International Journal of Periodontics & Restorative Dentistry, 04/2001

The success of bone-inductive cytokines in surgical alveolar defects is greatly dependent upon the ability of carrier materials to effectively deliver the inductive protein to the surgical site. An evaluation of three types of carrier materials was undertaken in six monkeys using an osseous defect of 2.0 cm that was produced by partial resection of the maxilla and mandible and placement of titanium implants in each alveolar quadrant. After 5 months, abutments were placed on the implants, which were allowed to function for an additional 5 months. Intravital labeling with tetracycline was used to evaluate the late healing remodeling processes. The carriers were evaluated by studying (1) the amount of surface osseointegration on the root-form implants; (2) the bone density as related to trabecular pattern and cortex formation; and (3) the quantitative and qualitative thickness of the alveolar bone buccolingually at the implanted sites. Of the three materials, the calcium carbonate coral (BioCoral) produced a decreased amount of bone regeneration in comparison with both the poly(methylethyl methacrylate) material (HTR) and the porous bone mineral (Bio-Oss). Both the HTR and Bio-Oss with rhBMP-2 produced excellent thickness of the repaired alveolar ridge. All three materials produced the same amount of osseointegration with the titanium implant surfaces. Good bone quality, as reflected in thickening of the trabecular bone patterns, was seen with both Bio-Oss and HTR. While all three of these carrier materials appeared to produce good osseointegration with the titanium implants, BioCoral did not effect a quantitative or qualitative restoration of the alveolar bone comparable to that following the use of either HTR or Bio-Oss with rhBMP-2.

Combining platelet-rich plasma (PRP) with autogenous bone graft materials has recently been advocated as a means of enhancing rate and quality of new bone formation in regenerative procedures. The aim of this case series was to evaluate the potential of PRP in combination with bone allograft to enhance bone regeneration in alveolar ridge defects exhibiting both vertical and horizontal loss prior to the placement of dental implants. Augmentation resulted in clinical and radiographic gains in both vertical and horizontal components of the osseous defects, thereby facilitating subsequent placement of dental implants. Histologic evaluation of the cases revealed the presence of residual allograft particles surrounded by connective tissue as well as newly formed bone within the grafted areas. However, the addition of PRP did not appear to enhance the quality or quantity of new bone formation over that reported in comparable guided bone regeneration (GBR) studies without PRP.

A series of 12 men and 13 women ranging in age from 24 to 71 years underwent two- or three-dimensional reconstruction of type C, D, or E ridges and placement of anterior implants. The mean horizontal augmentation was 6.4 mm (range 2 to 17 mm), and the mean vertical augmentation was 4.22 mm (range 0 to 15 mm). The 67 implants were all loaded, with the time averaging 34.4 months for the maxillary implants and 19 months for the mandibular implants. None of the implants have been lost to date. Two patients had flap retraction within the first 2 weeks that necessitated reapproximation. One patient had total failure of a J graft of iliac crestal bone from the maxillary left central incisor to canine starting 3 weeks after placement as the result of infection. The graft was removed at 6 weeks, and no implants were placed. Two patients suffered partial anterior graft loss, but their implants were successful in location and angulation. Implants and grafts can be combined with acceptable rates of complications and failure.

The dental transplant was already in use more than 2,000 years ago, reaching a peak in the Middle Ages, but it was only after the 1950s that this subject appeared in the scientific literature. This article describes the case of a young woman whose mandibular left second and right first molars had to be extracted and were replaced using the maxillary third molars. The positive clinical and radiographic results over a 5-year period encourage the use of this technique.

This case report covers the combined functional and perioprosthetic complete-mouth rehabilitation of a 67-year-old patient with severe temporomandibular joint pain caused by a prognathic forced incorrect centric relation and severe overclosure. Once bite guard treatment had been concluded and the pain had subsided completely, AGC electroformed crown and bridgework was fabricated. Electroformed crown-and-bridge copings exhibit extremely high precision of fit and, from the clinical point of view, perfect esthetics. As the coping material is pure gold and there are no bonding oxides in the gold-porcelain bonding layer, AGC restorations are readily integrated into the biologic structures around the crown margins. Perfectly healthy, noninflamed soft tissues, a lack of blueish-livid colored gingival margins, and visible gingival reattachment around the crown margins are considerable benefits from the perioprosthetic point of view. This leads to foreseeable clinical success and promises further use of electroformed porcelain restorations.

High implant survival rates are published with more than 15 years of observation time. Failures over time are often caused by ongoing marginal bone loss. Therefore, the need for reliable monitoring of the stability of periimplant attachment and/or bone level is extremely important. Marginal bone loss around osseointegrated implants has often been associated with periimplantitis, but clinical observations cannot prove this relationship. Otherwise, the impact of excessive loading on periimplant bone has been shown in animal studies and has been positively related to implant failure in terms of implant mobility and marginal bone loss. Some clinical observations support this hypothesis.

Recent developments in osseous regenerative techniques have increased the demand for bone-substitute grafting materials. Porous deproteinized bovine bone mineral (PBBM), a biocompatible xenograft, has been used in different osseous deficiencies prior to or in conjunction with the placement of titanium implants. The different PBBM applications in fresh extraction sites, anatomic defects, and subantral floor elevation techniques are described. The use of an occlusive barrier membrane to regenerate bone via guided tissue regeneration principles was determined for each patient by clinical parameters. PBBM was well amalgamated and incorporated with the augmented hard tissue, but the transition between preexisting bone and the newly regenerated bone-like tissue was distinguishable by clinical examination even after 12 months. Grafted material was also identified using follow-up radiographs. In the presented cases, PBBM showed clinically satisfactory results as a biocompatible filler in bone augmentation procedures.

Implant exposure during initial healing after placement has been considered important in both implant integration and postloading effects. This study evaluated the effect of early implant exposure on the clinical findings prerestoration and 6 months postrestoration. Forty-eight implants (24 CPTi and 24 Ti-13-13) were placed in maxillary and mandibular posterior sites in six baboons. Implant exposure was evaluated for 24 of the submerged implants at placement and at each weekly visit for 3 weeks after implant placement. The crestal bone level at maxillary posterior sites was measured at 6-month uncovering, and mandibular sites were measured at 3-month uncovering. All sites were again measured 6 months after restoration placement. Periotest readings were recorded at implant uncovering and again 6 months postloading. Arbitrary groupings of the Periotest values were assigned as good = -7 to -1; guarded = 0 to +2; and poor = +3 to +27. At 6 months postloading, there were no statistical differences between CPTi and Ti-13-13 for change in crestal bone height in either arch. The mean change in maxillary crestal bone height varied from a 0.59- to 1.35-mm loss. The differences between the mean exposed and nonexposed changes were not statistically significant. The mean change in mandibular crestal bone height varied from a 0.25- to 0.88-mm loss. Changes in crestal bone height for nonexposed sites from 3-month implant uncovering to 6 months postloading were statistically significant at the mesial, buccal, and lingual aspects. The mean change for the nonexposed distal aspect approached significance. The differences between the mean exposed and nonexposed changes were not statistically significant. The overall percentage of maxillary implants in the good category for nonexposed sites decreased by 41% from uncovering to 6 months after loading, while no change occurred for exposed sites; the percentage of implants in the good category was comparable for early exposed and nonexposed sites (57% and 59%, respectively). At 6 months after loading, the percentage of implants in the good category was more favorable for early exposed (88%) than nonexposed sites (50%). A one-stage implant approach should provide similar postloading clinical results as the two-stage surgical approach.