Effect of autogenous marrow and calcitonin on reactions to a ceramic.

The effect of autogenous marrow and calcitonin on reactions to a tricalcium phosphate ceramic was studied by subcutaneous implantation in rats. No bone formation was evident in association with uncoated and calcitonin-coated ceramic. At four weeks and thereafter bone formation was evident in association with all marrow-coated implants.

The effect of levamisole on DMBA-induced carcinogenesis in the hamster cheek pouch.

The effect of levamisole on DMBA-induced carcinogenesis in the cheek pouch of the hamster was studied. Findings indicate that levamisole modified the response of the pouch to DMBA at six weeks, while this effect was not maintained after 12 weeks of DMBA application.

Total cementum removal: a realistic objective?

The purpose of the study was to determine if total cementum removal from periodontally involved root surfaces was a clinically realistic objective. The experimental specimens were 36 periodontally involved teeth, extracted because of advanced periodontal disease. Eighteen teeth were from patients under age 36 while the other 18 were from patients over 36. All teeth had at least 6 mm of attachment loss on the proximal surface tested and showed no evidence of forceps damage. After removing all visible calculus, equal numbers of each tooth type in each age group were given 50 planing strokes with either a Jacquette scaler, a Gracey curet, or an Indiana University curet. Following the planing procedure the specimens were fixed, decalcified, and 7 microns thick sections prepared and stained with hematoxylin and eosin. Two teeth were excluded from the evaluation due to poor orientation. In none of the remaining 34 teeth was cementum totally removed over the entire proximal test surface. There was no apparent difference between the instruments in the amount of residual cementum found. Larger amounts of residual cementum were seen in more apical areas in both age groups.

The effect of retained subgingival calculus on healing after flap surgery.

This study investigated the effects of retained subgingival calculus on healing of the periodontium at ten, 30 and 120 days. Eight beagle dogs between eight and ten years old with naturally occurring periodontal disease were used. One dog that died before any procedures were done provided information on the extent of gingival inflammation prior to surgery. Quadrants from seven dogs meeting the criteria for inclusion were selected, and each quadrant was randomly designated as either an instrumented or noninstrumented, surgical site. The gingival index for the selected sites was recorded along with clinical probing measurements. Instrumented sites were treated by reflection of a facial mucoperiosteal flap followed by thorough root planing. Non instrumented sites were treated by a facial mucoperiosteal flap alone. All flaps were returned to their preoperative position and secured with interrupted sutures. No antibiotics were given. Meticulous daily plaque control was begun the day after surgery and continued until sacrifice. There was a statistically significant reduction in gingival index scores for the 30- and 120-day instrumented sites and for the 120-day noninstrumented sites. Mean probing depths for the instrumented group showed a significant reduction at 30 and 120 days and for the noninstrumented group at 120 days after surgery. Forty percent of the noninstrumented roots and 10% of the instrumented roots displayed subgingival calculus. At all evaluation periods and in both instrumented and noninstrumented roots, inflammation was more intense when calculus was present; the difference was significant at ten days with the instrumented and at ten and 30 days with the noninstrumented specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of citric acid on retained plaque and calculus. A short communication.

Five extracted human teeth with clinically demonstrable calculus were used. One proximal surface of each tooth was partly scaled, leaving a small amount of calculus. The crown was then cut off at the cementoenamel junction and the scaled proximal surface was divided vertically into two segments using a thin separating disk. One segment was treated by rubbing cotton pellets soaked in citric acid (pH1) over the surface for three minutes and then immersing the segment in saline to stop the reaction. The other (control) segment was treated by rubbing cotton pellets soaked in saline over the surface for three minutes. When viewed under a scanning electron microscope, the control sections displayed scaling striations, considerable surface debris, and large numbers of bacteria at the borders of the residual calculus. Citric acid-treated specimens displayed little debris on cementum or residual calculus and virtually no bacteria at the junction between calculus and cementum. The surface morphology of the citric acid-treated calculus varied from layered-like to honeycomb.

The effectiveness of hand versus ultrasonic instrumentation in open flap root planing.

