Qualitative and quantitative expression of bovine bone mineral in experimental bone defects. Part 1: Description of a dog model and histological observations

BACKGROUND: The purpose of this study was to evaluate histologically the contribution of inorganic bovine bone biomaterial in a new experimental bone defect in dogs at different healing periods and to examine newly formed bone around the grafted mineral particles and their relationship in membrane-protected (test) and non-protected intrabony (control) defects. METHODS: Four round intrabony defects, 5 x 4 mm were made bilaterally (at different times) on the lateral bony mandibular angle in eight dogs. Two defects were filled with bovine bone mineral (BBM) particles and two remained non-grafted but were blood clotted. A collagen membrane covered each defect type (n = 4). This procedure was repeated on the contralateral side at a different given time to obtain two different healing periods in each dog. Thus, four specimens were obtained at 3, 6, 12, and 24 months postoperatively for each healing period. The non-decalcification method (Donath technique) with Stevenel's blue and van Gieson's picro fuchsin staining was used for histological examination. RESULTS: Newly formed bone was observed at all examined defect types. The BBM particles were clearly evident regardless of the healing period. At 3 and 6 months, newly formed bone, woven in nature, was incorporated with the grafted particles. High cellular bone with occasional osteoclasts was noted towards the surface of the mineral particles. No substantial difference was observed between the protected and the non-protected defects except for higher ossified centers around the membrane-protected defects. At the non-grafted sites, the membrane-protected defect showed newly formed bone near the bony walls, and particularly under the membrane, establishing a bony bridge over the defect at the healing periods. The non-grafted unprotected defect (control) showed bone formation only at the base and close to the bony walls leaving a healed concave configuration. At 1 and 2 years, the grafted sites showed full bone healing configuration. However, the grafted particles still dominated the previous defect area and were completely surrounded by the newly formed bone. Osteons and lamellar bone arrangement were established but the bone was still highly cellular and osteoclasts could still be identified. The non-grafted membrane-protected sites showed excellent bone healing although areas of non-mineralized soft tissue were often seen. The control sites healed but still presented with a concave surface configuration. CONCLUSIONS: BBM biomaterial is a highly osteoconductive material. In a 4-wall bony defect, newly formed bone was well evident in establishing excellent bone healing configuration with or without a regenerative biological barrier. The grafted material dominated the experimental sites with no substantial resorption at any healing period up to 2 years observation.     

Local application of n-3 or n-6 polyunsaturated fatty acids in the treatment of human experimental gingivitis

BACKGROUND: Polyunsaturated fatty acids have the potential to attenuate inflammation by the synthesis of mediators of the 15-lipoxygenase pathways, which show opposite effects to the pro-inflammatory arachidonic acid metabolites such as leukotriene B4 (LTB4). AIMS: The aim of this clinical study was to evaluate the effects of topical application of n-6 or n-6 polyunsaturated fatty acids in patients with experimental gingivitis. METHODS: In each subject, similar teeth served as experimental and control over a 21-day non-hygiene phase and a 9-day resolving phase. Efficacy assessment was based on the bleeding on probing frequency (BOP) and the gingivocrevicular fluid volume (GCF). GCF was determined by inserting a filter paper strip for 30 s and measurements were performed on a Periotron 8000. The LTB4 concentration was analyzed by reversed-phase high-pressure liquid chromatography. RESULTS: After 21 days of plaque growth, the BOP, GCF and LTB4 levels were significantly increased in all groups, with no differences between the control and experimental side. Rinsing of an area with established gingivitis for a 9-day period significantly reduced the GCF in the n-6 group (71.9 (18.7) versus 47.4 (11.4) Periotron Units, median (inter quartile range)). CONCLUSION: The topical application of n-6 or n-6 fatty acids failed to inhibit the development of experimental gingivitis. Rinsing with n-6 fatty acids could reduce the level of GCF in established experimental gingivitis.     

