Biomedical subjects

R Nilvéus

Publications and source records attributed to R Nilvéus.

At least 19 recordsLinked to original sources

PubMed1994

Subepithelial connective tissue grafts in the treatment of gingival recessions. A comparative study of 2 procedures.

Thirty (30) class I and class II recessions in 30 subjects were treated with a subepithelial connective tissue graft procedure. In one group (15 sites), the surgery was carried out in a traditional fashion: the epithelial collar of the graft was preserved and left exposed (CTG group). In the second group (15 sites), the epithelial collar of the graft was removed and the recession areas were conditioned with citric acid. The graft was then sutured and completely immersed under the facial flap which was coronally repositioned (CR group). Clinical assessments included probing depth, probing attachment level, surface area of the recession, and gingival width. These measurements were taken at baseline and at 6 months. In addition, an esthetic evaluation was done. The differences between treatments were not statistically significant except for the augmentation of gingiva (P < or = 0.05). Based on the midfacial measurements taken in the central area of the recession, the mean percentage of root coverage was 69.2%. In the CR group, 3 of the 15 recessions exhibited complete root coverage; the gingival augmentation was 65.5%. In the CTG group, 5 of the 15 recessions exhibited complete root coverage; the gingival augmentation was 94.4%. The mean surface area of root exposure was reduced from 13.82 mm2 and 13.67 mm2 to 2.15 mm2 and 2.34 mm2 for the CR group and the CTG group, respectively. One-hundred percent (100%) of good-to-moderate esthetic results were found by a panel of independent examiners; there was tendency toward better results in the CR group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Treatment of periodontal furcation defects. Coronally positioned flap with or without citric acid root conditioning in class II defects.

A total of 27 mandibular, buccal class II furcation defects were treated in 16 subjects using a coronally positioned flap procedure, with or without citric acid conditioning of the root surfaces. The effect of the therapies was evaluated from a series of soft and hard tissue measurements. Mean improvements were slightly greater for acid treated than for non-acid treated defects. However, none of the mean differences reached statistical significance, indicating that citric acid conditioning may not be a necessary part of the regenerative, coronally positioned flap procedure in mandibular furcations.

Acid Etching, Dental↗

PubMed1992

The effect of hygiene instruments on dentin surfaces: scanning electron microscopic observations.

The present study consists of two separate parts. The first section is an in vitro evaluation of the relative abrasiveness of some hygiene instrumentations commonly used during maintenance therapy. In the second section, one of the instruments, a recently developed plastic tip for use on a sonic scaler, was examined for its ability to remove dental plaque from root surface specimens instead for 5 weeks in the oral cavities of dogs. The in vitro study was performed on recently obtained dentin specimens where a ridge had been machined parallel to the long axis of the tooth. The sonic scaler fitted with the plastic tip gave considerably less removal of dentin and a smoother dentin surface than the curet, the rubber cup with polishing paste, or the sonic scaler with an ordinary metal tip. These findings further demonstrated that the plastic tip was able to efficiently remove 5-week old dental plaque from experimental root surface areas within a time frame of 5 seconds. The new plastic tip may be valuable in maintenance therapy giving less risks for iatrogenic effects on the root surfaces than other debridement methods.

Alloys↗

PubMed1991

Periodontal repair in dogs. Healing patterns in large circumferential periodontal defects.

This report describes the healing patterns of large circumferential periodontal defects in the beagle dog. Approximately 5 mm large periodontal defects were created around the mandibular premolars (P2, P3 and P4) in 13 animals. The root surfaces were then instrumented to remove all cementum and the wounds immediately closed by replacing and suturing the flaps just coronal to the cemento-enamel junction. Block biopsies were harvested after 4 weeks. Most of the surgically denuded root surface healed with connective tissue repair. Cementum formation and regeneration of alveolar bone was limited and averaged approximately 30% and 20%, respectively, of the defect height. Almost all teeth exhibited root resorption. Ankylosis was observed in 1/3 of the teeth. There was no difference in the healing response between the 3 premolars or their buccal and lingual surfaces. The range of healing responses indicates that a biological potential exists which makes this model useful for testing the effect of various root and wound conditioners in (1) enhancing cementum formation on the root surface, (2) increasing regeneration of alveolar bone and (3) preventing aberrant healing events such as root resorption and ankylosis. Conversely, whether such agents may compromise wound healing and result in reduced connective tissue repair may concomitantly be tested.

