Principles of periodontology.

Periodontal diseases are among the most common diseases affecting humans. Dental biofilm is a contributor to the etiology of most periodontal diseases. It is also widely accepted that immunological and inflammatory responses to biofilm components are manifested by signs and symptoms of periodontal disease. The outcome of such interaction is modulated by risk factors (modifiers), either inherent (genetic) or acquired (environmental), significantly affecting the initiation and progression of different periodontal disease phenotypes. While definitive genetic determinants responsible for either susceptibility or resistance to periodontal disease have yet to be identified, many factors affecting the pathogenesis have been described, including smoking, diabetes, obesity, medications, and nutrition. Currently, periodontal diseases are classified based upon clinical disease traits using radiographs and clinical examination. Advances in genomics, molecular biology, and personalized medicine may result in new guidelines for unambiguous disease definition and diagnosis in the future. Recent studies have implied relationships between periodontal diseases and systemic conditions. Answering critical questions regarding host-parasite interactions in periodontal diseases may provide new insight in the pathogenesis of other biomedical disorders. Therapeutic efforts have focused on the microbial nature of the infection, as active treatment centers on biofilm disruption by non-surgical mechanical debridement with antimicrobial and sometimes anti-inflammatory adjuncts. The surgical treatment aims at gaining access to periodontal lesions and correcting unfavorable gingival/osseous contours to achieve a periodontal architecture that will provide for more effective oral hygiene and periodontal maintenance. In addition, advances in tissue engineering have provided innovative means to regenerate/repair periodontal defects, based upon principles of guided tissue regeneration and utilization of growth factors/biologic mediators. To maintain periodontal stability, these treatments need to be supplemented with long-term maintenance (supportive periodontal therapy) programs.

A novel marginal periosteal pedicle graft as an autogenous guided tissue membrane for the treatment of intrabony periodontal defects.

OBJECTIVE: The aim of the present study was to clinically examine the effects of a novel marginal periosteal pedicle graft (MPP) as a guided tissue membrane for treating proximal intrabony defects in comparison to a an open flap debridement. MATERIAL AND METHODS: Fifteen patients with severe chronic periodontitis and no systemic diseases participated in this prospective, controlled clinical trial. Each subject contributed matched pairs of interproximal two- or three-walled intrabony defects. Baseline clinical examination included plaque index (PlI), gingival index (GI), bleeding on probing (BOP), probing depth (PD) and clinical attachment level (CAL) of selected sites and were performed two weeks following completion of cause-related therapy. Radiographic measurements were also recorded to ascertain the radiographic depth of the defect. Each pair of periodontal defects were randomly assigned into the experimental group G1, marginal periosteal pedicle graft (MPP) guided tissue membrane or the control open flap debridement group, G2. In the MMP, partial thickness flaps were elevated at the vestibular surface of the tooth adjacent to the interproximal defect to harvest a 4 mm marginal pedicle periosteal graft. Exposed root surfaces were root planed and the remaining bony walls of the selected defect were degranulated prior to the periosteal pedicle barrier membrane being rotated to cover the intrabony defect. Sites representing the control group were treated with only open flap debridement. Clinical and radiographic parameters were recorded at 3, 6 and 9 months after surgery for treatment outcome evaluation. RESULTS: Baseline data showed no differences in any of the investigated parameters, suggesting parameters were balanced between the two groups. Both experimental and control groups showed significant improvements in all of the soft and hard tissue parameters when compared to baseline (p < 0.001). At nine months, the experimental MPP group showed significant improvement in PD reduction, CAL gain and intrabony defect reduction when compared to the control (p < 0.01). In the MPP group, the mean reduction in PD was 3.8 mm, mean CAL gain was 3.4 mm and mean reduction in intrabony defect was 2.2 mm. In sites treated with open flap DEBRIDEMENT, the mean PD reduction was 2.5 mm, CAL gain was 2.0 mm and mean reduction in intrabony defect was 0.6 mm. CONCLUSION: Within the limits of this study, it can be concluded that the placement of a marginal periosteal pedicle graft as a barrier membrane significantly improved clinical and radiographic parameters of deep intrabony defects and proved superior to OPEN FLAP DEBRIDEMENT alone.

Effects of EDTA gel preconditioning of periodontally affected human root surfaces on chlorhexidine substantivity - an SEM study.

