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Biomedical subjects

Daniel Buser

Publications and source records attributed to Daniel Buser.

At least 37 records · Page 2Linked to original sources
PubMed2004

[Oral leukoplakia. A retrospective study of clinical and histological data].

In this retrospective study, the charts of 91 patients who presented with oral leukoplakia at the Department of Oral Surgery and Stomatology at the University of Berne from August 1995 to December 2001 were analyzed. Critical points in the evaluation included the distribution of age and gender of the patients, type and localisation of the oral leukoplakias, grade of dysplasia, presence and type of potential noxious agents, type of surgical/nonsurgical therapy, and follow-up. The 91 patients included in this study had a total of 145 leukoplakias. Gender distribution corresponded to 39 women and 52 men. Age distribution showed a marked peak in the range of 50-59 years. Sixty-six patients were smokers and 44 patients drank alcoholic beverages on a daily basis. The most frequent localisation of oral leukoplakias was the buccal mucosa (24.5%) followed by the attached gingiva in the mandible including the so-called Trigonum retromolare (17.4%) and the floor of the mouth and ventral tongue (16.8%). Thirty-two of the 52 histologically examined lesions had no epithelial dysplasia, while 14 of the lesions only had a mild and three of the lesions a moderate dysplasia. Of the biopsies taken, three were histologically confirmed to be a carcinoma in situ.

Adult↗
PubMed2004

Outcome analysis of implant restorations located in the anterior maxilla: a review of the recent literature.

PURPOSE: To document the literature regarding outcomes of implant restorations in the anterior maxilla to formulate consensus statements with regard to esthetics in implant dentistry, to provide guidelines to clinicians, and to articulate remaining questions in this area to be addressed by future research. MATERIALS AND METHODS: The following areas of the recent literature were scrutinized: treatment outcomes of implant therapy for partial edentulism (including maxillary anterior tooth replacement); anterior maxillary single-tooth replacement; effect of implant design, diameter, and surface characteristics; soft tissue stability/contours around anterior implant restorations; ceramic abutments; influence of surgical techniques; and finally, evaluation of patient satisfaction. RESULTS: The use of dental implants in the esthetic zone is well documented in the literature, and numerous controlled clinical trials show that the respective overall implant survival and success rates are similar to those reported for other segments of the jaws. However, most of the published studies do not include well-defined esthetic parameters. Currently, the literature regarding esthetic outcome is inconclusive for the routine implementation of certain surgical approaches, such as flapless surgery and immediate implant placement with or without immediate loading/restoration in the anterior maxilla. Considering anterior single-tooth replacement in sites without tissue deficiencies, predictable treatment outcomes, including esthetics, can be achieved because of tissue support provided by adjacent teeth. The replacement of multiple adjacent missing teeth in the anterior maxilla with fixed implant restorations is poorly documented. In this context, esthetic restoration is not predictable, particularly regarding the contours of the interimplant soft tissue. DISCUSSION AND CONCLUSIONS: This review has demonstrated that scientific documentation of esthetically relevant and reproducible parameters is rather scarce. Most of the reported outcome analyses primarily focus on implant survival. Elements of anterior implant success such as maintenance or reestablishment of harmoniously scalloped soft tissue lines and natural contours should be included in future studies.

Dental Abutments↗
PubMed2004

Optimizing esthetics for implant restorations in the anterior maxilla: anatomic and surgical considerations.

The placement of dental implants in the anterior maxilla is a challenge for clinicians because of patients' exacting esthetic demands and difficult pre-existing anatomy. This article presents anatomic and surgical considerations for these demanding indications for implant therapy. First, potential causes of esthetic implant failures are reviewed, discussing anatomic factors such as horizontal or vertical bone deficiencies and iatrogenic factors such as improper implant selection or the malpositioning of dental implants for an esthetic implant restoration. Furthermore, aspects of preoperative analysis are described in various clinical situations, followed by recommendations for the surgical procedures in single-tooth gaps and in extended edentulous spaces with multiple missing teeth. An ideal implant position in all 3 dimensions is required. These mesiodistal, apicocoronal, and orofacial dimensions are well described, defining "comfort" and "danger" zones for proper implant position in the anterior maxilla. During surgery, the emphasis is on proper implant selection to avoid oversized implants, careful and low-trauma soft tissue handling, and implant placement in a proper position using either a periodontal probe or a prefabricated surgical guide. If missing, the facial bone wall is augmented using a proper surgical technique, such as guided bone regeneration with barrier membranes and appropriate bone grafts and/or bone substitutes. Finally, precise wound closure using a submerged or a semi-submerged healing modality is recommended. Following a healing period of between 6 and 12 weeks, a reopening procedure is recommended with a punch technique to initiate the restorative phase of therapy.

