Thomas W. Oates

Pivotal, Randomized, Parallel Evaluation of Recombinant Human Bone Morphogenetic Protein-2/Absorbable Collagen Sponge and Autogenous Bone Graft for Maxillary Sinus Floor Augmentation

PURPOSE The purpose of this prospective study was to evaluate the safety and effectiveness of recombinant human morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge (ACS) compared with an autogenous bone graft when used for 2-stage maxillary sinus floor augmentation. The study assessed new bone formation, placement integration, and functional loading after 6 months and long term for 2 years. MATERIALS AND METHODS A total of 160 subjects were randomized, enrolled, and followed from January 1999 to February 2004 at 21 centers in the United States. The subjects with less than 6 mm of native bone height were treated with 1.50 mg/mL rhBMP-2/ACS or with an autograft. The height and density measurements were quantified by computed tomography scans. Core biopsies were obtained at dental implant placement and used for histological analysis. Safety was evaluated by oral examinations, radiographs, serum chemistries, and hematology. RESULTS A significant amount of new bone was formed by 6 months postoperatively in each group. The mean change in bone height in the rhBMP-2/ACS subjects was 7.83 +/- 3.52 mm versus 9.46 +/- 4.11 mm for the bone graft subjects. At 6 months after dental restoration, the induced bone in the rhBMP-2/ACS group was significantly denser than that in the bone graft group. No marked differences were found in the histologic parameters evaluated between the 2 groups. The new bone was comparable to the native bone in density and structure in both groups. The success rate for the rhBMP-2/ACS group was 79% (64 of 81 subjects), and 201 of 251 implants placed in the bone graft group and 199 of 241 implants placed in the rhBMP-2/ACS group were integrated, retained, and functional at 6 months after loading. No adverse events were deemed related to the rhBMP-2/ACS treatment. The autograft group was noted to have a 17% rate of long-term parasthesia, pain, or gait disturbance related to the bone graft harvest. CONCLUSIONS The results of our multicenter, randomized, prospective, clinical trial have shown the effectiveness and safety of rhBMP-2/ACS compared with bone graft for sinus floor augmentation. The studys primary endpoint was exceeded, and the implants placed in rhBMP-2/ACS and bone graft groups performed similarly after functional loading.

Review of osteoimmunology and the host response in endodontic and periodontal lesions

Abstract Both lesions of endodontic origin and periodontal diseases involve the host response to bacteria and the formation of osteolytic lesions. Important for both is the upregulation of inflammatory cytokines that initiate and sustain the inflammatory response. Also important are chemokines that induce recruitment of leukocyte subsets and bone-resorptive factors that are largely produced by recruited inflammatory cells. However, there are differences also. Lesions of endodontic origin pose a particular challenge since that bacteria persist in a protected reservoir that is not readily accessible to the immune defenses. Thus, experiments in which the host response is inhibited in endodontic lesions tend to aggravate the formation of osteolytic lesions. In contrast, bacteria that invade the periodontium appear to be less problematic so that blocking arms of the host response tend to reduce the disease process. Interestingly, both lesions of endodontic origin and periodontitis exhibit inflammation that appears to inhibit bone formation. In periodontitis, the spatial location of the inflammation is likely to be important so that a host response that is restricted to a subepithelial space is associated with gingivitis, while a host response closer to bone is linked to bone resorption and periodontitis. However, the persistence of inflammation is also thought to be important in periodontitis since inflammation present during coupled bone formation may limit the capacity to repair the resorbed bone.

Glycemic Control and Implant Stabilization in Type 2 Diabetes Mellitus

Diabetes mellitus is considered a relative contra-indication for implant therapy. However, the effect of glycemic level on implant integration in persons with diabetes remains poorly understood. The hypothesis of this research was that poor glycemic control is directly related to short-term-impairment implant stabilization. This prospective clinical study evaluated 10 non-diabetic individuals (12 implants) and 20 persons with type 2 diabetes (30 implants). Glycated hemoglobin (HbA1c) levels ranged from 4.7–12.6%. Implant stability was assessed by resonance frequency analysis over 4 months following placement. Minimum stability levels were observed 2–6 weeks following placement for all 42 implants. Persons with HbA1c ≥ 8.1% had a greater maximum decrease in stability from baseline and required a longer time for healing, as indicated by return of stability level to baseline. This study demonstrates alterations in implant stability consistent with impaired implant integration for persons with type 2 diabetes mellitus in direct relation to hyperglycemic conditions.

