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Biomedical subjects

Daniel Buser

Publications and source records attributed to Daniel Buser.

At least 19 recordsLinked to original sources
PubMed2006

Enhanced bone apposition around biofunctionalized sandblasted and acid-etched titanium implant surfaces. A histomorphometric study in miniature pigs.

Microrough titanium (Ti) surfaces of dental implants have demonstrated more rapid and greater bone apposition when compared with machined Ti surfaces. However, further enhancement of osteoblastic activity and bone apposition by bio-functionalizing the implant surface with a monomolecular adsorbed layer of a co-polymer - i.e., poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and its derivatives (PLL-g-PEG/PEG-peptide) - has never been investigated. The aim of the present study was to examine early bone apposition to a modified sandblasted and acid-etched (SLA) surface coated with an Arg-Gly-Asp (RGD)-peptide-modified polymer (PLL-g-PEG/PEG-RGD) in the maxillae of miniature pigs, and to compare it with the standard SLA surface. Test and control implants had the same microrough topography (SLA), but differed in their surface chemistry (polymer coatings). The following surfaces were examined histomorphometrically: (i) control - SLA without coating; (ii) (PLL-g-PEG); (iii) (PLL-g-PEG/PEG-RDG) (RDG, Arg-Asp-Gly); and (iv) (PLL-g-PEG/PEG-RGD). At 2 weeks, RGD-coated implants demonstrated significantly higher percentages of bone-to-implant contact as compared with controls (61.68% vs. 43.62%; P < 0.001). It can be concluded that the (PLL-g-PEG/PEG-RGD) coatings may promote enhanced bone apposition during the early stages of bone regeneration.

Acid Etching, Dental↗
PubMed2006

Horizontal ridge augmentation using autogenous block grafts and the guided bone regeneration technique with collagen membranes: a clinical study with 42 patients.

OBJECTIVE: To analyze the clinical outcome of horizontal ridge augmentation using autogenous block grafts covered with an organic bovine bone mineral (ABBM) and a bioabsorbable collagen membrane. MATERIAL AND METHODS: In 42 patients with severe horizontal bone atrophy, a staged approach was chosen for implant placement following horizontal ridge augmentation. A block graft was harvested from the symphysis or retromolar area, and secured to the recipient site with fixation screws. The width of the ridge was measured before and after horizontal ridge augmentation. The block graft was subsequently covered with ABBM and a collagen membrane. Following a tension-free primary wound closure and a mean healing period of 5.8 months, the sites were re-entered, and the crest width was re-assessed prior to implant placement. RESULTS: Fifty-eight sites were augmented, including 41 sites located in the anterior maxilla. The mean initial crest width measured 3.06 mm. At re-entry, the mean width of the ridge was 7.66 mm, with a calculated mean gain of horizontal bone thickness of 4.6 mm (range 2-7 mm). Only minor surface resorption of 0.36 mm was observed from augmentation to re-entry. CONCLUSIONS: The presented technique of ridge augmentation using autogenous block grafts with ABBM filler and collagen membrane coverage demonstrated successful horizontal ridge augmentation with high predictability. The surgical method has been further simplified by using a resorbable membrane. The hydrophilic membrane was easy to apply, and did not cause wound infection in the rare instance of membrane exposure.

Adolescent↗
PubMed2006

Bone healing and graft resorption of autograft, anorganic bovine bone and beta-tricalcium phosphate. A histologic and histomorphometric study in the mandibles of minipigs.