Alveolar Bone Loss↗
PubMed2003

Appositional bone formation in marginal defects at implants.

In a previous experiment, it was demonstrated that a wide marginal defect around an implant can heal with a high degree of osseointegration. The present experiment was performed to evaluate the degree and quality of de novo bone formation and osseointegration in marginal defects adjacent to submerged titanium implants. All mandibular premolars and 1st molars were extracted in four Labrador dogs. Four experimental sites were identified in the right side of the mandible. In two sites, custom-made implants with a sandblasted, large grit, acid-etched (SLA) surface were installed without further ostectomy (control sites). In the two remaining sites (test sites), a specially designed step drill was used to widen the marginal 5 mm of the canal. A barrier membrane was used to cover the implants in the defect sites. All implants were submerged. One month later, an identical procedure, including site preparation and implant installation, was performed in the left side of the mandible. Two months following the first implant installation procedure, biopsies were collected and prepared for sectioning. Ostectomy and implant installation in the control location resulted in a series of bone tissue alterations which eventually allowed newly formed bone to establish contact with the SLA surface. The marginal defect lateral to the implant in the test locations gradually became filled with newly formed bone. De novo bone formation started within the walls of the surgically prepared defect. Bone-to-implant contact was first established in the apical portion of the gap. This new bone tissue was in the coronal direction continuous with a dense, non-mineralized 'implant attached' soft tissue which, over time, also became mineralized to increase the height of the zone of bone-to-implant contact. The results suggest that healing of a wide marginal defect around an implant is characterized by appositional bone growth from the lateral and apical bone walls of the defect.

Acid Etching, Dental↗
PubMed2003

IL-1 gene polymorphism and smoking as risk factors for peri-implant bone loss in a well-maintained population.

The aim of the present study was (i) to investigate the relation between specific interleukin-1 (IL-1) gene polymorphisms and peri-implant bone loss at osseointegrated ITI(R) dental implants and (ii) to explore the association between these allelic variants of the IL-1 gene complex and peri-implant mucosal inflammation, in both smoking and non-smoking individuals. A sample of 90 consecutive Caucasian patients (aged 33-88 years), treated with at least one ITI-implant participated in this retrospective investigation. Standardized periapical radiographs were taken after prosthetic rehabilitation (133.6 days, SD 136.9 days) and at the time of the re-examination, on average 5.6 years (SD 2.5 years) thereafter. The radiographs were analyzed by a calibrated examiner for changes in peri-implant bone levels. The examiner was blind with respect to clinical parameters and IL-1 status. The distance between the implant shoulder and the first visible bone-implant contact (DIB) at the respective time points were measured using a computerized method. The absolute bone level difference during the years of service (ABL) and the annual bone loss (DeltaBL/year) were calculated for all the implants. Percentages of full mouth bleeding on probing (BOP), as well as of BOP calculated separately for teeth and implants, were determined for all visits and averaged for the entire observation period. Out of the total patient sample, there were 14 heavy smokers (= 20 cigarettes/day), 14 moderate smokers (5-19 cigarettes/day), 23 previous smokers (smoking cessation > 5 years) and 39 non-smokers. Twenty-eight (31.11%) patients were IL-1 genotype positive. Upon stratification for smoking status, significant differences were found for the variables ABL (P < 0.04, U-test) and DeltaBL/year (P < 0.04, U-test) between non-smokers and heavy smokers for the IL-1 genotype positive group but not for the IL-1 genotype negative group. Moreover, significant differences in ABL (P < 0.04, U-test) and DeltaBL/year (P < 0.04, U-test) were identified between former smokers and heavy smokers for the IL-1 genotype positive group. The differences in inflammatory parameters (BOP) did not reach statistical significance. This study suggests that in heavy cigarette smokers, carriage of a functionally significant IL-1 gene complex polymorphism is associated with an increased risk for peri-implant bone loss following prosthetic reconstruction and during the supportive periodontal care phase of the treatment.

