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Biomedical subjects

S Ochi

Publications and source records attributed to S Ochi.

At least 37 records · Page 2Linked to original sources
PubMed2000

Implant survival in patients with type 2 diabetes: placement to 36 months.

BACKGROUND: Because the life expectancy of individuals continues to increase, dentists providing dental implant treatment can expect to see an increasing number of patients with diabetes mellitus. Today, there are little data available concerning the clinical outcomes involving the use of implant treatment for patients with diabetes mellitus. There are three types of diabetes mellitus: Type 1 (insulin dependent), Type 2 (non-insulin dependent), and gestational. Because of possible complications from patients with diabetes mellitus, they are excluded from participation in most clinical studies of endosseous dental implant survival. METHODS: This study attempted to determine if Type 2 diabetes represents a significant risk factor to the long-term clinical performance of dental implants, using the comprehensive DICRG database. Diabetes was a possible exclusion criterion; however, the final decision on Type 2 patients was left to the dental implant team at the research center. A total of 2,887 implants (663 patients) were surgically placed, restored, and followed for a period of 36 months. Of these, 2,632 (91%) implants were placed in non-diabetic patients and 255 (8.8%) in Type 2 patients. Failures (survival) were compared using descriptive data. Possible clustering was also studied. RESULTS: A model assuming independence showed that implants in Type 2 patients have significantly more failures (P = 0.020). However, if correlations among implants within the patient are considered, the significance level becomes marginal (P = 0.046). The experience of the surgeon did not produce a clinically significant improvement in implant survival. The use of chlorhexidine rinses following implant placement resulted in a slight improvement (2.5%) in survival in non-Type 2 patients and a greater improvement in Type 2 patients (9.1%); the use of preoperative antibiotics improved survival by 4.5% in non-Type 2 patients and 10.5% in Type 2 patients. The use of HA-coated implants improved survival by 13.2% in Type 2 diabetics. CONCLUSION: Type 2 diabetic patients tend to have more failures than non-diabetic patients; however, the influence was marginally significant. These findings need to be confirmed by other scientific clinical studies with a larger Type 2 diabetic sample size.

Adult↗
PubMed2000

The influence of preoperative antibiotics on success of endosseous implants at 36 months.

The benefits of prophylactic antibiotics are well recognized in dentistry. However, their routine use in the placement of endosseous dental implants remains controversial. As part of the comprehensive Dental Implant Clinical Research Group (DICRG) clinical implant study, the preoperative or postoperative use of antibiotics, the type used, and the duration of coverage were left to the discretion of the surgeon. These data for 2,973 implants were recorded and correlated with failure of osseointegration during healing (Stage 1), at surgical uncovering (Stage 2), before loading the prosthesis (Stage 3), and from prosthesis loading to 36 months (Stage 4). The results showed a significantly higher survival rate at each stage of treatment in patients who had received preoperative antibiotics.

Alloys↗
PubMed2000

Implant survival to 36 months as related to length and diameter.

BACKGROUND: It is generally accepted that diameter and length of an endosseous dental implant and its stability at placement are critical factors in achieving and maintaining osseointegration. In the event of slight implant mobility at placement, the conventional or accepted treatment is to place a longer implant and/or one of wider diameter. This manuscript presents stability and survival/failure data for implants of different diameters and lengths following 36 months post-placement, as well as crestal bone loss data between placement and uncovering. METHODS: A subset of the Dental Implant Clinical Research Group's database was used to study the 3-year survival and stability of various implant lengths (7 mm, 8 mm, 10 mm, 13 mm, and 16 mm) and diameters (3 mm+ and 4 mm+). Placement to uncovering crestal bone loss was also determined. The implants were generally representative of those available for clinical use (screws, basket, grooved, hydroxy-apatite-coated, CP-Ti, Ti-alloy). The study protocol specified that the implants be randomized to various jaw regions to accomplish the primary goals of the study--the comparison of each implant design's overall survival. A total of 2,917 implants were placed, restored, and followed. Data for all 3 mm to 3.9 mm diameter implants were pooled into a "3+" group, and the 4 mm to 4.9 mm diameter implants into a "4+" mm group. No attempt was made to look at the influence of any other variables on survival outcomes. The possible influence of clustering on survival was taken into consideration. RESULTS: The 3+ mm group had a mean stability (PTV) of -3.8 (SD = 2.9), and the 4+ group had a mean PTV of -4.4 (SD = 2.7) (P < 0.05). The PTVs for implant lengths ranged from -2.9 (SD = 2.8) for 7 mm lengths to -3.9 (SD = 2.9) for 16 mm lengths (P < 0.05). Survival to 36 months was 90.7% for the 3+ diameter and 94.6% for the 4+ group (P = 0.01). Survival ranged from 66.7% for the 7 mm implants to 96.4% for 16 mm implants (P = 0.001). Outcomes did not change when clustering was considered, although the P value decreased slightly. CONCLUSIONS: The results indicate that: 1) shorter implants had statistically lower survival rates as compared with longer implants; 2) 3+ mm diameter implants had a lower survival rate as compared with 4+ mm implants; 3) 3+ mm diameter implants are less stable (more positive PTVs) than 4+ mm implants; and 4) there was no significant difference in crestal bone loss for the two different implant diameters between placement and uncovering.

