Biomedical subjects

K A Selvig

Publications and source records attributed to K A Selvig.

At least 37 records · Page 2Linked to original sources

PubMed1995

Reproducibility of periodontal probing using a conventional manual and an automated force-controlled electronic probe.

A total of 1,128 sites in 15 periodontal maintenance patients were examined twice, 7 to 10 days apart, to evaluate reproducibility of periodontal probing by a conventional manual and an automated force-controlled electronic probe. Probing depths (PD) and relative attachment levels (AL) were recorded to the nearest 0.5 mm with both instruments. At each visit, all sites were probed first with the conventional and then with the electronic probe. Reproducibility of PD at shallow sites (PD < or = 3 mm) by the manual probe was 59.1% for exact agreement and 98.6% within +/- 1.0 mm variation. For the electronic probe, corresponding values were 41.3% and 91.5%, respectively. Reproducibility of PD measurements at deeper sites (PD > 3 mm), was 33.0% for exact match and 96.4% within +/- 1.0 mm for the manual and, correspondingly, 31.7% and 85.9% for the electronic probe. Reproducibility of AL followed a similar pattern, but was consistently lower than for PD. Reproducibility was consistently higher for anterior than for posterior sites and, for some comparisons, higher in the maxilla than in the mandible. These differences were smaller for the manual than for the electronic probe. Time required to complete the probing was longer for the conventional probe than for the electronic instrument. Under the prevailing study conditions, the automated force-controlled electronic probe failed to offer significant advantages over the conventional manual probe.

Adult↗

PubMed1995

Revascularization of an excisional wound in gingiva and oral mucosa. A scanning electron microscopic study using corrosion casts in rats.

The purpose of this study was to examine microvascular regeneration associated with gingival wound healing. A full-thickness piece of gingiva and oral mucosa was excised along the palatal aspect of the right maxillary first and second molars in 20 young Wistar rats. The contralateral side served as unoperated control. After 2, 4, 7, 10 or 20 days of healing, microvascular corrosion casts were produced and examined by scanning electron microscopy. At 2 days, vessels surrounding the wound were dilated and impressions representing sites of leukocyte margination were prominent in the walls of venules. Capillary buds were emerging from venules and capillaries. At 4 days, the vessel buds had lengthened and connected in pairs to produce capillary loops. At 7 days, new vessels extended deeply into the wound space, mainly from the medical side, in a palisade-like pattern. At 10 days, the denuded bone surface was still not completely revascularized and Volkman's canals opening to the wound area were empty. At 20 days, the bone surface was covered by large, irregular vessels which originated mainly from the palatal mucosa. The periodontal ligament was less important in the tissue repair process, while the bony vasculature contributed little or not at all to revascularization of the healing gingiva and palatal mucosa.

Animals↗

PubMed1995

Dynamics of wound healing in periodontal regenerative therapy.

Experimental animal and clinical studies have increased understanding of the biology of healing following periodontal regenerative therapy and factors that may influence the outcome. Formation of a new connective tissue attachment rather than a long junctional epithelium at the tooth-gingival flap interface is dependent upon the completion of a series of interactions among the root surface, plasma and tissue factors, and the connective tissue of the gingival flap. First, plasma proteins must adsorb to and remain in undisturbed contact with a generally noncompromised root surface. Next, adhesion of the established fibrin clot to the root surface must remain intact. Within days, a cellular and fibrous attachment will form; however, the tooth-gingival flap interface will still be vulnerable to wound-rupturing forces. Within two weeks the interface may have gained sufficient mechanical strength to offset such forces, at least in limited periodontal defects. Eventually, maturation of the fibrous attachment, including bone and cementum formation, will occur, particularly following adequate space provision by barrier membranes (guided tissue regeneration). A novel research focus involves how advances in molecular biology can translate to periodontal regenerative therapy. Bone morphogenetic proteins (BMPs) have been shown to support healing in a variety of skeletal sites. Recent research has demonstrated clinically significant alveolar bone and cementum regeneration with the use of a recombinant human BMP-2 implant. Such data suggest that growth-promoting substances, such as rhBMP-2, may significantly enhance periodontal regeneration and that use of such substances may radically recast current periodontal regenerative therapy.