OBJECTIVE: The purpose was to qualitatively and quantitatively compare the bone formation and graft resorption of two different bone substitutes used in both orthopedic and oral surgery, with autogenous bone as a positive control. MATERIALS AND METHODS: Three standardized bone defects were prepared in both mandibular angles of 12 adult minipigs. The defects were grafted with either autograft, anorganic bovine bone (ABB), or synthetic beta-tricalcium phosphate (beta-TCP). Sacrifice was performed after 1, 2, 4, and 8 weeks for histologic and histomorphometric analysis. RESULTS: At 2 weeks, more new bone formation was seen in defects filled with autograft than with ABB (P approximately 0.0005) and beta-TCP (P approximately 0.002). After 4 weeks, there was no significant difference between beta-TCP and the two other materials. Defects grafted with ABB still exhibited less bone formation as compared with autograft (P approximately 0.004). At 8 weeks, more bone formation was observed in defects grafted with autograft (P approximately 0.003) and beta-TCP (P approximately 0.00004) than with ABB. No difference could be demonstrated between beta-TCP and autograft. beta-TCP resorbed almost completely over 8 weeks, whereas ABB remained stable. CONCLUSION: Both bone substitutes seemed to decelerate bone regeneration in the early healing phase as compared with autograft. All defects ultimately regenerated with newly formed bone and a developing bone marrow. The grafting materials showed complete osseous integration. Both bone substitutes may have a place in reconstructive surgery where different clinical indications require differences in biodegradability.

Animals↗
PubMed2006

The effect of rhBMP-2 around endosseous implants with and without membranes in the canine model.

BACKGROUND: Bone morphogenetic protein (BMP) is a potent differentiating agent for cells of the osteoblastic lineage. It has been used in the oral cavity under a variety of indications and with different carriers. However, the optimal carrier for each indication is not known. This study examined a synthetic bioabsorbable carrier for BMP used in osseous defects around dental implants in the canine mandible. METHODS: Twelve canines had their mandibular four premolars and first molar teeth extracted bilaterally. After 5 months, four implants were placed with standardized circumferential defects around the coronal 4 mm of each implant. One-half of the defects received a polylactide/glycolide (PLGA) polymer carrier with or without recombinant human BMP-2 (rhBMP-2), and the other half received a collagen carrier with or without rhBMP-2. Additionally, one-half of the implants were covered with a non-resorbable (expanded polytetrafluoroethylene [ePTFE]) membrane to exclude soft tissues. Animals were sacrificed either 4 or 12 weeks later. Histomorphometric analysis included the percentage of new bone contact with the implant, the area of new bone, and the percentage of defect fill. This article describes results with the PLGA carrier. RESULTS: All implants demonstrated clinical and radiographic success with the amount of new bone formed dependent on the time and presence/absence of rhBMP-2 and presence/absence of a membrane. The percentage of bone-to-implant contact was greater with rhBMP-2, and after 12 weeks of healing, there was approximately one-third of the implant contacting bone in the defect site. After 4 weeks, the presence of a membrane appeared to slow new bone area formation. The percentage of fill in membrane-treated sites with rhBMP-2 rose from 24% fill to 42% after 4 and 12 weeks, respectively. Without rhBMP-2, the percentage of fill was 14% rising to 36% fill, respectively. CONCLUSIONS: After 4 weeks, the rhBMP-2-treated sites had a significantly higher percentage of contact, more new bone area, and higher percentage of defect fill than the sites without rhBMP-2. After 12 weeks, there was no significant difference in sites with or without rhBMP-2 regarding percentage of contact, new bone area, or percentage of defect fill. In regard to these three outcomes, comparing the results with this carrier to the results reported earlier with a collagen carrier in this study, only the area of new bone was significantly different with the collagen carrier resulting in greater bone than the PLGA carrier. Thus, the PLGA carrier for rhBMP-2 significantly stimulated bone formation around dental implants in this model after 1 month but not after 3 months of healing. The use of this growth factor and carrier combination appears to stimulate early bone healing events around the implants but not quite to the same degree as a collagen carrier.

Absorbable Implants↗
PubMed2006

Oral lichen planus and malignant transformation: a retrospective follow-up study of clinical and histopathologic data.