Adult↗
PubMed2003

The jumping distance revisited: An experimental study in the dog.

Following tooth extraction, a socket often presents dimensions that may be considerably greater that the diameter of a conventional implant. The present experiment was performed to study the healing that occurred adjacent to implants placed in recipient sites with a wide marginal defect. Four Labrador dogs were used. In the right side of the mandible, four experimental sites were prepared to receive titanium implants [sandblasted, large-grit, acid-etched (SLA) surface]. Traditional implant installation (control) was performed in one site. In the remaining three sites (test), a step drill was used to widen the marginal 5 mm of the canal. Following placement of an implant in a test site, a circumferential gap about 1-1.25 mm wide and 5 mm deep was present lateral to the implant. A resorbable barrier membrane was used to cover the implant and the bone tissue of two sites, while one site was left uncovered. Four months following implant installation, block biopsies of each implant site were obtained and prepared for ground sectioning. After 4 months of healing, the large marginal defect had been filled with newly formed bone. The degree of bone-to-implant contact between the newly formed tissue and the SLA surface was at all test sites high and similar to that obtained at control sites. The placement of a barrier membrane following implant installation did not improve the outcome of healing. We conclude that a marginal defect wider than 1 mm may heal with new bone and a high degree of osseointegration to an implant designed with a SLA surface.

Absorbable Implants↗
PubMed2003

Healing of periapical lesions with complete loss of the buccal bone plate: a histologic study in the canine mandible.

This study evaluated periapical healing of induced apical lesions with concomitant loss of the buccal bone plate in a dog model using four foxhounds. In an initial surgery, pulp cavities of mandibular premolars were exposed to induce apical lesions. In the same session, the cortical bone covering the buccal root surfaces was surgically removed to simulate buccal bone loss. After radiographic confirmation of the development of apical lesions, sites were reentered for surgical treatment. Following apical and buccal debridement, root-end resection, and root-end filling, sites were subjected to three different treatment modalities: (1) flap readaptation (controls); (2) placement of a collagen membrane covering the apical defect and denuded root surface; or (3) placement of an anorganic bovine bone filler into the apical defect and onto the exposed buccal root surface, with additional application of a collagen membrane. Animals were sacrificed 7 months following the second surgery. Step sections were analyzed histometrically and morphometrically for periapical healing. Sites with membrane + filler showed a statistically significantly lower mean percentage of new bone formation within the former defect compared to both membrane-alone and control sites. No significant differences were found for tissue components deposited on the cut root face across treatment groups. Formation of a continuous thin layer of new cementum covering the exposed dentin surface and root-end filling material was a frequent finding. Analysis of the tissue regeneration on the buccal root aspect as well as the clinical periodontal parameters will be presented in a separate article.

Absorbable Implants↗
PubMed2003

Ameloblastoma of the follicular, plexiform, and acanthomatous type in the maxillary sinus: a case report.

The ameloblastoma is a benign odontogenic tumor of epithelial origin. Histopathologically, it occurs in six patterns: plexiform, follicular, acanthomatous, granular cell, basal cell, and desmoplastic type. This report presents a rare case of an ameloblastoma in the maxillary sinus that consists of three types: follicular, plexiform, and acanthomatous. The diagnostic procedure, surgical therapy, and follow-up findings are described and discussed.

Aged↗
PubMed2003

[The CO2 laser in stomatology. Part 1].

Since its development in the early 60s of the last century, the CO2 laser has been rapidly introduced into medical research and almost every surgical specialty in medicine and dentistry. In dental surgery it is mainly used for oral soft tissue applications. For the treatment of some stomatologic lesions the CO2 laser is looked upon as the treatment method of choice, while for other lesions the evidence for its use is still not sufficient. The first part of this review discusses the typical aspects of wound healing in oral soft tissues following the application of a CO2 laser and will focus on histopathological issues of biopsies taken with a CO2 laser as compared to conventionally performed biopsies. The second part will review indications for the use of the CO2 laser for the therapy of stomatologic lesions.