Animals↗

PubMed1995

"Collagen adhesion" revisited.

Histologic studies of periodontal reconstructive therapies have repeatedly shown a zone of nondescript connective tissue adaptation, or collagen adhesion, to the root surface between the apical extension of the junctional epithelium and the coronal extension of identifiable regenerated cementum. To clarify the nature of this zone, supra-alveolar periodontal defects were created bilaterally in the mandibular premolar region in three beagle dogs, and exposed roots were instrumented to remove the cementum. Flaps were then coronally advanced and sutured. Histologic analysis after 12 weeks of healing showed instrumented root dentin not associated with junctional epithelium, new cementum, root resorption, or ankylosis in 27 of 60 root surfaces. In 10 of these specimens subsequently examined by transmission electron microscopy, collagen fibrils were generally oriented parallel to and in close proximity to the root. A mechanism of collagen attachment was, in fact, functioning at sites of collagen adhesion; these areas may validly be included in the histologic attachment level reported in studies of periodontal reconstructive therapy.

Animals↗

PubMed1994

Impaired early bone formation in periodontal fenestration defects in dogs following application of insulin-like growth factor (II). Basic fibroblast growth factor and transforming growth factor beta 1.

Effects of a topically applied growth factor combination on fibroblast migration, collagen fiber formation and bone regeneration were studied in standardized periodontal defects in 4 beagle dogs. Following elevation of facial mucoperiosteal flaps, fenestration defects, 3 mm in diameter, were made through the cortical bone and into the dentin of maxillary and mandibular teeth. Collagen sponges, impregnated with 200 ng insulin-like growth factor II, 20 ng basic fibroblast growth factor and 6 ng transforming growth factor beta 1 were fitted to defects randomly in right or left quadrants and the flaps repositioned and sutured. Contralateral control defects received the collagen with vehicle only. Experimental procedures were staggered to allow observations of healing 3, 7, 10, and 14 days after surgery. Histometric analysis showed no differences in fibroblast and collagen density between control and growth factor defects. Bone regeneration was significantly greater in control than in growth factor defects 10 and 14 days after surgery. The rate of healing generally appeared more affected by intra-dog variations or procedural variations than by the growth factor combination.

Alveolar Process↗

PubMed1994

Defluoridation of drinking water with pottery: effect of firing temperature.

Excessive fluoride (F) in drinking water should be removed, but simple, inexpensive methods of fluoride removal are not readily available. This study examines the F(-)-binding capacity of clay and clayware, especially the effect of the firing temperature on the F(-)-binding process. A series of pots were made from ordinary potter's clay and fired at 500-1000 degrees C. Likewise, small clay bricks were fired and then crushed and sieved. NaF solutions containing 10 mg/l F- (10 ppm F-) were prepared. Suitable aliquots of the solutions were poured into clay pots or exposed to powdered clayware. Samples were taken at storage periods of 30 min to 20 days and analyzed for F- by ion-selective electrodes. The rate and capacity of F(-)-binding in the clayware varied with the firing temperature. Clay fired at approximately 600 degrees C was most effective. Temperatures over 700 degrees C caused a decline in F(-)-binding, and pottery fired at 900 degrees C and above seemed unable to remove F- from water. Pots fired at 500 degrees C or less cracked in water. The findings indicate that clayware, fired at an optimal temperature, may be of practical value for partial defluoridation of drinking water.

Aluminum Silicates↗

PubMed1994

The vasculature of the periodontal ligament: a scanning electron microscopic study using corrosion casts in the rat.