The primary purpose of the study was to determine if, with an open flap approach, ultrasonic or hand instrumentation could remove all calculus from previously untreated teeth with moderate to severe loss of attachment. To be included in the study, teeth had to have at least 5 mm of attachment loss, be scheduled for extraction and be graded 2 or 3 on the Calculus Index of the Periodontal Disease Index system. Under local anesthesia, full-thickness, envelope-type flaps were elevated apical to the crest of bone to allow access to the root surfaces which were then treated with hand or ultrasonic instrumentation until the roots felt hard and smooth to a Hartzell explorer. The teeth were then removed, rinsed, and lightly scrubbed to remove debris and a No. 14 wheel bur was used to place a groove along the coronal extent of the connective tissue attachment. A stereomicroscope at magnification X 4.6 was used to quantitate the percentage of residual calculus on 25 teeth treated by each method. Overall, hand-scaled root surfaces demonstrated less residual calculus (5.78%) than ultrasonically treated surfaces (6.17%). Twenty teeth treated by each method were then prepared for histologic evaluation and evaluated under the light microscope at magnification X 100 for residual calculus and relative smoothness. Residual calculus was found on four ultrasonically and 12 hand-treated teeth and was almost evenly distributed between anterior and posterior teeth for both methods. The finding of considerably less calculus on histologic than on stereomicroscopic examination may have been due to the loosening of deposits by instrumentation, especially ultrasonic vibration, and their subsequent release during histologic preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Pocket epithelium removal via crestal and subcrestal scalloped internal bevel incisions.

This study assessed the extent of pocket epithelium removal by crestal and subcrestal scalloped inverse bevel incisions during mucoperiosteal flap surgery. Fifty-six gingival biopsies were obtained from 52 participants, who had extractions of periodontally involved teeth. Sulcular incisions which severed the epithelial attachment served as controls. Experimental scalloped internal bevel incisions were made: (1) at the gingival crest extending apical to the osseous crest (crestal incision) and (2) 1 to 2 mm apical to the gingival margin extending apical to the osseous crest (subcrestal incision). In the two procedures the initial incisions were followed by sulcular incisions to sever the epithelial attachment. After both crestal and subcrestal incisions full thickness flaps were reflected, pocket contents were removed, and flaps were replaced against the teeth. Gingival biopsies were then obtained from control and experimental sites followed by extraction of teeth. All specimens were processed, embedded in paraffin, sectioned, stained with hematoxylin and eosin and examined for residual pocket epithelium. Control incisions eliminated pocket epithelium in two of 20 specimens. Crestal incisions eliminated pocket epithelium in 11 of 25 areas, while subcrestal incisions eliminated pocket epithelium in 13 of 25 areas. All 10 papillary areas treated by crestal incisions and 8 of the 10 papillary areas treated by subcrestal incisions displayed residual pocket epithelium. Neither crestal nor subcrestal scalloped internal bevel incisions consistently eliminated all pocket epithelium.

Relative resistance of long junctional epithelial adhesions and connective tissue attachments to plaque-induced inflammation.

This study compared the resistance to periodontal disease of the long junctional epithelial adhesion and the naturally occurring dentogingival junction. Two groups were used, each containing three young male beagle dogs with all permanent teeth erupted. Periodontitis was induced around maxillary and mandibular premolars in the experimental dogs over a 42-day period, using subgingival ligatures and a soft diet. Fourteen days after ligature removal, flaps were reflected, granulation tissue was removed and the roots were planed to the alveolar crest. Reference grooves were placed in the root surfaces at the level of the alveolar bone, the flaps were positioned over the alveolar crests, and sutures were placed. A 60-day period permitted healing with formation of long junctional epithelial adhesions. During this 116-day period control dogs were maintained in gingival health by daily brushing and by prophylaxis every 14 days. Both groups had a high level of health (GI scores of 0) at the beginning of the 20-day combined disease phase. Inflammation was induced in both groups by subgingival ligature placement and a plaque-promoting diet. Right and left sides of both groups represented separate time intervals within the 20-day period. Block sections were secured at time of killing and the tissues were prepared for light and fluorescent microscopic evaluation. Mean GI scores and mean probing depths increased similarly in both groups. Tagge index scores of gingival inflammation were higher at the longer time periods in the experimental animals. However, they displayed an intact long junctional epithelial adhesion throughout the study, while control animals frequently showed ulceration of the sulcular epithelium. Neither group showed significant changes in location of the apical cells of the attachment epithelium. Crestal osteoblastic activity, confirmed with Procion labeling, predominated in the experimental animals, while osteoclastic activity predominated in the control. Under the conditions of this study, there appeared to be no appreciable difference in resistance to disease between a long junctional epithelial adhesion and a true connective tissue attachment.

Total calculus removal: an attainable objective?