Prospective evaluation of implants connected to teeth

PURPOSE: This prospective clinical trial examined the effect on teeth and implants when rigidly or non-rigidly connected in a cross-arch model. MATERIALS AND METHODS: Thirty patients received 2 implants, 1 on each side of the mandible, and were restored with 3-unit fixed partial dentures connected either rigidly or non-rigidly to an abutment tooth. Patients were followed for at least 5 years post-restoration. RESULTS: Repeated-measures analysis revealed no significant difference in crestal bone loss at implants (rigid versus non-rigid methods). An overall significant difference (P < .001) was found comparing methods for teeth. Paired t tests revealed no significant differences in crestal bone levels for implants or teeth at the 5-year recall. Kaplan-Meier methods and the Cox proportional hazards model showed no differences between attachment methods with regard to success based on survival and bone loss criteria. During the 5-year recall period, 1 implant (rigid side) was removed. Four implants developed bone loss greater than 2 mm during the course of this trial. One tooth on the rigid side and 2 teeth on the non-rigid side had greater than 2 mm of crestal bone loss and were removed secondary to fractures. In all, 5 abutment teeth were removed, all of which had been treated with root canal therapy and fractured at the interface of the post within the tooth. There was no clear relationship of tooth fracture to attachment. Repeated-measures analysis of mobility values revealed no significant changes over the time course of this study, and paired t tests revealed no statistically significant differences between implants for mobility. Repeated-measures analysis and paired t tests for probing depth revealed no significant changes over the time course of this study. There were no significant differences in soft tissue indices for either attachment method. The percentage of patients who had measurable intrusion was 66% for the non-rigid group, and 44% for the rigid group; 25% of the non-rigid teeth had greater than 0.5 mm intrusion, compared with 12.5% for the rigid group. For the 2 time periods evaluated, there was no significant increase in intrusion over time. The non-rigid-side implant required more nonscheduled visits to treat problems than the rigid implant and the teeth. Discussion: Most patients were treated successfully with rigid or non-rigid attachment of implants to teeth. CONCLUSION: The high incidence of intrusion and non-scheduled patient visits suggest that alternative treatments without connecting implants to teeth may be indicated.     

2.1 Evolving methods of assessment

This Working Section is concerned with evolving methods of assessment in dental education. It focuses on newer methods of assessment that might have relevance for broader application. Although it cannot provide answers to all the questions it raises, it is hoped that the contribution it makes is of value in the process of the development of a global network in dental education.     

The potential role of dentists in identifying patients' risk of experiencing coronary heart disease events

BACKGROUND: A substantial proportion of people with risk factors for cardiovascular disease (CVD) are not identified before they develop clinical signs and symptoms. A multidisciplinary approach that includes a cardiovascular screening by oral health care providers can affect the identification of people at risk of experiencing cardiovascular events. METHODS: The authors extracted data from the 1999-2000 National Health and Nutrition Examination Survey (NHANES) and the 2001-2002 NHANES for people aged 40 to 85 years with no reported specific risk factors for coronary heart disease (CHD) and who had not seen a physician in the previous 12 months but had seen a dentist. They used these data to estimate the 10-year Framingham-based risk calculation scores for each subject to determine their global risk of experiencing acute CHD events. RESULTS: Eighteen percent of the male subjects had an increased 10-year global risk of experiencing a CHD event (> 10 percent risk score), 14.3 percent had a moderate, above-average risk score (> 10-< 20 percent), and an additional 4.3 percent had a high risk score (> or = 20 percent). Only one female subject had a risk score greater than 10 percent. When the authors extrapolated these results to the 2000 U.S. census data, they found that among men aged 40 to 85 years without reported risk factors who had not seen a physician but had seen a dentist in the previous 12 months, 332,262 had a greater than 10 to less than 20 percent risk of experiencing a CHD event, and 72,625 had a 20 percent or greater 10-year risk of experiencing a CHD event. CONCLUSION: Dentists can play an important role in identifying people in need of primary prevention strategies for CVD.     

Platelet-derived growth factor stimulates bone fill and rate of attachment level gain: results of a large multicenter randomized controlled trial