OBJECTIVE: Patients in the stomatology service of the Department of Oral Surgery and Stomatology who were clinically and histopathologically diagnosed with oral lichen planus (OLP) in the years 1995 to 2001 were examined for a possible malignant transformation of a previously biopsied OLP site. METHOD AND MATERIALS: For the 145 patients included, the recordings were searched for initial localization and type of OLP lesion, potential noxious agents, distribution between symptomatic and asymptomatic OLP types, and for a malignant transformation of a known OLP site during the follow-up period up to December 2003. RESULTS: The group comprised 47 men and 98 women with a mean age of 56.3 years. Of the 497 lesions, almost half were classified as reticular or papular, predominantly located on the buccal mucosa, gingiva, and borders of the tongue. Four patients did not adhere to their scheduled control visits and were dropped from the study. During the follow-up period 4 patients developed malignant transformation of OLP. In 3 of these cases, dysplasia was present at the initial diagnosis of OLP. This results in a malignant transformation rate of 2.84% among the remaining 141 patients; if the 3 patients with initial dysplasia are excluded, the rate drops to 0.71%. CONCLUSIONS: Until further knowledge is derived from large prospective studies, the data supporting or negating a potential malignant character of OLP lesions remains inconclusive. Special emphasis has to be directed toward unified inclusion and exclusion criteria regarding clinical and histologic findings and identifiable risk factors to allow the comparison of different studies.

Adult↗
PubMed2006

[The "globulomaxillary cyst" a specific entity or a myth?].

The following review investigates the term and concept of the globulomaxillary cyst as a correct clinico-pathological diagnosis to describe a so-called fissural cyst said to be caused by epithelial entrapment between the nasal and maxillary process. After analyzing the available literature it has to be concluded that neither from an embryologic nor from a clinical or pathohistological standpoint the term globulomaxillary cyst represents a real entity by itself. Therefore, globulomaxillary cysts have to be diagnosed alternatively after a thorough clinical, radiological and histological examination as other odontogenic cysts like dentigerous cysts or odontogenic keratocysts, odontogenic tumors like ameloblastoma, central giant cell tumors, solitary bone cysts, etc.

Diagnosis, Differential↗
PubMed2006

[Oral mucosal lesions diagnosed in a stomatology service. An examination of clinico-pathological findings from the year 2003].

During 2003, a total of 258 new patients with oral soft tissue lesions were admitted at the Stomatology Service of the Department of Oral Surgery and Stomatology at the University of Berne. For the present study, 185 patients with clinically and histopathologically verified diagnoses were included. The following data was collected: prevalence of oral mucosal lesions, distribution of benign, precancerous and malign lesions in different age groups, and the concordance of the referral with the working diagnosis at the Stomatology Service. The most frequent pathological soft tissue findings were fibrous hyperplasias (n = 44) and oral lichen planus (n = 30). Precancerous lesions were present in 41 cases (30 patients with oral lichen planus, eleven oral leukoplakias), and ten patients had oral malignomas. Most lesions were found in patients between the age of 40 and 60 years. The referral diagnosis concurred in 36.6% (n = 67) of the cases with the definite diagnosis before initiation of treatment, the working diagnosis in 70% (n = 128) of the cases. Therefore, it can be concluded that a specialised Stomatology Service serves as a center of competence due to large numbers of patients/cases seen and treated, and the resulting high level of clinical experience of the staff. Moreover, it is important in the primary diagnosis of oral squamous cell carcinoma, in collaboration with the referring dentist in private practice.

Adolescent↗
PubMed2006

[Biphosphonate-associated osteonecrosis of the maxilla. Case report and review of the literature].

In recent years, a growing number of reports in the literature have linked osteonecrosis of the jaw bones with intravenously administered bisphosphonates prescribed for the treatment of hypercalcemia of malignancy due to bone lesions of multiple myeloma or bone metastases in patients with breast or prostate cancer. Furthermore, an association between chronic oral bisphosphonate use in patients with osteoporosis or Paget's disease, and bone necrosis in the mandible or maxilla has been demonstrated in numerous case reports and case series in the last couple of years. Therapeutically, osteonecrosis of the jaws seems to be difficult to treat surgically, often resulting in a recurring or even progressing lesion. In the present case report of a bisphosphonate-associated osteonecrosis of the maxilla in a patient with osteoporosis, the current literature will be discussed, and open research questions and potential problems for our daily dental practice routine will be addressed.

