Root surface debridement and endotoxin removal.

OBJECTIVE: This study assessed associations between the number of standardized scaling strokes and the reduction of endotoxin on the root surface. BACKGROUND: Therapy of periodontally involved teeth attempts removal of accretions by scaling and root planing. The amount of mechanical therapy required to free the root surface from etiologic factors remains unknown. METHODS: Twenty-four extracted human caries-free single rooted teeth with at least 5 mm attachment loss were used. A region of interest (ROI) which contained subgingival calculus was defined on the root surface of each tooth. Standardized force instrumentation was applied using a force-measuring curet. Fifty working strokes were applied to every ROI. Forces applied were recorded. The force recordings were converted from Millivolts into Newtons (N). After every unit of 5 strokes, presence of calculus was evaluated and scaling debris was collected. Endotoxin concentration was determined in the debris samples. RESULTS: The endotoxin values for strokes 1-5 were statistically significantly greater than the values from all other stroke intervals. Complete calculus removal occurred after a mean of 9.3 strokes. The endotoxin concentration reached a minimal level with concentrations of 0.03-0.306 EU/ml after calculus removal was complete. CONCLUSION: These findings suggest that completion of calculus removal coincides with endotoxin levels associated with clinically healthy teeth.

Accuracy of implant treatment planning utilizing template-guided reformatted computed tomography.

OBJECTIVES: To evaluate the magnitude of error in transferring the planned position of implants from reformatted CT scans to a surgical template. METHODS: The deviation between the position of the apex of the proposed implant in paraxial CT reformats and on the corresponding study cast was measured in 77 prospective sites in five maxillas and nine mandibles. RESULTS: The transfer error was 0.6 (s.d. 0.4) mm in the maxilla and 0.3 (s.d. 0.4) mm in the mandible. CONCLUSIONS: The transfer errors detected in this investigation are not clinically relevant. Other factors involved in transferring positional and angular measurements from reformatted CT to the surgical site may result in more significant errors.

Prevention of bacterial leakage into and from prefabricated screw-retained crowns on implants in vitro.

Previous in vitro studies have shown that a mean gap of less than 4 microns between prefabricated crowns and implants of the Ha-Ti implant system is not a barrier to infiltration by Staphylococcus aureus. These studies confirmed earlier in vivo work showing that a multitude of oral microorganisms could colonize and infiltrate these gaps. In the present investigation, 30 Ha-Ti implant-crown assemblies were tested for bacterial leakage after the gaps were sealed with the chlorhexidine-containing varnish Cervitec. S. aureus leakage into the totally submerged test specimens was detected in 1 of 5 samples incubated for 4 weeks, while no leakage was detected in specimens incubated for 3, 5, 6, 7, and 8 weeks. When the sealed test specimens were partially submerged (that is, excluding the screw hole of the crown) and incubated for 3 to 11 weeks, none of the internal surfaces of the 30 test specimens manifested contamination. The clinical relevance of gap sealing in maintaining inflammation-free marginal mucosa and in achieving clinically successful treatment of peri-implantitis has yet to be determined.

Bacterial leakage into and from prefabricated screw-retained implant-borne crowns in vitro.

A mean gap of less than 4 microm following laboratory procedures and continuous loading was demonstrated in prefabricated crowns of the Ha-Ti implant system in earlier studies. The clinical relevance of such high precision in maintaining inflammation free marginal mucosa is yet to be determined. In this present investigation, the complete assembly of Ha-Ti implants including prefabricated screw-retained crowns was tested for bacterial leakage under controlled conditions in vitro. The gaps were shown not to be a barrier for Staphylococcus aureus which were used as test bacteria. Bacterial leakage through these gaps from the environment to the interior of the assembly and vice versa was observed within 24-120 h. The main path of bacterial penetration was possibly found to be through the transversal screw hole and not through the marginal gap of the prefabricated crowns.

[Subgingival plaque due to gingivitis and inactive periodontitis sites in the adult periodontitis patient]. / Subgingivale Plaque aus Gingivitis- und inaktiven Parodontitisstellen beim erwachsenen Parodontitispatienten.

There are several discrepancies with respect to the composition of subgingival plaque in gingivitis and in inactive adult periodontitis (AP). In this study we compared subgingival plaque samples taken from gingivitis sites to those from inactive periodontitis sites of the same patients. Of 44 patients plaque samples from 86 gingivitis sites and 92 periodontitis sites were analysed. Darkfield microscopy showed a higher proportion of spirochetes and mobile rods in the periodontitis sites. Analysis of cultures revealed a higher and statistically significant number of anaerobes in the periodontitis sites (1.7 x 10(7) vs 3 x 10(6), p = 0.006). The following bacterial species were isolated more frequently from periodontitis sites than from gingivitis sites: Actinobacillus actinomycetemcomitans (18% vs 10%), as well as the black-pigmented Prevotella intermedia (68% vs 48%) and Porphyromonas gingivalis (48% vs 28%). On the one hand, these small differences in the bacteriological parameters can be explained by the fact that both gingivitis and periodontitis plaque samples were taken from the same periodontitis patients. An infection of the gingivitis sites from the parodontitis sites within the same patient could not be excluded. On the other hand, the mean probing depth of the gingivitis sites was relatively high, 3.6 mm (measuring point interdental plus pseudo-pocket) which may favor the growth of anaerobic bacteria.