BACKGROUND: Growth factors are generally accepted to be essential mediators of tissue repair via well-established mechanisms of action that include stimulatory effects on angiogenesis and cellular proliferation, ingrowth, differentiation, and matrix biosynthesis. The aim of this study was to evaluate in a large-scale, prospective, blinded, and randomized controlled clinical trial the safety and effectiveness of purified recombinant human platelet-derived growth factor (rhPDGF-BB) mixed with a synthetic beta-tricalcium phosphate (beta-TCP) matrix for the treatment of advanced periodontal osseous defects at 6 months of healing. METHODS: Eleven clinical centers enrolled 180 subjects, each requiring surgical treatment of a 4 mm or greater intrabony periodontal defect and meeting all inclusion and exclusion criteria. Subjects were randomized into one of three treatment groups: 1) beta-TCP + 0.3 mg/ml rhPDGF-BB in buffer; 2) beta-TCP + 1.0 mg/ml rhPDGF-BB in buffer; and 3) beta-TCP + buffer (active control). Safety data were assessed by the frequency and severity of adverse events. Effectiveness measurements included clinical attachment levels (CAL) and gingival recession (GR) measured clinically and linear bone growth (LBG) and percent bone fill (% BF) as assessed radiographically by an independent centralized radiology review center. The area under the curve (AUC), an assessment of the rate of healing, was also calculated for CAL measurements. The surgeons, clinical and radiographic evaluators, patients, and study sponsor were all masked with respect to treatment groups. RESULTS: CAL gain was significantly greater at 3 months for group 1 (rhPDGF 0.3 mg/ml) compared to group 3 (beta-TCP + buffer) (3.8 versus 3.3 mm; P = 0.032), although by 6 months, this finding was not statistically significant (P = 0.11). This early acceleration of CAL gain led to group 1 exhibiting a significantly greater rate of CAL gain between baseline and 6 months than group 3 as assessed by the AUC (68.4- versus 60.1-mm weeks; P = 0.033). rhPDGF (0.3 mg/ml)-treated sites also had significantly greater linear bone gain (2.6 versus 0.9 mm, respectively; P < 0.001) and percent defect fill (57% versus 18%, respectively; P < 0.001) than the sites receiving the bone substitute with buffer at 6 months. There was less GR at 3 months in group 1 compared to group 3 (P = 0.04); at 6 months, GR for group 1 remained unchanged, whereas there was a slight gain in gingival height for group 3 resulting in comparable GR. There were no serious adverse events attributable to any of the treatments. CONCLUSIONS: To our knowledge, this study is the largest prospective, randomized, triple-blinded, and controlled pivotal clinical trial reported to date assessing a putative periodontal regenerative and wound healing therapy. The study demonstrated that the use of rhPDGF-BB was safe and effective in the treatment of periodontal osseous defects. Treatment with rhPDGF-BB stimulated a significant increase in the rate of CAL gain, reduced gingival recession at 3 months post-surgery, and improved bone fill as compared to a beta-TCP bone substitute at 6 months.     

Template fabrication for a midpalatal orthodontic implant: technical note

An implant has been developed as an adjunct to conventional orthodontic anchorage. Planning is advisable to determine the available bone and soft tissue thickness and the optimum position for orthodontic utilization. A simple method is described for fabrication of a radiographic and surgical template to aid in optimal placement of the implant.     

Repair of alveolar clefts with recombinant human bone morphogenetic protein (rhBMP-2) in patients with clefts

This article demonstrates the feasibility of using recombinant human bone morphogenetic protein (rhBMP-2) as a substitute for autogenous iliac crest bone for repair of congenital facial clefts in humans. In this series, 50 cleft sites were repaired in 43 patients using rhBMP-2 without the use of autogenous graft tissue. Successful osseous union was achieved in 49 of the 50 sites. In one patient, the graft failed to consolidate. Severe clefts were managed by combining distraction osteogenesis and rhBMP-2. Eliminating the need to harvest autogenous iliac crest bone resulted in substantial decrease in morbidity. The constructed alveolus performed clinically as normal bone and responded to natural tooth eruption and orthodontic movement. Histology of the tissue constructed showed normal, vital bone. Although additional investigation is warranted to determine the optimum protocol for the use of this material in alveolar cleft repair, the technique should be considered as a viable treatment option in cases in which avoiding iliac crest harvesting is desirable.     

Osteotome-mediated sinus floor elevation: a clinical report

PURPOSE: It was the aim of the present study to clinically evaluate the success of osteotome-mediated sinus floor elevation (OMSFE) using autogenous and xenogenic bone and a variety of screw-type implants. MATERIALS AND METHODS: From August 1995 to February 2003, 276 OMSFE procedures with simultaneous implant placement were completed in 167 patients. RESULTS: The mean residual bone height (RBH) of the alveolar ridge was 7.1 mm (range 3 to 10 mm). The mean increase in height of the implant sites using osteotome techniques was 3.8 mm (range 2 to 7 mm). Of the 276 implants placed, 240 had been loaded for an average of 27.9 months (range 1 to 84 months). There were a total of 18 failures: Ten implants failed to integrate, 3 implants were lost within the first 18 months of loading, 1 implant fractured after 3 years in function, and 4 implants demonstrated excessive bone loss. The overall survival rate was 93.5%. When only sites with an RBH of 4 mm or less were considered, the survival rate dropped to 73.3%. Small tears in the schneiderian membrane were clinically assessed at 13 sites, for a detectable perforation rate of 4.7%. DISCUSSION: The primary determinant in implant survival with OMSFE procedures was the height of the residual alveolar ridge. Implant design, graft material, and the method of sinus floor infracture (direct or bone-cushioned) exerted minimal influence on survival outcome; however, factors such as edentulism, osteoporosis, and an overdenture prosthesis were shown to negatively influence postloading survival of implants placed in areas of limited RBH. CONCLUSION: OMSFE procedures can be used predictably for implant placement at sites with moderate vertical deficiencies in the posterior maxilla.