Search PubMed⌕ Search

Biomedical subjects

C F Cox

Publications and source records attributed to C F Cox.

At least 37 records · Page 2Linked to original sources
PubMed1998

Biocompatibility of Optibond and XR-Bond adhesive systems in nonhuman primate teeth.

This study evaluated the histologic responses of two different adhesive systems on the teeth of seven healthy adult monkeys. Class V cavities in 128 teeth were observed at 7,21 to 27, and 90 to 97 days. Statistical data showed no significant differences in pulp inflammation between the Optibond (Kerr), XR-Bond (Kerr), and IRM (Caulk) groups in pulps at the three time intervals. Some odontoblastic disruption and inflammation was seen in pulps restored with XR-Primer at the three time intervals. Pulp healing was similar in teeth treated with both direct-capped Optibond and calcium hydroxide, and there was no significant increase in pulpal inflammation with time. No abscesses or necrotic pulps were seen in any teeth. Optibond and XR-Bond adhesive systems are biologically acceptable in nonhuman primate pulp tissues.

Animals↗
PubMed1998

Biocompatibility of Clearfil Liner Bond 2 and Clearfil AP-X system on nonexposed and exposed primate teeth.

OBJECTIVE: Recent studies have demonstrated that acid etching of vital dentin and pulpal tissue does not retard pulpal healing, odontoblastoid cell differentiation, or dentinal bridge formation when the pulp is capped with adhesive resins. The purpose of this study was to evaluate the pulpal response in nonexposed and exposed monkey pulps to treatment with the Clearfil Liner Bond 2 and Clearfil AP-X system. METHOD AND MATERIALS: Class V and Class I cavities in nonexposed and exposed pulps were observed at 7 or 8, 27, and 97 days. RESULTS: There were no differences in pulpal inflammation between the Clearfil Liner Bond 2/Clearfil AP-X specimens and calcium hydroxide controls in either Class V or Class I cavities at the various time periods. CONCLUSION: Clearfil Liner Bond 2 and Clearfil AP-X system is not toxic to either nonexposed or exposed pulpal tissues when placed according to manufacturer's directions.

Animals↗
PubMed1998

"True normal" TMD control subjects: a rare clinical finding.

This study evaluated the accuracy of the clinical diagnosis of patients with temporomandibular joint dysfunction symptoms compared to a group of asymptomatic volunteers. The clinical examination and history questionnaire used during the evaluation of TMD patients were less accurate evaluating asymptomatic subjects than when combined with computerized joint vibration analysis. "True normal" control subjects were rarely found when these diagnostic modalities were combined in the TMD examination process. Most of the asymptomatic subjects had subclinical signs of TMD. The small sample size is significant, especially since large numbers of subjects appear to be necessary to obtain even small numbers of "true normals."

Adult↗
PubMed1998

Biocompatibility of primer, adhesive and resin composite systems on non-exposed and exposed pulps of non-human primate teeth.

PURPOSE: To evaluate the histologic response of 332 non-exposed and 127 exposed monkey pulps applying nine adhesive systems. MATERIALS AND METHODS: Class V and Class I cavities were used in non-exposed and exposed monkey pulps at the three ISO usage time intervals. RESULTS: There were no histologic differences in pulp responses among the nine adhesive systems used in either Class V and/or Class I cavities when compared to pulp responses of Ca(OH)2 controls at the ISO time intervals. The nine adhesive systems and resin composites are non-toxic to either non-exposed or exposed pulps, being biologically compatible to pulp tissues when placed on mechanical pulp exposures following hemorrhage control with a 2.5% NaOCl and per manufacturers' directions. It is imperative that clinicians understand the biological importance of hemorrhage control as well as the technique sensitivity of hydrophilic primers in order to optimize the efficacy of adhesives for clinical success against microleakage of bacterial factors.

Animals↗
PubMed1998

Periodontal healing of canine experimental grade-III furcation defects treated with autologous fibrinogen and absorbable barrier membrane.

