An in-vitro investigation of variables influencing mercury vapor release from dental amalgam.

Controversy regarding patient exposure to mercury from dental amalgam is more than 150 years old. Researchers continue to investigate the amount of mercury vapor released from amalgam both in vivo and in vitro. In this investigation, an in vitro testing method previously described in the literature was used to quantify the effect of operator-controlled variables on mercury release from dental amalgam. The variables tested were alloy morphology (spherical, admixed or atomized irregular particle), operator skill (inexperienced, novice and expert), operator technique (overfill and evenly fill) and cavity design (standard Class I, double volume and double surface area). Preparations fabricated in sections of acrylic rod were filled with dental amalgam, placed in 25 mL glass bottles and sealed. Mercury vapor concentrations were measured using a Jerome M-411 at specified times. Standardized mean concentrations for each time and total mercury released over time were calculated and analyzed with ANOVA and Tukey HSD. Statistically significant differences ((alpha = 0.05) were identified for all variables tested. Total mercury vapor release was consistently found to be greater for admixed as compared to spherical amalgam. Amalgam restorations prepared by an inexperienced operator demonstrated statistically less mercury vapor than a novice or experienced clinician for both spherical and admixed morphologies. A statistically significant difference in mercury vapor using different condensation and carving techniques was found for the spherical amalgam but not for the admixed material. Restoration design demonstrated significant differences in total mercury vapor dependent on volume and exposed surface area of the amalgam restoration. In this in vitro investigation, mercury vapor release from amalgam was dependent on alloy morphology, operator experience, operator technique and restoration design.

Evaluation of dental adhesive systems with amalgam and resin composite restorations: comparison of microleakage and bond strength results.

A variety of laboratory tests have been developed to assist in predicting the clinical performance of dental restorative materials. Additionally, more than one methodology is in use for many types of tests performed in vitro. This project assessed and compared results derived from two specific laboratory testing methods, one for bond strength and one for microleakage. Seven multi-purpose dental adhesives were tested with the two methodologies in both amalgam and resin composite restorations. Bond strength was determined with a punch-out method in sections of human molar dentin. Microleakage was analyzed with a digital imaging system (Image-Pro Plus, Version 1.3) to determine the extent of dye penetration in Class V preparations centered at the CEJ on both the buccal and lingual surfaces of human molar teeth. There were 32 treatment groups (n = 10); seven experimental (dental adhesives) and one control (copal varnish, 37% phosphoric acid) followed by restoration with either amalgam or resin composite. Specimens were thermocycled 500 times in 5 degrees and 55 degrees C water with a one-minute dwell time. Bond strength and microleakage values were determined for each group. ANOVA and Student-Newman-Keuls tests demonstrated an interaction between restorative material and adhesive system with a significant difference among adhesives (p < 0.05). Using a multi-purpose adhesive system resulted in both a statistically significant increase in bond strength and a statistically significant decrease in extent of microleakage (p < 0.05). The effect of the adhesive upon both microleakage and bond strength was greater in the resin composite restorations than in the amalgam restorations. Bond strength testing was more discriminating than microleakage evaluation in identifying differences among materials.

Quality assurance for the laboratory aspects of prosthodontic treatment.

Inconsistency in the product returned from the commercial dental laboratory led to the development of a formal quality assurance (QA) program at the University of Detroit Mercy School of Dentistry in 1994. The goal of the program was to improve the quality of prosthodontic laboratory submissions and the returned product, facilitate laboratory communications, and, ultimately, enhance the quality and timeliness of patient care. Each student submission is evaluated with a criterion-referenced evaluation form. Deficiencies are communicated to the student, and the corrected submission is then sent to the laboratory. Three-year remake data from the main clinic (QA site) and an extramural clinic (non-QA site) demonstrate the effectiveness of the program. The major benefits are more efficient, cost-effective patient care, as well as the provision of a model for the student to practice the skills needed for effective communication with the dental technician, upon graduation.

A utility analysis of dental implants.

By applying a utility (usefulness) scale termed the "Feeling Thermometer" to 111 edentulous patients, a measure of effectiveness (quality-adjusted prosthesis years) that can be compared across several treatment strategies was developed. The results suggest that the utility scale was a valid (known group, P < .05), reliable (intraclass correlation coefficient = .713) measure of patients' preferences for the three treatment strategies: (1) conventional complete dentures (controls, n = 77), (2) transosteal implant-supported prostheses (n = 19), and (3) endosseous implant-supported prostheses (n = 15). The implant-treated patients rated their prostheses as high or higher (Feeling Thermometer score of 86.3 [endosseous] and 82.3 [transosteal]) than a functional fitting, esthetic conventional denture (score of 85.0 [endosseous] and 82.0 [transosteal]). They were also younger, more educated, and had received more sets of dentures (P < .05) than conventional denture patients.

Clinical and microbiologic comparisons of two dental implant systems.

Clinical soft tissue examination and microbiologic findings were compared for two dental implant systems. Of 20 edentulous patients, ten had been reconstructed with a transosteal implant of gold alloy, TMI-system (Bosker), of and ten with endosseous implants of titanium (Brånemark-system). Clinical parameters evaluated included plaque, gingivitis, sulcus depth and bleeding on probing. Plaque samples from 14 patients were cultured for selected periodontal pathogens. Although some differences in soft tissue clinical behavior were identified, the incidence and prevalence of selected periodontal pathogens appeared to be similar.

A technique for evaluating bony changes in the anterior edentulous maxilla: a modification of a cephalometric analysis.

