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.

Radiographic evaluation of juvenile periodontitis (periodontosis).

Of 49,380 male naval recruits who were screened for juvenile periodontitis (JP), 270 were clinically diagnosed as having the disease. Full-mouth radiographs identified 182 of these 270 patients as having JP with extensive bone loss on permanent first molars and/or incisors. These 182 patients, 137 (75.3%) of whom were black, were further classified into Type I: bone loss involving first molars and/or incisors and up to two additional teeth; Type II: involvement of first molars/incisors and several additional teeth; and Type III: generalized involvement (more than 14 teeth) but with bone loss notably more extensive on the first molars and/or incisors. Of the 182 patients, 129 (70.9%) were Type I; 43 (23.6%) were Type II, and 10 (5.5%) were Type III. The molars were involved more frequently than the incisors; more than one molar was always involved, with or without incisor involvement. Most cases had minimal or no radiographic caries, and 46% had demonstrable calculus. Of the remaining 88 cases from the 270 with the initial diagnosis of JP, 63 demonstrated severe bone loss on more than 14 teeth, with many of the teeth being involved to the same degree. These cases were termed rapidly progressive periodontitis. Six of the 88 cases had bone loss on only one tooth surface of the dentition. These cases were termed acute localized destruction of alveolar bone. The status of the other 19 cases could not be determined.

Histologic evaluation of periodontal healing in humans following regenerative therapy with enamel matrix derivative. A 10-case series.

BACKGROUND: Enamel matrix derivative (EMD) has been developed as a stimulus of periodontal regeneration. Human histology following its use has not been evaluated on pathologically altered root surfaces. METHODS: Ten intrabony defects in 8 patients were evaluated at 2 centers. Teeth with advanced adult periodontitis that were treatment planned for extraction were treated with sulcular incisions; full-thickness flap reflection; debridement of granulomatous tissue from the defect; placement of a notch in the root at the apical extent of calculus; mechanical root planing; conditioning with citric acid; application of EMD; wound closure with sutures; and placement of a periodontal dressing. Biweekly to monthly recalls were made until removal of small block section biopsies at about 6 months. The biopsies were fixed, decalcified, step-serial sectioned at 6 microns to 8 microns, and stained with hematoxylin and eosin or Masson's trichrome. RESULTS: Histologic evaluation of the region coronal to the base of the calculus notch showed evidence of regeneration (new cementum, new bone, and new periodontal ligament) in 3 specimens, new attachment (connective tissue attachment/adhesion only) in 3 specimens, and a long junctional epithelium in 4 specimens. No evidence of root resorption, ankylosis, or untoward inflammation was seen. CONCLUSIONS: The results of this study fulfill the proof of principle that use of EMD can result in periodontal regeneration on previously diseased root surfaces in humans, but on an inconsistent basis.

The osteogenic potential of two human demineralized bone preparations using a xenogeneic model.

The relative osteogenic potential of two different preparations of lyophilized human demineralized bone were evaluated using a heterotopic site in a rodent model. Human diaphyseal cortical bone (75-850 microns) was demineralized according to two different protocols for decalcified bone allograft (A.H. Reddi and M.R. Urist). Equal volumes of mineralized lyophilized human bone and a proprietary hydroxylapatite served as controls. Thirty-two Long-Evans rats divided into four groups received subcutaneous implants of one of these four preparations. Implants were harvested at two, four, and six weeks. Histometric analysis of limited serial sections at six weeks demonstrated new bone formation by the two demineralized preparations only. The Reddi protocol produced significantly more bone formation (1.13 +/- 1.21%) than the Urist preparation (0.53 +/- 0.31%). Although bone induction by both the Reddi and Urist protocol was sparse within this xenogeneic system, the Reddi preparation may offer some slight advantage of greater osteogenic potential and ease of preparation. The low yields of induced bone in response to implants of human demineralized bone would limit the use of this model system in assessing osteogenic potential prior to clinical use.