OBJECTIVE: To determine the effects of autologous fibrinogen (AF) and absorbable barrier membrane (ABM) on periodontal healing of canine experimental grade-III furcation defects. ANIMALS: 18 conditioned, laboratory-source, adult Beagles. PROCEDURE: Defects were developed bilaterally at the second and fourth premolars and maintained for 12 weeks. Defects were treated with AF, ABM, AF and ABM, or debridement. Digital subtraction radiography, histologic evaluation, and histomorphometric analysis of defect healing was done at 1, 3, and 6 months after treatment to determine percentage increases in bone volume, height, area, and length of periodontal regeneration along the perimeter of the defect. RESULTS: Comparison of defects at post-treatment intervals indicated significantly greater healing of debridement and AF-treated defects, compared with ABM-treated defects at 3 months; however, by 6 months, there were no significant differences in defect healing for all histomorphometric variables. Defects treated with ABM were associated with significantly less root ankylosis than other treatments. Defects treated with debridement had significantly greater increases in bone volume at 6 months after treatment, compared with groups treated with ABM. There was a significant correlation between regenerated bone area, bone volume, and periodontal regeneration for all treatments at 3 and 6 months after treatment. CONCLUSION AND CLINICAL RELEVANCE: Use of AF and ABM did not enhance the amount of periodontal healing, compared with debridement only. The ABM-treated defects were essentially devoid of root ankylosis. Grade-III furcation defects may respond equally well to conservative periodontal surgery or guided tissue regenerative techniques. The prevention of root ankylosis is a substantial benefit favoring this latter method of treatment.

Absorption↗
PubMed1998

Pulpal response to a resin-modified glass-ionomer material on nonexposed and exposed monkey pulps.

OBJECTIVE: This study evaluated the biocompatibility of a resin-modified glass-ionomer material on monkey pulps. METHOD AND MATERIALS: Standardized Class V cavities were prepared in 112 teeth distributed in six healthy adult monkeys. The resin-modified glass-ionomer cement was placed in 24 nonexposed and 36 exposed pulps according to manufacturer's instructions. ZOE was used as a control in nonexposed pulps, while calcium hydroxide was used as a control for exposed pulps. Tissues were collected at 6 to 7, 21 to 27, and 90 to 97 days. After demineralization, the teeth were serially sectioned, stained, and observed by light microscopy. RESULTS: Except for one resin-modified glass-ionomer pulp at 6 days, there were no differences between the responses of nonexposed pulps to resin-modified glass-ionomer specimens and ZOE controls. In exposed pulps, eight of 36 resin-modified glass-ionomer pulps showed various grades of inflammatory response, all associated with stained bacteria. Pulpal healing was similar in both resin-modified glass-ionomer and calcium hydroxide direct-capped exposures. Twenty-two of 26 exposed pulps restored with the resin-modified glass-ionomer cement showed dentin bridge formation at 21 and 97 days. CONCLUSION: The resin-modified glass-ionomer material exhibited acceptable biologic compatibility in exposed and nonexposed cavities.

Analysis of Variance↗
PubMed1997

Evaluation of wear: enamel opposing three ceramic materials and a gold alloy.

STATEMENT OF PROBLEM: The wear of human enamel and of the restorative material is often a critical concern when selecting a restorative material for any given clinical restorative treatment. PURPOSE: This in vitro wear investigation evaluated three ceramic restorative materials and one type III gold (the control) opposing enamel. MATERIAL AND METHODS: The area of enamel lost at specified time intervals, the stylus area lost, and the combined stylus and enamel vertical height lost were evaluated. RESULTS: Enamel wear opposing one type III gold was statistically similar to that of Dicor MGC, which was lower than that of Vita Mark II and IPS Empress, which were also statistically similar in value. CONCLUSIONS: The total vertical height lost from the type III gold specimens and opposing enamel was statistically lower than that of Dicor MGC and IPS Empress (alpha < 0.05).

Aluminum Silicates↗
PubMed1996

Evaluating the antagonistic wear of restorative materials when placed against human enamel.

Several clinical and laboratory studies have reported data on the nature of tooth wear against restorative materials (that is, amalgam, gold, glass ceramic and various composite resin systems). Several antagonistic substrates are known to cause various in vitro wear rates when placed in opposition to enamel. In this study, the authors evaluated 10 commercially available posterior composite resin systems and a gold alloy control. The findings showed that posterior composite resins containing zirconium silicate or quartz fillers caused greater antagonistic enamel wear than did microfilled or barium silicate-filled composite resins.

Analysis of Variance↗
PubMed1996

Biocompatibility of various dental materials: pulp healing with a surface seal.