A prospective multicenter 5-year radiographic evaluation of crestal bone levels over time in 596 dental implants placed in 192 patients

BACKGROUND Dental implants have been used to replace missing teeth to provide function and esthetics. One goal of such restorations is to maintain host tissue around the implants. The purpose of this prospective multicenter human clinical trial was to evaluate radiographic marginal bone levels around non-submerged hollow cylindrical and solid-screw implants for 5 years after loading. METHODS Patients older than 18 years of age with sufficient native bone to surround a dental implant without imposing on a vital structure were recruited at five sites. Solid-screw or hollow-cylinder implants with a titanium plasma-sprayed implant surface were placed in the anterior maxilla or anterior mandible and restored with fixed restorations. Baseline radiographs were taken at the time of implant placement. Subsequent radiographs were taken at the time of final prosthesis placement, at 6 months after prosthesis placement, and annually from prosthesis placement for 5 years. RESULTS The results of 596 implants in 192 patients at five international sites revealed that clinically significant remodeling of the marginal bone occurred during the first 6 months after implant placement, with a mean (+/- SD) marginal bone loss of 2.44 +/- 1.20 mm. After that, clinically insignificant mean changes in the bone were observed. Overall, 0.22 +/- 0.42 mm of bone loss occurred between the time of prosthesis placement and 1-year postloading. Between 1-year postloading and the last 5-year recall, 0.18 +/- 0.88 mm bone loss occurred. Because 2.84 +/- 1.63 mm of bone loss occurred between implant placement and the 5-year postloading follow-up, 86% of the total mean bone loss over the course of 5 years was accounted for at the time of prosthesis placement. These same trends occurred if the data were analyzed with regard to implant design (solid screw and hollow cylinder), type of restoration (single and multiple), and length of implant (8 to 10, 12, and 14 to 16 mm). CONCLUSIONS These data demonstrate that, in general, clinically significant marginal bone remodeling occurred between the time of implant placement and final prosthesis placement around one-stage non-submerged titanium implants with a titanium plasma-sprayed surface. Subsequent to that, bone loss observed around implants up to 5 years postloading was minimal. These results suggest that the factors that influence early healing around implants are significantly different from those that affect later marginal bone remodeling.

Long-term changes in soft tissue height on the facial surface of dental implants.

The success of osseous healing around dental implants has allowed for an increased emphasis on soft tissue healing and esthetic results. However, there is limited information profiling the long-term healing of the soft tissues following prosthesis placement. The purpose of this study was to assess the long-term changes in the position of the facial soft tissue margins following restoration of a one-stage implant system. One hundred and six one-stage ITI implants were evaluated in 39 patients. Implants were placed in maxillary and mandibular anterior regions. Clinical assessment of the soft tissues on the midfacial aspect of the implants was performed over a 2-year period, at 3 and 6 month intervals, following placement of the final restoration. A total of 63 implants were placed as multiple units in the mandible, 23 as single units in the maxilla, and 20 as multiple units in the maxilla. There were no implant failures over this time period. Overall, on the facial aspect of 61% of the 106 implants there was 1 mm or more of soft tissue recession, whereas 19% of the implants showed 1 mm or more of gain in soft tissue height. There was a significantly (P < 0.01) greater number of implants showing a gain in soft tissue levels in the mandibular implants compared with the maxillary implants. Of the 39 patients assessed, 24 showed a loss and five showed a gain of 1 mm or more of the soft tissue levels around the implants. Overall, there was a significant decrease in the mean levels of tissue height of 0.6 mm within the first 6 months, with relatively little change afterward. However, in evaluating only patients showing a loss in tissue height around one or more implants, the mean loss in tissue height was 1.6 mm after 24 months. These results suggest that the potential for significant changes in soft tissue levels after completion of restorative therapy need to be considered for implant therapy in esthetic areas.

A Critical Review of Diabetes, Glycemic Control and Dental Implant Therapy

OBJECTIVES To systematically examine the evidence guiding the use of implant therapy relative to glycemic control for patients with diabetes and to consider the potential for both implant therapy to support diabetes management and hyperglycemia to compromise implant integration. MATERIAL AND METHODS A systematic approach was used to identify and review clinical investigations directly assessing implant survival or failure for patients with diabetes. A MEDLINE (PubMED) database search identified potential articles for inclusion using the search strategy: (dental implants OR oral implants) AND (diabetes OR diabetic). Inclusion in this review required longitudinal assessments including at least 10 patients, with included articles assessed relative to documentation of glycemic status for patients. RESULTS Although the initial search identified 129 publications, this was reduced to 16, for inclusion. Reported implant failure rates for diabetic patients ranged from 0% to 14.3%. The identification and reporting of glycemic control was insufficient or lacking in 13 of the 16 studies with 11 of these enrolling only patients deemed as having acceptable glycemic control, limiting interpretation of findings relative to glycemic control. Three of the 16 studies having interpretable information on glycemic control failed to demonstrate a significant relationship between glycemic control and implant failure, with failure rates ranging from 0% to 2.9%. CONCLUSIONS Clinical evidence is lacking for the association of glycemic control with implant failure while support is emerging for implant therapy in diabetes patients with appropriate accommodations for delays in implant integration based on glycemic control. The role for implants to improve oral function in diabetes management and the effects of hyperglycemia on implant integration remain to be determined.

