"Biologic width"and crestal bone remodeling with sintered porous-surfaced dental implants: a study in dogs.

PURPOSE: The aim of this study was to obtain histometric measurements of bone and peri-implant mucosal tissue contact with implants of 2 sintered porous-surfaced designs. The "short-collar" design had a collar height (smooth coronal region) of 0.75 mm, while the "long-collar" model had a smooth coronal region of 1.8 mm. MATERIALS AND METHODS: Implants (2 per side) were placed in healed mandibular extraction sites of 4 beagle dogs using a submerged technique. After 4 weeks of healing, they were uncovered and used to support fixed partial dentures for a 9-month period. After sacrifice, specimens were retrieved and nondemineralized sections were examined histometrically to determine the most coronal bone-to-implant contact (first BIC) using the microgap as a reference and standard mucosal parameters of "biologic width." RESULTS: Significant (P = .001) differences in first BIC were found between designs (1.97 mm for long-collar versus 1.16 mm for short-collar implants) for posteriorly located implants but not for anteriorly located ones (1.21 mm versus 1.38 mm; P = .40). If crestal bone loss involved sintered surface, fibrous connective tissue ingrowth was observed to replace lost bone. No significant differences in peri-implant mucosal measurements (total peri-implant mucosal thickness; length of the epithelial component of this mucosa, and thickness of the connective tissue component) were detected between implant designs. CONCLUSIONS: Results suggest that "biologic width" accommodation drives initial crestal bone loss with sintered porous-surfaced implants. Histometric data obtained for bone contact showed no significant differences between the long- and short-collar implant designs.

Osteotome sinus elevation and simultaneous placement of porous-surfaced dental implants: a morphometric study in rabbits.

The objective was to establish a model in rabbits in which to study the healing events associated with localized indirect osteotome-mediated maxillary sinus floor elevation in conjunction with simultaneous placement of sintered porous-surfaced dental implants. On one side of the maxilla of each of 28 rabbits, a sintered porous-surfaced titanium alloy press-fit implant was placed without the use of a bone graft material, while on the collateral side an implant was placed after first adding Bio-Oss graft particles to the osteotomy. Specimens were retrieved for morphometric assessment of bone contact and bone ingrowth of the porous implant surface after 2, 4, 6 and 8 weeks of healing. All implants became osseointegrated by bone ingrowth into the porous implant surface. While the addition of graft particles did not result in a statistically significant increase in the parameters measured, a trend for greater bone contact and particularly bone ingrowth at the apices of the implants was seen as healing time increased. The rabbit maxillary sinus can be used to study healing following placement of sintered porous-surfaced dental implants using the indirect sinus elevation procedure.

Calcium phosphate sol-gel-derived thin films on porous-surfaced implants for enhanced osteoconductivity. Part II: Short-term in vivo studies.

Osseointegration rates of porous-surfaced Ti6Al4V implants with control (unmodified sintered coatings) were compared to porous-surfaced implants modified through the addition of either an Inorganic or Organic Route-formed-Ca-P film. Implants were placed in distal femoral rabbit condyle sites and, following a 9-day healing period, implant fixation strength was evaluated using a pull-out test. Three groups of ten rabbits each were evaluated. Inorganic Route Ca-P-coated implants were compared with control implants in Group I. Organic Route Ca-P-coated implants with control implants in Group II, and Inorganic- with Organic Route-Ca-P-coated implants in Group III. Maximum pull-out force and interface stiffness were compared while selected extracted implants were examined by SEM to characterise failure surfaces. Both types of Ca-P coatings significantly enhanced the early rate of bone ingrowth and fixation as evidenced by higher pull-out force and interface stiffness compared with controls. However, there was no significant difference between Ca-P-coated implants prepared using the two different methods. The enhanced osteoconductivity observed with the Organic Route-formed films despite the absence of any obvious new surface topographic features introduced with the films suggests that the increased rate of bone ingrowth was due primarily to altered surface chemistry rather than changes in topography, at least for these sintered porous-surfaced implants.