Alloys↗
PubMed2000

Three-year post-placement survival of implants mobile at placement.

BACKGROUND: Although rigid fixation of endosseous implants at the time of placement is generally thought to be a prerequisite for successful osseointegration, the Dental implant Clinical Research Group (DICRG) of the Department of Veterans Affairs has reported on implants that integrated despite being mobile at placement. The present study examines the frequency of osseointegration and the 36-month post-placement survival of implants mobile at placement in a prospective, multicenter, longitudinal clinical study of more than 3,000 implants conducted by the DICRG. METHODS: A total of 3,111 implants of 6 different designs were placed in all jaw regions in more than 800 patients at 32 study centers. At the time of this report, 2,770 of these implants had been followed for 36 months post-placement. They included 89 implants that were mobile at placement. Data for demographic variables, implant coating, bone quality, incision type, bone augmentation, and antibiotic usage were recorded. An electronic hand-held probe was used to measure mobility at uncovering and at regular follow-up intervals. RESULTS: Eighty-nine of 2,770 inserted implants were mobile at placement. Results are reported for two periods: from placement to 36 months and from prosthetic loading to 36 months. The latter method eliminated early failures and resulted in substantially higher scores for both mobile implants at placement (95.9% survival from prosthetic loading to 36 months post-placement versus 79.8% from placement to 36 months) and implants not mobile at placement (98.4% versus 93.4%). Mobility at placement was significant to 3-year survival (P < 0.001). Hydroxyapatite (HA) coating improved the performance of implants mobile at placement (91.8% for HA-coated versus 53.6% for non-HA) and those not mobile at placement (97.2% for HA-coated versus 87.4% for non-HA). Radiographic findings suggested that crestal bone response around implants which were mobile versus immobile at placement was similar. CONCLUSIONS: Although implant stability at the time of placement is clearly desirable as seen in the superior 3-year survival of stable implants, it may not be an absolute prerequisite to osseointegration or to long-term survival. Several factors may influence the decision to remove or replace a mobile implant. HA-coating significantly improved the performance of both mobile and immobile implants at placement to 3 years post-placement (P < 0.001).

Adult↗
PubMed2000

Stability of the bone-implant complex. Results of longitudinal testing to 60 months with the Periotest device on endosseous dental implants.

