Marvin M. Stark

Use of glass ionomers as retrofilling materials

Many materials have been used as retrofillings. Because of the bonding property of glass ionomer cement, this study was conducted to evaluate its possible use as a retrofilling material. Seventy human maxillary anterior teeth were chosen. The root canal systems were cleansed and shaped, and the teeth were assigned to six groups of 10 each. The root canals were obturated with gutta-percha and Grossman sealer, and the apical 2 mm of each root was resected. In all groups a retrofilling preparation was made to a depth of a number 331 bur. The apical preparations were filled in the following manner: silver amalgam (group I), silver amalgam plus two layers of varnish (group II), Ketac-Silver plus two layers of varnish (group III), Ketac-Silver without varnish (group IV), Ketac-Fil plus two layers of varnish (group V), Ketac-Fil without varnish (group VI), and Ketac-Bond (group VII). All the root surfaces with the exception of 2 mm from the resected line were coated with two layers of clear varnish. All the teeth were immersed in methylene blue for 24 hours. After vertical sectioning, dye penetration was measured under a dissecting microscope. The mean apical leakage (in millimeters) was as follows: I = 0.57, II = 0.39, III = 0.22, IV = 0.54, V = 0.11, VI = 0.46, and VII = 0.17. One-way analysis of variance performed on the group means indicated that Ketac-Fil with varnish (group V) and Ketac-Bond (group VII) had significantly less leakage than other groups (p less than 0.05). This study indicates that Ketac-Fil and Ketac-Bond may have potential as retrofilling materials.

Sealing ability of intermediate restorations and cavity design used in endodontics

Temporary filling materials are used in endodontics to prevent contamination of the root canal system during intertreatment visits. Recently, a new composition resin (TERM) has been introduced as an interim restoration in endodontics. The purpose of this investigation was to evaluate the efficacy of this resin as an interim restoration and possible effect of access cavity design with respect to its sealing ability compared with other temporary restorative materials. Sixty human teeth were divided into two categories, and two types of access cavities were prepared, namely tapered access with walls divergent toward the occlusal surface and straight access with parallel walls. The prepared teeth from each category were divided into three subgroups of ten each to receive Cavit (group I), IRM (group II), or TERM (group III). After the fillings were placed, the teeth were transferred into a humidor where they stayed for 24 hours. The teeth were then thermocycled. Each group was thermocycled for 2 hours at 1 minute intervals at 60 degrees C and 4 degrees C. Then the teeth were sealed with a compound and coated with two layers of clear varnish, with the exception of cavity margins. Each occlusal surface was immersed in a vial containing silver nitrate. The teeth were sectioned longitudinally, and the degree of dye penetration was evaluated under a dissection microscope according to set criteria. Our findings demonstrated that design of cavity preparation was not a functional parameter in leakage pattern. Results indicated that Cavit had the best sealing ability whereas IRM showed the maximum dye penetration.

Human blood pressure and pulse rate response to racemic epinephrine retraction cord

1. The pulse rate of patients after application of racemic epinephrine-impregnated retraction cords depends more on the level of anxiety and stress than on the level of the epinephrine. 2. Blood pressure is elevated by placement of racemic epinephrine-impregnated retraction cords upon an exposed vascular bed or lacerated tissue. 3. Four percent racemic epinephrine-impregnated retraction cords cause less elevation of blood pressure than 8% racemic epinephrine cords. 4. Although the elevations in blood pressure from 8% cord occur within a narrow range, this range may be hazardous to cardiac patients. Therefore, 4% racemic epinephrine cord should be used. 5. A desirable amount of tissue retraction is produced by 4% racemic epinephrine cord. 6. Dry cords do not provide adequate retraction of tissue and are contraindicated for tissue-retraction purposes.

Technical note: Antimicrobial action of glass-ionomer lining cement on S. sanguis and S. mutans

There are a number of glass-ionomer lining cements available to the profession. It is generally agreed that the glass-ionomer cements demonstrate reasonably good biocompatibility. The purpose of this study was to evaluate the antimicrobial activity of six glass-ionomer cements on S. sanguis and S. mutans. Forty-eight plates of TSA-SRBC (10%), each with 3.0-mm-diam. wells, were divided into two groups (1 and 2) of 24 each. Group 1 was inoculated with S. sanguis (10558) and Group 2 with S. mutans (6715-13 w.t.). Each well was filled with 4.0 mg of one of the following liners: Glassic (A), Shofu lining cement (B), GC lining cement (C), Ever Bond (D), Gingiva Seal (E), and Ketac Bond (F); the empty wells served as control. Plates were incubated under microaerophilic conditions at 37 degrees C, and checked daily over seven days for inhibition zones. Average inhibition zones (mm) at 7 days were as follows: Group 1-1A = 10.00, 1B = 7.83, 1C = 18.50, 1D = 13.00, 1E = 8.67, and 1F = 9.33; Group 2-2A = 3.08, 2B = 10.25, 2C = 12.75, 2D = 15.58, 2E = 8.83, and 2F = 3.20. All control wells were 0.0 GC liner and Ever Bond showed significantly greater overall inhibition of microbial growth than did other tested liners (p less than 0.5). A one-way ANOVA and SNK test showed that all tested liners were significantly more toxic toward S. sanguis than toward S. mutans (p less than 0.05).

