James T. Mellonig

Histologic Evaluation of New Attachment Apparatus Formation in Humans

There is conflicting evidence regarding the value of graft materials in enhancing the formation of new bone, cementum, and periodontal ligament (new attachment apparatus). Part II of this study compared the healing of intrabony defects with and without the placement of decalcified freeze-dried bone allograft (DFDBA) in a submerged environment. The most apical level of calculus on the root served as a histologic reference point to measure regeneration on root surfaces exposed to the oral environment. Biopsies were obtained at 6-months and evaluated histometrically by two investigators unaware of the treatment performed. Data from 9 patients with 30 grafted defects and 13 nongrafted defects were submitted for statistical analysis. Results indicate that in a submerged environment significantly more new attachment apparatus (P less than .05) and new bone (P less than .05) formed in grafted than nongrafted sites. Significantly greater loss of alveolar crest height occurred in nongrafted than grafted defects (P less than .05); regeneration of new attachment apparatus, new bone, and new cementum occurred more frequently in grafted than nongrafted defects. There was a greater chance for the regeneration of a connective tissue attachment in nongrafted intrabony defects than in grafted defects; new cellular cementum formed equally well on old cementum, dentin, or both old cementum and dentin in the same defect. The periodontal ligament was oriented parallel, perpendicular, or both parallel and perpendicular in the same defect; and, no extensive root resorption, ankylosis, or pulp death was observed in grafted or nongrafted defects.

Persistent Acute Inflammation at the Implant-Abutment Interface:

The inflammatory response adjacent to implants has not been well-investigated and may influence peri-implant tissue levels. The purpose of this study was to assess, histomorphometrically, (1) the timing of abutment connection and (2) the influence of a microgap. Three implant designs were placed in the mandibles of dogs. Two-piece implants were placed at the alveolar crest and abutments connected either at initial surgery (non-submerged) or three months later (submerged). The third implant was one-piece. Adjacent interstitial tissues were analyzed. Both two-piece implants resulted in a peak of inflammatory cells approximately 0.50 mm coronal to the microgap and consisted primarily of neutrophilic polymorphonuclear leukocytes. For one-piece implants, no such peak was observed. Also, significantly greater bone loss was observed for both two-piece implants compared with one-piece implants. In summary, the absence of an implant-abutment interface (microgap) at the bone crest was associated with reduced peri-implant inflammatory cell accumulation and minimal bone loss.

Autogenous and Allogeneic Bone Grafts in Periodontal Therapy

This article is limited to a review of bone autografts and allografts, as used in periodontal therapy. The various graft materials are discussed with respect to case reports, controlled clinical trials, and human histology. Other reviewed areas are wound healing with periodontal bone grafts, tissue banking and freeze-dried bone allografts, and the use of bone grafts in guided tissue regeneration.

Living Cellular Construct for Increasing the Width of Keratinized Gingiva: Results From a Randomized, Within-Patient, Controlled Trial

BACKGROUND The standard of care for increasing keratinized gingiva adjacent to teeth that do not require root coverage is the free gingival graft (FGG). A pilot study indicated that the use of a living cellular construct (LCC) could be effective in this clinical scenario. METHODS A pivotal, multicenter, randomized, within-patient, controlled, open-label trial was conducted (N = 96 patients). After removing the mucosa and keratinized gingiva from the test site, either an LCC or FGG was applied. The primary efficacy endpoint was the ability of the LCC to regenerate ≥2 mm keratinized gingiva at 6 months. Secondary measures were the same color and texture as the adjacent tissue, a 1-mm width of keratinized gingiva at 6 months, patient treatment preference, surgical site sensitivity at 1 week, and patient-reported pain after 3 days. Safety was assessed by reports of adverse events. RESULTS At 6 months, the LCC regenerated ≥2 mm of keratinized gingiva in 95.3% of patients (81 of 85 patients; P <0.001 versus a 50% predefined standard). As expected, the FGG generated more keratinized gingiva than the LCC (4.57 ± 1.0 mm versus 3.2 ± 1.1 mm, respectively). The gingiva regenerated with the LCC matched the color and texture of the adjacent gingiva. All patients achieved ≥1 mm keratinized gingiva with the LCC treatment by 6 months, and more patients preferred treatment with the LCC than with the FGG. No difference in sensitivity or pain was noted between the treatments. The treatments were well tolerated, and reported adverse events were typical for this type of periodontal surgery. CONCLUSION The use of an LCC may provide a safe and effective therapy for augmenting the zone of keratinized gingiva.