Animals↗
PubMed2003

[The CO2 laser in stomatology. Part 2].

The second part of this review presents and discusses evidence in the recent literature for the application of the CO2 laser for the therapy of stomatologic lesions. Clinical outcomes and complications for the use of the CO2 laser are presented for the following stomatological conditions: leukoplakia, lichen planus, benign soft-tissue and salivary gland tumors, reactive soft tissue changes (i.e., fibroepithelial polyps), recurrent aphthous stomatitis, drug-induced gingival hyperplasia, mucous extravasation and mucous retention cysts, herpes simplex virus-induced lesions, maxillary midline frenum, and ankyloglossia (tongue-tie). This review outlines indications in which the CO2 laser is the treatment method of choice and in which situations the laser has still to be applied with caution.

Carbon Dioxide↗
PubMed2002

Biomechanical comparison of the sandblasted and acid-etched and the machined and acid-etched titanium surface for dental implants.

To make a direct biomechanical comparison between the sandblasted and acid-etched surface (SLA) and the machined and acid-etched surface (MA), a well-established animal model for implant removal torque testing was employed, using a split-mouth experimental design. All implants had an identical cylindrical solid-screw shape with the standard ITI thread configuration, without any macroscopic retentive structures. After 4, 8, and 12 weeks of bone healing, removal torque testing was performed to evaluate the interfacial shear strength of each surface type. Results showed that the SLA surface was more powerful in enhancing the interfacial shear strength of implants in comparison with the MA surface. Removal torque values of the SLA-surfaced implants were about 30% higher than those of the MA-surfaced implants (p = 0.002) except at 4 weeks, when the difference was at the threshold of statistical significance (p = 0.0519). The mean removal torque values for the SLA implants were 1.5074 Nm at 4 weeks, 1.8022 Nm at 8 weeks, and 1.7130 Nm at 12 weeks; and correspondingly, 1.1924 Nm, 1.3092 Nm, and 1.3226 Nm for the MA implants. It can be concluded that the SLA surface achieves a better bone anchorage than the MA surface, and that sandblasting before acid etching has a beneficial effect on the interfacial shear strength. As regards the bone-implant interfacial stiffness calculated from the torque-rotation curve, the SLA implants showed an overall more than 5% higher stiffness compared with the MA implants, although the difference did not reach the statistical significance level.

Acid Etching, Dental↗
PubMed2002

The use of reduced healing times on ITI implants with a sandblasted and acid-etched (SLA) surface: early results from clinical trials on ITI SLA implants.

ITI dental implants are available with two bone-anchoring surfaces, a titanium plasma-sprayed (TPS) surface, and a recently introduced sandblasted and acid-etched (SLA) surface. Cell culture and animal tests demonstrate that the SLA surface stimulates bone cell differentiation and protein production, has large amounts of bone-to-implant contact, and results in large removal torque values in functional testing of the bone contact. As a result of these studies, a prospective human clinical trial was initiated to determine whether the 4.1 mm diameter SLA ITI solid screw implants could be predictably and safely restored as early as six weeks after implant placement surgery. The protocol restricted the use of the reduced healing time to a) healthy patients with sufficient bone volume to surround the implant, and b) those patients who had good bone quality (classes I-III) at the implant recipient site. Patients with poorer bone quality (class IV) did not have restorations until 12 weeks after implant placement. The clinical trial is an ongoing multicenter trial, with six centers in four countries, and with follow-up over five years. The primary outcome variable was abutment placement with a 35 Ncm force, with no countertorque and no pain or rotation of the implant. A secondary outcome was implant success, as defined by no mobility, no persistent pain or infection, and no peri-implant radiolucency. To date, 110 patients with 326 implants have completed the one-year post-loading recall visit, while 47 patients with 138 implants have completed the two-year recall. Three implants were lost prior to abutment connection. Prosthetic restoration was commenced after shortened healing times on 307 implants. The success rate for these implants, as judged by abutment placement, was 99.3% (with an average healing time of 49 days). Life table analyses demonstrated an implant success rate of 99.1%, both for 329 implants at one year and for 138 implants at two years. In the 24-month period after restoration, no implant losses were reported for the 138 implants. These results demonstrate that, under defined conditions, solid screw ITI implants with an SLA endosseous surface can be restored after approximately six weeks of healing with a high predictability of success, defined by abutment placement at 35 Ncm without countertorque, and with subsequent implant success rates of greater than 99% two years after restoration.

