxilla 2.39+/-1.46 mm-1, mandible -0.84+/-3.27 mm-1) (P=0.140 and 0.602, respectively). However, the resonance frequency analysis values did correlate with bone-to-implant contact of the oral aspect of the specimens (maxilla 12.6+/-6.0%, mandible 35.1+/-5.1%) and with the height of the crestal cortical bone penetrated by the implants in the oral aspect of the implant sites (maxilla 2.1+/-0.7 mm, mandible 5.1+/-3.7 mm) (P=0.024 and 0.002, respectively). The Periotest values showed a correlation with the height of the crestal cortical bone penetrated by the implants in the buccal aspect of the implant sites (maxilla 2.5+/-1.2 mm, mandible 5.4+/-1.2 mm) (P=0.015). The resonance frequency analysis revealed more correlations to the histomorphometric parameters than the Periotest measurements. However, it seems that the noninvasive determination of implant stability has to be improved in order to give a more comprehensive prediction of the bone characteristics of the implant site.

20 retromolar bone grafts were harvested in outpatients for augmentation of the implant site from January to June 2000 (10 female, 10 male, 40.9 +/- 12.8 years, minimum 17 years, maximum 66 years). The aim of the study was to assess typical complications of this procedure in a prospective manner. For the determination of the superficial sensory function of the inferior alveolar and the lingual nerve, an objective method was used. The bone grafts were harvested for single tooth reconstruction. In 14 cases a ridge augmentation and in 6 cases an endoscopically controlled crestal sinus floor elevation was performed. Preoperatively, the height of bone above the cranial aspect of the inferior alveolar nerve in the retromolar region was assessed radiologically with known markers. The maximum mouth opening was determined. The superficial sensory function of the inferior alveolar and the lingual nerve was assessed with the Pointed-Blunt Test, the Two-Point-Discrimination Test and the objective method of the 'Pain and Thermal Sensitivity' Test (PATH Test). Moreover, the pulp sensitivity of the teeth of the donor site was determined by cold vitality testing. All tests were repeated 1 week postoperatively. Intraoperatively, the width of the retromolar region was measured with a caliper. The patients rated the operative strain on a visual analogue scale. The height of bone above the inferior alveolar nerve in the retromolar region was 11.0 +/- 2.2 mm. The width of the retromolar area was 14.2 +/- 1.9 mm. Postoperatively, the maximal mouth opening changed significantly (40.8 +/- 3.5 mm preoperatively, 38.9 +/- 3.7 mm postoperatively, P = 0.006). However, the reduction was not relevant clinically. A direct injury of the inferior alveolar or lingual nerve did not occur. A sensitivity impairment could not be detected for either of the nerves by the different test methods 1 week postoperatively. The operative strain related to the donor site was significantly less than the strain generated by the implant placement (rating on a visual analogue scale 2.8 +/- 1.0 and 4.1 +/- 2.0, respectively, P = 0.027). Retromolar bone grafts are a viable method for augmentation of the implant site in conjunction with single tooth reconstruction with low strain on the patient and minimal risk of complications.

Background: The obstructive sleep apnoea syndrome (OSA) is a frequent condition, as well as type 2 diabetes mellitus. Both diseases are characterized by insulin resistance. Objectives: The aim of this study was to establish whether OSA is an independent risk factor for increased insulin resistance in diabetics. For this purpose, we tested the hypothesis that the insulin sensitivity in patients with type 2 diabetes and OSA can be improved by 2 days or 3 months of continuous positive airway pressure (CPAP) treatment. Methods: In 9 obese patients with type 2 diabetes and OSA [apnoea/hypopnoea index 43.1 ± 21.3; body mass index (BMI) 37.3 ± 5.6 kg/m²] and good glycaemic control on oral antidiabetics or on diet alone (HbA1c 6.4 ± 0.7%), the insulin sensitivity index (ISI) was established by euglycaemic hyperinsulinaemic clamp tests at baseline, after 2 days and after 3 months of effective CPAP treatment. Results: ISI was unchanged after 2 days of CPAP treatment, but was significantly improved after 3 months (4.38 ± 2.94 vs. 2.74 ± 2.25 at baseline; p = 0.021), without any significant changes in BMI. Glycaemic control was unaffected after 3 months (HbA1c 6.3 ± 0.6%; not significant). Fasting leptin levels showed no significant changes. Conclusions: These results indicate that OSA itself is an independent risk factor for insulin resistance. This effect may be explained by the elevated sympathetic activity in OSA.