Clinical and Histologic Evaluation of Non-Surgical Periodontal Therapy With Enamel Matrix Derivative: A Report of Four Cases

BACKGROUND Enamel matrix derivative (EMD) is a composite of proteins that was demonstrated histologically to work as an adjunct to periodontal regenerative surgical therapy. The purpose of this study was to evaluate the clinical and histologic effects of EMD as an adjunct to scaling and root planing. METHODS Four patients with severe chronic periodontitis and scheduled to receive complete dentures were accrued. Probing depth and clinical attachment levels were obtained. Unlimited time was allowed for hand and ultrasonic instrumentation. A notch was placed in the root >or=1 to 2 mm from the apical extent of root planing. EMD was inserted into the pocket, and a periodontal dressing was placed. Patients were seen every 2 weeks for plaque control. At 6 months post-treatment, soft tissue measurements were repeated, and the teeth were removed en bloc and prepared for histomorphologic analysis. RESULTS Probing depth reduction and clinical attachment level gain were obtained in three-fourths of the specimens. Three of the four specimens analyzed histologically demonstrated new cementum, bone, periodontal ligament, and connective tissue attachment coronal to the notch. In one specimen, the gingival margin had receded below the notch. CONCLUSIONS The results were unexpected and may represent an aberration. However, the substantial reduction in deep probing depths and clinical attachment level gain in three of four specimens, in addition to the histologic findings of new cementum, new bone, a new periodontal ligament, and a new connective tissue attachment, suggest that EMD may be useful as an adjunct to scaling and root planing in single-rooted teeth.

Periodontal regeneration using an anabolic peptide with two carriers in baboons

BACKGROUND Various growth proteins have been used to encourage periodontal tissue regeneration. The purpose of this pilot study is to evaluate the periodontal regeneration achieved with the use of a synthetic anabolic peptide (AP) combined with either beta-tricalcium phosphate (beta-TCP) or an absorbable collagen sponge (ACS) as the carrier. METHODS Periodontal defects were created bilaterally adjacent to four mandibular teeth in five baboons. Plaque was allowed to accumulate around wire ligatures placed into the defects. After 2 months, the wire ligatures were removed, and a notch was placed at the base of the defect. The four teeth were randomly treated with one of the following treatments: 1) saline + ACS serving as the control, 2) AP + ACS, 3) saline + beta-TCP serving as another control, or 4) AP + beta-TCP. The baboons were sacrificed 5 months post-treatment, and histomorphometric analyses were performed under masked conditions. RESULTS At 5 months post-surgery, the mean length of new cementum for sites treated with AP + ACS, AP + beta-TCP, saline + ACS, saline + beta-TCP amounted to 3.32 +/- 1.7 mm, 3.86 +/- 1.0 mm, 2.87 +/- 1.3 mm, and 3.15 +/- 1.9 mm, respectively. The mean width of new cementum for the corresponding values was 52.5 +/- 14.7 microm, 54.5 +/- 24.2 microm, 37.4 +/- 12.7 microm, and 48.9 +/- 12.4 microm, respectively. The mean width of new periodontal ligament for corresponding values was 246 +/- 140 microm, 166 +/- 26 microm, 251 +/- 92 microm, and 240 +/- 91 microm. No statistically significant difference was observed for any of the parameters among groups in this pilot study. CONCLUSIONS Preclinical studies showed that AP has positive anabolic effects on bone cells. In this study, no adverse tissue reactions were observed in the AP-treated sites, including root resorption, ankylosis, or a foreign body reaction. The cementum length and width were greater in the sites treated with AP versus sites treated with a control; however, these differences were not significant in the small number of animals used. Further research is needed to define the potential of AP as a periodontal therapeutic agent.