Alveolar Bone Loss↗

PubMed1991

Early healing events at the dentin-connective tissue interface. Light and transmission electron microscopy observations.

The objective of these studies was to follow early healing at the dentin-connective tissue interface. Small dentin blocks were surgically implanted in bone cavities under mucoperiosteal flaps in the edentulous alveolar ridges of five beagle dogs at various times. In two separate experiments, wound maturation on native dentin surfaces and on citric acid or heparin conditioned dentin surfaces was observed. Block specimens including bone, dentin, and surrounding soft tissues were obtained at 10 minutes, 1 and 6 hours, and 1, 3, and 7 days after flap closure and prepared for light and transmission electron microscopic examination of the interface. The very initial attachment to native dentin was mediated by a granular precipitate. At 1 and 6 hours, the intercellular matrix was more organized with fibrin formation around red blood cell aggregates and at the dentin surface. Polymorphonuclear leukocytes were observed throughout the interface. Red blood cells were undergoing degradation at day 1 and polymorphonuclear cells were prevalent at the dentin surface. The 3-day observation interval was characterized by further maturation of the fibrin clot. Macrophages were observed near the dentin surface and fibroblasts could be identified. The 7-day specimens exhibited areas of cell rich connective tissue attachment without inflammatory cells as well as areas showing the fibrin clot in various stages of decomposition. These observations suggest that connective tissue attachment to dentin surfaces is mediated by adsorption of plasma proteins to the surface and subsequent development and maturation of a fibrin clot. The sequence of healing events at dentin surfaces conditioned with citric acid or heparin was largely similar to healing at native dentin surfaces. However, at day 1 and later time points, clot adhesion to heparin-conditioned dentin appeared compromised, whereas the fibrin clot seemed to adhere to citric acid-conditioned dentin at all observation periods. These observations indicate that in the absence of mechanical trauma, epithelial proliferation, and infection, wound maturation at the dentin-connective tissue interface may not necessarily be affected by treatments that either enhance or inhibit clot adhesion to the dentin surface.

Alveolectomy↗

PubMed1991

Periodontal repair in dogs: effect of root surface treatment with stannous fluoride or citric acid on root resorption.

This study evaluated healing, with emphasis on root resorption, following root surface treatment with 1% aqueous stannous fluoride (SnF2), saturated citric acid (CA), or saline control (C) in conjunction with periodontal flap surgery. Supraalveolar periodontal defects were surgically created and immediately treated in the mandibular premolars in 6 beagle dogs. The defect height approximated 5 to 6 mm from the reduced alveolar bone to the cemento-enamel junction. Root treatments were rotated between experimental teeth within jaw quadrants and duplicated in left and right quadrants in the dogs. Flaps were raised to cover most of the crowns of the teeth and sutured. The dogs were sacrificed 12 weeks after surgery and tissue blocks with teeth and adjacent structures were processed for histometric analysis. SnF2-treated teeth healed with significantly longer junctional epithelium, less connective tissue repair to the root surface, and less bone regeneration than CA and C-treated teeth. New cementum formation was limited in all treatment groups. Root resorption was observed in almost all teeth exhibiting connective tissue repair, however to a lesser amount and not as frequent in SnF2 treated teeth due to limited connective tissue repair. No differences were found in amount and frequency of root resorption in CA and C-treated teeth. An inhibitory effect on root resorption of SnF2 could not be disclosed in this experiment, however, it may be concluded that CA treatment of the root surface in conjunction with reconstructive periodontal flap surgery does not seem to enhance root resorption.

Alveolar Process↗

PubMed1991

Periodontal repair in dogs: healing in experimentally created chronic periodontal defects.

