rhBMP-2 significantly enhances guided bone regeneration

BACKGROUND: Previous studies have shown a limited potential for bone augmentation following guided bone regeneration (GBR) in horizontal alveolar defects. Surgical implantation of recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge carrier (ACS) significantly enhances bone regeneration in such defects; however, sufficient quantities of bone for implant dentistry are not routinely obtained. The objective of this study was to evaluate the potential of rhBMP-2/ACS to enhance GBR using a space-providing, macro-porous expanded polytetrafluoroethylene (ePTFE) device. METHODS: Bilateral, critical size, supra-alveolar, peri-implant defects were surgically created in four Hound Labrador mongrel dogs. Two turned and one surface-etched 10-mm titanium dental implant were placed 5 mm into the surgically reduced alveolar ridge creating 5-mm supra-alveolar defects. rhBMP-2/ACS (rhBMP-2 at 0.2 mg/ml) or buffer/ACS was randomly assigned to left and right jaw quadrants in subsequent animals. The space-providing, macro-porous ePTFE device was placed to cover rhBMP-2/ACS and control constructs and dental implants. Gingival flaps were advanced for primary wound closure. The animals were euthanized at 8 weeks postsurgery for histologic and histometric analysis. RESULTS: Bone formation was significantly enhanced in defects receiving rhBMP-2/ACS compared to control. Vertical bone gain averaged (+/- SD) 4.7 +/- 0.3 and 4.8 +/- 0.1 mm, and new bone area 10.3 +/- 2.0 and 8.0 +/- 2.5 mm2 at turned and surface-etched dental implants, respectively. Corresponding values for the control were 1.8 +/- 2.0 and 1.3 +/- 1.3 mm, and 1.8 +/- 1.3 and 1.2 +/- 0.6 mm2. Bone-implant contact in rhBMP-2-induced bone averaged 6.4 +/- 1.4% and 9.6 +/- 7.5% for turned and surface-etched dental implants, respectively (P=0.399). Corresponding values for the control were 14.6 +/- 19.4% and 23.7 +/- 9.7% (P=0.473). Bone-implant contact in resident bone ranged between 43% and 58% without significant differences between dental implant surfaces. CONCLUSIONS: rhBMP-2/ACS significantly enhances GBR at turned and surface-etched dental implants. The dental implant surface technology does not appear to substantially influence bone formation.     

A chewing gum containing 7.5% sodium hexametaphosphate inhibits stain deposition compared with a placebo chewing gum

The 2-period, randomized, double-blind, placebo-controlled, crossover study compared the stain-prevention and stain-removal benefit of a chewing gum containing 7.5% sodium hexametaphosphate (measured by digital image analysis) with a placebo chewing gum. The results of this study support that sodium hexametaphosphate delivered from a chewing gum prevents dental stain formation and facilitates stain removal, which leads to a perceptible whitening benefit. The long-term clinical benefits of sodium hexametaphosphate delivered from chewing gum have not been reported in the literature.     

Microbial complexes detected in the second/third molar region in patients with asymptomatic third molars.

PURPOSE: Our goal was to report the detection and levels of pathogenic bacteria in subgingival plaque samples taken from the distal of all second molars in 295 patients with asymptomatic third molars. PATIENTS AND METHODS: Data assessing oral health were collected from each of these healthy patients (ASA Classes I and II). Probing depth (PD), at 6 sites per tooth, including third molars, was obtained to determine periodontal status. Subgingival plaque samples were taken from the distal of all second molars before periodontal probing. The presence and levels of 11 bacterial species were determined using whole chromosomal DNA probes and checkerboard DNA-DNA hybridization. Detected bacterial species were grouped into clusters of periodontal pathogens designated as "red" or "orange" complex microorganisms as described by Socransky et al (J Clin Periodontal 25:134, 1998) who found an association of these specific microorganisms with periodontitis. RESULTS: As a group these relatively young patients were periodontally healthy. "Orange and red" complex microorganisms were detected at levels equal to or greater than 10(5) more often if patients had a PD equal to or greater than 5 mm with periodontal attachment loss at the distal of second molars or around third molars at their entry examination. In patients with no PD equal to or greater than 5 mm in the third molar region, "orange and red" complex microorganisms were detected at levels equal to or greater than 10(5) more frequently than would be anticipated in patients with little clinical evidence of periodontal disease. CONCLUSIONS: The clinical findings of increased periodontal PDs and periodontal attachment loss coupled with colonization of periodontal pathogens support the concept that clinical and microbial changes associated with the initiation of periodontitis may present first in the third molar region in young adults.     

