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Biomedical subjects

U Brägger

Publications and source records attributed to U Brägger.

At least 19 recordsLinked to original sources
PubMed1992

Surgical lengthening of the clinical crown.

The aim of the present study was to assess the changes in the periodontal tissue levels as an immediate result of the surgical crown lengthening procedure and over a 6-months healing period. 25 patients ranging between 20 to 81 years of age were included in the study. A total of 85 teeth (43 test and 42 control teeth not exposed to surgery) were evaluated over 6 months. After initial therapy, the indication for crown lengthening comprised need for increased retention and accessibility to deep subgingival preparation margins hampering impression taking. During surgery, the alveolar crest was reduced, thereby creating a distance of 3 mm to the future reconstruction margin. The results of this study demonstrated that the mean probable changes in the levels of the periodontal tissues from those defined after surgery were minimal, resulting in changes comparable to the shifts observed at control teeth not exposed to any surgical procedures. Frequency analysis of the number of sites with dislocation of the free gingival margin demonstrated that 12% of the sites with crown lengthening procedure showed 2-4 mm recession of the free gingival margin between 6 weeks and 6 months postoperatively. In esthetically critical, visible areas of the dentition, recessions must be closely observed in the healing period after surgical crown lengthening, when prosthetic reconstructions are planned on such teeth.

Adult↗
PubMed1992

Remodelling of periodontal tissues adjacent to sites treated according to the principles of guided tissue regeneration (GTR).

The aim of the present study was to assess the remodelling of alveolar bone adjacent to periodontal sites following therapy according to the principles of guided tissue regeneration (GTR) using computer-assisted densitometric image analysis (CADIA), and to compare the radiographic results to traditional clinical parameters. As required for digital subtraction analyses, periodically reproducible radiographs were obtained using a modification of the Rinn System and individual acrylic bite blocks for periodical identical radiographs. Ideally, a digital subtraction image from a site where absolutely no change in density had occurred would show a perfect cancellation of the structures. An average grey level value of 128 (the middle of the digitizer grey level range set by software) would show up at each pixel. Areas with grey levels < 128 in the subtraction image would indicate loss in density and grey levels > 128 would indicate increase in density. Within the subtraction images, areas were defined using the cursor to draw "regions of interest" (ROI) projected on the bony defect exposed to GTR covering the crestal bone as well as the region of potential "bonefill". The mean, median, the standard deviation and range of the grey levels of pixels within a particular ROI were calculated. Similarly sized ROI were drawn in bone areas not exposed to the GTR procedure serving as controls. The differences in the mean grey levels of all pixels within a particular ROI between the baseline, 3 and 12 months images were calculated for documentation of gain or loss in density. From 14 patients, standardized radiographs were available from baseline, 3 months and 12 months postsurgically, depicting one infraosseous defect before and after treatment according to the principles of GTR. The densitometric changes observed in these defects were compared to the clinically assessed changes measured at the site with the deepest baseline pocket depth. A mean clinical attachment gain of 2.36 mm after 3 and 3.22 mm after 12 months was measured. This was associated with a mean reduction in the PPD amounting to 3.36 mm and 3.79 mm, respectively. The changes in the level of the FGM were rather small considering the deep original mean PPD of 7.07 mm. Over the first months, a mean recession of 1.14 mm was observed which was followed by a coronal displacement of 0.43 mm. With respect to the remodelling of the alveolar bone adjacent to the defects assessed by means of CADIA, the most pronounced changes occurred when comparing the baseline to the 12 months radiographs.(ABSTRACT TRUNCATED AT 400 WORDS)

Absorptiometry, Photon↗
PubMed1992

Progression of periodontal disease in patients with mild to moderate adult periodontitis.

