Jan Willem Verhoeven

The combined use of endosteal implants and iliac crest onlay grafts in the severely atrophic mandible: a longitudinal study

Thirteen patients, who received an onlay bone graft augmentation to their severely atrophic mandible in combination with a simultaneous implant insertion, were studied prospectively. A reproducible method that allowed for accurate assessment of graft resorption, consisting of lateral and oblique-lateral cephalometric radiographs in combination with an image analysis system, was used to assess the resorption rate in all patients and between subgroups of patients, according to selected patient and treatment characteristics. Thirty implants were placed, none of which were lost, and all patients expressed satisfaction after a mean observation period of 877 days. A mean resorption rate of 36% of the grafted bone height occurred, mainly during the first year and with some degree of individual variance. After three years the resorption had virtually stopped. No statistically significant differences between any of the subgroups of patients could be distinguished. Peri-implantitis was found around eight implants in seven patients. It is concluded that the described surgical technique should be used only if there are stringent indications.

Early bacterial colonization and soft tissue health around zirconia and titanium abutments: an in vivo study in man

AIM To compare the early bacterial colonization and soft tissue health of mucosa adjacent to zirconia (ZrO(2)) and titanium (Ti) abutment surfaces in vivo. MATERIALS AND METHODS Twenty edentulous subjects received two endosseous mandibular implants. The implants were fitted with either a ZrO(2) or a Ti abutment (non-submerged implant placement, within-subject comparison, left-right randomization). Sulcular bacterial sampling and the assessment of probing pocket depth, recession and bleeding on probing were performed at 2 weeks and 3 months post-surgery. Wilcoxon matched-pairs, sign-rank tests were applied to test differences in the counts of seven marker bacteria and the clinical parameters that were associated with the ZrO(2) and Ti abutments, at the two observation time points. RESULTS ZrO(2) and Ti abutments harboured similar counts of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Peptostreptococcus micros, Fusobacterium nucleatum and Treponema denticola at 2 weeks and 3 months. Healthy clinical conditions were seen around both ZrO(2) and Ti abutments at all times, without significant differences in most clinical parameters of peri-implant soft tissue health. Mean probing depths around Ti abutments were slightly deeper than around ZrO(2) abutments after 3 months (2.2 SD 0.8 mm vs. 1.7 SD 0.7 mm, P=0.03). CONCLUSIONS No difference in health of the soft tissues adjacent to ZrO(2) and Ti abutment surfaces or in early bacterial colonization could be demonstrated, although somewhat shallower probing depths were observed around ZrO(2) abutments after 3 month.

Radiographic Features of Mandibular Trabecular Bone Structure in Hypodontia

PURPOSE Radiographic parameters of mandibular trabecular bone structure between 67 subjects having hypodontia and those without were studied on digital panoramic radiographs. MATERIALS AND METHODS Three regions of interest (ROI) were defined: the ascending ramus, apical of the mandibular molar and mesial of the first mandibular molar. The effects of the presence of hypodontia and the ROI on the mandibular trabecular bone structure were tested for statistical significance by means of multivariate analysis. RESULTS Radiographic parameters of trabecular bone architecture were found to differ between various regions of the mandible (p = 0.000), but not between the group of hypodontia subjects and their controls (p = 0.23). There was no interaction effect between the ROIs and the two groups (p = 0.79). For people having hypodontia, some directional parameters of trabecular bone have a reverse correlation with the number of missing teeth. The fractal dimension and the number and perimeter of white segments in the binarized image correlate positively with the number of congenitally missing teeth. CONCLUSIONS A limited number of parameters of radiographic mandibular trabecular bone structure correlate with the number of missing teeth. However, a markable difference in radiographic parameters of mandibular trabecular bone structure between hypodontia and non-hypodontia subjects could not be demonstrated.

The association of clinical and microbiologic parameters with histologic observations in relatively healthy peri-implant conditions- a preliminary short-term in vivo study

PURPOSE To determine whether clinical findings-bleeding on probing, pocket depth, recession, and bacterial sampling-correlate with histologic outcomes in relatively healthy peri-implant soft tissues in people. MATERIALS AND METHODS In this cross-sectional study, a convenience sample of 20 edentulous subjects received two endosseous mandibular implants each. The abutments were either zirconia (ZrO₂) or titanium (Ti) (nonsubmerged implant placement, within-subject comparison, leftright randomization). Sulcular bacterial sampling and assessment of probing pocket depth, recession, and bleeding on probing were performed 3 months postsurgery. Mucosal biopsy specimens were obtained, and the blood vessel density and a score on an inflammation grading scale were determined. RESULTS Simple linear and linear regression models revealed that the clinical or microbiologic parameters were not associated with either of the histologic parameters. The soft tissues impressed as healthy, regardless of the abutment material. CONCLUSIONS The peri-implant mucosa around ZrO₂and Ti abutments was considered healthy in most situations when examined histologically after 3 months but showed variation in clinical and microbiologic parameters.

Early bacterial colonization and soft tissue health around zirconia and titanium abutments: an in vivo study in man: Bacterial colonization and soft tissue health around zirconia and titanium

AIM To compare the early bacterial colonization and soft tissue health of mucosa adjacent to zirconia (ZrO(2)) and titanium (Ti) abutment surfaces in vivo. MATERIALS AND METHODS Twenty edentulous subjects received two endosseous mandibular implants. The implants were fitted with either a ZrO(2) or a Ti abutment (non-submerged implant placement, within-subject comparison, left-right randomization). Sulcular bacterial sampling and the assessment of probing pocket depth, recession and bleeding on probing were performed at 2 weeks and 3 months post-surgery. Wilcoxon matched-pairs, sign-rank tests were applied to test differences in the counts of seven marker bacteria and the clinical parameters that were associated with the ZrO(2) and Ti abutments, at the two observation time points. RESULTS ZrO(2) and Ti abutments harboured similar counts of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Peptostreptococcus micros, Fusobacterium nucleatum and Treponema denticola at 2 weeks and 3 months. Healthy clinical conditions were seen around both ZrO(2) and Ti abutments at all times, without significant differences in most clinical parameters of peri-implant soft tissue health. Mean probing depths around Ti abutments were slightly deeper than around ZrO(2) abutments after 3 months (2.2 SD 0.8 mm vs. 1.7 SD 0.7 mm, P=0.03). CONCLUSIONS No difference in health of the soft tissues adjacent to ZrO(2) and Ti abutment surfaces or in early bacterial colonization could be demonstrated, although somewhat shallower probing depths were observed around ZrO(2) abutments after 3 month.

Augmented mandibular bone structurally adapts to functional loading

Long-term changes in trabecular bone structure during the 10 years following onlay grafting with simultaneous mandibular implant placement were studied. Extraoral radiographs of both mandibular sides in eight patients were taken regularly. Bone structure was analysed using a custom-written image analysis program. Parameters studied were trabecular area and perimeter and marrow cavity area and perimeter. After skeletonisation of the trabecular network, the number of end points and branching points, skeleton length, and branch angle were determined. The observed structural changes agree with the development of a more complex and more delicate or fine osseous structure. The bone shows more trabecular branching. All changes are most pronounced in the graft spongiosa, but are also found in the graft cortex and in the original mandible. The mean trabecular branch angle becomes more horizontal. The applied technique can be used to analyse long-term changes in the architecture of bone grafts. Changes found in the graft architecture correspond to changes expected after functional adaptation to loading.