The primary purpose of this study was to determine if two sessions of scaling and root planing, one using a "closed" approach and the other using an "open" approach, would remove all calculus from teeth with severe periodontal disease. Fourteen teeth (8 single-rooted, 6 multi-rooted) were treated by closed scaling and root planing with an ultrasonic instrument, and 17 others (10 single-rooted, 7 multi-rooted) were treated with hand instruments. After a healing period of 4 to 8 weeks, anesthesia was secured, periodontal flaps were raised, and the teeth were treated a second time using the same instrumentation as before. The teeth were then extracted and prepared for light microscopic evaluation. Twelve of the 14 teeth treated by ultrasonics and 12 of the 17 treated by hand instruments retained calculus. The two types of instruments had similar scores in the treatment of proximal root surfaces, furcal walls, and furcal summits. Hand instrumentation appeared to be more effective than ultrasonics in removing cementum from proximal surfaces, although this is not based on a formal statistical comparison of the two methods. Neither instrument was effective in removing cementum from the furcal walls or summits. Five randomly selected blocks containing remaining root structure were deparaffinized and prepared for scanning electron microscopy. One hand-instrumented specimen, which had not shown calculus with light microscopy, displayed calculus at the SEM level. All five specimens displayed residual calculus at either the light microscope, the SEM level, or both. The results of this study indicate that complete removal of calculus from a periodontally diseases root surfaces is rare.

The effect of different treatment modalities on connective tissue attachment.

This study compared the effect of four treatment modalities on connective tissue attachment. Ligature-induced periodontitis was established around the mandibular premolars of five young beagle dogs over 8 weeks. Following a 2-week period without ligatures, a reference dog was sacrificed to estimate the extent and nature of the disease. Three dogs received flap procedures in one mandibular posterior segment, and the six experimental roots were treated with citric acid (pH 1) for 3 minutes; the contralateral mandibular segments received flap procedures and the roots were treated with 4% chlorhexidine gluconate in the Hibiclens preparation for 3 minutes. One segment of the control dog received flap procedures, and the roots were treated with sterile normal saline; the contralateral segment received closed root planning. The experimental dogs were sacrificed 1, 2 and 3 months after treatment. The control dog was sacrificed 3 months postoperatively. One week before sacrifice each dog received a Procion dye injection. At sacrifice the study segments of all four treated dogs were clinically healthy, with no observable differences between the different treatment modalities. Histologically, the 1, and 3-month chlorhexidine, the 3-month saline and 3-month root planed specimens had long junctional epithelial adhesions with little connective tissue attachment. The 2-month chlorhexidine and all citric acid-treated sections showed appreciable amounts of new connective tissue attachment. Some 2-month and 3-month citric acid and 2-month chlorhexidine sections showed cementum over the apical portion of the long junctional epithelium. The frequency of occurrence and the length of cementum overlapping epithelium increased appreciably over time.(ABSTRACT TRUNCATED AT 250 WORDS)

A scanning electron microscope study of the effects of various agents on instrumented periodontally involved root surfaces.

This study evaluated the effects of chemical and biologic agents on periodontally diseased root surfaces which had been scaled or root planed. The proximal surfaces of 25 teeth were scaled to remove all visible calculus, and the proximal surfaces of another 25 teeth were vigorously root planed to remove all cementum and to achieve a hard, smooth, glass-like surface. Five scaled and five root planed specimens were randomly selected for light microscopic examination to determine the amount of cementum removed. Cementum remained on all scaled surfaces but root planing had removed most of the more coronal cementum. Each of the 40 remaining teeth (20 scaled and 20 root planed) was longitudinally sectioned to obtain an experimental and control specimen. Four scaled and four root planed sections were randomly selected as experimental specimens for a test of each of the following five agents: (1) saturated citric acid for three minutes; (2) 15% EDTA for 5 minutes; (3) sodium hypochlorite for 5 minutes, followed by a 30-second application of 5% citric acid; (4) sodium hypochlorite alone for 5 minutes; and (5) 2% sodium deoxycholate (NAD) for 1 minute, followed by a 1-minute rinse in distilled water, and then a 1-minute application of 5% Cohn's fraction IV1. The control for each experimental specimen was treated with saline. All samples were prepared for SEM and examined at 3,000 X. Areas of particular interest were also examined at 12,000 X. The chemical treatments exposed only individual collagen fibers or irregular fiber bundles on the scaled surfaces. Saturated citric acid, EDTA, and sodium hypochlorite with citric acid neutralization removed debris and exposed openings in the root surfaces. Sodium hypochlorite alone and NaD/Cohn's fraction IV1 were less effective in removing surface debris and had an effect similar to that seen in the saline controls. Application to root planed specimens of saturated citric acid, EDTA, and sodium hypochlorite followed by 30 seconds of citric acid neutralization resulted in surfaces virtually free of debris and with numerous collagen fibers exposed on the surface. EDTA appeared to cause a morphologic change in the collagen fibers. Sodium hypochlorite alone, sodium deoxycholate followed by Cohn's fraction IV1, and physiologic saline were relatively ineffective in surface debridement.