BACKGROUND: Maintenance of the health and integrity of the bone-implant complex (osseointegration) has been shown to be essential for long term success of root-form, endosseous dental implants. If reliable clinical indicators of adequacy of the bone-implant complex existed, they could stimulate new and innovative early intervention research to arrest of reverse early deterioration of the bone-implant complex. In the absence of such indicators, this has been problematic. The Periotest may have the potential to provide this information by indirectly assessing the status of the bone-implant complex. However, little information is available that documents either the capability of the Periotest to reliably assess changes of the bone-implant complex or the "normal variations" in Periotest values (PTVs) for both HA-coated and non-coated implants. METHODS: The purpose of this paper was to document changes in PTVs as influenced by various implant surfaces, implant designs, and bone densities. The mean PTVs recorded for each visit, for all implant types and bone densities, were combined to provide an overall average PTV (A-PTV). The changes in stability (PTVs) were analyzed using a generalized linear model (GLM) with repeated measures (Hotelling's Trace). RESULTS: The A-PTV for all implants over all visits was -3.5. The mean PTVs ranged from -4.2 (SD = 2.4) at uncovering to -3.9 (SD = 2.9) at 60 months. All implants in bone qualities 1 and 2 (BQ-1 and BQ-2) became more stable over time, while those in bone quality 3 or 4 (BQ-3 and BQ-4) showed a slight decrease in stability. In BQ-1, the mean PTVs increased from -4.7 at uncovering to -4.9 at 60 months. A similar increase in stability occurred in BQ-2 (-4.1 at uncovering to -4.4 at 60 months). In BQ-3, the stability of the implants decreased over time (-3.6 at uncovering to -2.9 at 60 months), with similar changes recorded for BQ-4 (-2.5 at uncovering to -1.0 at 60 months). When comparing the stability of all HA-coated with all non-coated implants, the HA implants became less stable (-4.4 to -3.4) over time, while non-coated implants showed an improvement in stability (-3.5 to -4.5). The changes in stability found in BQ-1, BQ-2, and BQ-3 were similar, with HA implants becoming less stable and non-coated more stable. HA- and non-coated comparisons were not possible in BQ-4 since there were too few non-coated implants placed in this type of bone. The HA-coated screw showed a decrease in stability when compared to the non-coated screw. CONCLUSIONS: Conclusions of the study are as follows: 1) PTVs are influenced by bone quality and surface coating of the implant; 2) the PTVs at the time of uncovering provide the best estimate of a clinically acceptable PTV for that bone-implant complex; 3) while the PTVs for any bone-implant complex may fluctuate +/- 1.0 around the uncovering PTV during routine healing and loading of the implant, a consistent shift toward a positive PTV that approaches "0" should be cause for concern that the bone-implant complex may be at risk of failure; 4) HA-coated implants became slightly less stable (more positive PTVs) over time, while the non-coated implants became more stable (more negative PTVs); and 5) until a "critical PTV" can be accurately identified, it is suggested that a consistent shift in recorded PTVs that exceeds the +3.0 value on the PTV scale should be viewed with concern for possible deterioration at the bone-implant complex.

Alloys↗
PubMed2000

Periodontal-type measurements associated with hydroxyapatite-coated and non-HA-coated implants: uncovering to 36 months.

BACKGROUND: While the use of hydroxyapatite (HA)-coated endosseous dental implants has gained in popularity over the past 10 years, the short-term and long-term predictability and indications for their use remain highly controversial. Some reports suggest that the HA coating may separate from the substructure, undergo dissolution in tissue fluids, and/or contribute to rapid osseous breakdown around the implant. Other reports, however, relate favorable responses to HA-coated implants, which include rapid bone adaptation to the HA, greater stability at uncovering, and increased coronal bone growth. These contradictions may be related to differences in chemical composition of the HA on the implant surface. Most clinicians and researchers may agree that long-term, independent, scientific clinical studies are needed to compare HA-coated and non-HA-coated (titanium-alloy and CP-titanium) implants under the same conditions. Concerns appear in the literature that HA-coated implants experience greater breakdown because they are more susceptible to bacterial colonization due to their roughness and hydrophilicity. Some studies suggest that specific putative periodontal pathogens may adhere to the HA, thereby predisposing the implant to greater peri-implantitis than that experienced by non-HA implants. METHODS: A total of 32 clinical research centers, located in various geographic regions of the United States, were selected to participate in a comprehensive clinical study. More than 2,900 HA-coated and non-HA implants were randomized as to location within one of three jaw regions--maxillary anterior, mandibular anterior, and mandibular posterior--and followed for 36 months. It can be assumed that in each of these jaw regions, the conditions associated with both implant surface types would be similar enough to permit meaningful comparisons of periodontal-type measurements that have not previously been reported. Periodontal-type measurements (gingiva, plaque, suppuration, and calculus indices; probing depth; attachment levels; recession; and keratinized tissue width) for each aspect of each implant (mesial, facial, distal, and lingual) were recorded at 3, 6, 9, 12, 18, 24, and 36 months following implant uncovering. The implant was considered the experimental unit for analysis using generalized estimating equation and repeated measure methods. Data for the four aspects of each implant, as well as measurements over time, were all clustered in the unit of analysis. RESULTS: The percentages of implants with zeros recorded for the indices was remarkably similar for both HA-coated and non-HA implants. While statistically significant differences were found for some of the measurements associated with HA-coated and non-HA implants under certain conditions, these differences were too small to be considered clinically significant. CONCLUSIONS: Overall, there was no clinically significant difference between the periodontal-type measurements for HA-coated and non-HA-coated implants followed for a period from 3 through 36 months. The concerns about HA-coated implants being associated with adverse periodontal responses for the HA chemical composition included in this study appear to be unfounded for a period of clinical performance up to 36 months.

Adult↗
PubMed2000

Variables affecting survival of single-tooth hydroxyapatite-coated implants in anterior maxillae at 3 years.