Diabetes and oral disease: implications for health professionals

“Diabetes and Oral Disease: Implications for Health Professionals” was a one‐day conference convened by the Columbia University College of Dental Medicine, the Columbia University College of Physicians and Surgeons, and the New York Academy of Sciences on May 4, 2011 in New York City. The program included an examination of the bidirectional relationship between oral disease and diabetes and the interprofessional working relationships for the care of people who have diabetes. The overall goal of the conference was to promote discussion among the healthcare professions who treat people with diabetes, encourage improved communication and collaboration among them, and, ultimately, improve patient management of the oral and overall effects of diabetes. Attracting over 150 members of the medical and dental professions from eight different countries, the conference included speakers from academia and government and was divided into four sessions. This report summarizes the scientific presentations of the event.a

The effects of elevated hemoglobin A1c in patients with type 2 diabetes mellitus on dental implants

BACKGROUND The authors conducted a prospective cohort study to determine whether poor glycemic control is a contraindication to implant therapy in patients with type 2 diabetes. METHODS The study sample consisted of 117 edentulous patients, each of whom received two mandibular implants, for a total of 234 implants. Implant-retained mandibular overdentures were loaded after a four-month healing period and followed up for an additional one year. The authors assessed implant survival and stability (by means of resonance frequency analysis) relative to glycated hemoglobin A1c (HbA1c) levels, with baseline levels up to 11.1 percent and levels as high as 13.3 percent over one year. RESULTS Implant survival rates for 110 of 117 patients who were followed up for one year after loading were 99.0 percent, 98.9 percent and 100 percent, respectively, for patients who did not have diabetes (n = 47), those with well-controlled diabetes (n = 44) and those with poorly controlled diabetes (n = 19). The authors considered the seven patients lost to follow-up as having had failed implants; consequently, their conservative estimates of survival rates in the three groups were 93.0 percent, 92.6 percent and 95.0 percent (P = .6510). Two implants failed at four weeks, one in the nondiabetes group and the other in the well-controlled diabetes group. Delays in implant stabilization were related directly to poor glycemic control. CONCLUSIONS The results of this study indicate that elevated HbA1c levels in patients with type 2 diabetes were not associated with altered implant survival one year after loading. However, alterations in early bone healing and implant stability were associated with hyperglycemia.

A 5-Year Prospective Multicenter Clinical Trial of Non-Submerged Dental Implants With a Titanium Plasma-Sprayed Surface in 200 Patients

BACKGROUND Endosseous dental implants are a popular treatment to replace missing teeth. Although many advances have occurred and affected the macrogeometry and surface characteristics of dental implants, among other aspects, it is important to document how the implants perform in patients over time. Such evaluations are helpful not only to document the clinical survival of the implants but also patient satisfaction over an extended period. METHODS A formal prospective multicenter human clinical was performed at five centers involving 200 patients and 626 implants. Specific inclusion and exclusion criteria were used and detailed data collected at specified times using case report forms. An independent study monitor reviewed all study data before entry into the study database. Two implant designs were used in two different clinical indications. A non-submerged titanium plasma-sprayed (TPS) hollow cylindrical implant with a smooth transgingival collar was evaluated in the maxillary anterior sextant and a non-submerged TPS solid screw implant with similar collar in the mandible. RESULTS Over the course of the 5-year clinical trial, there was one early failure occurring before definitive prosthesis delivery. Three late failures were documented, one occurring at each of the 6, 12, and 18 months postoperative visits. Life table analysis at 5 years revealed a 99.4% survival rate and a 92.5% success rate. Patient satisfaction was rated as good to excellent for 96.1% of implants in regards to esthetics after 5 years; 98.8% for appearance; and 99.4% for prosthesis comfort, ability to chew and taste, fit, and general satisfaction. No serious adverse events were reported. CONCLUSIONS Implant success and survival was over 92% and 99%, respectively, in a formal 5-year prospective multicenter clinical trial involving 200 patients and 626 non-submerged TPS implants. These implants included hollow cylinder implants in the anterior maxilla and solid screw implants placed in the mandible. These findings document the predictability and patient satisfaction of tooth replacement using a non-submerged surgical technique involving a tissue-level, rough surfaced endosseous dental implant.

Relation between smoking and biomarkers of bone resorption associated with dental endosseous implants.

The aim of this study was to determine the effects of smoking on pyridinoline concentrations in crevicular fluid collected from around dental implants. Samples of crevicular fluid were collected from 4 sites around each implant and tooth, if present, for a group of 16 patients using methylcellulose strips. Samples were collected from 104 implants and 49 teeth. Eight of the 16 patients were current smokers. Crevicular fluid samples were eluted from methylcellulose strips using phosphate-buffered saline containing 0.1% bovine serum albumin and centrifugation. Pyridinoline was quantified using a competitive enzyme immunoassay. Results showed that there were statistically insignificant differences between the amounts of pyridinoline (mean ± standard deviation [SD]) around teeth of nonsmokers versus smokers (0.011 ± 0.003 and 0.014 ± 0.006 nmol/L, respectively). However, the mean (± SD) pyridinoline levels around the implants of nonsmokers (0.012 ± 0.018 nmol/L) were significantly (P <0.01) less than that of smokers (0.030 ± 0.006 nmol/L). These results demonstrate that pyridinoline levels are specifically elevated in the crevicular fluid associated with endosseous dental implants of smokers and suggest that smoking may affect implant success in part through alterations in the levels of bone resorption.