The purpose of this study was to examine the 3-dimensional architecture of the microvascular system of the rat periodontal ligament (PDL). Vascular corrosion casts were prepared and examined by scanning electron microscopy. Cervically, arterioles and venules communicated with the profuse capillary network of the gingiva. The mid-root segment of the PDL contained arterioles and venules that mainly coursed occluso-apically near the alveolar wall, as well as capillary loops located closer to the root surface. Arterioles entered the PDL through vascular canals from the bone marrow, then coursed coronally and branched into an interconnected network of capillaries. The capillaries formed hairpin loops pointing coronally. At the tip, the capillary loops were enlarged in diameter and had an irregular luminar surface. The capillaries then coursed apically, anastomosing freely, until entering a venule. Large venules mainly followed a coronal-apical path, giving the PDL vasculature a palisade-like appearance. These vessels either left the PDL through vascular canals in the alveolar wall or connected in an apical, venous cap with venules exiting through the apical foramen. The results show that the microvasculature forms a highly organized system presumably related to the specialized functions of the periodontium. Cervically, a dense capillary system may be required for antimicrobial defense and rapid tissue turnover. The vasculature in the middle segment supports the suspensory structures, while the venous cap in the apical region may be designed to cushion masticatory forces.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1994

Discussion: animal models in reconstructive therapy.

Experimentation in animal models has created a basis for highly improved therapeutic procedures in reconstructive periodontal surgery. This symposium has discussed several animal models currently used; additional models have been described in recent literature. The presentations by Drs. Caton, Wikesjö, and Lynch illustrated the need for further discussion of some of the problems inherent in animal experimentation, including: standardization of periodontal defect configuration; adequate recording of preoperative attachment level; minimizing the effect of biological variability; use of surgically-created versus naturally-developed periodontal lesions; choice of observation period; and regenerative potential of the model chosen.

Animals↗

PubMed1994

Influence of tooth instrumentation roughness on subgingival microbial colonization.

This study evaluated microbial colonization of periodontal pockets subjected to root instrumentation with a curet or a rotating diamond. Ten maxillary and 10 mandibular subgingival pockets were established in the canines of 5 beagle dogs. The subgingival root surface areas were debrided by a sharp curet or a flame-shaped, fine-grained, rotating diamond point. The dogs were fed a plaque-inducing diet for 70 days. Specimens from both instrumentation groups were then harvested and prepared for stereomicroscopic and scanning electron microscopic evaluation. Grading of the extent of subgingival colonization was performed in coded specimens directly on the fluorescent screen of the scanning electron microscope in a grid-counting system. Error of the method was assessed by duplicate counts. The subgingival root surface areas were divided into 3 zones: cervical, middle, and apical, and statistical differences between these zones as well as between the 2 instrumentation groups were calculated. The results revealed that curet-treated surfaces were smoother and promoted less subgingival colonization than diamond-treated surfaces. The difference in amount of bacterial colonization between the 2 groups was statistically significant (P < 0.05) in all zones. Bacterial colonization decreased in apical direction in both instrumentation groups. For the diamond-treated specimens, this decrease was significant (P < 0.05) between each of the 3 zones. In the curet-treated specimens, the decrease was significant only between the cervical and the apical zone (P < 0.05). The present study has demonstrated that subgingival instrumentation roughness significantly influences the subgingival microbial colonization.

Animals↗

PubMed1994

Root grooves: a risk factor in periodontal attachment loss.

Periodontal health reflects a balance between harmful and protective elements in the gingival margin area. The total plaque mass, specific periodontopathogens, and local environmental factors may challenge this balance. The aim of this retrospective study was to evaluate the effect of proximal root grooves as a risk factor in periodontal attachment loss. One-hundred and three (103) extracted, formalin-stored, single-rooted teeth showing loss of attachment and having one non-grooved and one grooved proximal root surface were selected for the study. Following staining in 0.1% toluidine blue to visualize attached periodontal ligament remnants, the teeth were examined in a light microscope under incident light. On each tooth, loss of attachment was measured along the long axis of the root from the cemento-enamel junction to the most coronal level of the stained periodontal ligament remnants on mesial as well as on distal surfaces. Incisors and premolars were grouped separately. For both groups, a statistically significant greater loss of attachment was present on grooved than on non-grooved surfaces (P < 0.0001). Generally, there was a direct relationship between groove location and maximum loss of attachment. The results indicate that proximal root grooves should be considered in periodontal diagnosis, prognosis, and treatment planning.

