Clinical Application of Chitosan in Dental Specialities.

Chitosan is a linear amino-polysaccharide and a natural polymer with a structure based on repetitive deacetylated and acetylated units randomly distributed. It is produced from chitin, one of the most common naturally occurring polysaccharides. Its numerous biomedical applications have been extensively described in the literature. It becomes more and more popular as a therapeutic agent and its use is constantly extended. Given its commonness, regenerative properties, easy chemical treatment, and biocompatibility, it might be used in the treatment of damaged oral cavity tissues. Due to its antimicrobial and regenerative-inducting properties as well as high biocompetency, chitosan is more and more frequently used in medicine and dentistry. It can be applied in all fields of dentistry including preventive dentistry, conservative dentistry, endodontics, surgery, periodontology, prosthodontics and orthodontics. Several data discussing the effectiveness of chitosan use on new bone formation are still inconclusive. The aim of the paper was to evaluate the applicability and biochemical impact of chitosan on oral health maintenance. Even though chitosan might find its adhibition in all dental specialities, it should still be considered as a potential allergen and thus further studies on this topic should be carried out.

Ceramic Defects in Metal-Ceramic Fixed Dental Prostheses Made from Co-Cr and Au-Pt Alloys: A Retrospective Study.

PURPOSE: Ceramic defects in porcelain-fused-to-metal (PFM) restorations may depend on framework alloy type. This study assessed ceramic defects on cobalt-chromium- (Co-Cr-) and gold-platinum- (Au-Pt-) based PFM restorations. MATERIALS AND METHODS: In this study, 147 Co-Cr-based and 168 Au-Pt-based PFM restorations inserted between 1998 and 2010 (139 patients) were examined for ceramic defects. Detected defects were assigned to three groups according to clinical defect relevance. RESULTS: Ceramic defect rates (Co-Cr-based: 12.9%; Au-Pt-based: 7.2%) revealed no significant difference but a strong statistical trend (U test, P = .082). Most defects were of little clinical relevance. CONCLUSIONS: Co-Cr PFM restorations may be at higher risk for ceramic defects compared to Au-Pt-based restorations.

Survival of teeth treated with cast post and cores: A retrospective analysis over an observation period of up to 19.5 years.

STATEMENT OF PROBLEM: Scientific data about the long-term survival of teeth treated with cast post and cores are scarce. Retrospective studies often use different target events for their analyses. A comparison is therefore complicated. For associated tooth-, jaw-, and patient-related factors little evidence exists as to their effect on survival. PURPOSE: The purpose of this study was to extend the knowledge on the survival of teeth treated with cast post and cores for observation periods of more than 10 years. A decrease or increase in survival times according to the presence or absence of associated parameters needs to be evaluated. MATERIAL AND METHODS: A retrospective evaluation was conducted of all cast post and cores inserted in 1 university clinic between January 1992 and June 2011. A Kaplan-Meier survival analysis was carried out by using extraction as the target event. The survival curves for different tooth types, the presence or absence of adjacent teeth, and the prosthetic restoration of the respective jaws were compared by using the log-rank test (α=.05). A Cox regression model was calculated for multivariate analyses. RESULTS: A total of 717 cast post and cores for 343 patients were recorded. The mean survival time was 13.5 years. A statistically significant decrease in survival times was found for canines (11.9 years) and premolars (13.4 years) versus molars (14.1 years), no adjacent teeth (10.6 years) versus at least 1 adjacent tooth (13.8 years), and the restoration with removable dental prostheses (12.5 years) versus fixed dental prostheses and single crowns (13.9 years). The largest reduction in survival time was found for teeth being used as an abutment for a double crown-retained removable partial dental prosthesis (telescopic denture) (9.8 years). Tooth type and adjacent tooth status remained as significant variables within the multivariate Cox regression model. CONCLUSIONS: Cast post and cores have an acceptable long-term survival time. Because different factors may influence survival, considering these factors in treatment planning may increase the long-term success of these restorations.

Posterior alveolar ridge resorption in bar-retained mandibular overdentures: 10-year results of a prospective clinical trial.

OBJECTIVES: Data on posterior alveolar ridge resorption (PARR) in patients with two implant supported mandibular overdentures is very heterogeneous. The aim of this prospective study was to observe the PARR after ten years for a study population treated with a titanium bar retained overdenture on two IMZ-implants. MATERIAL AND METHODS: The data pool consisted of digital and digitized conventional panoramic radiographs taken prior to implant placement and at follow up appointments. Digital measurements were carried out following an established procedure ("Tuebingen method" by Gomez-Roman). For each patient a linear regression was calculated resulting in a relative area related PARR-value per year. A simplified geometrical scenario was used for the estimation of absolute bone height losses. RESULTS: Data of 23 patients was available. The mean observation period was 9.4 years (±2.4 years). An average area related PARR-rate of 1.02% per year was observed with high individual differences ranging from 0.15% and 2.63% per year. The estimated average ten year vertical bone loss in the chewing center was 1.5 mm. CONCLUSIONS: Posterior bone resorption was found to be in the range previously reported for different implant restorations and therefore does not represent a particular problem of two implant bar retained overdentures. The results strengthen the two implant concept.

