Biomedical subjects

K W Boening

Publications and source records attributed to K W Boening.

11 recordsLinked to original sources

PubMed2001

Plaque, gingival health and post-operative sensitivity in titanium inlays and onlays: a randomized controlled clinical trial.

OBJECTIVES: Few clinical data on the use of titanium for restorative appliances are available. The aim of this study was to clinically evaluate titanium restorations compared to gold alloy restorations with regard to plaque, gingival health and post-operative sensitivity. METHODS: In 54 patients, 99 titanium restorations were placed. The control group comprised 56 patients with 96 high gold alloy restorations. The material was chosen by random. Each patient received one or two Class II restorations. Plaque Index (Silness and Löe, 0-3), Gingival Index (Löe and Silness, 0-3), and post-operative sensitivity (1-4, 1=none) were rated at 2 weeks, 3 months, 6 months, 12 months, and 18 months, post-operatively. RESULTS: The mean plaque scores ranged from 0.89 to 0.99 in the titanium group, and from 0.88 to 1.04 in the gold group. The mean gingival scores ranged from 0.91 to 1.07 in the titanium group, and from 0.82 to 0.99 in the gold group. The mean plaque and gingival scores of the titanium and gold group did not differ significantly at any visit (P>0.05). To evaluate post-operative sensitivity, patients with one MOD restoration each were included, resulting in 46 titanium and 44 high gold restored teeth. Mean values of the post-operative sensitivity scores in the titanium group were significantly higher than in the gold group (P<0.05). The restoration material was found to be the dominating variable with regard to post-operative sensitivity, which was not influenced by age, sex and the application of calcium hydroxide liner. CONCLUSIONS: It is concluded that neither higher plaque scores nor adverse effects on gingival health are to be expected in titanium restorations.

Adolescent↗

PubMed2001

Multivariate analysis of oral hygiene data from a representative sample.

BACKGROUND: This analysis was based on an oral health survey with dental examination and interview by questionnaire. METHOD: The data set comprised a representative random sample of the over 14-year-old residents of the German Federal State of Saxony (n=714), in which a multivariate logistic regression analysis was conducted. The dependent variable was the debris index (DI) score of the oral hygiene index scoring system. The subjects were split into 2 groups by dividing DI scores into tertiles: those with acceptable oral hygiene (1st tertile, DI 0.00< or =1.20) and unacceptable oral hygiene (2nd and 3rd tertile, DI>1.20). The most important explanatory variable was the community periodontal index of treatment need (CPITN). RESULTS: The higher the CPITN score, the lower the probability of acceptable oral hygiene. In relation to the reference category score 0, higher CPITN scores were associated with acceptable oral hygiene, with an odds ratio 0.05 (95% confidence interval (CI)=0.01-0.23) for CPITN score 1, and an odds ratio 0.02 (95% CI: 0.01-0.08) for score 4. Further significant variables were: self-evaluation of tooth condition, gender, and the number of missing teeth.

Adolescent↗

PubMed2001

Prosthetic treatment need in a representative German sample.

Regarding declining resources epidemiological data on needs for oral rehabilitation are required. Within the framework of an oral health survey a non-stratified two-stage random sample was taken to represent the over 14-year-old population of Saxony/Germany. The participation rate was 55%. Normative need was determined by dental assessment and guidelines developed in a consensus process, subjective prosthetic treatment need by self-complete questionnaire. About 97% of the realized sample could be planned within the guidelines. About 81% had normative prosthetic treatment need. Compared with the rate of normative need the rate of subjective need (13%) was considerably lower (chi(2) P < 0;01). Different predictive parameters of subjective need were identified by logistic regression. Besides other factors subjective need was associated with giving dentist's recommendation as significant reason for prosthetic restorations [odds ratio (OR)=5;43], not believing that the own teeth were all right (OR=0;17), and the existence of prosthetic restorations (OR=3;87 for fixed restorations; OR=4;05 for removable dentures). The guidelines proved their suitability to assess normative prosthetic treatment need in oral health surveys. Further research is necessary to find adequate options for including patients' preferences in an adequate need definition.

Adult↗

PubMed2001

Burs with guide pins for standardized tooth preparation.