Determination of the presence of root-bound endotoxin using the local Shwartzman phenomenon (LSP).

The purpose of these studies was to determine, by attempting to elicit the local Shwartzman phenomenon (LSP), if the material extracted from periodontally involved root surfaces is actually endotoxin or only an endotoxin-like substance. A total of 719 periodontally involved teeth and 201 unerupted third molars yielded pooled samples of root surface grindings which were treated with the endotoxin extraction technique nonpyrogenic saline or pyrogen-free water. In the first study each of the reconstituted extracts was injected into the right palatal gingiva of New Zealand white rabbits which had demonstrated the ability to elicit an LSP. Commercial Salmonella enteritidis endotoxin was injected into the left (control) palatal gingiva. This was followed 18 hours later by a provoking injection of 200 to 300 microgram S enteritidis endotoxin in a marginal ear vein. In the second study, reconstituted extracts were injected into the right side of the abdomen of New Zealand white rabbits. The left (control) side received varying amounts of S enteritidis endotoxin. Twelve hours later each animal received a provoking injection of 400 microgram of S enteritidis endotoxin in a marginal ear vein. In both studies the animals were examined 6 hours later for visual signs of an LSP. After sacrifice, the tissues were prepared and histologic sections evaluated by two examiners who were unaware of how the specimens had been treated. The results indicated that a heat-stable, phenol-water extractable and highly irritating substance could be obtained from periodontally involved root surfaces. However, it is questionable if the substance extracted was actually endotoxin. If a true endotoxin, it was present only in extremely small amounts.

The clinical and histological response of periodontal pockets to root planing and oral hygiene.

The study evaluated, clinically and microscopically, the soft tissue response of suprabony periodontal pockets treated by root planing and oral hygiene or by oral hygiene measures alone. The participants were 22 adults beginning treatment for inflammatory periodontal disease. For each patient, three clinically similar labial or lingual pockets were scored for gingival inflammation, pocket depth, and the extent of plaque and calculus. One pocket in each patient served as a control, and a gingival biopsy was obtained to determine the pretreatment level of inflammation. The second pocket was treated by root planing and by the patient's oral hygiene measures. The third pocket was treated only by the patient's daily oral hygiene measures. Fifty-six to 63 days later, treated areas were reevaluated clinically, and biopsies were secured. Each type of therapy reduced the mean pocket depth and the incidence and severity of gingivitis; however, root planing accompanied by oral hygiene measures resulted in a statistically greater improvement than did oral hygiene measures alone.

Histological examination of paraformaldehyde-exposed gutta-percha implanted in rats.

Adsorption of some paraformaldehyde was noted in a previous study evaluating its sterilizing effect on gutta-percha (GP). This study examined histologically the effect of this adsorption when formaldehyde-exposed GP was implanted into the subcutaneous connective tissue of rats. GP implants were prepared in cylinder shape using a template designed to standardize size. Fifty GP cylinders were exposed to paraformaldehyde for 7 days before being implanted, while 50 others were implanted without exposure. Fifty rats had two implant sites prepared, at dorsal-interscapular and dorsal-caudal regions. Sham operations were performed on 10 rats to examine the effect of the surgery itself. The animals were killed at 4, 7, 14, 28, and 56 days. There was a significant difference between the two categories of implants only at 7 days, with the GP specimens without paraformaldehyde exposure showing more inflammation than GP with paraformaldehyde specimens (p = 0.043). Although the GP-alone specimens showed greater initial inflammation, both groups recovered in the same time period. One of the GP specimens with paraformaldehyde still showed a moderate/severe response at 56 days, whereas all of the GP-alone specimens showed only none/mild responses. The GP examined appeared to cause more inflammation than was expected.

Biocompatibility of two apatite cements.

Biocompatibility and osteogenic potential of two calcium phosphate cements (G-5 and G-6) and Super-EBA were investigated by subcutaneous and intraosseous implantation in 90 rats. Reactions were studied microscopically at 15, 30, and 60 days after implantation. Super-EBA was well tolerated by both soft and hard tissues. G-5 was highly biocompatible with resorption and bone replacement at intraosseous implantation sites. G-6 promoted moderate inflammation and a foreign body giant cell response over the 60-day study period. None of the materials elicited osteogenesis or dystrophic calcification at the subcutaneous implantation sites.