Bicuspid↗

PubMed1993

Microvasculature of the dorsum of the rat tongue: a scanning electron microscopic study using corrosion casts.

The purpose of this study was to examine the microvascular system of the dorsum of the rat tongue in relation to the subepithelial connective tissue relief. Methylmethacrylate corrosion casts of the vasculature as well as specimens in which the epithelium had been removed were prepared and examined by scanning electron microscopy (SEM). The SEM images revealed four distinct layers in the vasculature of the lamina propria. Superficially, Layer 1 comprised the irregularly shaped ends of capillary loops. Layer 2 consisted of parallel ascending and descending capillaries. These two layers were drained by the subjacent Layer 3, a fish-net-like venous plexus. More deeply, Layer 4 contained arterioles ascending from the muscular layers of the tongue. The vessels of larger papillary structures formed cylindric networks supplied by several arterioles and drained through a single venule to the venous plexus in Layer 3. At their base, the capillary loops often showed a constriction, suggestive of a sphincter. Arteriovenous anastomoses were rare. The epithelium-connective tissue interface showed short conical papillae as well as larger papillary structures which corresponded in both distribution and size to the capillary loops found in the vascular casts. The results confirm that the tongue is highly vascularized and demonstrate that the vascular supply to the papillae, taste buds, and other surface structures forms a highly organized and specific system which is adapted to the specific functions of this organ in the rat.

Animals↗

PubMed1993

Surgical treatment of intrabony periodontal defects using expanded polytetrafluoroethylene barrier membranes: influence of defect configuration on healing response.

Twenty-six proximal, intrabony periodontal defects with probing depths equal to or exceeding 6 mm in 23 patients were treated with gingival flap surgery supported by an expanded polytetrafluoroethylene barrier membrane. The material included 1, 2, and 3-wall defects with crestal involvement relative to the root circumference ranging between 90 degrees and 270 degrees. Healing was evaluated clinically 12 months after surgery. Deep defects exhibited greater probing depth reduction and attachment gain than shallower defects. Probing depth reduction, attachment gain, and bone fill were positively correlated to the depth of the 3-wall intrabony component of the defect. The extent of crestal involvement, and wall form in the fundus of the defect did not appear to influence the healing response. The treatment also affected the proximal surface of the defect-adjacent tooth, which showed some reduction in bone level as well as gingival recession. Thus, the overall healing pattern following barrier membrane-supported flap surgery appears similar to that generally observed for conventional reconstructive flap surgery in intrabony periodontal defects.

Adult↗

PubMed1992

Effect of stannous fluoride and tetracycline on periodontal repair after delayed tooth replantation in dogs.

Previous studies have indicated that inflammatory resorption and ankylosis, which are frequent sequela after delayed tooth replantation, can be greatly reduced by treating the root surface with 1% solutions of stannous fluoride and tetracycline. However, the SnF2 conditioning leaves a long-standing inflammatory reaction in the periodontal ligament. To examine whether a more dilute SnF2 solution would reduce postoperative inflammation without jeopardizing any beneficial effects, anterior teeth in three young adult beagles were extracted and allowed to air-dry for 45 min. They were then immersed in 0.1% SnF2 for 5 min, rinsed in saline, immersed in 1% doxycycline HCl for 5 min, rinsed, and replanted. Control teeth were air-dried and replanted without further treatment. Block biopsies were harvested after 4 wk of healing and processed for histometric analysis. In experimental teeth, 85% of the root surface area showed normal healing, compared to 33% in control teeth. Conversely, resorption and ankylosis were more frequent in controls than in experimental teeth. A persisting inflammatory reaction either adjacent to or at a distance from the root surface was seen in limited areas in both experimental and control teeth. Compared to preceding studies, the findings indicate that reducing the strength of the SnF2 solution from 1% to 0.1% may result in less persistent inflammation, at the cost, however, of less complete prevention of inflammatory resorption and ankylosis.

