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Biomedical subjects

D Buser

Publications and source records attributed to D Buser.

At least 55 records · Page 3Linked to original sources
PubMed1998

Long-lasting osseointegration of immediately loaded, bar-connected TPS screws after 12 years of function: a histologic case report of a 95-year-old patient.

The present case report provides histologic findings on four titanium plasma-sprayed screw implants after 12 years of incorporation and functional load in a 95-year-old patient. At the time of implant placement, the four implants were immediately connected with a bar and functionally loaded with a bar-supported overdenture. The histologic analysis demonstrated excellent osseointegration in either cortical or cancellous bone for all implants. The histomorphometric analysis showed direct bone-implant contact of approximately 70% to 80% at the interface. Close to the implant surface, signs of ongoing bone remodeling activities were present. The present histologic case report confirms the validity of the applied treatment concept--to immediately load titanium implants with a titanium plasma-sprayed surface in the anterior region of the mandible--if a minimum of four implants can be inserted and if the four implants are splinted with a bar.

Aged↗
PubMed1998

Esthetic single-tooth replacement with implants: a team approach.

The range of indications for implant-borne prostheses in partially edentulous patients has expanded in recent years as a consequence of advances in regenerative techniques for bone and soft tissues. The esthetic demands of both patients and dentists have risen in parallel with these advances. Esthetic compromises in prostheses have become increasingly less tolerable, particularly in the anterior region of the maxilla. If the presenting situation is less than optimal, extensive preprosthetic measures may be required to prepare local tissues for acceptance of esthetically and functionally adequate prostheses. Particularly in difficult situations, collaboration by a team is recommended. The exchange of ideas and experience among specialists should begin as early as the treatment planning stage and extend over the entire course of therapy. The objective should be defined and the various steps of treatment should be coordinated with participation from all team members.

Adolescent↗
PubMed1997

[Amalgam problems: recommendations on patient assessment and counseling].

Assessment of patients with alleged or supposed amalgam-associated problems is difficult. Various methods, classified as medical, dental and "traditional" are discussed. Medical methods comprise epicutaneous sensitivity testing and determination of the mercury concentration of various body fluids such as saliva, urine and blood. Patients with amalgam restorations regularly exhibit increased readings. However, such measurements are not very appropriate since there are no generally applicable threshold values. Dental examination focuses primarily on oral lichenoid lesions of the mucosa in the vicinity of alloy restorations. Aggravation of a patient's general health status and/or exacerbation of pre-existing symptoms following the insertion or removal of an alloy filling may be indicative for amalgam incompatibility. Recommendations for everyday practice are given.

Body Fluids↗
PubMed1997

A randomized comparison between misoprostol and dinoprostone for cervical ripening and labor induction in patients with unfavorable cervices.

OBJECTIVE: To compare the efficacy and safety of two prostaglandin derivatives, misoprostol and dinoprostone, for ripening the cervix and inducing labor in women with an unfavorable cervix. METHODS: One hundred fifty-five women admitted for induction of labor to St. John's Mercy Medical Center, a teaching community hospital, were randomized to one of two methods: intravaginal misoprostol, 50 microg every 4 hours up to three doses (n = 76); and intracervical dinoprostone gel, 0.5 mg every 6 hours up to three doses (n = 79). RESULTS: Misoprostol was more effective than dinoprostone in causing cervical ripening (P = .01), inducing labor (P < .001), shortening the duration of labor (P < .001), and decreasing the need for oxytocin augmentation (P < .001). Nonreassuring fetal heart monitoring patterns associated with hyperstimulation were significantly more frequent (P < .001), and the incidence of cesarean deliveries because of this indication was significantly higher (P = .002) in patients receiving misoprostol. CONCLUSIONS: Misoprostol is an effective agent for cervical ripening and labor induction, but it causes an increase in cesarean deliveries associated with uterine hyperstimulation.

Adult↗
PubMed1997

Long-term evaluation of non-submerged ITI implants. Part 1: 8-year life table analysis of a prospective multi-center study with 2359 implants.