BACKGROUND: Infection control is an important requirement during the early stages of periodontal healing. This study was performed to assess the preconditioning effect of EDTA gel on chlorhexidine (CHX) substantivity to periodontally involved root surfaces. METHODS: Eighty patients with severe chronic periodontitis were enrolled in this study. Following cause-related therapy, patients were divided randomly into four groups. Each group consisted of 20 subjects with one tooth that was diagnosed as hopeless and designated for extraction. In group 1 (G1), selected periodontal pockets were filled with a placebo gel in a silica base for 2 minutes. Exposed roots in group 2 (G2) were etched for 2 minutes with a neutral EDTA conditioning agent, followed by pocket fill with the placebo gel. Pockets in group 3 (G3) were filled with 0.12% CHX digluconate gel in a silica base. Exposed roots in group 4 (G4) were etched for 2 minutes with a neutral EDTA conditioning agent, followed by pocket fill with the CHX gel. Four teeth from each group were extracted immediately and at 3, 12, 24, and 48 hours for SEM evaluation. RESULTS: G1 and G2 specimens showed no evidence of silica adherent to any of the examined root surfaces. At 3 hours following CHX gel application, G3 specimens showed marked reduction in CHX-coated silica. At 24 and 48 hours following EDTA and CHX gel application, G4 specimens demonstrated adherent CHX-coated silica particles despite the reclogging of the tubule orifices. CONCLUSION: EDTA and CHX gel root conditioning is a valuable regimen that improves CHX substantivity to periodontally involved root surfaces.

An evaluation of the origin of trabecular bone patterns using visual and digital image analysis.

OBJECTIVE: The purpose of this research project was to investigate the origin of the anatomical structures interpreted as trabecula bone on dental radiographic images. STUDY DESIGN: Mandible sections were cut sagitally into halves. Trabecular bone was removed from each section in 4 stages. Following each stage, standardized radiographs were made, using CDR direct digital equipment. Trabecular bone in the resulting digital images was measured with 4 methods: (1) mean gray level; (2) the fractal dimension of the basic images; and, following morphological image processing, (3) counting the number of trabecular ends, intercepts, and segments (EIS) and (4) performing fractal analyses of the skeletonized images. Additionally, human visual interpretation of the collected images was conducted through a written examination. Repeated measures analysis of variance (ANOVA) was used to test for changes in measurements attributable to bone removal. RESULTS: Repeated measures ANOVA indicated that the use of gray levels, fractal dimension, and morphologic operations quantifying using EIS or fractal analysis had similar performance and resulted in significant changes in measurements following bone removal ( P < .05). Visual differences were not always apparent between each stage of bone reduction. Radiometric and morphologic analysis showed measurable differences between stages. CONCLUSIONS: These results imply that the inner trabecula, the junctional trabecula, and the actual cortical housing all contribute to some extent to the radiograph, although changes in the radiographic architecture are not always clinically detectible.

A multicenter study evaluating the sensitization potential of enamel matrix derivative after treatment of two infrabony defects.

BACKGROUND: Several studies reported some success toward regeneration in infrabony defects using enamel matrix derivative (EMD). Clinically and statistically significant improvements in probing depth reduction, clinical attachment levels, and bone fill have been demonstrated. This multi-center study evaluated the potential for sensitization to EMD in a subgroup of periodontal patients treated at least twice with at least 2 months between treatments. METHODS: Three hundred seventy-six (376) patients in 11 university-based postgraduate periodontics programs and five private practices were selected. Surgeries were performed on infrabony defects. Following reflection of mucoperiosteal flaps and debridement of the root surface and defect, root conditioning (either citric acid pH = 1 or 24% EDTA) was performed and the site was irrigated with sterile saline. Enamel matrix derivative was reconstituted and applied to the exposed root surface and the bony defect. Flaps were sutured and pressure applied for 5 minutes. The second test defect was treated in a similar manner at least 8 weeks after the first surgery. The patient was given a diary card where any subjective adverse events (erythema, swelling, itching, headache, root hypersensitivity, or pain) were recorded at weeks 1 and 2 post-surgery. In addition, objective adverse events (gingival inflammation, ulcers, abscess, cratering, and lesions) were recorded by the investigator on an adverse event form. RESULTS: No clinical adverse reactions to multiple applications of EMD were noted. Of 376 patients, two were referred to a dermatologist for evaluation, but neither had signs indicating any adverse events due to EMD treatment. Instead their reactions were classified as a small local abscess and tinea cruris. The single immunoassay performed (on the patient with a small local abscess) did not demonstrate any EMD-reactive antibodies, neither IgE nor IgG. Other subjective/objective reactions that occurred during this study were of the type that are commonly experienced by patients immediately following periodontal surgery, but were not related to EMD. They included headache, swelling, itching, pain, and root hypersensitivity. CONCLUSIONS: This study demonstrated a lack of clinical adverse reactions following two separate applications of EMD. Any subjective/objective adverse reactions experienced by the patient were typical complications following routine periodontal surgery and were not directly related to the use of enamel matrix derivative.

In vivo effectiveness of a glycerol-compounded demineralized freeze-dried bone xenograft in the rat calvarium.