Administration, Oral↗
PubMed2005

Early loading of non-submerged titanium implants with a sandblasted and acid-etched surface. 5-year results of a prospective study in partially edentulous patients.

OBJECTIVES: The aim of this prospective cohort study was to evaluate the success rate of titanium screw-type implants with the sandblasted and acid-etched (SLA) surface loaded early, after 6 weeks of healing. MATERIAL AND METHODS: A total of 104 implants were inserted into posterior sites of 51 partially edentulous patients exhibiting bone densities of class I-III. After a healing period of 6 weeks, all implants were functionally loaded with cemented crowns or fixed partial dentures. The patients were recalled at 3, 12, 24, 36, 48 and 60 months for clinical and radiographic examination. RESULTS: One implant failed to integrate during healing, and three implants were lost to follow-up and were considered drop-outs. The remaining 100 implants showed favorable clinical and radiographic findings at the 5-year examination. The peri-implant soft tissues were stable over time; the mean probing depths and mean attachment levels did not change during the follow-up period. None of the radiographs exhibited signs of continuous peri-implant radiolucency, which confirmed ankylotic stability for all 100 implants. The measurement of the bone crest levels (DIB values) indicated stability as well. Based on strict success criteria, all 100 implants were considered successfully integrated, resulting in a 5-year success rate of 99%. CONCLUSION: This prospective study using an early loading protocol with 6 weeks of healing demonstrated that titanium implants with the SLA surface can achieve and maintain successful tissue integration with high predictability for at least 5 years of follow-up in selected patients and sites.

Crowns↗
PubMed2005

The use of guided tissue regeneration principles in endodontic surgery for induced chronic periodontic-endodontic lesions: a clinical, radiographic, and histologic evaluation.

BACKGROUND: Chronic periodontic-endodontic lesions are not uncommon in clinical practice and their regenerative capacity has long been questioned. However, there are no published studies investigating the application of guided tissue regeneration techniques in combination with endodontic surgery using an induced perio-endo defect model. This study evaluated the clinical, radiographic, and histologic outcomes of three surgical procedures used to treat induced perio-endo lesions. METHODS: Pulpal necrosis was induced in foxhounds along with surgical removal of radicular buccal bone. After 4 weeks, chronic lesions were clinically and radiographically assessed. Treatment surgery consisted of apicoectomy, root canal instrumentation, and retrofilling with mineral trioxide aggregate. Teeth were then assigned to one of the following treatment groups: open flap debridement only (OFD), OFD with bioabsorbable porcine-derived collagen membrane (BG), or OFD with BG and anorganic bovine bone matrix (BO/BG). Clinical parameters and standardized radiographs were assessed at defect creation; treatment surgery; and at 1, 2, 4, and 6 months. Animals were sacrificed at 6 months and specimens prepared for histometric analysis. RESULTS: Clinical and radiographic conditions improved during the study period. Mean epithelial attachment was similar between all groups. Mean connective tissue attachment for groups OFD, BG, and BO/BG was 3.79 mm, 2.63 mm, and 1.75 mm, respectively, and mean radicular bone height was 2.16 mm, 3.24 mm, and 3.45 mm, respectively. Statistically significant increases in the amount of new cementum were observed in groups BG and BO/BG when compared with OFD (P <0.05). CONCLUSIONS: Treatment of combined induced perio-endo lesions using bioabsorbable collagen membranes alone or in combination with anorganic bovine bone matrix resulted in increased amounts of bone, periodontal ligament, and significant increases in the amount of new cementum when compared to open flap debridement in a canine model.

Absorbable Implants↗
PubMed2005

[The odontogenic keratocyst--odontogenic cyst or benign tumor?].