Effect of thermocycling on the shear bond strength of different resins bonded to thermoplastic foil applied in occlusal splint therapy.

PURPOSE: Temporomandibular disorders are a group of symptoms related to the impaired function of the temporomandibular joints and associated muscles. Occlusal splint therapy is a common treatment in the aforementioned syndrome. One of the methods of manufacturing occlusal splints is to place a polymer on thermoplastic foil. The aim of this study was to evaluate the shear bond strength of light- and self-cured resins bonded to thermoplastic foil dependent on artificial aging. MATERIALS AND METHODS: Thirty cylinders composed of light-cured resin and 30 cylinders made of self-cured resin were attached to 60 rectangular thermoplastic plates. All specimens were divided into six groups. A control study was conducted for groups 1 and 2. The other preparation groups were subjected to thermocycling by setting appropriately 1000 cycles for groups 3 and 4 and 3000 cycles for groups 5 and 6 in distilled water. Bond strength was measured in a universal testing machine. The results were subjected to statistical analysis using the Mann-Whitney U test (p ≤ 0.05). RESULTS: The statistics revealed that the values of the shear bond strength for specimens composed of self-cured resin after 1000 and 3000 thermocycles were significantly higher than on those made of light-cured resin (p = 0.003 and p = 0.002). CONCLUSION: The shear bond strength between the self-cured resin and the thermoplastic foil was higher and more resistant to aging than the shear bond strength between the light-cured resin and the thermoplastic foil.

Physical properties of polyamide-12 versus PMMA denture base material.

OBJECTIVES: Polyamide-12 (PA) is a flexible material suited for denture bases and clasping. This study investigated its potential aging effects with a focus on surface roughness, color stability, and elasticity. METHODS: PA specimens (Valplast) of 40×10×2 mm and equally measuring PMMA specimens (Palapress) as control were fabricated. Color changes after storage in air, water, coffee, and red wine (n=10) were measured using the CIE L*a*b* color specification. Elasticity after thermocycling (1000, 3000, and 7000 cycles, n=15) was measured by three-point bending testing. Mean surface roughness (Ra) was determined after storage in the liquids mentioned above and thermocycling (n=10). RESULTS: Tukey's HSD test (P<0.05) revealed statistically significant color changes of PA in red wine (ΔE=4.27 after 12 days, ΔE=6.90 after 12 days) and coffee (ΔE=3.93 after 36 days) but no color changes in PMMA. Elastic modulus of PA was 845 MPa and not affected by thermocycling (Tukey's HSD test, P>0.81). Dry specimens showed significantly decreased elasticity (P<0.001). Mean surface roughness (PA 0.20 µ m, PMMA 0.28 µ m) did not change significantly after thermocycling or storage (Mann-Whitney U-test, 0.16

The use of light-cured resin as an alternative method of occlusal splints manufacturing--in vitro study.

BACKGROUND: Temporomandibular disorders are very common nowadays. One of the methods to treat these problems is occlusal splint therapy. Modern materials should be introduced to this treatment. OBJECTIVES: The aim of this paper was to evaluate the properties of light-activated urethane dimethacrylate and the quality of the bonds it creates with thermoforming foils. MATERIAL AND METHODS: Thermoforming foils were covered with light-cured resin. A bond was formed between the materials using an adhesive. A coating lacquer was used on the resin as a final preparatory step. Three laboratory tests were run: dye penetrant inspection, a Vickers microhardness test and a linear polymerization shrinkage test. The materials were layered and then cured with a polymerizing lamp emitting light of a wavelength of 400 Nm, according to the manufacturer's instructions. All the occlusal splints were fitted to upper dental arch. The devices had been made in an articulator on specially prepared gypsum models. The results were analyzed statistically using a one-sided binomial test, Spearman's rank-order correlation coefficient and the Friedman ANOVA (p=0.05). RESULTS: In the dye penetrant inspection, only one sample out of sixty showed the effects of color penetration to the adhesive connection. The dye only penetrated the layer of lacquer coating the resin. The average value of the Vickers microhardness test with a load of F=50 g applied to the material surface for 30 s was HV0.05=7.43 N/mm2. The average linear shrinkage of the resin observed after polymerization was 1.175%. CONCLUSIONS: Light-cured resin and an adhesive connection between the resin and thermoforming foil do not show susceptibility even to strong dye. The maximum polymerization shrinkage occurs immediately after curing. The light-cured resin that was tested seems to be a good alternative method for occlusal splints manufacturing.