Histologic evaluation of bone inductive proteins complexed with coralline hydroxylapatite in an extraskeletal site of the rat.

The purpose of this histologic and biochemical study was to assess the osteogenic potential of bone inductive proteins complexed with coralline hydroxylapatite as the carrier vehicle after implantation in an extraskeletal site of the rat. Inductive proteins were extracted from bovine demineralized bone. Implants were placed in 16 male, 3-month old Long-Evans rats (200-300 grams), using paired subcutaneous sites overlying the ventral thorax. There were four experimental groups, with eight implants per group. These included hydroxylapatite alone (HA), hydroxylapatite with inductive protein (HA + P), inactive demineralized bone matrix with (IBM + P), and without inductive protein (IBM). All implants were harvested at 21 days. Findings indicate a lack of osteogenic potential in groups HA, HA + P, and IBM. However, when HA and HA + P were compared, there was a 79% increase in standardized field mean nuclear point counts in the HA + P group. Also, compared to the other three implant groups, controls of IBM + P histomorphometrically showed chondroid bone formation and increased alkaline phosphatase activity. In this model system it may be concluded that with a composite system of coralline hydroxylapatite and bovine-derived inductive protein, bone formation was not seen; positive controls consisting of IBM + P demonstrated a statistically significant increase in AP activity with corresponding histologic evidence of bone formation.

Comparison of bone graft materials. Part I. New bone formation with autografts and allografts determined by Strontium-85.

The purpose of this study was to obtain a direct comparison of the bone forming abilities of autogenous osseous coagulum, autogenous bone blend, freeze-dried bone allograft, and decalcified freeze-dried bone allograft. Defects were created in the calvaria of 35 guinea pigs. The graft materials were placed in porous nylon chambers and implanted into the defects. Empty nylon chambers served as the controls. Three days prior to sacrifice, each animal received an injection of 85Sr. The animals were killed in groups of five at 3, 7, 14, 21 28, 35, and 42 days. At sacrifice, a small section of ilium was removed from each animal. The samples were recovered, weighed, and the uptake of 85Sr into new bone determined. An osteogenic index was obtained by dividing cpm/mg for each sample by cpm/mg of ilium. It was concluded that in this model system decalcified freeze-dried bone allograft is a graft material of high osteogenic potential while autogenous bone blend and osseous coagulum were of less potential, and freeze-dried bone allograft even less.

Comparison of bone graft materials. Part II. New bone formation with autografts and allografts: a histological evaluation.

The purpose of this study was to make a direct histological comparison of new bone formation evoked by decalcified freeze-dried bone allograft, freeze-dried bone allograft, autogenous osseous coagulum, and autogenous bone blend. Defects were surgically created in the calvaria of 35 guinea pigs. The graft materials were placed in porous nylon chambers and implanted into the defects. Implanted empty nylon chambers served as controls. The animals were sacrificed at 3, 7, 14, 21, 28, 35, and 42 days. New bone formation was determined quantitatively from histologic preparations. It was concluded that, in this model system, decalcified freeze-dried bone allograft is a graft material of high osteogenic potential; autogenous osseous coagulum and bone blend of less potential, and freeze-dried bone allograft even less.

HIV inactivation in a bone allograft.