Elevated antibody to D-alanyl lipoteichoic acid indicates caries experience associated with fluoride and gingival health

Background  

Acidogenic, acid-tolerant bacteria induce dental caries and require D-alanyl glycerol lipoteichoic acid (D-alanyl LTA) on their cell surface. Because fluoride inhibits acid-mediated enamel demineralization, an elevated antibody response to D-alanyl LTA may indicate subjects with more acidogenic bacteria and, therefore, an association of DMFT with fluoride exposure and gingival health not apparent in low responders.     

Assessment of the oral health related quality of life of patients awaiting initial prosthetic assessment

The aim of the study was to quantify the impact of oral health problems on the quality of life of patients who were experiencing difficulties with dentures. Two hundred and ten patients who were awaiting an initial specialist assessment appointment were asked to complete the short form Oral Health Impact Profile (OHIP-14). One hundred and sixty three (78%) questionnaires were completed correctly and were analyzed. Overall, the prevalence of impacts was high in all sub-scales, indicating that denture related problems had a negative impact on quality of life of both partially dentate and elderly patients.     

Electron microscopic study of the regeneration of cementum and periodontal connective tissue attachment in the cat

Regeneration of periodontal connective tissue attachment was studied at the ultrastructural level in cats following the removal of cementum and superficial dentin through a surgically created fenestration in the facial alveolar plate. Non-decalcified specimens were examined 33, 45, 70, and 105 days after surgery. In early stages of healing, fibroblasts were aligned parallel, and immediately adjacent, to the cut, irregular dentin surface; subsequently, collagenous matrix formation was observed at this site. Some regions of the defects showed surface demineralization and extension of collagen into dentinal tubules. The first indication of cementum mineralization was the deposition of small crystallites along the irregularities of the dentin surface. After further development, a well-defined zone containing c1osel packed crystallites was usually evident at the new dentin-cementum junction. Peripheral to this, collagen orientation in the calcified cementum was primarily parallel to the tooth surface, with some perpendicular orientation suggestive of Sharpey's fiber formation. Collagen-mineral patterns typical of the normal cementum surface were observed, and cementoblasts were seen in various stages of inclusion into the calcified matrix. Where the injury had not reached the dentin, collagen fibrils of new and old cementum were interwoven, and the junctional region demonstrated incomplete mineralization.     

A clinical study of horizontal jaw relationships in edentulous patients

Six methods of registering horizontal jaw relationships were investigated on 13 edentulous patients in order to find the consistency of each method and any differences in location between them.

Graphical recordings were made using intra-oral acrylic resin appliances. The upper appliance incorporated a central bearing point and the lower a recess for accommodating interchangeable steel plates. Each tracing was made on a separate plate which had been painted with blue layout fluid. The recordings were measured on a modified microscope to give mediolateral and anteroposterior readings.

The results showed that the active gothic arch tracing method was the most consistent of the methods studied. Passive retruded closure and active closure from rest position showed low consistency in comparison. Passive retruded closure was recorded an average of 0·21 mm posteriorly to the active gothic arch tracing. Active closure from rest position was recorded an average of 0·63 mm anteriorly to the active gothic arch tracing.     

Efficacy of bisphosphonates for the control of alveolar bone loss in periodontitis

Periodontal disease is characterized by periodontal bone loss. For this reason, we conducted a study to test the effect of alendronate (ALN), an inhibitor of bone resorption, on alveolar bone mass. A total of 335 patients with periodontal disease (men = 162, women = 173), aged 30 to 79, were randomized to either placebo or ALN 70 mg once weekly. All patients received prophylaxis at baseline, and at 6, 12, and 18 months. Smokers accounted for 62% of patients, and 71% of the patients had severe periodontal disease. The primary efficacy endpoint was the change in alveolar bone loss (ABL). When all subjects were analyzed, 2 years of treatment with alendronate 70 mg once weekly did not significantly change either ABL or alveolar bone density (ABD) relative to placebo. However, in the subgroup of patients with low mandibular bone mineral density (BMD) at baseline, alendronate significantly reduced bone loss relative to placebo (p < 0.01). No such effect was seen in patients with normal baseline mandibular BMD. The overall and upper gastrointestinal safety and tolerability profile of alendronate after 2 years of treatment was very favorable compared to placebo. No cases of osteonecrosis of the jaw were observed. In summary, in patients with periodontal disease receiving prophylaxis, alendronate 70 mg once weekly was well tolerated, but did not have a detectable effect on alveolar bone loss, except in those patients with low mandibular BMD at baseline.