Class V cavities with mechanical exposures were prepared in 178 teeth of seven monkeys to observe the temporal healing of exposed pulps in direct contact with various dental materials, with or without a biologic seal of zinc-oxide eugenol cement against microleakage. Thirty pulps were direct capped as calcium hydroxide controls. The remaining 148 exposures were direct capped, 41 with silicate, 39 with zinc phosphate, 33 with amalgam, and 35 with an auto-cured composite. Sixty-four were restored to their cavosurface margin with their respective material and 84 were sealed to the covosurface margin with zinc-oxide eugenol cement. Tissues were obtained by perfusion fixation at intervals of 35, 21, 14, 10, 5, and 3 days, and then processed and evaluated. The results of this study demonstrated that exposed dental pulps possess an inherent healing capacity, allowing cell reorganization and dentin bridge formation when adequately sealed with zinc-oxide eugenol cement to prevent bacterial microleakage.

Animals↗
PubMed1996

Marginal integrity of bonded amalgam restorations.

PURPOSE: To evaluate the marginal integrity of amalgam restorations in association with four different bonding agents in an in vitro stressing system. MATERIALS AND METHODS: Cylindrical cavities were prepared in extracted human molars. The enamel-dentin interface of each cavity was treated with one of four different bonding agents and a non-bonded group. Following treatment with one of the four systems; Amalgambond (AB), Amalgambond Plus (AP) Superbond D-liner II (SD) and Bond-It (BI). Each cavity was then restored with a high-copper spherical amalgam alloy Tytin (TY). Using a load of 75 Newtons (N), a total of 100,000 cycles were applied to each restoration surface. Marginal integrity of each tooth restoration interface was replicated with epoxy and evaluated for gap width with a profilometer and SEM. RESULTS: There were no significant differences in gap width between the loaded and unloaded groups. The non-bonded group (before loading) was statistically different than AB, AP, and SD. In addition, there were no significant differences among the 4-META bonded groups, regardless of the type of bond system, whether loaded or unloaded. The four different bonding agents were significantly different after loading than the non-bonded group. Our SEM and profilometry data demonstrate that the marginal integrity of amalgam alloy restorations is significantly improved by use of bonding systems.

Dental Amalgam↗
PubMed1995

Human pulp response after partial pulpotomy with two calcium hydroxide products.

Twenty human permanent teeth were used to study the pulpal response of two calcium hydroxide products, Dycal and Pulpdent Multi-Cal, after partial pulpotomy. Teeth were extracted at 4 months, fixed, and prepared for histologic examination. All 10 teeth treated with Dycal showed complete soft tissue healing and bridge formation. No stained bacteria were seen throughout the serial sections. One tooth treated with Dycal showed acceptable histologic results, dentin deposition in the root canal. Six cases dressed with Pulpdent Multi-Cal showed acceptable histologic results, whereas four teeth showed severe inflammation or necrosis associated with bacterial penetration into the pulp tissue. Clinically, one tooth treated with Pulpdent Multi-Cal showed pulpal pain and was extracted at 90 days. Our data support the thesis that human permanent pulps will promote tissue healing and dentin bridge formation as long as bacterial microleakage is excluded.

Bacteria↗
PubMed1995

Biocompatibility of dental adhesives.

This article provides biological and technological information to support routine use of new cohesive bonding systems with definitive restorations. With these systems, clinicians may expect many advantages over the more traditional water soluble base and liner systems. Hybridization of vital dentin will prevent postoperative hypersensitivity under restorations and completely seal the tooth-restoration interface to prevent bacterial infection of the underlying substrate, ultimately reducing recurrent caries underneath the hybridized restoration.

Acid Etching, Dental↗
PubMed1995

A new copolymerized composite resin system: a multiphased evaluation.

Most microfilled composite resins are relatively resistant to generalized wear; however, they commonly exhibit poor resistance to localized wear because of debonding of prepolymerized particles from the resin matrix. A copolymerized new composite resin, in which the filler particle trimethylolpropane-trimethacrylate is chemically bonded to the resin matrix, is evaluated. Epic-TMPT was subjected to both generalized and localized wear tests that revealed that its wear resistance was higher than that of other composite resin systems. Epic-TMPT in posterior occlusal cavities showed less than 8 microns of wear for each restoration, 1 year after placement. Placement of Epic-TMPT into large anterior abfraction lesions without mechanical retention, with surface etching, and subject to severe traumatic occlusion resulted in 87% retention 1 year after placement. In vivo usage biocompatibility tests demonstrated no pulpal irritation or inflammation when Epic-TMPT was placed on vital dentin of crown preparations with complete enamel removal.

Animals↗
PubMed1994

Re-evaluating pulp protection: calcium hydroxide liners vs. cohesive hybridization.