A need exists for well-defined animal models to objectively evaluate surgical principles and a possible role for biochemical wound conditioning and biomaterials in promoting periodontal regeneration. To test an existing model for its usefulness in quantitative evaluation of periodontal wound healing, large supraalveolar periodontal defects were surgically created around the mandibular premolars (P2, P3, P4) in left or right jaw quadrants in 5 beagle dogs. The defects were exposed to the oral environment for 6 months and were then subjected to reconstructive flap surgery (chronic defects). Healing in these defects was compared to healing following reconstructive surgery in similar contralateral defects which had not been exposed to plaque and calculus (acute defects). The animals were sacrificed after a 4-week healing period and tissue blocks including teeth and surrounding structures were processed for histometric analysis. Mean defect height (+/- s.d.) for chronic and acute defects amounted to 4.6 +/- 0.3 and 4.4 +/- 0.4 mm, respectively. Mean connective tissue repair to the root surface in chronic defects amounted to 62% (range 49% to 74%) of the defect height. Mean connective tissue repair in the acute defects exceeded 94% of the defect height in 4 of the dogs, but amounted to only 48% in 1 dog. Regeneration of alveolar bone and cementum was limited under both experimental conditions. Root resorption was frequently encountered, whereas ankylosis was seen in only few teeth. This study indicates that healing may vary not only as a result of controlled experimental variables, but also due to differences in biological response between dogs or to fortuitous traumatic factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗

PubMed1990

5-year follow up of periodontal intraosseous defects treated by root planing or flap surgery.

Intraosseous, periodontal defects in 12 subjects initially treated by root planing alone (21 defects) or by flap surgery (21 defects) were monitored during a 5-year postoperative interval. Maintenance therapy during this interval was limited to reinforcement of oral hygiene and tooth polishing every 6 months. No subgingival instrumentation was performed at the defect sites. Longitudinal clinical measurements demonstrated that surgically-treated lesions responded with somewhat more reduction of probing depth and more gain of probing bone level than root-planed lesions. Mean gains of probing attachment level were similar for the 2 treatments. Some relapse of the clinical conditions could be observed towards the end of the 5-year observation interval compared to the results at year 1 and year 2. However, the majority of defects subjected to either treatment showed 60-month recordings of probing attachment and probing bone levels equal to or slightly improved compared to those at baseline. Counts from cultures of subgingival, microbial samples were obtained at 42, 48 and 60 months. No significant difference between the 2 therapies was observed for the investigated groups of micro-organisms.

Adult↗

PubMed1990

Scores of plaque, bleeding, suppuration and probing depth to predict probing attachment loss. 5 years of observation following nonsurgical periodontal therapy.

The purpose of the present study was to determine the diagnostic value of clinical scores of supragingival plaque, bleeding, suppuration and probing depth to predict probing attachment loss in patients on maintenance following nonsurgical periodontal therapy. Non-molar teeth in 39 subjects were monitored and the above scores were repeatedly obtained throughout 5 years of observation following initial treatment. Probing attachment loss between 0-60 months was determined by a combination of linear regression analysis and end-point analysis. The results revealed that all the investigated scores were associated with probing attachment loss. This association was demonstrated by improved diagnostic predictability along with increased frequency or magnitude of the various scores. Also, the diagnostic predictability improved with increase in length of time for recording of the scores. The diagnostic predictability of either accumulated plaque scores and accumulated bleeding scores reached a maximum of about 30%. Residual probing depth greater than or equal to 7 mm reached a predictability of around 50% and increase in probing depth greater than or equal to 1.0 mm reached about 80% after 60 months. Thus, of the clinical scores investigated, increase in probing depth was found to be most valuable in predicting probing attachment loss.

Adult↗

PubMed1990

Periodontal repair in dogs: effect of wound stabilization on healing.

This study evaluated a biodegradable polylactic acid matrix as a wound stabilizing implant in reconstructive periodontal surgery. Supra-alveolar circumferential periodontal defects, 5 to 6 mm large, were surgically created around the mandibular premolars in 7 beagle dogs. The root surfaces in left and right jaw quadrants were treated with either heparin or saline. In this model, root surface treatment with heparin compromises periodontal repair and results in a long junctional epithelium and a reduced connective tissue repair to the root surface, whereas saline treatment results in almost complete connective tissue repair. Following heparin or saline treatment a polylactic acid implant was placed on 1 premolar in each quadrant. After 4 weeks of wound healing, the dogs were sacrificed and tissue blocks prepared for histometric analysis. Postoperatively, the implant became exposed and infected in 3 dogs and had to be removed. Therefore, the results reflect the 4 dogs in which healing progressed uneventfully. Connective tissue repair to the root surface in teeth treated with heparin averaged 82% of the defect height. Mean connective tissue repair in teeth treated with heparin and the implant was significantly greater and comprised approximately 99% of the defect height (P less than 0.05). Teeth treated with saline either with or without the implant also healed with almost complete connective tissue repair. The results support the importance of wound stabilization in periodontal wound healing. Development of biodegradable implant systems aimed at stabilizing and supporting the healing wound seems a desirable direction for future research in regenerative periodontal procedures.