Alveolar Process↗

PubMed1992

Healing of the intrabony periodontal lesion following root conditioning with citric acid and wound closure including an expanded PTFE membrane.

The effect of citric acid conditioning of the root surface in conjunction with gingival flap surgery including barrier membranes (expanded polytetrafluoroethylene) was clinically evaluated in 26 intrabony periodontal defects in 23 patients. Control treatment included gingival flap surgery with barrier membranes alone. Twelve defects were treated with the experimental and 14 with the control protocol. Healing was evaluated 12 months after surgery. Initial probing depths approximated 6.9 mm and defect depths measured during surgery exceeded 4 mm. The patients exhibited good oral hygiene over the study interval as substantiated by low plaque and bleeding scores. Acid conditioning of the root surface did not enhance periodontal healing in this study, similar amounts of defect resolution were observed following either treatment protocol. Probing depth reduction generally approximated 1.8 mm; gain of clinical attachment, 0.8 mm; and defect bone fill, 1.2 mm. Under the prevailing conditions, the barrier membrane procedure apparently gave a healing result beyond which further improvement could not be achieved by root surface conditioning.

Adult↗

PubMed1992

Regenerative surgery of intrabony periodontal defects using ePTFE barrier membranes: scanning electron microscopic evaluation of retrieved membranes versus clinical healing.

Sixteen intrabony defects in 12 patients were treated by gingival flap surgery including root surface debridement and placement of an expanded polytetrafluoroethylene (ePTFE) membrane. The membranes were removed after 4 to 6 weeks and examined by scanning electron microscopy (SEM) for bacterial contamination and adherent connective tissue elements. Twelve months postsurgery, the defect sites were reexamined for changes in probing attachment level and probing bone level. Comparison of ultrastructural findings and clinical observations revealed that extent of bacterial contamination of the membrane correlated inversely with clinical assessment of attachment gain. The results indicate that the extent of oral exposure and bacterial contamination of the ePTFE membrane at the time of removal may be an indicator of the long-term success or failure of the regenerative procedure.

Adult↗

PubMed1992

Significance of early healing events on periodontal repair: a review.

Wound healing in an incisional wound is a highly predictable process which has been studied extensively hour-by-hour and day-by-day. Healing in a periodontal defect following gingival flap surgery is, conceptually, a more complex process as one wound margin consists of calcified tissue, including the avascular and rigid root surface. Another complicating factor in this wound healing is the transgingival position of the tooth. Experimental studies, however, have indicated that healing at a dento-gingival interface under optimal conditions occurs at the same rate as in a skin wound. Generally, periodontal healing is characterized by maturation of gingival connective tissue, limited regeneration of alveolar bone and cementum, and the formation of a long junctional epithelium. Such observations have nurtured the hypothesis that the epithelium of the surgical flap needs to be prevented from early access to the root surface during the healing period to achieve connective tissue repair of the root surface-gingival flap interface. Recent experimental findings suggest, however, that connective tissue repair to the root surface following reconstructive periodontal surgery is a function of the establishment and maintenance of a root surface-adhering fibrin clot. Since fibrin adherence to the wound margins is a natural event, it is additionally suggested that apical migration of the gingival epithelium in periodontal surgical wounds may only follow interruption of the adherence of the fibrin clot to the root surface.

Animals↗

PubMed1992

Cemental tear related to rapid periodontal breakdown: a case report.

Cemental tears have been described both in exposed and unexposed cementum. The phenomenon is believed to be elicited by overloading or acute trauma from occlusion. In this case report a patient, with a history of periodontal health, presented with an acute periodontal lesion on the distal aspect of a bridge abutment tooth. Periapical radiographs demonstrated an extensive vertical intrabony defect adjacent to the vital abutment tooth containing a radiopaque "foreign body." Histological examination of the surgically removed "foreign body" revealed a piece of dental cementum with some attached soft tissue. The lesion responded well to a surgical approach. Healing was uneventful and periodontal health was restored. This case illustrates that cemental tear should be considered as a differential diagnostic entity in isolated sites with rapid periodontal breakdown.

Aged↗

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↗