Certain clinical and biological studies have reported that prepared dentin and the underlying pulp must be protected with a calcium hydroxide base and liners that supposedly impart biological and structural integrity to tissues. Since the mid-1950s, dentists have relied on a number of calcium hydroxide medicaments for this goal. But recent studies imply that clinicians need to re-evaluate the generous use of certain calcium hydroxide medicaments under restorations.

Acid Etching, Dental↗
PubMed1994

Etiology and treatment of root hypersensitivity.

Class V cervical lesions are often observed in older patients during their treatment planning phase, resulting from root caries, toothbrush abrasion, chemical erosion, or to absraction due to unusual tooth flexure. Besides providing a nuisance space as a food trap or plaque buildup, patients also complain of hypersensitivity to air blasts, mechanical stimulation, thermal extremes, or to osmotic fluid shifts. The location of the root lesion in relation to the cemento-enamel junction is of extreme importance. For that reason root lesions limited to the coronal portion of the tooth and completely surrounded by enamel lend themselves to traditional restorative treatment procedures. However, as the root lesion moves apically and its cavosurface circumference is increasingly bound by cementum, clinical treatment becomes much more difficult and in most cases virtually impossible with conventional retentive restorations, and they tend to threaten the root structure and the dental pulp. If these root lesions are left untreated, progressive destruction of root structure occurs and if the causative agents are not removed, the depth of the lesion will threaten the periodontium, dental pulp, and the occlusal integrity of the tooth crown. In addition, cemental lesions are often associated with increased levels of hypersensitivity. Historically, dentistry treated root lesions with direct gold, gold or porcelain inlays, amalgam alloys and crowns, all relying on resistance and retention form. When unrestorable, modification of tooth-brushing techniques along with desensitizing agents were the only desirable treatment due to problems involved with the insertion of a proper restoration. Clinical studies have reported these procedures are often transient, offering no durable restoration of the tooth or elimination of the hypersensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Restoration, Permanent↗
PubMed1994

Evaluation and treatment of bacterial microleakage.

Recent data have shown a correlation between pulp response and material biocompatibility when microleakage is prevented. Considering vital dentin, the dentist must keep in mind that it is an extension of the pulp, presenting the first line of response to the consequences of microleakage. Healing of the dental pulp is ensured when a clinical seal is provided to prevent bacterial microleakage. Microleakage is a biological phenomenon with several important clinical implications. The affective component clinically presents as dentin postoperative hypersensitivity due to the episodic hydrodynamic fluid movement within the tubule complex. The effective component is the disease process which signals the dentin and pulp complex to respond by deposition of sclerotic and reparative dentin deposition. Uncontrolled microleakage generally produces patient pain as well as to later allow bacterial infection resulting in recurrent caries and pulp inflammation. The dynamic, permeable nature of the dentin interface allows residual bacteria to proliferate following cavity preparation. Following sterile operative procedures, bacteria have been shown to percolate into the cavosurface margin resulting in recurrent caries and pulp inflammation. This report considers biological data emphasizing the clinical necessity to provide a hermetic seal to prepared dentin to prevent both dentin hypersensitivity and pulp inflammation.

Dental Leakage↗
PubMed1994

Resorption patterns following intentional vital root transection in Macaca mulatta.

Previous studies have shown degeneration of nerve tissue as well as reorganization by periodontal tissue in dental pulp chambers following intentional vital root transection in Macaca mulatta. The supporting structures of the teeth, as well as the root itself, have not been fully studied following such surgery. The purpose of this study was to observe histopathologic changes in bone and root structure over a 1-year postoperative period. Three adult Macaca mulatta were evaluated for this study. Roots were transected within the apical one third and the areas were surgically closed. Following a postoperative soft diet for 7 days, the monkeys were allowed normal masticatory function. Maxillary and mandibular quadrants were removed following vascular perfusion of the animals at 1, 2, 3, 6, 24, and 52 weeks; quadrants were then demineralized, embedded, sectioned, and stained with Preece's trichrome. Resorption of cementum, dentin, and bone was independently evaluated on microslides for each tooth at consecutive intervals of approximately 70 microns. Resorption was rated as mild, moderate, or severe depending on the number of Howship's lacunae and the dimension of the resorptive area. Severe bone resorption was evident at 1 week, decreasing at 2 weeks, and then progressively decreasing up to 52 weeks. Most active inflammatory root resorption was noted on maxillary and mandibular premolars and molars on first-week specimens. Arrested resorptive areas were present in similar locations in second- and third-week specimens. New cementum was present along the cut surface on specimens from 2 to 52 weeks and within the pulp canal beginning at 2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