In the present multi-center study, non-submerged ITI implants were prospectively followed to evaluate their long-term prognosis in fully and partially edentulous patients. In a total of 1003 patients, 2359 implants were consecutively inserted. Following a healing period of 3-6 months, the successfully integrated implants were restored with 393 removable and 758 fixed restorations. Subsequently, all consecutive implants were documented annually up to 8 years. At each examination, the clinical status of all implants was evaluated according to predefined criteria of success. Therefore, the data base allowed the evaluation of 8-year cumulative survival and success rates for 2359 implants. In addition, cumulative success rates were calculated for implant subgroups divided per implant type, implant length, and implant location. Furthermore, the actual 5-year survival and success rates could be determined for 488 implants. During the healing period, 13 implants did not successfully integrate, whereas 2346 implants fulfilled the predefined criteria of success. This corresponds with an early failure rate of 0.55%. During follow-up, 19 implants were classified as failures due to several reasons. In addition, 17 implants (approximately 0.8%) demonstrated at the last annual examination a suppurative periimplant infection. Including 127 drop out implants (= 5.4% drop out rate) into the calculation, the 8-year cumulative survival and success rates resulted in 96.7% and 93.3%, respectively. The analysis of implant subgroups showed slightly more favorable cumulative success rates for screw type implants (> 95%) compared to hollow-cylinder implants (91.3%), and clearly better success rates for mandibular implants (approximately 95%) when compared to maxillary implants (approximately 87%). The actual 5-year survival and success rates of 488 implants with 98.2% and 97.3%, respectively, were slightly better than the estimated 5-year cumulative survival and success rates of 2359 implants indicating that the applied life table analysis is a reliable statistical method to evaluate the long-term prognosis of dental implants. It can be concluded that non-submerged ITI implants maintain success rates well above 90% in different clinical centers for observation periods up to 8 years.

Adolescent↗
PubMed1997

Hypothetical mortality risk associated with spiral tomography of the maxilla and mandible prior to endosseous implant treatment.

Radiation dose delivered from the SCANORA radiography unit during the cross-sectional mode for dentotangential projections was determined. With regard to oral implantology, patient situations of an edentulous maxilla and mandible as well as a single tooth gap in regions 16 and 46 were simulated. Radiation doses were measured between 0.2 and 22.5 mGy to organs and tissues in the head and neck region when the complete maxilla or mandible was examined. When examining a single tooth gap, only 8% to 40% of that radiation dose was generally observed. Based on these results, the mortality risk was estimated according to a calculation model recommended by the Committee on the Biological Effects of Ionizing Radiations. The mortality risk ranged from 31.4 x 10(-6) for 20-year-old men to 4.8 x 10(-6) for 65-year-old women when cross-sectional imaging of the complete maxilla was performed. The values decreased by 70% when a single tooth gap in the molar region of the maxilla was radiographed. The figures for the mortality risk for examinations of the complete mandible were similar to those for the complete maxilla, but the mortality risk decreased by 80% if only a single tooth gap in the molar region of the mandible was examined. Calculations according to the International Commission on Radiological Protection carried out for comparison did not reveal the decrease of the mortality risk with age and resulted in a higher risk value in comparison to the group of 35-year old individuals in calculations according to the Committee on the Biological Effects of Ionizing Radiations.

Adult↗
PubMed1997

Crestal bone changes around titanium implants. A radiographic evaluation of unloaded nonsubmerged and submerged implants in the canine mandible.