BACKGROUND: The development and expanded use of endosseous dental implants over the last two decades have been remarkably rapid. It is, therefore, imperative that the dental profession closely monitor the performance of root-form implants used in a variety of applications. The Dental Implant Clinical Research Group (DICRG) was established in 1990 by the Department of Veterans Affairs as a forum for conducting prospective, multidisciplinary, multicentered studies in the field of implant dentistry. The DICRG comprised 30 VA medical centers and 2 dental schools at the time of this study. This paper reports on the survival of hydroxyapatite (HA)-coated grooved implants used to replace single missing teeth in anterior maxillae at 3 years post-implant placement. METHODS: During a 4-year accrual period, a total of 247 single-tooth implant restorations were placed in anterior maxillae. This paper focuses on the survival of 222 implants (149 patients) for which 3-year data were recorded for the period from placement. Survival was examined with respect to patient demographics and health status, implant location, surgical variables, and 2-week post-placement use of chlorhexidine digluconate (0.12%) rinses. Implant stability was recorded using a hand-held probe. Periodontal-type measures were recorded and evaluated, and all complications related to osseointegration were noted. Failure was defined as removal of the implant for any reason. RESULTS: Establishment and maintenance of osseointegration at 3 years post-placement was 97.3%. During this 3 year period, 6 implants were removed due to either failure to osseointegrate or loss of osseointegration. Implant length correlated positively with 3-year survival (P = 0.003, exact test). The use of preoperative antibiotics was nearly significant to implant survival (P = 0.051. Pearson chi-square). Mean stability values (PTVs) increased incrementally from -4.5 at uncovering to +1.1 at 36 months, indicating a decrease in stability of the bone-implant-prosthesis complex. The most common complication was related to inadequate available bone to fully house implants. CONCLUSIONS: Three-year post-placement survival data suggest that the use of HA-coated, grooved, endosseous implants to support maxillary anterior single-tooth replacements is a predictable and reliable procedure that can offer significant benefits. Longer implants demonstrated higher survival than shorter implants. The use of preoperative antibiotics was nearly significant to implant survival, and there was an increase in mean PTVs observed over the duration of the study. Further research is needed to assess stability of the hydroxyapatite-bone interface over time.

Adult↗
PubMed2000

The influence of smoking on 3-year clinical success of osseointegrated dental implants.

BACKGROUND: Health risks associated with smoking have been exhaustively documented and include increased incidence of periodontal disease, greater risk of osteitis following oral surgery, and compromised wound healing due to hypoxia. Information related directly to dental implants, although limited, points to higher rates of implant failures among smokers than non-smokers. This paper reports on long-term clinical outcomes of osseointegrated dental implants placed in smokers and non-smokers in a longitudinal clinical study of endosseous dental implants. METHODS: In 1990, the Dental Implant Clinical Research Group (DICRG) of the Department of Veterans Affairs (DVA) launched an 8-year, randomized, prospective clinical study of more than 2,900 endosseous dental implants in more than 800 patients at 32 study centers. Confounding variables, including smoking patterns, were recorded. For this report, new follow-up data were analyzed for two groups: 1) current smokers and 2) those who never smoked combined with those who quit. Most of the variables recorded for each implant were screened on a univariate basis as possible predictors associated with implant survival/failure. Those with P values less than 0.15 and those likely to be a factor of clinical importance were placed in a logistic regression equation and analyzed for a simultaneous effect on survival. A step-wise procedure was used to eliminate those variables that showed the least significance, until only those variables with a Wald chi-square of significance in the presence of others remained. The effects of clustering within patients and of unbalanced distribution within hospitals were standardized to facilitate analysis of influence of demographic variables. The GEE analysis was performed with the patient as the primary cluster. RESULTS: Current data do not support earlier findings that smoking contributes to early implant failure (placement to uncovering). A trend of greater failures in smokers appeared between the time after uncovering and before insertion of the prosthesis. Hydroxyapatite (HA)-coated implants had significantly lower failure rates. For the entire 3-year period, overall failures were significantly higher for smokers than non-smokers. CONCLUSIONS: Results suggest that increased implant failures in smokers are not the result of poor healing or osseointegration, but of exposure of peri-implant tissues to tobacco smoke. Data also suggest that detrimental effects may be reduced by: 1) cessation of smoking; 2) the use of preoperative antibiotics; and 3) the use of HA-coated implants.

Adult↗
PubMed2000

Influence of two different approaches to reporting implant survival outcomes for five different prosthodontic applications.