The use of exclusionary techniques in the procurement of donors for bone allografts greatly reduces chances for disease transmission. Furthermore, treatment of HIV with either chemical agents or strong acids will effectively inactivate the AIDS virus. These data are taken as indirect proof that the risk of obtaining AIDS from a freeze-dried bone allograft is highly remote. The purpose of this study is to obtain direct evidence that the processing of a demineralized freeze-dried bone allograft would render the allograft safe for human use. In Part I, human cortical bone was obtained from a cadaveric source and tested to be free of HIV contamination. The bone was spiked with 5.26 x 10(9) viral particles. This corresponded to 148 micrograms of total viral protein. In Part II, cortical bone was procured from a donor who died of AIDS. In both Parts I and II, the cortical bone was ground to yield particle sizes of 90 to 500 microns. Test samples were treated with a virucidal agent and demineralized in HCl. Control samples were left untreated. All samples were cocultivated with stimulated peripheral blood lymphocytes and assayed for p24 core protein, reverse transcriptase, and viral gag gene by polymerase chain reaction (PCR). In Part I, the HIV spiking experiment, untreated virus infected particulate bone was positive for HIV replication. Treated samples were negative when assayed for HIV. Bone samples in Part II, HIV infected bone, were positive by PCR. Replication of viable HIV could not be demonstrated after treatment. It was concluded that demineralization and treatment with a virucidal agent inactivates HIV in spiked and infected bone.

Antigenicity of freeze-dried cortical bone allograft in human periodontal osseous defects.

The purpose of this investigation was to determine whether donor-specific anti-HLA antibodies could be detected against freeze-dried cortical bone allograft (FDBA) placed in human periodontal osseous defects. Twenty patients with multiple periodontal bony defects amenable to treatment in two allografting procedures were enrolled. No patient had pre-existing anti-HLA antibodies. FDBA used for all allografting procedures was obtained from one donor of known HLA antigens, and all patients were tissue-typed. Serum samples were taken two weeks after the first allograft (primary challenge), two weeks after the second allograft (secondary challenge) and at three months. Serum samples were assayed for the presence of anti-HLA antibodies using an Amos modified microcytotoxicity assay. At no time could any donor-specific anti-HLA antibodies be detected in any patient. All allografts were judged clinically successful, with no adverse tissue reactions to the donor material. FDBA may be regarded as a graft material lacking clinically significant antigenicity.

A six-month clinical evaluation of decalcified freeze-dried bone allografts in periodontal osseous defects.

The osteogenic potential of decalcified freeze-dried bone allografts in the treatment of human periodontal osseous defects was evaluated over a 6 month period. Cortical bone, obtained under sterile conditions from a human donor within 24 hours after death, was decalcified, freeze-dried and ground to a particle size of 250 to 500 microns. Twenty-seven osseous defects with one-, two- and wide three-wall morphology were treated. Clinical measurements were made with a stent and a calibrated periodontal probe before surgery, at the time of surgery, and at re-entry. The combined mean osseous regeneration for all defects was 2.4 mm. This represented a 65% mean bone-fill of the original defect. The findings demonstrate that decalcified freeze-dried bone allograft has potential as an osseous grafting material in periodontal therapy.

Comparison of bioactive glass to demineralized freeze-dried bone allograft in the treatment of intrabony defects around implants in the canine mandible.

BACKGROUND: The purpose of this study was to evaluate and compare the healing of different bone grafting materials adjacent to titanium plasma-sprayed (TPS) endosseous dental implants. METHODS: Implant osteotomy sites were prepared and standardized 3-walled intrabony defects (3 mm x 5 mm x 5 mm) were created at the mesial of each implant site. Thirty-two TPS implants were placed in edentulous mandibular ridges of the 4 dogs. Periodontal dressings were placed in the defect sites so as to create a defect simulating bone loss around an implant. After 3 months, the periodontal dressing was removed, the defect sites debrided and evaluated for size, and intramarrow penetration performed. The graft materials tested were 1) canine demineralized freeze-dried bone allograft (cDFDBA); 2) bioactive glass granules of a broad size range 90 to 710 microns (BRG); and 3) bioactive glass granules of narrow size range 300 to 355 microns (NRG). One site on each side of the mandible was not filled and served as a control. Dogs were sacrificed 4 months after graft placement. RESULTS: Histologically, differences in percent bone-to-implant contact in the defect area were observed between the treatment groups. cDFDBA>control=BRG=NRG with statistical significance found between cDFDBA and control (P = 0.0379), but no statistically significant difference between control or either bioactive glass material. When comparing percent bone height fill of the defect in the grafted area, cDFDBA (65.7%) was significantly better than the control (48.9%; P < or = 0.05) with no statistically significant difference between control, broad range bioactive glass (57.3%) and narrow range bioactive glass (56.6%). When total bone area was measured, the percentage of new bone in the grafted area was cDFDBA (42.1%), broad range glass (33.1%) and narrow range glass (22.6%) with significance found between cDFDBA and NRG (P = 0.0102). The content of residual graft particles in soft tissue was significant (P = 0.0304) between cDFDBA (1.4%) and NRG (11.4%) with no significant difference between graft material for residual particle content in bone tissue. CONCLUSIONS: The results of this study indicate that percent bone-to-implant contact and percent bone height fill in an intrabony defect around titanium plasma-sprayed implants are statistically significantly higher with the use of DFDBA when compared to bioactive glass material.