Current implant placement utilizes both nonsubmerged and submerged techniques. However, the implications of the location of a rough/smooth implant interface as well as the location of a microgap between implant and abutment on crestal bone changes are not well understood. The purpose of this study was to radiographically evaluate crestal bone changes around unloaded nonsubmerged and submerged titanium implants in a side-by-side comparison. Fifty-nine (59) implants were placed at different levels to the alveolar crest in 5 foxhounds. Standardized radiographs were taken at baseline and at monthly intervals until sacrifice at 6 months. Radiographic assessment was carried out by measuring the distance between the top of the implant/abutment and the most coronal bone-to-implant contact (DIB), and by evaluation of bone density changes using computer-assisted densitometric image analysis (CADIA). DIB measurements revealed that in 1-part, nonsubmerged implants, the most coronal bone-to-implant contact followed at all time points the rough/smooth implant interface. In all 2-part implants, nonsubmerged and submerged, the most coronal bone-to-implant contact was consistently located approximately 2 mm below the microgap. In addition, CADIA values for all 2-part implants were decreased in the most coronal area-of-interest (AOI). All bone changes were statistically significant and detectable 1 month after implant placement in nonsubmerged implants or 1 month after abutment connection in submerged implants. Neither implant position nor individual dog effects were statistically significant. These results demonstrate that the rough/smooth implant interface as well as the location of the microgap have a significant effect on marginal bone formation as evaluated by standardized longitudinal radiography. Bone remodeling occurs rapidly during the early healing phase after implant placement for non-submerged implants and after abutment connection for submerged implants.

Alveolar Process↗
PubMed1997

Biologic width around titanium implants. A histometric analysis of the implanto-gingival junction around unloaded and loaded nonsubmerged implants in the canine mandible.

The use of endosseous dental implants as transmucosal devices necessitates the successful integration of three different tissues: bone, connective tissue, and epithelium. So far, studies have predominantly focused on hard tissue integration. Much less is known about soft tissues. This study examined the dimensions of the implantogingival junction in relation to clinically healthy unloaded and loaded nonsubmerged implants. In total, 69 titanium plasma-sprayed (TPS) and sandblasted acid-etched (SLA) implants were placed in an alternating fashion in six foxhounds and allowed to heal for 3 months. Two dogs were sacrificed after the initial healing period. The remaining four dogs had crowns fabricated that were allowed to function for up to 12 months. These animals were sacrificed after 3 and 12 months of loading. Histometric analysis of undecalcified histologic sections included the evaluation of the sulcus depth (SD), the dimensions of the junctional epithelium (JE), and the connective tissue contact (CTC). Mean values in the 3 month unloaded group were 0.49 mm for SD, 1.16 mm for JE, and 1.36 mm for CTC. These dimensions were 0.50 mm for SD, 1.44 mm for JE, and 1.01 mm for CTC for the 3 month loaded group. After 12 months of loading, these values were 0.16 mm for SD, 1.88 mm for JE, and 1.05 mm for CTC. The sum of these measurements was similar for the different time points and similar to the same dimensions around teeth. TPS and SLA surfaces had no influence on the evaluated parameters (P > 0.05). The data suggest that a biologic width exists around unloaded and loaded nonsubmerged one-part titanium implants and that this is a physiologically formed and stable dimension as is found around teeth.

Analysis of Variance↗
PubMed1996

Lateral ridge augmentation using autografts and barrier membranes: a clinical study with 40 partially edentulous patients.

PURPOSE: This study evaluated predictability and treatment outcome of the combined application of autografts and expanded-polytetrafluoroethylene (e-PTFE) membranes for lateral ridge augmentation in partially edentulous patients using a staged approach. MATERIALS AND METHODS: Forty partially edentulous patients were consecutively treated. Emphasis was given to a lateral incision technique, perforation of the cortex to open the marrow cavity, stable placement of corticocancellous autografts and bone chips, precise adaptation of the e-PTFE membranes and stabilization with miniscrews, and a tension-free primary soft tissue closure. After 7 to 13 months, the sites were reopened for membrane removal and implant placement. RESULTS: All but one patient showed complication-free soft tissue healing. After reopening, 38 patients exhibited excellent ridge augmentation, whereas two had compromised results, with soft tissue encapsulation of some bone chips. None of the applied block grafts showed clinical signs of resorption. Preaugmentation and postaugmentation measurements showed an enlargement of the crest width from a mean of 3.5 mm to 7.1 mm. This allowed the placement of nonsubmerged titanium implants in all 40 patients. CONCLUSIONS: The current study demonstrates that the combined application of autografts and e-PTFE membranes is a predictable surgical procedure for lateral ridge augmentation that results in an enlargement of the alveolar crest in partially edentulous patients. The autografts support the membrane and activate bone formation with their osteoconductive and osteoinductive properties. The membrane acts as a physical barrier to nonosteogenic soft tissue cells, and protects the autografts against resorption during healing.