A modification of a cephalometric analysis is presented for evaluating maxillary bone loss in the edentulous maxilla. The analysis involves tracing a lateral cephalometric radiograph of an edentulous maxilla, identifying the new landmarks, and measuring the appropriate vertical and horizontal distances of the maxilla. Comparison of the measurements for the patient's initial or baseline radiographic analysis with those of the patient's follow-up radiographic analysis identifies the amount of bone loss that has occurred between the two examinations.

Evaluation of anterior maxillary alveolar ridge resorption when opposed by the transmandibular implant.

Fifteen edentulous patients with complaints regarding denture comfort and/or function were treated with the transmandibular implant. All patients were restored with conventional maxillary dentures opposed by implant-supported removable prostheses. Two to 4 years after surgery, these patients were evaluated for vertical and horizontal maxillary bone loss with a radiographic analysis developed by the authors. With this technique, attention was focused on vertical alveolar ridge resorption in the anterior maxilla. Although the sample size was small, the findings from this study indicate that vertical bone loss in the anterior maxilla does occur when a maxillary denture is opposed by an implant-supported overdenture. Comparison of these results with a previous study that evaluated anterior maxillary resorption when a complete maxillary denture opposed natural mandibular anterior teeth and a distal extension removable partial denture demonstrated no statistically significant difference.

Allogeneic bone for secondary alveolar cleft osteoplasty.

The purpose of this retrospective clinical study was to determine the efficacy of allogeneic bone for secondary alveolar cleft osteoplasty. Twenty-four patients with unilateral cleft lip and palate treated with allogeneic bone grafts were examined by a surgeon, orthodontist, and prosthodontist 20 to 47 months after surgery. Radiographic and clinical examination of the periodontal status of the teeth adjacent to the cleft and their antimeres were compared for differences with Student's t test and the Wilcoxon test. Radiographs indicated complete bone bridging in 21 patients. Two of the remaining three patients had a 1-mm radiolucent gap in the cleft site. The third patient had a 6-mm-wide radiolucency and recurrence of an oronasal fistula which was regrafted with autogenous bone. No statistically significant differences between the cleft and noncleft tooth antimeres were found for plaque, gingivitis, bleeding, sulcus depth, or level of attachment. A statistically significant difference in the amount of attached gingiva was found between the cleft and noncleft tooth antimeres. Nine patients with missing lateral incisor teeth avoided prosthetic replacement by orthodontic movement of the canine tooth into the grafted edentulous space. In those cases where the maxillary canine was unerupted at the time of the surgery, eruption into the graft occurred. Stability of the maxillary segments was sufficient to allow prosthodontic restoration with a fixed partial denture in those cases where it was indicated.

Prosthodontic considerations for the transmandibular implant.

The transmandibular implant has been designed to provide the patient with a severely atrophic mandible an implant that will bear the masticatory load. Thirteen edentulous patients treated with maxillary complete dentures and mandibular overdentures retained by the transmandibular implant were examined biannually for 2 years. Prosthodontic complications included the development of parafunctional habits, "combination syndrome," and epulis in association with the mandibular denture. Surgery was necessary to control chronic mucosal irritation related to muscle pull in one patient. Among the soft tissue parameters, plaque index, gingival index, and sulcus depth demonstrated statistically significant correlations (Spearman). All patients reported an absence of discomfort and those with previous functional complaints reported the ability to masticate all foods. Patient response to overdenture reconstruction with the transmandibular implant seems to be similar to that observed with the combination case. Oral hygiene appears to be directly related to the soft tissue response.

Management of oral squamous cell carcinoma in situ with topical 5-fluorouracil and laser surgery.

Oral squamous cell carcinoma in situ has been described as a relatively rare lesion. However, difficult decisions with respect to clinical management of the lesion in this location parallel those reported for other mucosal sites, such as the cervix or the larynx. The lesion, though superficial, may extend over a large area of tissue, and attempts at irradication with surgery or radiation therapy may be associated with a great deal of morbidity. However, the risks in deferral of treatment while "watchfully waiting" may also be unacceptable. A method and rationale for management of oral squamous cell carcinoma in situ with the use of topical 5-fluorouracil and carbon dioxide laser are described in this article. A technique for using an intraoral prosthesis to potentiate drug delivery is also described. Though morbidity can be very significantly reduced, patient compliance is an important consideration for success with this protocol.

The transmandibular implant: a 2-year prospective study.

Thirteen consecutive patients with complaints of dysfunction and pain associated with a mandibular denture were treated with the transmandibular implant. The implant was placed from a submental approach with an atraumatic surgical technique. No load was placed on the implant for 12 weeks. Patients were evaluated for pain, paresthesia, healing of the submental wound, soft tissue response, radiographic change, and mobility of the implant for a period of 2 years. Patient satisfaction was recorded at the 1- and 2-year examinations. The results demonstrate the reliability and reparability of the transmandibular implant system.

A new inexpensive customized plaque for choroidal melanoma iodine-125 plaque therapy.

The authors have developed a new inexpensive precious metal alloy plaque for use in customized iodine-125 plaque therapy. Each plaque is formed from two flat circular gold/palladium foils which are used in dental crown work. Using a simple manual mechanism, the two forms are stamped over a customized acrylic die shaped to the dimensions of the tumor base plus a 2-mm margin. Completed plaques consist of a back wall, a 2-mm side wall, and a 1.5-mm wide lip with holes for suture placement. Advantages include: simple construction from inexpensive components, customized shape, and iodine seeds that are readily visible on plane radiographs.