The use of a synthetic skin substitute as a physical barrier to enhance healing in human periodontal furcation defects: a follow-up report.

The purpose of this investigation is to compare the clinical response of guided tissue regeneration using a synthetic wound dressing with open flap debridement versus open flap debridement alone in the treatment of human furcation defects. The study group was composed of 19 patients with moderate to advanced adult periodontitis and at least one bilateral pair of Class II molar furcation defects. After the hygiene phase of therapy was completed, measurements were made with calibrated periodontal probes of the clinical attachment levels, probing depths, and soft tissue recession. Paired sites were randomly selected for treatment with either open flap debridement alone (control) or open flap debridement and placement of the synthetic wound dressing over the furcation (experimental). At the time of surgery, measurements of vertical and horizontal open probing attachment were recorded. The dressing was removed 5 to 6 weeks post-surgery. The sites were reentered at 6 months to evaluate healing and to repeat all measurements. Statistical comparisons using the Wilcoxon Sign Rank Test were made between the control and experimental sites. The results of 19 pairs of Class II molar furcation defects reveal statistically significant differences between the experimental and control sites in attachment levels, probing depths, and horizontal open probing attachment. These differences were of such small magnitude that they may not be clinically relevant. There were no other significant differences for any other clinical parameter, and none of the furcations in either group was completely closed.(ABSTRACT TRUNCATED AT 250 WORDS)

Scaling and root planing effectiveness: the effect of root surface access and operator experience.

This study investigated two variables associated with scaling and planning (S&RP): operator experience level and root surface access. One hundred and fourteen periodontally involved, single-rooted teeth designated for extraction were randomly distributed among four operators of various experience levels for either an open or closed session of S&RP. Immediately after treatment, the teeth were extracted, washed, and scored for residual calculus in a blind manner. Results showed that there was no difference in S&RP effectiveness for experience level or type of procedure in shallow (1-3 mm) pockets. However, in moderate (4-6 mm) and deep (greater than 6 mm) periodontal pockets, S&RP combined with an open flap procedure was more effective than S&RP alone for both experience levels. Also, the more experienced operators produced a significantly greater number of calculus-free root surfaces than the less experienced operators in periodontal pockets with moderate and deep probing depths. Clinical application of these results suggests that surgical access is associated with thorough surface debridement in periodontal pockets with moderate-to-advanced probing depths. However, more experienced operators could be expected to render more effective soft surface debridement.

Comparison of decalcified freeze-dried bone allograft and porous particulate hydroxyapatite in human periodontal osseous defects.