Adolescent↗
PubMed1996

Comparison of healed tissues adjacent to submerged and non-submerged unloaded titanium dental implants. A histometric study in beagle dogs.

This study involved histometry of the healed tissues around submerged and nonsubmerged dental implants in beagle dogs. In a split-mouth design, 19 submerged and 19 nonsubmerged commercially pure titanium implants, titanium plasma-sprayed in the bone anchoring part and smooth in the transmucosal portion, were placed in the mandibles of 6 dogs. Oral hygiene was performed 3 times weekly. After 3 months of healing, transmucosal abutments were inserted in the submerged implants. Six weeks after second stage surgery, the dogs were sacrificed and specimens obtained and processed for histology and histometry. Using a light microscope and a digitizing pad, the distance from implant top to mucosa border (DIM), the extent of epithelial downgrowth (ED), the attachment level, (AL), the length of connective tissue contact (CTC) and the distance of the first coronal alveolar bone contact from the implant top (DIB) were measured at the mesial and distal aspects. Means +/- standard deviations for submerged and nonsubmerged implants were calculated, with the dog being the unit of measure. No statistically significant differences between submerged and nonsubmerged implants were found for DIM, CTC and DIB. However, significant differences were observed for ED and AL. This study in beagle dogs indicates that the apical extension of the peri-implant epithelium is significantly greater and the attachment level significantly lower adjacent to submerged implants with second-stage transmucosal abutments than in nonsubmerged, one-stage implants.

Alveolar Process↗
PubMed1996

Long-term stability of osseointegrated implants in bone regenerated with the membrane technique. 5-year results of a prospective study with 12 implants.

The purpose of the present clinical study was to evaluate the 5-year results of the first 12 implants inserted at the University of Berne in regenerated bone following successful ridge augmentation with the membrane technique. The patients were recalled and examined with clinical and radiographic parameters routinely utilized in prospective studies with standard implants in non-regenerated bone. Based on clinical and radiographic findings, all 12 implants were considered successfully integrated according to strict criteria of success. The detailed analysis of clinical parameters revealed no differences to results of prospective studies on standard implants in non-regenerated bone. All implants demonstrated ankylotic stability which was confirmed by a mean Periotest value of -2.08. The radiographic analysis showed stable bone crest levels with a mean bone loss between the 1- and 5-year examination of 0.30 mm. However, 2 implants exhibited a bone loss of more than 1 mm between the 1- and 5-year examination. Therefore, the prognosis of these 2 implants seems questionable at the present time. It can be concluded that bone regenerated with the membrane technique reacts to implant placement like non-regenerated bone, since all 12 implants achieved successful tissue integration with functional ankylosis. Furthermore, this bone is also load-bearing, since all 12 implants maintained osseointegration over a 5-year period.

Alveolar Bone Loss↗
PubMed1996

Correlations between radiographic, clinical and mobility parameters after loading of oral implants with fixed partial dentures. A 2-year longitudinal study.

The aim of present study was to correlate the changes in the peri-implant tissues occurring after functional loading of non-submerged titanium implants and assessed by radiographic, clinical and mobility measurements. 11 patients with distal extension situations received 18 implants of the ITI Dental Implant System. After a healing period of 3 months, the suprastructures were fabricated and seated 5 months post-surgically. For the assessment of peri-implant bone changes, standardized vertical bitewing radiographs with reproducible exposure geometry were evaluated using computer assisted densitometric image analyses (CADIA) and bone height measurements. Since the radiographic evaluations were performed at mesial and distal sites only, the clinical parameters from these implant aspects were included in the analysis. Clinical periodontal parameters modified for the use around implants were obtained, damping characteristics were expressed as Periotest readings and standardized radiographs were obtained at 1, 3, 6, 12 and 24 months after loading. In addition, radiographs were also taken at the start of functional loading. The data obtained from this small sample of implants demonstrated a wide range of different tissue alterations when using radiographic, clinical and mobility assessments. The parameters of probing attachment level (PAL) in combination with radiographic parameters obtained at 1, 3, and 6 months after loading were good predictors for the peri-implant tissue status at 2 years. This was shown by means of multiple stepwise regression analyses. Mobility measurements did not reveal valuable predictive information with the statistical models applied. Assessments of probing attachment levels using periodontal probes rendered information on peri-implant tissue alterations, which were closely correlated to the radiographically measurable peri-implant bone changes.