BACKGROUND: Over the years, the definition of implant failure has varied, with some investigators accounting for all implants placed, while others discard failures that occurred before clinical loading. The influence of stresses transmitted to various bone densities, by different prosthetic appliances as well as the method used to determine failures, needs to be clearly understood. This paper reports on the influence of two different methods of determining 36-month survival of implants used to support different dental prostheses. METHODS: More than 2,900 implants with six different designs were placed in 829 patients at 32 study centers and followed for 3 years. The first method of determining survival accounted for all failures from placement through 36 months, while the second method counted only failures from post-loading of the prosthesis to 36 months. Survival curves were used to determine differences in survival outcomes for the two methods. RESULTS: For the maxillary single-tooth prosthetic application, implant survival from placement to 36 months was 94.7% when all failures were counted and increased to 98.3% with the post-loading method. For upper completely edentulous applications, implant survival was 85.3% with all failures counted and 95.6% with the post-loading method. This 10.3% difference is clinically important. The survival for implants in lower completely edentulous applications increased by 4.4% simply by using the post-loading approach. Implants used for upper posterior, partially edentulous applications involved only hydroxyapatite (HA)-coated implants, and the survival rates were similar (96.4% for all implants and 98.2% for the post-loading method). The difference in reported survival rates for implants in the lower posterior, partially edentulous application was 5.8%. Since failures tended to occur in the earlier phases of treatment, the post-loading approach always resulted in more favorable survival data. With the post-loading approach, valuable information related to implant performance before loading is lost. In all comparisons, HA-coated implant survival was always better than non-HA implants. Clinical investigators should clearly state the method used for determining failures. For all implants included in the study, survival curves illustrated different failure patterns for each method of determining overall survival. CONCLUSION: Reporting of implant survival rates based on the post-loading method provides more favorable survival rates; however, accounting for all implants provides a more accurate method of determining survival.

Adult↗
PubMed1999

Clostridium perfringens beta-toxin is sensitive to thiol-group modification but does not require a thiol group for lethal activity.

The beta-toxin gene isolated from Clostridium perfringens type B was expressed as a glutathione S-transferase (GST) fusion gene in Escherichia coli. The purified GST-beta-toxin fusion protein from the E. coli transformant cells was not lethal. The N-terminal amino acid sequence of the recombinant beta-toxin (r toxin) isolated by thrombin cleavage of the fusion protein was G-S-N-D-I-G-K-T-T-T. Biological activities and molecular mass of r toxin were indistinguishable from those of native beta-toxin (n toxin) purified from C. perfringens type C. Replacement of Cys-265 with alanine or serine by site-directed mutagenesis resulted in little loss of the activity. Treatment of C265A with N-ethylmaleimide (NEM), which inactivated lethal activity of r toxin and n toxin, led to no loss of the activity. The substitution of tyrosine or histidine for Cys-265 significantly diminished lethal activity. In addition, treatment of C265H with ethoxyformic anhydride which specifically modifies histidyl residue resulted in significant decrease in lethal activity, but that of r toxin with the agent did not. These results showed that replacement of the cysteine residue at position 265 with amino acids with large size of side chain or introduction of functional groups in the position resulted in loss of lethal activity of the toxin. Replacement of Tyr-266, Leu-268 or Trp-275 resulted in complete loss of lethal activity. Simultaneous administration of r toxin and W275A led to a decrease in lethal activity of beta-toxin. These observations suggest that the site essential for the activity is close to the cysteine residue.

Amino Acid Sequence↗
PubMed1999

Sustained release liquid preparation using sodium alginate for eradication of Helicobacter pyroli.

We prepared a new liquid preparation for eradication of Helicobacter pylori (HP), and examined drug release in vitro and in vivo. The liquid preparation mainly consisted of a sodium alginate (AG) aqueous solution containing ampicillin (ABPC), an antibiotic drug, or methylene blue, a dye. Drug release was retarded by Ca pre-treatment (0.10 M, 20 s) of the AG preparation in in vitro drug release studies due to gel-formation at the liquid surface. In in vivo experiments, the AG preparations were administered orally to rats. The rats were divided into two groups, with or without pre-administration of ranitidine hydrochloride (RH, an H2-blocker). The total remaining % of ABPC in the stomach was high in the rats administered the AG preparation compared to the ABPC solution. The AG preparation might float in the stomach without adhering to the gastric wall in the rats without pre-administration of RH. The total remaining % of ABPC at 30 min was almost 100% in the RH pre-administration rats administered the AG preparation, and about 80% of the drug existed in fraction 2 (implying adhesion of the preparation on the gastric mucus). At 60 min, the total remaining % in the AG preparation plus Ca (mean 87%) increased about 2-fold compared to that in the AG preparation alone (mean 44%). In this case, a large portion of the remaining ABPC also existed in fraction 2. This preparation may be useful for eradication of HP.