Acid Etching, Dental↗
PubMed2002

Influence of the size of the microgap on crestal bone levels in non-submerged dental implants: a radiographic study in the canine mandible.

BACKGROUND: Accumulating evidence suggests that alveolar crestal bone resorption occurs as a result of the microgap that is present between the implant-abutment interface in dental implants. The objective of this longitudinal radiographic study was to determine whether the size of the interface or the microgap between the implant and abutment influences the amount of crestal bone loss in unloaded non-submerged implants. METHODS: Sixty titanium implants having sandblasted with large grit, acid-etched (SLA) endosseous surfaces were placed in edentulous mandibular areas of 5 American fox hounds. Implant groups A, B, and C had a microgap between the implant-abutment connection of <10 microm, 50 microm, or 100 microm, respectively, as did groups D, E, and F, respectively. Abutments were either welded (1 -piece) in groups A, B, and C or non-welded (2-piece screwed) in D, E, and F. All abutment interfaces were placed 1 mm above the alveolar crest. Radiographic assessment was undertaken to evaluate peri-implant crestal bone levels at baseline and at 1, 2, and 3 months after implant placement whereupon all animals were sacrificed. RESULTS: The size of the microgap at the abutment/implant interface had no significant effect upon crestal bone loss. At 1 month, most implants developed crestal bone loss compared with baseline levels. However, during this early healing period, the non-welded group (D, E, and F) showed significantly greater crestal bone loss from baseline to one month (P <0.04) and 2 months (P < 0.02) compared with the welded group (A, B, and C). No significant differences were observed between these 2 groups at 3 months (P > 0.70). CONCLUSIONS: Crestal bone loss was an early manifestation of wound healing occurring after 1 month of implant placement. However, the size of the microgap at the implant-abutment interface had no significant effect upon crestal bone resorption. Thus, 2-piece non-welded implants showed significantly greater crestal bone loss compared with 1-piece welded implants after 1 and 2 months suggesting that the stability of the implant/abutment interface may have an important early role to play in determining crestal bone levels. At 3 months, this influence followed a similar trend but was not observed to be statistically significant. This finding implies that implant configurations incorporating interfaces will be associated with biological changes regardless of interface size and that mobility between components may have an early influence on wound healing around the implant.

Alveolar Bone Loss↗
PubMed2002

Endoscope- and video-assisted endodontic surgery.

Since the introduction of microsurgical principles in the 1990s, the field of endodontic surgery has made continuous and substantial progress. Particularly, root-end cavity preparation has been simplified and optimized by means of newly developed surgical microinstruments. However, the successful outcome of endodontic surgery depends to a large extent on accurate intraoperative diagnostics. Conventionally, micromirrors (retromirrors) and microprobes have been used for this purpose. Recently, the surgical microscope has been used to enhance visibility during dental procedures. In addition, endoscopy has been reported to provide the surgeon with outstanding vision and ease of use. This article describes the technical specifications and the diagnostic application of the endoscope during endodontic surgery.

Apicoectomy↗
PubMed2002

Long-term stability of osseointegrated implants in augmented bone: a 5-year prospective study in partially edentulous patients.

This prospective clinical study evaluated the 5-year survival and success rates of 66 titanium implants placed in bone that had been previously augmented with autografts and nonresorbable barrier membranes. During the observation period, three patients with five implants dropped out of the study. None of the remaining 61 implants were lost during the follow-up period (implant survival rate of 100%). One implant exhibited a periimplant infection, whereas 60 implants were considered clinically successful at the 5-year examination, resulting in a 5-year success rate of 98.3%. It can be concluded that the clinical results of implants in regenerated bone are comparable to those of implants in nonregenerated bone.

Alveolar Ridge Augmentation↗