The odontogenic keratocyst is the third most common cyst of the jaws, after the follicular and radicular cyst. Keratocysts most commonly occur as single lesions in the jaw of otherwise healthy persons. Multiple odontogenic keratocysts are a well-recognized feature of the nevoid basal cell carcinoma syndrome. The mandible, especially the third molar region, the angle of the mandible and the ascending ramus are involved far more frequently than the maxilla. Clinically, the cysts often remain asymptomatic and there are two specific histological entities: the orthokeratinized and the parakeratinized odontogenic keratocyst. Different surgical treatment options like marsupialization, enucleation with curettage or peripheral ostectomy, and osseous resection (marginal or segmental) have been discussed in the literature with variable rates of recurrence. Besides a predilection for recurrence, the keratocysts, in contrast to other odontogenic cysts, show a more aggressive clinical behavior and demonstrate a high mitotic count and higher turnover rate of the epithelium. This led to the tentative suggestion that the keratocyst might be a benign cystic neoplasm rather than simply an odontogenic cyst.

Basal Cell Nevus Syndrome↗
PubMed2005

The CO2 laser for excisional biopsies of oral lesions: a case series study.

During a period of 12 months, 139 patients with 164 intraoral pathologic lesions were treated with a CO2 laser. Intra- and postoperative complications and the method of pain control during and after surgery were recorded. The diagnostic evaluability of the 133 soft tissue biopsy specimens sent for histopathologic analysis was examined, and the clinical and histopathologic diagnoses were compared. Nine intra- and six postoperative complications occurred. Pain control during CO2 laser surgery could be performed with a topical anesthetic in almost one third of the lesions; in the other 111 lesions, a local anesthetic had to be applied. For pain relief after the operation, 101 patients (72.7%) used only an adhesive wound paste, without any additional oral analgesic. The thermal damage from the CO2 laser on the borders of the biopsy specimens never interfered with the pathologist's establishment of a firm diagnosis. The CO2 laser is an appropriate instrument for excisional biopsies of oral soft tissue lesions. Intra- and postoperative complications were minimal, pain relief during and after surgery could be achieved in many cases through topical anesthetics, and incisional or excisional biospsies caused no diagnostic problems because of collateral thermal damage of the specimen from the laser.

Administration, Topical↗
PubMed2005

[Primary diagnosis of oral squamous cell carcinoma. A retrospective study of patient data from 1990 to 2002].

In this retrospective study, charts were analyzed of 94 patients who presented with oral squamous cell carcinoma (OSCC) at the Department of Oral Surgery and Stomatology at the University of Bern from 1990 to 2002. Critical points in the evaluation included presence and type of potential noxious agents, tumor size and palpable lymph nodes at the first oral cancer examination, and the delay (patient and professional delay) from the appearance of the first clinical signs to the definitive diagnosis. Of the patients included, 56 patients were smokers, 48 patients reported regular consumption of alcoholic beverages, and 41 patients had a combination of smoking and drinking habits. Invasion of neighbouring tissues by the OSCCs (= cT4), mainly into alveolar bone, was found in 25 cases, and 35 patients already had clinically suspicious lymph nodes upon examination (cN1-cN3). The total delay until the definitive diagnosis "OSCC" was between two (median) and five months (mean). These results suggest that further efforts in primary and secondary OSCC prevention programs, such as smoking cessation and screening of patients at risk, are necessary to optimize the longterm prognosis and to minimize morbidity of patients suffering from OSCC.

Adult↗
PubMed2004

Impact of IL-1 genotype and smoking status on the prognosis of osseointegrated implants.

AIM: This study evaluated the impact of the IL-1 genotype and smoking status on the prognosis and development of complications of osseointegrated implants. MATERIAL AND METHODS: The clinical charts of 180 consecutively admitted patients were analyzed with respect to the occurrence of biological complications in conjunction with oral implants. Biologic complications were defined as clinical conditions with suppuration from the peri-implant sulcus, development of a fistula or peri-implantitis with radiologic bone loss. All patients had received one or more ITI dental implants, which had been in function for at least 8 (range: 8-15) years. This patient population had received 292 implants. From these, 51 implants in 34 patients showed late (infectious) biologic complications, and 241 implants had survived without any biologic complications at all. RESULTS: Of the 180 patients, 53 were smokers, who were subdivided in a series of classes according to their intensity of smoking and 127 were never smokers. Sixty-four of 180 (36%) patients tested positive for the IL-1 genotype polymorphism. This prevalence corresponds to previous reports for the prevalence of European descent populations. The results for the non-smoking group indicated no significant correlation between implant complications and a positive IL-1 genotype. However, there was a clear association for heavy smokers between a positive IL-1 genotype and implant complications. 6 of 12 or half of the heavy smokers and IL-1 genotype-positive patients had either an implant failure, i.e. loss of implant, or a biologic complication during the follow-up period. CONCLUSIONS: These findings have led to the conclusion that there is a synergistic effect between a positive IL-1 genotype and smoking that puts dental implants at a significantly higher risk of developing biologic complications during function.