The aim of the present study was to determine the progression rate of periodontal disease in patients treated for localized or generalized mild to moderate adult periodontitis. 52 patients with a mean age of 53.7 years (S.D. 12.6 years) were instructed in optimal home care procedures and exposed to initial periodontal therapy, before reconstructive therapy was initiated. Following completion of the prosthetic procedures, supportive therapy was offered to a limited extent and maintenance visits were irregularly scheduled corresponding to traditional dental care. Clinical periodontal parameters from 4 sites per tooth were assessed at the initial examination, at the time of reevaluation after initial therapy and at the re-examination after 8-years. Full sets of intraoral radiographs from the initial and the 8-year re-examination were analyzed with respect to changes in the radiographic alveolar bone height as a % of the total tooth length. As the result of the home care instructions, the mean plaque index (plaque control record) amounted to 21% at the end of initial periodontal therapy. 8 years later, the re-examination revealed a mean plaque index of 49% and a mean gingival bleeding index of 24%. At the initial examination, the 52 patients presented with an average of 18.7 teeth. During treatment, 26 teeth were sacrificed and 19 teeth were lost over the 8 years of supportive therapy. Bicuspids were the most frequent teeth to be lost over the observation period. As a result of initial therapy, the mean pocket probing depths decreased significantly. However, after 8 years, only minor differences were found when compared to the initial examination.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1992

Periodontal conditions in adult patients with cleft lip, alveolus, and palate.

The present study assessed the progression rate of periodontal disease over 8 years in a group of 52 adult patients with various forms of cleft lip, alveolus, and palate considered at risk for progression of periodontal disease. Of special interest was the evaluation of periodontal disease progression at sites adjacent to cleft regions compared to changes found at control sites not directly affected by such defects. High incidences of generalized plaque accumulation and bleeding on probing were noted at both examinations in 1979 and 1987. A mean apical shift of the clinical attachment level amounting to 0.2 mm had occurred over the 8-year observation period. A slight apical displacement of the mesial and distal mean crestal alveolar bone was also noted. The rate of progression of periodontal disease over the 8 years was not found to be different at statistically significant levels at cleft sites compared to control sites. However, the results of this study documented that the cumulative periodontal destruction at 26 to 28 years of age was statistically significant and more pronounced at cleft sites as revealed by greater probing pocket depth and loss of clinical attachment. The differences between test and control sites amounted to 0.3 and 0.4 mm respectively for probing depth and 0.6 mm for loss of clinical attachment. In addition, the discrepancy between alveolar bone height and the levels of the clinical attachment at cleft sites demonstrated the presence of a long supracrestal connective tissue attachment adjacent to cleft defects. Therefore, the alveolar bone height as visualized in radiographs at such sites was considered an unreliable diagnostic tool for the assessment of the degree of periodontal destruction.

Adolescent↗
PubMed1992

Microbiota associated with residual clefts and neighboring teeth in patients with cleft lip, alveolus, and palate.

Twenty patients with residual clefts or pronounced soft tissue grooves, treated for uni- or bilateral cleft lip, alveolus, and palate were included in this study. Ten patients were recalled for dental prophylaxis at regular intervals, 10 patients were not. One microbiologic sample was obtained from the cleft area and two samples from a tooth adjacent to the cleft (sites adjacent and distant to the cleft). Between the recall and the nonrecall group there were notable differences in the presence of anaerobic Gram-negative organisms. Fusobacterium spp., Prevotella melaninogenica, and P. intermedia were more often found in nonrecall patients. While rarely seen in recall patients, spirochetes and motile rods were a common feature of nonrecall patients. The putative periodontal pathogens Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were not detected in either group. The differences between the recall and the nonrecall groups were more pronounced when the respective samples from teeth were related to each other than when the samples obtained from the clefts were compared. The cleft flora was less complex irrespective of how good maintenance was and resembled the flora of teeth of well-maintained patients. Samples from clefts were never Wolinella positive, and harbored significantly less Capnocytophaga and Actinomyces viscosus than samples from dental sites.

