Current Dentistry - Volume 2, Issue 1, 2020

Background: The use of zirconia-based ceramics to produce monolithic restorations has increased due to improvements in the optical properties of the materials. Traditionally, zirconia-based ceramics were veneered with porcelain or glass-ceramic and were not directly exposed to the oral environment. Therefore, there are several doubts regarding the wear of the monolithic zirconia restoration and their antagonists. Additionally, different surface treatments are recommended to promote a smooth surface, including glaze and several polishing protocols. To support the correct clinical application, it is important to understand the advantages and limitations of each surface treatment.

Objective: The aim of this short literature review is to investigate the factors that may affect the wear of monolithic zirconia restorations in service and their antagonists.

Methods: Pubmed/Medline database was accessed to review the literature from a 10-year period using the keywords: zirconia, monolithic, prosthesis, wear. Both clinical and in vitro studies were included in the review.

Results: Studies investigated the effect of several surface treatments, including grinding with diamond-burs, polishing and glazing, on the surface roughness, phase transformation and wear capacity of monolithic zirconia. The wear behavior of monolithic zirconia was frequently compared to the wear behavior of other ceramics, such as feldspathic porcelain, lithium disilicate-based glass-ceramic and leucite-reinforced glass-ceramic. Human tooth, ceramics and resin composites were used as antagonist in the investigations. Only short-term clinical studies are available (up to 2 years).

Conclusion: Literature findings suggest that zirconia monolithic restorations are wear resistant and unlikely to cause excessive wear to the antagonist, especially when compared to feldspathic porcelain and glass-ceramics. Monolithic zirconia should be polished rather than glazed. Yet, none of the polishing systems studied was able to completely restore the initial surface conditions of zirconia after being adjusted with burs. More clinical evidence of the antagonist tooth wear potential of monolithic zirconia is needed.

Background: The drug delivery across buccal mucosa is a very interesting option for the treatment of various oro-mucosal disorders such as aphthous stomatitis, periodontitis, gingivitis, toothache, periodontitis, and sjorgensen syndrome. But it is quite difficult because of target site movements, limited area for drug absorption, drinking of fluids, intake of food and saliva flow at regular intervals, contributing to poor retention and sub-therapeutic level of drug at the target site. Due to this, the mucoadhesive buccal drug delivery system has gained a great deal of attention among the various scientists and researchers over the last two decades.

Methods: Mucoadhesion is a process of attachment between the natural or synthetic macromolecule and mucosal epithelial surface with the aid of interfacial attractive forces. The process of mucoadhesion has been extensively encouraged by the utilization of mucoadhesive polymers within the formulation that on contact with salivary fluid swells and adheres to buccal epithelium membrane, thus prolonging the drug release, retention time and improving therapeutic performance in case of oral diseases. The present review tries to cover the basic anatomy and structure of oral mucosa, pathways of drug absorption, the theory of mucoadhesion, mechanisms involved in mucoadhesion and various factors affecting mucoadhesion.

Results: It highlights the properties of mucoadhesive polymers in drug delivery along with various dosage forms such as mucoadhesive tablets, films, patches, gels, and pastes. Furthermore, it also sheds light on the recent developments made in the field of mucoadhesive buccal drug delivery system that reflects the potential of this system for the effective treatment of oro-mucosal disorders.

Conclusion: It can be concluded that the mucoadhesive buccal drug delivery system has great potential in the near future for treating oro-mucosal disorders.

Background: It’s shown that the clinical success of ceramic restorations much depends on the quality and durability of the bond to ceramic. For zirconia-based ceramics (Y-TZP), the surface treatment has a substantial impact on bond strength. Therefore, the bond strength evaluation of Y-TZP surface treatments is a requirement for predicting the clinical performance of such restorations.

Objective: Evaluating the resin bond strength to Y-TZP after different surface treatments.