Administration, Oral↗
PubMed1998

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.

Antibiotic Prophylaxis↗
PubMed1998

Mechanism of membrane damage by Clostridium perfringens alpha-toxin.

The effect of Clostridium perfringens alpha-toxin on liposomes prepared from phosphatidylcholine (PC) containing the fatty acyl residues of 18 carbon atoms was investigated. The toxin-induced carboxyfluorescein (CF) leakage and phosphorylcholine release from multilamellar liposomes increased as the phase transition temperature of the phosphatidylcholines containing unsaturated fatty acyl residues decreased. However, there was no difference between the sensitivity of the different phosphatidylcholines solubilized by deoxycholate to the phospholipase C (PLC) activity of the toxin. However, the toxin did not hydrolyze solubilized distearoyl-L-alpha-phosphatidylcholine (DSPC) or phosphatidylcholine containing saturated fatty acyl residue, and caused no effect on liposomes composed of DSPC. These results suggest that the activity of the toxin is closely related to the membrane fluidity and double bond in PC. The N-terminal domain of alpha-toxin (AT1-246) and variant H148G did not induce CF leakage from liposomes composed of dioleoyl-L-alpha-phosphatidylcholine (DOPC). H148G bound to the liposomes, but AT1-246 did not. However, the C-terminal domain (AT251-370) conferred binding to liposomes and the membrane-damaging activity on AT1-246. These observations suggest that the membrane-damaging action of alpha-toxin is due to the binding of the C-terminal domain of the toxin to the double bond in the PC in the bilayer and hydrolysis of the PC by the N-terminal domain.

Bacterial Toxins↗
PubMed1998

Factors affecting implant mobility at placement and integration of mobile implants at uncovering.

This study examined 1) factors that contributed to implant stability at placement and 2) the likelihood for an implant that was mobile at placement to osseointegrate. Eighty-one (3.1%) of 2,641 implants placed by the Dental Implant Clinical Research Group between 1991 and 1995 were found to be mobile at placement. Seventy-six (93.8%) of the 81 mobile implants were integrated at uncovering compared to 97.5% for the 2,560 immobile implants. Variables that influenced mobility at placement included patient age, implant design and material, anterior-posterior jaw location, bone density, and use of a bone tap. Hydroxyapatite (HA)-coated implants were slightly more likely to be mobile at placement (P = 0.324) than non-hydroxypatite (HA)-coated implants. Of the 54 HA-coated implants that were mobile at placement, all (100%) integrated, while only 17 (81.5%) of the 22 mobile non-HA-coated implants integrated (P = 0.003). Mean electronic mobility testing device values (PTVs) at uncovering for all implants mobile or immobile at placement that integrated were -2.9 and -3.6 respectively. PTVs for HA-coated implants that were mobile (-3.5 PTV) or immobile (-4.0 PTV) at placement differed by 0.5 PTV, whereas non-HA-coated implants exhibited a greater difference of 1.2 PTVs at uncovering. HA-coated implants, regardless of mobility at placement, integrated more frequently and exhibited greater stability than non HA-coated implants.

Adult↗
PubMed1998

Assembly of Clostridium perfringens epsilon-toxin on MDCK cell membrane.

Clostridium perfringens epsilon-toxin bound to the Madin Darby canine kidney (MDCK) cells and aggregated. The complex of the toxin was formed in a dose- and a time-dependent manner. The formation of the complex increased with a decrease in viable counts of MDCK cells and with increasing K+ release from the cells. The inactivated toxin heated at 100 degrees C did not aggregate under the condition. In addition, the prototoxin dose-dependently bound to the cells, but did not form the complex. Incubation of the toxin with MDCK cell membranes also showed the formation of the complex, but that with membrane preparations prepared from Vero cells or sheep erythrocytes, which are insensitive for the toxin, showed no formation of the complex. Incubation of the toxin with mouse brain homogenates resulted in formation of the complex, but that with brain homogenates heated at 80 degrees C or mouse liver homogenates showed no formation of the complex. These observations show that the complex formation of epsilon-toxin is essential for toxicity of the toxin.

Animals↗
PubMed1997

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.

Clinical Competence↗
PubMed1997

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.

Anti-Bacterial Agents↗