Actinomyces viscosus↗
PubMed1992

[Dental imaging].

Explore the source record for details and available documents.

Dentistry↗
PubMed1991

Diagnosis of alveolar bone changes with digital subtraction images and conventional radiographs. An in vitro study.

The purpose of the present study was to compare the diagnostic properties of radiographs obtained with Ultra-Speed and Ektaspeed films when analyzed conventionally radiographs and after conversion in digital subtraction images. Artificial lesions, measuring 0.5, 0.7, 0.9, and 1.1 mm in diameter, were drilled in a dry skull with slow-speed burs. Standardized radiographs were obtained by means of acrylic bite blocks and a modification of the Rinn system. The results of this study demonstrated that sensitivity in the detection of the lesions was doubled after digitizing and displaying subtraction images compared with the conventional radiographic interpretation, independent of the use of Ektaspeed or Ultra-Speed films for the original radiographs. The diagnostic information seemed to be equal in radiographs obtained from Ultra-Speed and Ektaspeed films after digitization and image processing procedures.

Alveolar Bone Loss↗
PubMed1991

Periodontal diagnosis in the 1990s.

Clinicians are usually inclined to reduce data obtained from diagnosis to a simpler form such as "yes or no" answers in order to obtain useful parameters for daily practice. It should be realized, however, that the diagnostic process very rarely exhibits "black and white" situations. Rather the evaluation of numerous "grey levels" is imperative. The diagnostic process, therefore, remains always incomplete and inaccurate, and it represents an evaluation of probabilities rather than certainties. For this reason, the diagnostician should realize and understand the mathematical relations between the information provided by diagnostic tests and the clinical situation actually present at the time of the test. This will allow one to convert diagnostic results into therapeutic procedures with a high degree of confidence. Since results from diagnostic tests are quite often used to decide on treatment, complex data are reduced to simple dichotomy, such as presence or absence of disease, normal or abnormal conditions, etc. In order to react to diagnostic tests in an ordinal, dichotomous manner, the clinician has to choose a particular level of a test at which he initiates treatment without having the assurance that this level represents the one and only standard at which treatment has to be initiated.

Humans↗
PubMed1991

Effect of region-of-interest in computerized densitometric analysis of radiographs.

The region-of-interest (ROI) in computer-assisted densitometric image analysis (CADIA) is defined by its size and location. This study evaluated the effects of these variables on two quantitative parameters, the change in density and the area with change in density. Pairs of radiographs for these analyses were obtained from sites with "no change" or "known loss" in Cynomolgus monkeys during a study of ligature-induced periodontitis. The size and location of the ROI had clear effects on the two CADIA parameters. To reduce these effects, a corrective procedure hypothesizing a linear relationship between the ROI size and the area with change in density was tested. While this procedure was sufficient to correct for ROI size-dependent differences among "no change" images, it was not effective in images with "known loss". In such images, additional adjustments by increasing threshold levels for the registered change in density were found to reduce but not to eliminate differences between ROIs of different size and location. When densitometric radiographic analysis is used for quantitative comparison of different sites, it is primarily recommended to select ROIs of similar size and location. Application of corrective procedures should follow only after careful evaluation of their effects on sensitivity and specificity.

Alveolar Bone Loss↗
PubMed1991

Long-term stability of treatment results in cleft lip and palate patients.

The stability of the orthodontic and prosthetic results of the treatment of 18 individuals with isolated cleft of the palate, 18 subjects with a complete unilateral and 8 with a complete bilateral cleft was evaluated in an eight-year follow-up period. The subjects were examined at the age of 19 years, after completed orthodontic and surgical treatment, and again at the age of 27 years. After the first examination the majority of the individuals with a complete cleft had at the age of 20 to 21 years been treated with a fixed bridge which was only minimally extended. The width of the upper dental arch at the second bicuspid decreased slightly in the subjects with an isolated cleft of the palate and in those with a bilateral cleft. In the subjects with a unilateral cleft there was a slight decrease of the upper dental arch widths at both bicuspids and at the first molar. In the subjects with complete clefts the slight decrease in upper dental arch widths was accompanied by a slight increase of the number of posterior teeth in cross-bite. The total number of teeth in cross-bite was small, however. On the whole, the upper dental arch was relatively stable during the follow-up period. This was found in the group with bilateral clefts, reconstructed with 5-8 unit bridges, as well as in the subjects with a unilateral cleft who had received no or only minimally extended reconstructions and in the group with an isolated cleft of the palate (no bridge).