Alveolar Process↗

PubMed1985

Effect of non-surgical periodontal therapy (IV). Operator variability.

Healing following non-surgical periodontal therapy was studied and the results of instrumentation performed by 6 operators compared. Incisors, cuspids and premolars with periodontal pockets up to 11 mm deep in 20 patients were treated by plaque control and a single episode of supra- and subgingival debridement. A split-mouth approach was used to compare the participating therapists. The effects of the therapy were monitored using changes in plaque score, bleeding score, probing pocket depth and probing attachment level. Marked improvement, similar to that seen in previous studies evaluating non-surgical therapy was noted during the initial 6-9 months. No further changes of the recorded parameters could be observed during the rest of the 24-month observation period. Differences between sites treated by the various operators were negligible. Thus, it appears, that deep periodontal pockets in incisors, cuspids and premolars may be successfully treated by plaque control and 1 episode of instrumentation and that operator variability may be limited.

Adult↗

PubMed1985

Effect of non-surgical periodontal therapy. VI. Localization of sites with probing attachment loss.

Incisors, cuspids and premolars in 49 patients with advanced chronic periodontitis were treated with initial, non-surgical periodontal therapy. The results were monitored by probing attachment level measurements at 6 sites of each tooth every 3rd month during a period of 24 months. A series of 9 probing attachment level measurements for each site was subjected to linear regression analysis. The slope of the regression line, the projected probing attachment loss during the 24-month interval (delta y) and the probability level of the slope were calculated for each site. 2 groups of sites with probing attachment loss were identified: group 1: sites with delta y greater than 1.5 mm and p less than 0.05; group 2: sites with delta y greater than 1.0 mm and p less than 0.05. Group 1 included 120 sites (5%) and group 2 included 265 sites (10%) of the total of 2532 available sites. In both groups, probing attachment loss was more frequently noticed for sites with an initial probing depth less than or equal to 3.5 mm than for sites with initial probing depth greater than or equal to 7.0 mm. The finding that the majority of sites with probing, attachment loss was found amongst initially shallow or moderately deep lesions may indicate attachment loss due to trauma associated with therapy rather than loss as a result of a continuing, inflammatory disease process.

Adult↗

PubMed1985

Effect of crown-attached sutures on healing of experimental furcation defects in dogs.

This study evaluates whether suturing of replaced flaps with crown-attached sutures, following reconstructive surgery, counteracts postoperative recession of the gingival margins and facilitates new attachment. Through-and-through furcation defects were created in the mandibular premolars of 5 beagle dogs. Bone was surgically removed from the furcation and around each root to a level 3 to 4 mm below the cemento-enamel junction. Steel wires were placed in the furcations for 6 weeks to enhance plaque formation. After 12 weeks, reconstructive surgery that included acid conditioning of root surfaces was performed. On 1 side of the mandible, the flaps were replaced and secured by bonding the sutures to the teeth with composite resin. On the other side, the replaced flaps were sutured interdentally with single sutures. The results demonstrated that the margins of flaps secured with interdental sutures shifted apically to the fornix of the furcations after 1 week, and histologically all 10 furcations were found to be lined with epithelium. Margins of flaps secured with crown-attached sutures remained an average of 0.5 mm coronally to the fornix, and 13 of the 14 teeth showed new attachment. The results indicate that a suturing technique which counteracts gingival recession, favours the formation of new attachment in this beagle dog model.

Animals↗

PubMed1985

Healing after treatment of periodontal intraosseous defects. V. Effect of root planing versus flap surgery.