The purpose of this study was to clinically compare the healing potential of the osteoinductive decalcified freeze-dried bone allograft (DFDBA) with an osteoconductive synthetic graft, particulate porous hydroxyapatite (HA). Six patients ranging in age from 28 to 52 (mean age 42.6) participated in this investigation. They were without significant systemic disorders and had advanced periodontitis with at least two comparable periodontal defects. Each patient received initial therapy consisting of oral hygiene instruction, scaling, root planing, and occlusal adjustment as indicated. Probing pocket depth, gingival recession, attachment levels, and bleeding on probing were recorded in the posthygiene phase of therapy. Alveolar crest height and depth of osseous defect were obtained at the time of surgery. The cemento-enamel junction was used as the fixed reference point. All measurements were repeated at the time of a 6-month reentry. There was no significant difference in any of the soft tissue measurements when DFDBA and HA were compared. However, both treatment modalities reduced pocket depth and demonstrated a gain in clinical attachment levels. There was 2.2 mm of bone repair with DFDBA and 2.1 mm with HA. These values corresponded to a percent defect fill of 61% for DFDBA and 53% for HA. These values were likewise not statistically different.

Comparison of freeze-dried bone allograft and porous hydroxylapatite in human periodontal defects.

This study was conducted to clinically compare the efficacy of freeze-dried bone allograft (FDBA) and porous hydroxylapatite granules. Nineteen pairs of intraosseous defects were grafted in seven patients. One defect of each pair was implanted with FDBA, the other with granular porous hydroxylapatite. Matching defects were treated similarly in all other aspects. Evaluations were based on both preoperative and postoperative measurements from a fixed reference point, standardized radiographs, surgical osseous measurements, and histology of degranulated tissues. Grafted sites were reentered 6 to 11 months postsurgery. Results showed a mean osseous fill of 2.1 mm for FDBA versus 1.3 mm for granular porous hydroxylapatite (P = .07). A mean clinical attachment gain of 2.2 mm for FDBA versus 1.3 mm for granular porous hydroxylapatite (P less than .05), and a mean decrease in probing depths of 3.0 mm for FDBA versus 1.4 mm for granular porous hydroxylapatite (P less than 0.5) was found. FDBA was clinically indistinguishable from host bone, whereas porous hydroxylapatite appeared to be separated from host bone by soft tissue. The data and clinical findings suggested that FDBA may have some enhanced reparative potential when compared to granular porous hydroxylapatite in the treatment of periodontal defects in humans.

Clinical evaluation of the use of decalcified freeze-dried bone allograft with guided tissue regeneration in the treatment of molar furcation invasions.

The purpose of this study is to evaluate the potential of decalcified freeze-dried bone allograft (DFDBA) combined with a barrier material in the treatment of human molar furcation defects (experimental) as compared to the barrier technique alone (control). Fifteen pairs of Class II or III furcation invasion defects comprised the study group. Measurements with calibrated periodontal probes were made to determine soft tissue recession, probing depth, and attachment levels. Defects from each pair were randomly selected to be treated with an expanded polytetrafluoroethylene membrane (e-PTFE) and DFDBA or the membrane alone. Additional measurements were made during surgery to determine crestal resorption, and vertical and horizontal open probing attachment. The membrane was removed 4 to 6 weeks post-insertion. Six months post-treatment, each site was surgically reentered and measurements repeated. Following either treatment, recession was minimal with statistically significant improvement in probing depth reduction and clinical attachment level gain favoring the combined technique. Hard tissue changes were comparable for alveolar crestal resorption, however, there was a distinct difference, statistically, for both horizontal and vertical bone repair favoring the use of the demineralized bone graft in combination with the e-PTFE membrane.

A comparison of freeze-dried bone allograft and demineralized freeze-dried bone allograft in human periodontal osseous defects.

This study was conducted to clinically compare freeze-dried bone allograft (FDBA) and demineralized freeze-dried bone allograft (DFDBA). Twenty-two defects (11 intrapatient pairs) in 9 patients were grafted with either DFDBA or FDBA. Evaluations were based on standardized radiographs, presurgical and postsurgical soft tissue measurements using the cemento-enamel junction as a fixed reference point, and osseous measurements at the time of surgery. Grafted sites were re-entered at a minimum of 6 months following placement. A mean osseous repair of 1.7 mm (59%) occurred with DFDBA and 2.4 mm (66%) with FDBA. A mean clinical attachment gain of 1.7 mm was obtained with DFDBA and 2.0 mm with FDBA. Probing depths decreased a mean of 2.00 mm with both DFDBA and FDBA. These findings reveal no significant differences between the two materials in primarily intraosseous defects when evaluated at a minimum 6 months postsurgery.