BACKGROUND: Demineralized freeze-dried bone (DFDB) is commonly hydrated with sterile water into a paste-like consistency for improved clinical handling or reconstituted with biodegradable barriers, such as glycerol, to promote handling and wound stability following human periodontal surgery. The purpose of this study was to evaluate the in vivo effects of glycerol-compounded human DFDB on bone formation in the rat calvarial critical-sized defect (CSD) model. METHODS: Forty-eight adult male Harland Sprague-Dawley rats were assigned to one of four treatment groups: glycerol, DFDB, DFDB plus glycerol, or a non-grafted control, and placed into 8 mm calvarial CSDs. DFDB (particle size 0.106 to 0.5 mm), glycerol, and their combination were from identical sources. Calvaria were harvested at 8 weeks postsurgery and evaluated histomorphometrically. RESULTS: A statistically significant increased percentage of total bone fill was detected in the glycerol plus DFDB group and DFDB group as compared to glycerol group or the control. However, no significant difference was noted between the DFDB plus glycerol group and the DFDB group. CONCLUSION: The addition of glycerol to DFDB results in comparable osseous regeneration in the rat calvarium defect model versus DFDB alone; however, based upon clinical judgment, handling characteristics of DFDB were greatly improved.

Digital image analysis of cadaver mandibular trabecular bone patterns.

BACKGROUND: The purpose of this study was to investigate the source of radiographic trabecular patterns by removing trabecular bone in four sequential steps from six cadaver mandible sections, radiographing the sections after each removal, and using four digital-image analysis methods to quantify any resulting changes to the radiographs. METHODS: Mandible sections were cut sagittally into halves. Trabecular bone was removed from each section in four stages. Following each stage, standardized radiographs were taken, using direct digital equipment. Trabecular bone in the resulting digital images was measured with four methods. Mean gray level values (method 1) and cumulative percent histograms (method 2) were calculated from the raw data. Morphological image processing was used to skeletonize the trabecular structure, which was quantified by counting the number of trabecular ends and segments in the skeletonized images (method 3) and performing fractal analyses of the skeletonized images (method 4). Repeated measures analysis of variance (ANOVA) was used to test for changes in measurements attributable to bone removal. RESULTS: Repeated measures ANOVA indicated that the use of gray levels, cumulative percent histograms, and morphologic operators resulted in highly significant changes in measurements following bone removal (P < 0.01). Ends and segments demonstrated similar performance, with changes highly significant over time (P < 0.01). Fractal analysis also resulted in highly significant changes over time (P < 0.01). CONCLUSIONS: The analyses performed in this study demonstrated consistent image differences following the four steps of bone removal. These differences appeared whether light, cancellous bone or heavier endosteal bone was removed. These findings indicate that trabecular and endosteal bone combine to form the structure that most dentists identify as trabeculae on intraoral radiographs.

The effects of EDTA gel conditioning exposure time on periodontitis-affected human root surfaces: surface topography and PDL cell adhesion.

OBJECTIVE: The purpose of this investigation was to study the surface topography of periodontally-affected human roots following EDTA gel application at different time periods with and without scaling and root planing. In addition, to assess any correlations between root surface changes following EDTA gel conditioning and periodontal ligament fibroblast adhesion. METHODS: Forty-eight teeth that had a labial probing depth and clinical attachment loss of more than 7mm were used in this study. Periodontally-affected teeth were randomly divided into 4 groups of 12 teeth in each. Furthermore, a sample group of 6 teeth, which had a healthy periodontium, were used to serve as the healthy control (G1). The second group (G2) served as a diseased treated control in which sample teeth were only scaled and root planed prior to immediate extraction. Teeth in the third group (G3) were conditioned with a pH neutral, 24% Ethylenediaminetetraacetic acid (EDTA gel), for 2 minutes without any scaling or root planing and immediately extracted. The teeth in the fourth group (G4) were scaled, root planed, and then conditioned with the EDTA gel preparation for 2 minutes before immediate extraction. Finally the teeth in the fifth group (G5) were conditioned with EDTA gel for 4 minutes following scaling and root planing and immediately extracted. Half the samples in each group were randomly selected and processed for SEM evaluation of the surface topography. The other half were prepared to assess PDL cell adhesion with PDL fibroblasts being cultured and seeded on the root surface for 24 hours then processed for SEM evaluation of the adherent cells. RESULTS: SEM evaluation of the root planed surfaces in G2 revealed the typical appearance of a smear layer. The root surfaces of all samples in G3 exhibited a uniform coating of calculus that was covered by a considerable amount of loosely attached material including residual plaque and debris. In G4 EDTA gel exposure for 2-minutes following scaling and root planing resulted in removal of the smear layer and a marked exposure of round to oval dentinal tubule orifices. Areas of bacterial accumulation were observed in 4 out of the 6 samples examined in this group. The root surfaces after the 4-minute EDTA gel application (G5) had a fibrillar texture associated with a marked decrease in the number and an increased diameter of the exposed dentinal tubule openings. With regard to PDL cell adhesion, the majority of the 2-minute EDTA gel conditioning on the non-instrumented samples in G3, showed a failure of cells to adhere to the diseased root surface. The examined samples in G4 showed a significant increase in the number of flat and round adherent cells when compared to the diseased control samples (G2) (P > or = 0.01). The G5 samples showed a significant increase in the number of flat cells when compared to G4 (P > or = 0.01). CONCLUSION: The present study confirms the capability of EDTA gel to remove a root surface associated smear layer and to expose a collagen matrix when it was applied after scaling and root planing. In addition, a positive correlation was found between time of EDTA gel conditioning and the degree of PDL cell adhesion. It appears from the present investigation that EDTA gel conditioning for 4 minutes provides the most desirable root surface to which maximum PDL cells can adhere and on which they can grow.