Human saliva coronal microleakage in obturated root canals: an in vitro study.

This study assessed salivary penetration through obturated root canals as related to time by using two methods of analysis--histological examination and dye penetrations. A total of 160 human maxillary anterior teeth were instrumented to size 60 Hedstrom file. Ten of the teeth were not obturated; 150 teeth were obturated by lateral condensation of gutta-percha and Roth's root canal sealer. Fifty of these teeth received intermediate restorative material temporaries to a thickness of approximately 3 mm. All teeth were immersed in 50 ml of whole human saliva and kept at 37 degrees C and 100% humidity. The saliva was changed daily. At 2, 7, 14, 28, and 90 days, 32 teeth were removed from the saliva. Of these, two were unobturated and were examined for bacterial penetration by culturing of the apical one-third. Ten teeth without temporaries were immersed in Pelikan ink for 2 days to demonstrate the extent of salivary penetration. These teeth were decalcified and cleared to allow direct measurement of dye penetration. Decalcified serial 7-microns-thick sections were prepared from the remaining 20 teeth, 10 with and 10 without intermediate restorative material temporaries. The sections were stained with hematoxylin and eosin stain and Brown and Hopps stain. Saliva penetration assessed in histological sections was significantly less than was visualized with dye analysis. Salivary penetration at 3 months was significantly greater than at the four earlier study periods. This amount of salivary penetration was considered to be clinically significant. The results strongly suggest retreatment of obturated root canals that have been exposed to the oral cavity for at least 3 months.

An immunohistochemical study of osteoprotegerin in the human dental pulp.

This study investigated the expression of osteoprotegerin (OPG) in healthy and inflamed dental pulps. Histological sections 7 microm thick of 47 teeth, either caries-free or affected by gross caries, were used. Sections were stained with hematoxylin-eosin, and other sections of the same specimen were subjected to the avidin-biotin peroxidase complex immunohistochemical procedure for detection of OPG. The study focused on the coronal pulp that was divided into peripheral and central regions. In the peripheral pulp healthy and inflamed specimens showed high OPG immunoreactivity of the odontoblastic layer. When no inflammation was present in the central pulp OPG immunoreactivity was light. Fibroblasts and endothelial cells showed immunoreactivity ranging from none to intense. When inflammation was present in the central pulp the chronic inflammatory cells showed intense immunoreactivity.

Immunohistochemical study of gamma-aminobutyric acid and bombesin/gastrin releasing peptide in human dental pulp.

This study investigated the presence of the putative peripheral neuromodulators Gamma-aminobutyric Acid (GABA) and Bombesin/Gastrin-Releasing Peptide (BN/GRP) in the human tooth pulp. Caries free and asymptomatic carious teeth were processed for paraffin embedding and sectioned at six microns. From each specimen, sections were stained with hematoxylin and eosin; other sections were subjected to Avidin-Biotin-Peroxidase Complex immunohistochemistry for GABA and BN/GRP. Sections of rat brain and small cell lung carcinoma served as positive controls. Results indicate the presence of specific GABA-like and BN/GRP-like immunoreactivity within the pulps of both normal and carious teeth. Overall staining for both ligands was significantly more intense within inflamed pulps. Based on their actions elsewhere, GABA and BN/GRP may play a role in the dental pulp as peripheral neuromodulators or as growth factors.

In vitro evaluation of effects of ultrasonic root-end preparation on resected root surfaces.

This in vitro study investigated structural alterations in resected roots that had root-end preparations made with a conventional microhead handpiece and ultrasonics at two intensity levels. Root ends were examined with fluorescence confocal microscopy. Serial histologic sections to the 2 mm levels and then at the level of 3 mm and 4 mm from the resected surface were examined. Statistical analysis of the confocal data indicated no significant difference between the groups in the number and length of the fractures. Results of the histologic data indicated that root ends prepared by ultrasonics had a statistically greater number of fractures than both the control and the conventionally prepared groups. The latter did not differ significantly from each other.

Clinical, radiographic, and histological study of endodontically treated retained roots to preserve alveolar bone.

Endodontically treated, submerged roots in two Macaca speciosa monkeys were studied clinically, radiographically, and histologically. The roots were successfully covered by soft tissue, except in two areas. In several sites, radiographic evidence of bone formation was observed; this was confirmed by histologic examination. Bone formation coronal to the submerged roots was not a predictable occurrence. Even though epithelium and inflammation commonly occurred over the amputation sites, their presence did not seem to affect bone formation.