The present study compared surgical therapy to root planing alone in the treatment of periodontal intraosseous defects. 25 defects in 14 patients were subjected to root planing only and another 25 defects in the same patients were surgically exposed and citric acid treated. The healing response was evaluated 6 months after treatment. The mean gain of probing attachment level was 0.8 mm in the root-planed defects as compared to 1.3 mm for the surgically exposed and acid-treated defects. The probing bone level improved an average of 0.2 mm for the root-planed areas as compared to 0.6 mm for the acid-treated defects. The mean preoperative probing pocket depths of 6.7 mm and 6.8 mm for the 2 groups were reduced to 5.2 mm and 4.1 mm, respectively. The differences in these parameters were statistically significant between the 2 groups. However, both groups demonstrated limited regeneration.

Adult↗

PubMed1985

Effect of nonsurgical periodontal therapy. VII. Bleeding, suppuration and probing depth in sites with probing attachment loss.

Incisors, cuspids and premolars in 49 patients with advanced chronic periodontitis were treated with initial, nonsurgical periodontal therapy. The results were monitored by probing attachment level measurements for 6 sites of each tooth every 3rd month during a period of 24 months. Amongst sites with initial probing depth greater than or equal to 4.0 mm, sites with probing attachment loss were identified using regression analysis. Scores for plaque, bleeding, suppuration on probing and probing depth, obtained for these sites during the 24-month study, were analyzed to determine whether any of the scores could be used diagnostically as an indicator of probing attachment loss. Diagnostic sensitivity and predictability were calculated for different levels of each of the scores. The results showed that sites with probing attachment loss were more frequent for sites with high scores for plaque, bleeding, residual probing depth and suppuration than in sites with low scores. However, the diagnostic sensitivity and predictability of these clinical indicators was generally low. Thus, records of plaque, bleeding, suppuration and probing depth do not obviate the need for probing attachment level measurements for identification of sites with probing attachment loss following initial, nonsurgical periodontal therapy.

Adult↗

PubMed1985

Bone regeneration pattern and ankylosis in experimental furcation defects in dogs.

This study reports on the pattern of interradicular bone formation and the frequency and localization of ankylosis following regenerative surgery of experimentally-induced furcation defects in 12 beagle dogs. Observations were made in 39 specimens showing healing with connective tissue attachment in the full circumference of the furcation. The findings indicate that bone regeneration first occurs adjacent to the root surfaces, followed by a subsequent fill of the central portion of the interradicular area. Ankylosis, observed in 24 of the 39 specimens, was more frequent in large defects than in small defects. The incidence of ankylosis increased with increased distance from the base of the original wound. These findings suggest that coronal bone apposition may require or be facilitated by the presence of a root surface, and that undisturbed coronal regeneration may be dependent upon cellular or some other activity from the intact periodontal ligament.

Animals↗

PubMed1985

Healing after treatment of periodontal intraosseous defects. VI. Factors influencing the healing response.

84 periodontal intraosseous defects treated with mucoperiosteal replaced flap surgery and citric acid root conditioning were used to study the relationships between various defect characteristics and the healing response as expressed by change of probing attachment level, change of probing bone level and residual probing depth. More gains in probing attachment and probing bone levels were observed in deep defects than in shallower lesions. Other defect characteristics showed weak or no correlations to defect fill. The findings of this study seem to indicate that the outcome of treatment of intraosseous defects may be difficult to predict based upon evaluation of defect characteristics.

Adult↗

PubMed1985

Effect of nonsurgical periodontal therapy. V. Patterns of probing attachment loss in non-responding sites.

Incisors, cuspids and premolars in 33 patients with advanced chronic periodontitis were treated by plaque control and 1 single episode of supra- and subgingival debridement. The results were monitored by probing attachment level measurements for 6 sites of each tooth every 3rd month during a period of 24 months. A total of 1368 sites were observed. From these were selected 280 "non-responding" sites showing 1.0 mm or more loss of probing attachment at 24 months compared to baseline. Scatter diagrams of the sequence of 9 probing attachment recordings obtained during the 24-month study were produced for each of these 280 sites. Study of these scatter diagrams resulted in identification of 7 different patterns of probing attachment change over time. A linear pattern of gradual loss of probing attachment throughout the 24-month observation period was found for 73% of the non-responding sites. Of the less frequently seen patterns, 3 approximated a linear course and 3 were non-linear. Linear analysis of regression as a statistical method to determine attachment loss for individual sites seems to be suitable for sites with linear patterns and for sites approximating a linear pattern. The insensitivity of regression analysis in non-linear patterns may be acceptable if a cautious analysis is warranted.

Adult↗