Adolescent↗
PubMed1991

Digital subtraction radiography for the assessment of changes in peri-implant bone density.

Digital subtraction radiography is proposed as a potential diagnostic tool for implant research and patient monitoring. Examples of the application of this technique are given observing peri-implant density changes during the early healing phase and during ligature-induced peri-implantitis in an animal model. Additional cases document the loss of peri-implant bone density associated with an infection and increase in density caused by remodeling after functional loading of an implant with a single crown. Digital subtraction radiography might be one of the most sensitive noninvasive methods for assessing subtle density changes in peri-implant tissues, providing additional diagnostic information on implant tissue integration and maintenance.

Alveolar Bone Loss↗
PubMed1991

[Diagnosis of furcation involvement].

The diagnostic aids for the assessment of furcation involvement are identical with the ones used for periodontal assessment. For probing of the furcation area, a special curved probe is indispensable. A new imaging procedure for diagnosis of alterations in the furcation area is presented: after congruently superimposing digitalized x-ray films on each other, the only structures left visible are the ones whose density has changed.

Epithelial Attachment↗
PubMed1991

[Methods aimed at lengthening the clinical crown: a review].

This review deals with the different methods of lengthening the clinical crown and discusses the advantages and/or disadvantages of each method. Different flap procedures, including ostectomy and osteoplasty, reduce the height of the alveolar crest aiming at a distance of about 3 mm to a future reconstruction margin. Root planing may avoid reattachment of surgically separated fibers. Other methods like gingivectomy, electrosurgery, intra-alveolar transplantation, and forced eruption might contain considerable biological disadvantages. However, if the extrusion is combined with regular fiberotomy, this method becomes the most conservative with respect to the periodontal tissues of neighboring teeth. On the other hand, not all situations which require lengthening of the clinical crown can be solved by orthodontic extrusion and fiberotomy. Therefore, depending on the clinical problem, either the surgical lengthening of the clinical crown or the orthodontic extrusion with separation of the fibers are the recommended procedures.

Alveolectomy↗
PubMed1990

Regeneration and enlargement of jaw bone using guided tissue regeneration.

The purpose of this study was to present the surgical procedures and the clinical results of guided tissue regeneration (GTR) treatment aimed at regenerating local jaw bone in situations where the anatomy of the ridge did not allow the placement of dental implants. 12 patients were selected for ridge enlargement or bony defect regeneration. A combined split- and full-thickness flap was raised in areas designated for subsequent implant placement. Following perforation of the cortical bone to create a bleeding bone surface, a PTFE membrane was adjusted to the surgical site in such a way that a secluded space was created between the membrane and the subjacent bone surface in order to increase the width of the ridge or to regenerate bony defects present. Complete tension-free closure of the soft tissue flap was emphasized. Following a healing period of 6 to 10 months, reopening procedures were performed and the gain of bone dimension was assessed. In 9 patients with 12 potential implant sites, a sufficient bone volume was obtained to allow subsequent implant placement. The gain of new bone formation varied between 1.5 and 5.5 mm. In 3 patients, acute infections developed which necessitated early removal of the membranes and no bone regeneration could be achieved. The results of the study indicate that the biological principle of GTR is highly predictable for ridge enlargement or defect regeneration under the prerequisite of a complication-free healing.

Adolescent↗