Calculus and stain removal from acrylic resin dentures

Abstract Under the conditions of this study, the cleaning of dentures is related to the chemical activity of the solutions and has little relationship to vibratory activity of cleaning devices. The use of common household bleach followed by light brushing seemed to offer the most effective means of cleaning.

A 30-month Clinical Evaluation of the Influence of Finishing and Size of Restoration on the Margin Performance of Five Amalgam Alloys

The influence of finishing and size of the restoration on the margin performance of 286 Class II restorations using five amalgam alloys (Aristaloy, Dispersalloy, Oraloy, Sybraloy, and Tytin) was evaluated at 30 mo. When size of the restoration was considered, Dispersalloy displayed the best margin performance. Oraloy, Sybraloy, and Tytin were inferior to Dispersalloy and were grouped together. Aristaloy was inferior to all other alloys in the study. When the aspect of finishing was considered, Dispersalloy and Sybraloy evidenced excellent margin performance when unfinished. Aristaloy showed the worst margin performance of all the alloys in the study when unfinished, but showed remarkable improvement in margin performance when finished.

9-Aminoacridine, an effective antibacterial agent with caries-disclosing features

Abstract Acriphen is offered, by virtue of its extremely low order of toxicity and high antimicrobial properties, as a useful disinfectant in dentistry. Its caries-disclosing feature, as well as its debriding property, make it a useful agent for clinical practice.

Laser Evaluation of Handpiece Contamination

Six different models of ultra-high speed handpieces were evaluated in regard to debris accumulation following cutting through tooth structure. A weight-load machine and a laser particle detector were utilized to evaluate the amount of the debris retained. Amounts of debris accumulated after dry and wet cutting were also evaluated. The effect of simple wiping of the handpieces with alcohol gauze was assessed. The results obtained show that the longer the cutting time, the larger the amounts of debris retained on the handpieces. Dry cutting resulted in smaller amounts of debris entrapped than following wet cutting. The cleaning by wiping with alcohol gauze reduced the amounts of the debris, but is insufficient and cannot be utilized as a single procedure for decontaminating handpieces. The external head design is a cardinal factor in retention of debris: larger but smoother surfaces will retain less debris than smaller but more complicated surfaces. External tubings are debris retention foci.

Clinical and Materials Sciences The Effects of Retraction Cords and Electrosurgery upon Blood Pressure and Tissue Regeneration in Rhesus Monkeys

evices were used for gingival retraction prior to impression-taking procedures. The effects of these retraction methods upon blood pressure and loss of gingival tissue height were evaluated on three Rhesus monkeys. Chamfer finishing lines were prepared on all of the teeth and penetrating into the gingival sulcus. All the retraction devices were used to produce the desired amount of retraction which would allow an acceptable impression. Contralateral teeth, on which a chamfer was cut but no retraction performed were used as control teeth.The only retraction device which had no effect on blood pressure and caused no tissue loss was the nonepinephrine retraction cord. The 8% r-epinephrine string and the two electrosurgical devices caused elevated blood pressures. With the 8% r-epinephrine retraction cord, no tissue loss was observed and complete healing occurred within nine days. Both electrosurgical devices caused tissue loss. The fully rectified current device caused a slight loss in gingival tissue height...evices were used for gingival retraction prior to impression-taking procedures. The effects of these retraction methods upon blood pressure and loss of gingival tissue height were evaluated on three Rhesus monkeys. Chamfer finishing lines were prepared on all of the teeth and penetrating into the gingival sulcus. All the retraction devices were used to produce the desired amount of retraction which would allow an acceptable impression. Contralateral teeth, on which a chamfer was cut but no retraction performed were used as control teeth. The only retraction device which had no effect on blood pressure and caused no tissue loss was the nonepinephrine retraction cord. The 8% r-epinephrine string and the two electrosurgical devices caused elevated blood pressures. With the 8% r-epinephrine retraction cord, no tissue loss was observed and complete healing occurred within nine days. Both electrosurgical devices caused tissue loss. The fully rectified current device caused a slight loss in gingival tissue height, while the spark gap generator caused a marked amount of tissue height to be lost. The Hyfrecator should not be used for gingival retraction because of the tissue damage that results. It appears that the safest retraction device is the retraction cord, when used properly. Further research is recommended to establish the possible systemic effects of the electrosurgical techniques.

The pulpal effects of brushing with a 5 percent potassium nitrate paste used for desensitization

Subjects who brushed twice daily for one month with a 5 percent potassium nitrate paste or with a commercially available fluoride toothpaste had no histologically observable pulpal changes. This use period encompassed that length of time wherein potassium nitrate has been shown to exert a significant desensitizing effect in hypersensitive teeth. Study results thus confirm that 5 percent potassium nitrate is safe for use as a tooth-desensitizing agent with respect to the tooth pulp.