OBJECTIVE: The aim of this study was to develop and test self-limiting diamond burs to ease precise chamfer preparation and to fulfill the special requirements of computer-aided design/computer-aided manufacturing and all-ceramic restorations. METHOD AND MATERIALS: Rounded cylinder (based on ISO 881) and torpedo (based on ISO 879) diamond burs with a polished guide pin, 0.5 mm in length and 0.15 mm in radius, at the front end were developed in cooperation with an industrial partner. The in vitro testing involved a total of 140 human teeth. Experimental variables were the quality of the finish line, the microhardness of the enamel, and the thermal alteration of the dentin. Conventional diamonds served as a control. RESULTS: No mechanical or thermal damage related to the bur design was found in the hard tissues that had potentially been in contact with or in close proximity to the guide pin. Microhardness of the enamel at the finish line was significantly higher when prepared with burs with a guide pin compared to conventional burs. The results of using the guide pin might indicate the beneficial effect of reduced vibration. CONCLUSION: The guide pins of the self-limiting diamond burs reduce, rather than increase, the risk of hard tissue damage at the preparation margin. No adverse effects were found. Clinical use is justified.

Body Temperature↗

PubMed2000

Clinical fit of Procera AllCeram crowns.

STATEMENT OF PROBLEM: Color stability, strength, and accuracy of fit are the main requirements for complete-ceramic crowns. The Procera AllCeram crown system is a CAD/CAM system used to fabricate individual complete-ceramic crowns that have a dry sintered, aluminum oxide core and appear to match clinical requirements. However, there are few articles about the clinical fit of all-ceramic crowns. PURPOSE: This in vivo study measured the accuracy of fit of Procera AllCeram crowns in anterior and posterior teeth. MATERIAL AND METHODS: The clinical fit of 80 anterior and posterior Procera AllCeram crowns was evaluated by a replica technique with a light body silicone to fill space between crown and tooth and a heavy body silicone to stabilize the light body film. After removal from the artificial crowns, the replicas were segmented, and measurements of the film thickness were performed with a light microscope. RESULTS: Medians of mean marginal gap widths were between 80 and 95 microm in anterior teeth and between 90 and 145 microm in posterior teeth. Medians of maximal marginal gap widths ranged from 80 to 180 microm in anterior teeth and from 115 to 245 microm in posterior teeth. CONCLUSION: The accuracy of fit achieved by Procera AllCeram was comparable to other conventional and innovative systems.

Adult↗

PubMed1998

Margin quality of titanium and high-gold inlays and onlays--a clinical study.

OBJECTIVES: Unalloyed titanium may be an economical substitute for gold alloys. The purpose of this study was to evaluate the suitability of unalloyed titanium as an alternative to gold alloys for posterior inlay and onlay restorations. METHODS: Fifty-four patients received 99 titanium restorations, 56 patients 96 gold alloy restorations. All titanium restorations were cast in a vacuum-pressure casting machine. Two weeks after insertion the clinical margin integrity was evaluated by replica technique. The maximum marginal gaps were assessed under the optical measuring microscope. The two tailed t-test for independent samples was used for statistical analysis. RESULTS: Accuracy of fit was significantly better in gold alloy than in titanium restorations. Mean maximum marginal gap between restoration margin and tooth structure were 72 +/- 18 microns (mean +/- S.D.) for titanium and 64 +/- 18 microns (mean +/- S.D.) for gold restorations. SIGNIFICANCE: Though marginal gap widths in titanium restorations did not yet match the gold standard, the data justify the use of titanium as an alternative to gold alloy for inlay and onlay restorations.

Adolescent↗

PubMed1996

Clinical performance of resin-bonded fixed partial dentures.

Resin-bonded fixed partial dentures (RBFPDs) initially recorded poor survival rates because of indefinite tooth preparations and arbitrary selection of composite resin cements. In this study, 46 RBFPDs were inserted for a longitudinal study up to 45 months. The influence of location--anterior/posterior, or maxilla/mandible--and the inclusion of pontics in occlusal excursions on the survival rates was investigated. Periodontal parameters were recorded from abutments and controls (teeth). Eight RBFPDs lost retention and two RBFPDs failed because of porcelain fractures. The anterior to posterior location and the maxillary or mandibular arch had significant influence on the survival rates. Gingival scores of abutments and controls differed significantly, but statistically significant differences were not recorded for plaque scores.