Adult↗
PubMed2004

Study on the necessity for cross-section imaging of the posterior mandible for treatment planning of standard cases in implant dentistry.

OBJECTIVE: To investigate whether cross-section imaging influences the planning and therapy of standard implant cases in the posterior mandible. MATERIAL AND METHODS: In a prospective study conducted over 16 months, the planned treatment (standard implant therapy without bone augmentation procedures in the premolar and molar regions of the mandible) was compared with the postoperative result in 50 randomly selected patients. Clinical examinations and panoramic radiographs were performed pre- and postoperatively, whereas cross-sectional tomography was performed only preoperatively. RESULTS: The vertical magnification factor in the panoramic radiographs was very constant pre- and postoperatively with 1 : 1.27 and in the spiral tomograms with 1 : 1.52. In 11 of 77 implant sites, the mandibular canal could not be evaluated in the spiral tomograms. The additional information from cross-sectional spiral tomography did not influence the original planning in 74 of 77 (96.1%) implant sites. Based on the postoperative panoramic radiograph, the average distance from the tip of the implants to the mandibular canal was 3.04+/-2.06 mm. In two cases (2.6%), transient postoperative altered tactile sensation of the mental nerve was found. CONCLUSION: The information from preoperative cross-sectional spiral tomography has minor impact on treatment planning in standard implant cases in mandibular premolar and molar regions. The clinical examination provides sufficient information for selecting implant diameter and the panoramic radiograph provides sufficient information for implant length selection.

Bicuspid↗
PubMed2004

Osteosarcoma of the maxilla and the maxillary sinus: a case report.

Osteosarcoma of the jawbones is a rare malignant mesenchymal neoplasm with the tendency for new bone being directly formed by the tumor cells. Clinically, the tumor may be central or peripheral--periosteal--and histologically can be divided into three subtypes: osteoblastic, fibroblastic, and chondroblastic. This report presents a case of a central osteoblastic osteosarcoma of the left maxillary tuberosity and maxillary sinus. Problems related to definitive diagnosis and therapy are described and discussed.

Humans↗
PubMed2004

[Indications for oral implantology in a referral clinic. A three-year retrospective analysis of 737 patients with 1176 implants].

The following study reviews patients from the Department of Oral Surgery and Stomatology at the University of Berne undergoing implant therapy. Between 2000 and 2002, 737 patients received 1176 ITI screw-type implants. At least 70% of these patients were 50 years or older. The main reason for tooth loss in this group was often periodontitis, followed by carious, periapical infection and root fractures. Only 15% of the patients were younger than 30 years. They had lost their teeth mainly due to trauma or agenesis of teeth. This study reports a trend towards treatment of partially edentulous patients (>90%), with single tooth gaps (>50%) being the most frequent indication for implant therapy. The analysis also demonstrated the importance of augmentation procedures prior to implant placement. Almost 40% of the implant cases required either ridge augmentation or sinus lift procedures. The GBR technique was frequently utilized in the anterior maxilla, especially with bone defects resulting from dental trauma. Data also showed that with these augmentation procedures more implants were inserted in the maxilla (53%) than in the mandible. During the healing or early loading phase only six implants out of 1176 were lost, resulting in an early failure rate of 0.51%. Our study has demonstrated that a high level of implant success can be achieved with the ITI system when using a strict selection criteria and stringent operating protocols.

Adult↗