Shigeru Ochi

Distribution of Bone Quality in Patients Receiving Endosseous Dental Implants

Knowledge of the distribution of bone quality in the various jaw regions assists the clinician in dental implant treatment planning. Bone quality was assessed with radiographs and tactile sensation for 2,839 implants at the time of placement into four anatomic regions of the jaw. The Lekholm-Zarb classification system was used. Overall, bone quality types 1 and 4 were found much less frequently than types 2 and 3. Although variations in density existed in each region, quality 2 bone dominated the mandible, and quality 3 bone was more prevalent in the maxilla. For both anterior and posterior jaw regions, types 2 and 3 bone predominated. The anterior mandible had the densest bone, followed by the posterior mandible, anterior maxilla, and posterior maxilla.

The Influence of Preoperative Antibiotics on Success of Endosseous Implants Up to and Including Stage II Surgery: A Study of 2,641 Implants

According to the American College of Surgeons, complex oral surgical procedures, including the transoral placement of endosseous implants, are of the type that may require prophylactic antibiotics. However, the routine use of prophylactic antibiotics in the field of dental implantology continues to be controversial, and their utilization varies widely. No data from a randomized prospective clinical study of the prophylactic use of antibiotics in implant surgery have been previously published. As part of the comprehensive Dental Implant Clinical Research Group clinical implant study, the preoperative or postoperative use of antibiotics, the type used, and the duration of coverage was left to the discretion of the surgeon. These data were recorded and correlated with failure of osseointegration during healing (stage I) and at stage II surgery (uncovering). The results showed that significantly fewer failures occurred when preoperative antibiotics were used.

THE EFFECT OF SMOKING ON IMPLANT SURVIVAL AT SECOND-STAGE SURGERY: DICRG INTERIM REPROT NO. 5

Smoking has been reported to have a deleterious effect on the oral cavity. Research has associated smoking with oral cancer, periodontal disease, leukoplakia, stomatitis nicotina, and impaired gingival bleeding. In 1991 the Dental Implant Clinical Research Group initiated a prospective, randomized cSmoking has been reported to have a deleterious effect on the oral cavity. Research has associated smoking with oral cancer, periodontal disease, leukoplakia, stomatitis nicotina, and impaired gingival bleeding. In 1991 the Dental Implant Clinical Research Group initiated a prospective, randomized clinical study in cooperation with the Department of Veterans Affairs to investigate the influence of implant design, application, and site of placement on long-term clinical performance and crestal bone height. Over 70 dental and medical history variables and exclusion factors were analyzed to determine relationships, if any, with implant failure at the time of second-stage surgery. The variables were analyzed separately for individual implants, cases (prostheses), and patients. The cases ranged from one to five implants each, and more than one case from a single patient could be included in the investigation. At this interim analysis, 2,066 implants have been placed representing 433 cases in 310 patients. With regard to implant failure rates, possible exclusion variable (9) and medical history variables (39) were not found to be statistically significant. For the dental history variables (23), only the question related to smoking was statistically significant on an implant, case, and patient basis (P < 0.007). Results of this interim analysis suggest that smoking is detrimental to implant success.

Positive Effect of Surgical Experience With Implants on Second-Stage Implant Survival

This Dental Implant Clinical Research Group study defined a learning curve for dental implant placement. Implants placed by inexperienced surgeons (< 50 implants) failed twice as often as those placed by experienced surgeons (> or = 50 implants). Implants placed during the first 6, 8, 10, 12, and 16 cases were compared with all others. The greatest difference was seen between the first nine cases and all others (P = .001), with later cases failing significantly less often. Inexperienced surgeons had more failures in the first nine cases (5.9%) than more experienced surgeons (2.4%). Surgeons with little or no previous experience must expect a definite learning curve. Previous experience may transfer and result in a shallower learning curve for subsequent systems.

The influence of 0.12% chlorhexidine digluconate rinses on the incidence of infectious complications and implant success.

The effect of perioperative chlorhexidine on the frequency of infectious complications through stage II was examined. Chlorhexidine was used perioperatively in 54.6% of patients (52.5% of implants) in a Dental Implant Clinical Research Group study with a database of 2,641 implants (595 patients). With chlorhexidine, there was a significant reduction in the number of infectious complications (4.1% vs 8.7%). Two percent of implants failed in the absence of an infectious complication, whereas 12% with infectious complications failed. This sixfold difference is highly significant. Chlorhexidine may reduce microbial complications when used in the immediate perioperative period.