Methods: Monolithic Y-TZP (Zenostar Zr Translucent, Wieland Dental, Rosbach vor der Höhe, Germany) blocks were bonded to resin composite blocks using a resin-based cement system after two Y-TZP surface treatments: APA- airborne particle abrasion with alumina particles; and CJ- silicatization (Cojet sand, 3M ESPE, St. Paul, MN, USA). A silane coupling agent and an adhesive system were applied to the treated Y-TZP surfaces and resin composite blocks were cemented (RelyX Ultimate, 3M ESPE, St. Paul, MN, USA) and light activated from all sides. These structures were cut to obtain bar-shaped specimens (n=30), which were stored in 37ºC distilled water for 7 days before microtensile testing. Specimens were loaded to failure under tension using a universal testing machine. Data was statistically analyzed using Students t test (α=0.05) and Weibull distribution. Failure modes were evaluated using optical (OM) and scanning electron microscopy (SEM).

Results: Mean bond strength values (CJ= 25.7±8.2 MPa; APA= 22.0±6.3 MPa) were statistically similar (p>0.05). No difference was found for the characteristic strengths (σ0) and for Weibull moduli (m) since the confidence intervals (95% CI) overlapped. The bond strength values for a 5% failure probability (σ5%) were 12.4 (CJ) and 11.5 (APA). All fractures were due to cohesive failure within the adhesive cement system.

Conclusion: Both Y-TZP surface treatments (CJ and APA) produced similar structural reliability and short-term bond strength to a resin cement system.

Objective: To compare the success rate of different obturation procedures in primary mandibular second molars clinically and also by digital radiovisiography.

Methods: A total of 40 children aged between 4-8 years with deeply carious mandibular second primary molars indicated for single session pulpectomy were selected. Canals were obturated with Metapex. The 3 study groups (Endodontic plugger, Handheld lentulospiral, Navi Tip syringe) were compared with the control group (reamer) both clinically and radiovisiographically. The data collected were statistically analyzed using Pearson’s Chi-square and Fisher’s exact test.

Results: The use of Navi tip syringe led to the least number of voids followed by Endodontic plugger and Reamer and the highest number of voids was reported with Lentulospiral. Navitip presented maximum number of optimally filled cases followed by Endodontic plugger and Lentulospiral and least number of optimally filled cases with reamer. However, there was no statistically significant difference (p>0.05) in any of the groups with clinical (pain and tenderness to percussion) and radiographic parameters (presence or absence of voids and length of obturation).

Conclusion: Within the limitations of the present study, though the clinical outcome was statistically insignificant, Navitip syringe exhibited encouraging results and is a promising option for obturation in primary teeth.

Objective: To investigate the effect of filler content and the time spent before light-curing on mechanical properties of dual-cured cement.

Methods: Experimental dual-cured resin cements were formulated with 60, 65 or 68wt% of filler. The viscosity of experimental cement was measured using a digital viscometer. Bar-shaped specimens (25 x 2 x 2 mm) were fabricated, while the light-curing was started immediately or 5 minutes after the insertion of cement into the mold (n = 7). A three-point bending test was performed and the values of flexural strength and elastic modulus were measured. The Vickers hardness of fractured specimens was measured on the surface of the cement. Data from viscosity were submitted to one-way ANOVA, while the data from mechanical properties were analyzed by two-way ANOVA. All pair-wise comparisons were performed using Tukey’s test (α = 0.05).

Results: The experimental cement with 68wt% of filler showed the highest viscosity and those with 60wt% showed the the lowest viscosity. Irrespective of the time spent before light-curing, the cement with 65wt% of filler presented the highest values of flexural strength and elastic modulus. The addition of 60wt% of filler resulted in the lowest elastic modulus, while 68wt% of filler resulted in lowest flexural strength. Regarding the hardness, the cement with 68wt% of filler showed the highest values, while there was no difference between 60 and 65wt% of filler.

Conclusion: Filler content affected the mechanical properties of the experimental cement and this effect did not depend on the waiting time before the light-curing procedure.

Objective: This study aimed to analyze the presence of lesions in the skull and face and the associated factors in pedestrian victims of traffic accidents.