Enhancement of osteoblast proliferation in vitro by selective enrichment of demineralized freeze-dried bone allograft with specific growth factors.

Decalcified freeze-dried bone allograft (DFDBA), believed to serve as a matrix for new bone growth and to contain various bone-inducing growth factors, is currently used to regenerate periodontal defects and to restore and maintain dental alveolar ridges. Growth factors within DFDBA are extracted during the demineralization process, thus rendering the allograft incapable of spontaneous osteogenesis; however, exogenous growth factor addition to DFDBA may enhance the osteogenic capacity of native osteoblasts. This study's purpose is to evaluate murine osteoblast proliferation in the presence of various exogenous soluble growth factors as measured by fluorescence units. Osteoblasts harvested from mouse pup calvaria were cultured with 2% residual calcium-DFDBA and supplemented by one of the following growth factors or combinations of these factors: transforming growth factor-beta (TGF-beta), insulin-like growth factor-I (IGF-I), platelet-derived growth factor (PDGF), fibroblast growth factors basic (bFGF), or vascular endothelial growth factors (VEGF). Osteoblast proliferation rates indicate that the in vitro supplementation of 2% residual calcium-DFDBA with the combination of IGF and TGF-beta, IGF and PDGF, and PDGF and TGF-beta significantly (P < or = .05) enhance murine osteoblast activity and proliferation at 7 days compared with the control containing no exogenous growth factors.

The effects of varying degrees of allograft decalcification on cultured porcine osteoclast cells.

BACKGROUND: Demineralized freeze-dried bone allograft (DFDBA) is widely used in periodontal therapy as a scaffold for new bone formation in periodontal defects. It is demineralized, theoretically, to expose osteoinductive or osteoconductive bone matrix proteins that should facilitate osteogenesis. The degree of DFDBA demineralization varies between tissue banks and may affect clinical regeneration. A 2% residual calcium level in DFDBA has been shown to result in the highest alkaline phosphatase activity levels in cultured human periosteal cells and is optimally osteoinductive or osteoconductive for new bone formation. The purpose of this study was to evaluate the effect of 4 different residual calcium levels in commercially available DFDBA samples on porcine osteoclast activity as measured by resorption on calcium phosphate-coated disks. METHODS: Bone marrow was harvested from the femurs of 3-week-old farm pigs and cultured for 3 weeks. Hematopoietic stem cells were allowed to differentiate into mature active polykaryons displaying genuine osteoclast characteristics. The osteoclast cells displayed a dense actin band inside the margins of the cytoplasm under light microscopy. Culture media was decanted and collagenase added to free the attached cells. Equal cell samples were pipetted onto calcium phosphate-coated disks in 24-well plates. DFDBA samples with 1.44%, 2.41%, and 5.29% residual calcium; FDBA (30% residual calcium); and control cultures without allograft samples were prepared and all samples incubated for 1 week. Cells were fixed and stained for tartrate-resistant acid phosphatase (TRAP), Oregon Green 488-phalloidin, a stain for cytoskeletal proteins, and counterstained with propidium iodide. Specimens were examined by light and fluorescence microscopy using epi-illumination. Calcium phosphate disks were then rinsed in 5% sodium hypochlorite to remove adherent osteoclasts, and substrate surface changes were measured by white light interferometry and image analysis. RESULTS: A higher yield of TRAP-positive cells was produced without DFDBA; however, resorptive activity appears to be significantly increased in the presence of 2.41% residual calcium as compared to all other experimental groups (P<0.0065). CONCLUSION: In this in vitro model, porcine osteoclasts show significantly more resorptive activity as measured on calcium phosphate-coated disks in the presence of 2.41% residual calcium in DFDBA than in other DFDBA residual calcium levels.