Hydroxyapatite-coated implants: A case for their use☆☆☆

The information on which this article is based comprises a small fraction of the large database compiled from the DICRG study. These results represent the early performance for HA implants (up to 36 months). The study has been ongoing for 6 years, and there are more than 2,000 implants with 4-year data and 1,500 with 5-year data. These data are similar to the 36-month data, and when they are eventually released, they are likely to reinforce the results reported here. Meanwhile, the evidence presented in this article, along with other corroborating studies cited in the introduction, are sufficient grounds to reach the following conclusion: The ideal implant design and material is one that is easy to use, requires average skills, involves minimal bone trauma, presents a biocompatible contact surface, and produces a high rate of survival in most patients. Based on 36-month survival in the DICRG study, HA-coated implants appeared to satisfy these basic requirements better than the other implants used in the study. HA-coated implants were placed in the most challenging bone types and jaw region, in patients with compromised medical histories, by dentists with different training, skills, and experience, under less than ideal clinical conditions, and still showed the highest survival rates of all implants at every point in the treatment up to 36 months.

Second – stage failures related to bone quality in patients receiving endosseous dental implants: Dicrg interim report no. 7

The quality of bone plays an important role in the long-term clinical success of dental implant treatment. An interim evaluation of the relationship between bone quality and the incidence of failure at second-stage surgery is presented. The data include 2,131 root form implants placed by the Dental Implant Clinical Research Group over the past three years. Trends to date suggest differences in the rates of osseointegration among the various bone qualities. Quality 1 bone experienced the greatest failure rate, whereas quality 2 and quality 3 bone had the lowest failure rates. (Implant Dent 1994;3:252–255)

Bone Quality and Implant Design-Related Outcomes Through Stage II Surgical Uncovering of Spectra-System Root Form Implants

Failure rates at second-stage surgery were reported for the ongoing Dental Implant Clinical Research Group studies of the Spectra-System (Core-Vent Corporation, Las Vegas, NV) implants. As of May 1995, 69 implants failed out of 2,633 placed and uncovered. The overall failure rate was 2.6%, with 3.6% in bone quality 1 (BQ-1), 2.4% in BQ-2, 2.5% in BQ-3, and 3.1% in BQ-4. HA-coated cylinders had the lowest number of failures and titanium alloy baskets the highest. The basket design failed more often in the posterior jaw areas; 9 of 32 clinical centers (28%) accounted for 72% of these failures.

The influence of implant design, application, and site on clinical performance and crestal bone: a multicenter, multidisciplinary clinical study. Dental Implant Clinical Research Group (Planning Committee).

This investigation is designed to provide scientific data that is directly relevant to the placement of dental implants. The study is concerned with the influence of implant design, application, and location on long-term clinical performance and crestal bone response over 5 years of function. It involves approximately 700 patients at 30 Veterans Administration Medical Centers from various geographic regions. Patients are being entered into the study over an 18-month period and monitored (post-loading) over 5 years. The participating centers were randomly assigned to one of two separate, independent study groups. Complications and adverse responses associated with the placement and use of the implants will be evaluated and all failures thoroughly documented. The experimental design and sample size are based on the primary hypothesis that an implant-supported prosthesis will be successful/functional over a 5-year period in at least 90 percent of the cases treated. Secondary hypotheses to be tested are (1) the success rate among implant designs are the same over a 5-year period; (2) the success rate among implant applications are the same over a 5-year period; (3) the success rate of individual implants are the same with regard to jaw location over a 5-year period; (4) the loss of crestal bone at the individual implant sites are the same among the implant designs over a 5-year period; and (5) the complications and adverse responses experienced with the different implant designs are the same over a 5-year period. The experimental design of this multicenter, multidisciplinary, randomized investigation is a cooperative effort of the Department of Veterans Affairs and several United States dental schools. (Implant Dent 1992;1:49–55)

An evaluation of the Periotest system. Part I: Examiner reliability and repeatability of readings. Dental Implant Clinical Group (Planning Committee).

The clinical success of endosseous dental implants is related to the extent of osseointegration. Many of the presently used methods of evaluating osseointegration are highly subjective. The Periotest is claimed to offer a more objective means to assess osseointegration and supporting bone stability of implants by means of microcomputer-controlled percussion. Investigators involved in a clinical study on dental implants being conducted by the Dental Implant Clinical Research Group participated in a two-part in vitro evaluation of the Periotest system. The first part, with which this article is concerned, involved each of 35 investigators taking three readings for each of 16 models designed to simulate an implant in place in the oral cavity and to cover most of the effective measuring range of the instrument. The Periotest system generally demonstrated a high degree of reliability and repeatability, with higher variability associated with specific model samples. Further evaluation of the Periotest as a research instrument will be conducted within the clinical environment of the Dental Implant Clinical Research Group study. (Implant Dent 1992;1:142–146)