Adolescent↗
PubMed1996

Evaluation of an endosseous titanium implant with a sandblasted and acid-etched surface in the canine mandible: radiographic results.

Previous studies have demonstrated in short-term experiments that sandblasted and acid-etched (SLA) titanium implant had a greater bone-to-implant contact than a titanium plasma-sprayed (TPS) implant in non-oral bone. In the present study, an SLA implant was compared radiographically to a TPS implant under unloaded and loaded conditions in the canine mandible for up to 15 months. 69 implants were placed in 6 foxhounds. Standardized radiographs were taken at baseline, preload, 3, 6, 9, and 12 months of loading. Loaded implants were restored with gold crowns similar to the natural dentition. Radiographic assessment of the bone response to the implants was carried out by measuring the distance between the implant shoulder and the most coronal bone-to-implant contact (DIB) and by evaluated of bone density changes using computer-assisted densitometric image analysis (CADIA). 5 different areas-of-interest (AOI) were defined coronally and apically along the implant. DIB measurements revealed that SLA implants had significantly less bone height loss (0.52 mm) than TPS implants (0.69 mm) at the preload evaluation (p = 0.0142) as well as at 3 months of loading (0.73 mm/1.06 mm; p = 0.0337). This difference was maintained between the implant types during the 1-year follow-up period. The same trend was also evident for CADIA measurements with SLA implants showing higher crestal bone density values when comparing preload to baseline data (p = 0.0890) and 3 months to baseline data (p = 0.0912). No measurable bone density changes were apparent in the apical areas of either implant. These results suggest that SLA implants are superior to TPS implants as measured radiographically in oral bone under unloaded and loaded conditions.

Alveolar Bone Loss↗
PubMed1996

Guided bone regeneration for dental implants.

The application of barrier membranes to promote bone regeneration was first described by Hurley et al. (J Bone Joint Surg 1959, 41A:1243-1254) in orthopedic research. However, the clinical potential of this membrane technique was recognized in the early 1980s for periodontal regeneration. Based on promising results in periodontology, researchers started to evaluate the potential of this technique--often called guided bone regeneration (GBR)--to regenerate bone defects in the alveolar process. This review describes the current knowledge of GBR in implant dentistry. Emphasis is placed on the scientific basis of GBR and the various surgical factors necessary to achieve predictable results with GBR procedures. In addition, unanswered questions that require future research are addressed including long-term success rates of dental implants placed in combination with barrier membranes, evaluation of resorbable membranes, and use of bone substitutes or growth factors to enhance bone regeneration in membrane-protected defects.

Alveolar Bone Loss↗
PubMed1996

Treatment of buccal gingival recessions with e-PTFE membranes and miniscrews: surgical procedure and results of 12 cases.

A surgical technique to achieve root coverage in buccal gingival recessions by means of expanded polytetrafluoroethylene membranes in combination with miniscrews is presented. After raising a trapezoidal split flap, supporting screws were used to create a large space underneath the membrane, while head screws were employed for perfect stabilization of the Teflon barrier. Intramarrow perforations were made to induce the rapid formation of a large blood clot with abundant availability of progenitor cells. The membrane and the miniscrews were removed after 3 or 4 weeks. The treatment of 12 cases, with mucogingival defects 4 to 7 mm deep, resulted in a mean root coverage of 84%.

Adult↗