Scaling and root planing efficacy in multirooted teeth.

The effect of operator experience level and root surface access on instrumentation of multirooted teeth was investigated. Fifty molars designated for extraction were randomly distributed among four operators of two different experience levels for scaling and root planing with or without surgical access. Following treatment the teeth were extracted and scored in a blind manner for residual calculus. Teeth were sectioned to allow assessment of the furcal aspects. Results show that operators of both experience levels obtained calculus-free root surfaces significantly more often with flap access than with a non-surgical approach. Additionally, operators with more experience achieved calculus-free root surfaces significantly more often than operators of lesser experience with both an open and closed procedure. However, when furcation aspects alone were assessed, it was found that the more experienced operators obtained a calculus-free surface only 68% of the time with an open approach. Results suggest that, although both surgical access and a more experienced operator significantly enhance calculus removal in molars with furcation invasion, total calculus removal in furcations utilizing conventional instrumentation may be limited.

The osteogenic potential of two composite graft systems using osteogenin.

The purpose of this study was to determine the quantity of new bone formation in critical sized calvaria defects in rats treated with two composite graft systems. The systems consisted of either a combination of the bone inductive protein (osteogenin) plus type I collagen (Os + C) or the combination of osteogenin with coralline hydroxyapatite (Os + HA). Additional treatments consisted of coralline hydroxyapatite (HA) or untreated control defects. After 28 days the calvaria were recovered and processed for quantitative radiography (radiomorphometry) and histomorphometry. Histomorphometric results were based on quantitation of regenerated trabecular bone. Results indicated that the Os + C combination produced substantially more bone than the Os + HA, HA, or control groups (P less than 0.05). Radiomorphometric assessment was based on the detection of radiopacity in the calvarial wounds. Due to the radiopaque property of HA, it was not possible to accurately quantitate the radiopacity of the regenerating bone from HA and host bone. Therefore, conclusions about the efficacy of the treatments must be derived from histomorphometric data. Results from histometric measurements of healing indicate that the Os + C combination has the greatest potential for regenerating calvarial bone defects. The potential for osteogenin in regenerating alveolar bone lost due to periodontal disease is suggested by these studies.

Clinical evaluation of guided tissue regeneration in the treatment of maxillary class II molar furcation invasions.

This investigation assessed and compared the clinical efficacy of combined open flap debridement/occlusive membrane therapy versus open flap debridement therapy alone, in the treatment of maxillary periodontal furcation defects. Seventeen patients presenting with advanced adult periodontitis, including at least one pair of Class II maxillary furcal defects, comprised the study group. Following completion of a hygienic phase of treatment, measurements were made with calibrated periodontal probes to determine soft tissue recession, probing pocket depths, and attachment levels. Each pair of furcation defects was surgically exposed and hard tissue measurements obtained. Defects were treated with either open flap debridement and a polytetrafluoroethylene periodontal membrane or open flap debridement alone. Membranes were removed at 4 to 6 weeks. Six months postsurgery, soft tissue measurements were repeated and all sites were surgically re-entered to obtain hard tissue measurements. No statistically significant differences were found in recession, probing depth reductions, clinical attachment gains, or resorption of alveolar crest height between test and control groups. Results for these parameters were inconsistent and unpredictable. Statistically significant improvements were found, however, in horizontal open probing attachment (HOPA) and vertical open probing attachment (VOPA) between experimental and control sites. The GTR procedure as used in this study likely has limited application as a therapeutic modality for Class II furcations of maxillary molars. Modifications or improvements in the procedure may result in more predictable healing of these lesions.