A retrospective study of the clinical performance of porcelain-fused-to-metal resin-bonded fixed partial dentures.

PURPOSE: This study investigated the clinical performance of resin-bonded fixed partial dentures (RBFPDs) using minimally invasive, nonretentive abutment tooth preparation. MATERIALS AND METHODS: Forty-four patients received 56 porcelain-fused-to-metal RBFPDs (52 three-unit RBFPDs, 4 four-unit RBFPDs). All RBFPDs were inserted between 1995 and 2010 according to a standardized protocol. Thirty-eight RBFPDs replaced anterior teeth in the maxilla, 18 RBFPDs replaced anterior teeth in the mandible, and 3 RBFPDs replaced premolars (1 maxillary, 2 mandibular). At annual recall appointments, RBFPDs were carefully inspected for technical and biologic failures or complications (eg, debonding, abutment tooth caries). RESULTS: The mean observation period was 76 months, with a minimum of 4 months and a maximum of 198 months. Five RBFPDs debonded. Further complications comprised one instance of porcelain chipping and one caries lesion underneath a loose retainer. One patient was dissatisfied with the esthetic appearance of her RBFPD. The cumulative survival rate with the event "debonding" dropped to 90% after 23 months and then remained constant. Survival rate with the event "any restoration complication" dropped to 84% after 77 months and then remained constant. CONCLUSIONS: With regard to the high patient satisfaction and relatively low incidence of failures and complications, the clinical performance of nonretentive RBFPDs can be considered satisfactory. Hence, within the limitations of this study, the data justify nonretentive RBFPDs as long-term provisional restorations.

Six-year clinical performance of lithium disilicate fixed partial dentures.

The aim of this randomized controlled trial was to evaluate the clinical performance of lithium disilicate fixed partial dentures (FPDs). Eighteen patients received lithium disilicate FPDs (study group), and 19 patients received porcelain-fused-to-metal FPDs (control). After 6 years, the survival probabilities were found to be 63% in the study group and 95% in the control group (log-rank test, P = .028). The data suggest that strict conditions should be considered before the use of lithium disilicate glass-ceramic for FPDs.

Oral health related quality of life and its association with sociodemographic and clinical findings in 3 northern outreach clinics.

OBJECTIVE: Aspects of oral health related quality of life (OHQOL) are attracting increased attention in dentistry. Knowledge in this field is limited, especially in terms of significant indicators and predictors of impaired OHQOL. The aim of this cross-sectional study was to examine the influence of various sociodemographic and clinical variables on OHQOL in the setting of outreach clinics in northern Alberta, Canada. METHODS: OHQOL was measured with the 49-item Oral Health Impact Profile questionnaire (OHIP-49), administered to adult patients attending 3 dental outreach clinics managed by the University of Alberta. Sociodemographic and clinical data were also collected. Data were analyzed using descriptive and multivariable methods. RESULTS: The OHIP-49 scores were comparatively low for a patient sample. After multivariable stepwise logistic regression analysis, only gender, missing anterior teeth and need for endodontic treatment remained as significant variables in the final model for impaired OHQOL. Missing anterior teeth (regardless of replacement) had the strongest effect. Subjects with this feature had an approximately 21-fold greater risk of impaired OHQOL relative to those who retained all of their anterior teeth. CONCLUSIONS: The clientele of these outreach clinics was generally young but had high treatment needs. OHQOL results can be useful in considering treatment strategies in similar rural environments, but the complexity of this indicator necessitates an individual patient-centred approach in clinical decision-making.

Six-year clinical performance of all-ceramic crowns with alumina cores.

PURPOSE: The aim of the study was to evaluate the clinical performance of Procera Alumina AllCeram crowns (Nobel Biocare). MATERIALS AND METHODS: In 70 patients, 61 anterior and 46 posterior teeth were provided with single crowns and cemented with a glass-ionomer cement. RESULTS: Four patients were lost to follow-up. Six crowns had to be removed, all because of nonreparable fracture. At 6 years, the cumulative survival rate was 94.3% for all crowns, 96.7% for anterior crowns, and 91.3% for posterior crowns (survival = not removed). Most of the defects occurred within the first 1.5 years. CONCLUSION: The findings indicate a good clinical prognosis of both anterior and posterior Procera Alumina crowns.