Adolescent↗

PubMed1992

Computer-aided evaluation of occlusal load in complete dentures.

A computerized diagnostic system was tested for its capability to evaluate the occlusal equilibrium of complete dentures. Its electronic sensor foil was calibrated to intraorally compute a load index for the left and right sides of the denture. The index is calculated by the measured force and number of occlusal contacts. Perfect equilibrium is given by a ratio of load left-to-load right of 1:1. Centric occlusion of complete dentures was examined before and after remounting. A good correlation between load index and the occlusal relationship on the articulator could be observed. The system appears to be suitable for verifying the need for occlusal adjustment. However, improvements concerning the hardware and software are necessary.

Bite Force↗

PubMed1992

Non-cast titanium restorations in fixed prosthodontics.

The problems encountered in casting titanium in dentistry have not been completely resolved. The Procera system forms crowns by means of a combination of spark-erosion and milling. The accuracy of fit was examined before and after ceramic veneering both in vitro and in vivo. Before veneering, on conical surfaces space widths were approximately 53 microns in vitro and 69 microns in vivo. At shoulders and occlusal surfaces, spaces of about 430 microns were measured in vitro and of about 500 microns were measured in vivo. After ceramic veneering, slight increases in space widths could be observed. The metal-ceramic compound was tested by the 3-point bending test (DIN) and the bending test (ISO). The DIN test was satisfactory, but not the ISO test. It is concluded that titanium crowns processed by the Procera System are suitable for clinical usage, if the space widths at shoulders and the occlusal surface and the special requirements of tooth preparation are taken into account.

Ceramics↗

PubMedDate not supplied

Clinical significance of surface activation of silicone impression materials.

OBJECTIVES: Surface activation of silicone impression materials enhances impression accuracy as well as the quality of stone casts. This study examined the relation between impression quality and the hydrophilicity of silicone impression materials used in a two-stage putty and wash technique. METHODS: The study included 14 silicone impression materials with and without surface activation. The contact angles of the light body materials were measured using deionised water. Free surface energies were calculated. A total of 140 impressions of wet intact permanent molar teeth were examined for definition of the gingival sulcus reproduction and then classified in a quality ranking. The percentage of the sulcus reproduction ability of each material was calculated from the sulcus depths of cross-sectioned resin casts from the impressions and clinically measured sulcus depths. RESULTS: Free surface energies (mJ/m2) of hydrophobic materials (contact angle > 90 degrees) ranged from 16.8 to 26.8 mJ/m2. Surface activated materials (contact angle < 90 degrees) exhibited free surface energies from 38.1 to 55.7 mJ/m2. Not all materials described as surface activated showed hydrophilic properties. Medians of impression quality ranking ranged from 1.75 (best) to 13.25 (worst), mean sulcus reproduction ranged from 30 to 52%. Significant differences (P < 0.05) in quality ranking and sulcus reproduction were found between certain materials but correlations were found neither between sulcus reproduction and free surface energy nor between quality ranking and free surface energy. CONCLUSIONS: For clinical impression recording, surface activation seems to be of minor relevance, at least in the two-stage putty and wash technique investigated and is superimposed by other material properties.

Calcium Sulfate↗

PubMedDate not supplied

Displacement of mandibular removable partial denture bases by tongue movements during speech.

PURPOSE: The purpose of this study was to evaluate denture base displacement caused by tongue movements during speech. MATERIALS AND METHODS: Ten patients with new Kennedy Class I mandibular removable partial dentures participated in this study. All prostheses were made according to a standardized protocol. Denture base displacements when speaking a test sentence were measured with a computer-aided device that was developed for this purpose. It included 4 Hall sensors, mounted on a paraocclusal splint and magnets, embedded in the denture bases. Vertical and transverse base displacements were calculated from Hall voltages. Clasp retention was measured with a dynamometer. RESULTS: Mean displacements were 145 microns seating, 72 microns unseating, 87 microns buccally, and 74 microns lingually. Seating and unseating displacements differed statistically significantly in absolute values. Mean clasp retention was 2.5 N. No correlation was found between clasp retention and unseating base displacements. CONCLUSION: Tongue movements during speech induced only minimal displacements in the dentures investigated. Additionally, tongue activity was found to be denture stabilizing rather than denture displacing in this study.

Adult↗