Methods: A cross-sectional, descriptive-analytical study carried out through the analysis of medical records of pedestrian victims of traffic accidents in an emergency service in the city of Campina Grande, Brazil, during the year of 2016. Information was collected regarding gender, age group, day of the week, time of the accident, type of vehicle involved, presence of trauma to the skull and face, and outcomes. The Chi-square and Fisher's Exact tests were used, with a significance level of 5%.

Results: A total of 1,884 medical records were evaluated, out of which 7.1% (n = 133) involved pedestrians. Men were the most frequent victims (68.4%), and victims of age 60 years old or over (30.5%) predominated. Almost one-third of the cases were recorded during the weekends (30.5%), and the most prevalent time was at night (52.7%). Regarding the type of vehicle involved, motorcycles predominated (47.4%). Head trauma was present in 37.6% of victims, while facial injuries corresponded to 8.2%. In 12% of cases, the victims died. The variables of gender, age group, occurrence on weekends, and trauma to the face showed a statistically significant association with the occurrence of traffic accidents (Chi-square test; p<0.05).

Conclusion: Among pedestrian victims of traffic accidents, there is a predominance of men aged 65 years or over. Accidents are frequent at night, and motorcycles are the main vehicles involved. The presence of trauma to the skull and face regions is high.

Aim: The aim of the present study was the preparation and in vitro evaluation of polymeric molds with amoxicillin trihydrate, lidocaine hydrochloride, and metronidazole for sustained drug release for prolonged local action on an affected tooth (during carries and gum problems).

Background: Periodontal diseases with infection and inflammation cause dental pain. For the treatment of dental problems such as dental pain, analgesics with antibiotics are prescribed at the initial stage.

Objective: The main objective of the present study was to develop polymer-based dental mold containing three drugs (amoxicillin trihydrate, lidocaine hydrochloride, and metronidazole) to provide local drug action on the affected tooth or gingiva for a prolonged period of time.

Methods: Dental molds were prepared with drugs and the optimum combination of polymers (determined by initial screening) such as corn zein, carbopol 934 P, gum acacia powder and poloxamer 407 by mixing together in ethanol (95%) followed by solvent evaporation. The developed dental molds were evaluated using different in vitro physio-chemical methods such as tooth adhesion test, percent swelling, surface pH, scanning electron microscopy, drug content and drug-release study by simultaneous UV spectroscopy.

Results: The mean adhesive strength obtained in our formulation was 46.5 g-wt with a surface pH value of 6.5 The percentage of swelling of the dental molds varied from 43% to 73% in 4 h. Scanning electron microscopy (SEM) showed very small and uniformly distributed drug particles in the matrix. Drug loading was high and reproducible. The cumulative percentage release of lidocaine hydrochloride, amoxicillin trihydrate and metronidazole in vitro was about 93.81%, 59.67%, and 48.7%, respectively, over 24 h.

Conclusion: The developed dental mold containing three drugs may be applied to the affected tooth for prolonged drug action locally and an easy option to relieve from dental pain and infection by local drug action.

Background: Cast metal posts-and-core are frequently used to retain restorations to extensively destroyed teeth. However, the influence of different cements on the posts bond strength to dentin remains unclear. Objective: to evaluate the effect of different cements on the bond strength of cast metal posts and dentin.

Methods: Forty roots (14 mm length) of extracted human teeth were endodontically treated and prepared. Impressions of each root canal were taken to obtain customized cast metal posts. The roots were randomly divided into 4 groups (n=10): (1) ZP: zinc phosphate cement (non adhesive); (2) ARC_Sin: Single Bond adhesive and RelyX ARC; (3) ARC_Sco: Scotchbond adhesive and RelyX ARC; (4) U200: RelyX U200. After cementation, the samples were cross-sectioned to obtain specimens of 1mm thickness. Push-out test was performed applying a compressive load (0.5 mm/min) to the center of the metal post until failure. Bond strength was calculated based on the diameter of the root canal and the thickness of each specimen. Data were analyzed using ANOVA and Tukey (α=0.05). The fracture mode was analyzed.

Results: Bond strength values were statistically similar between the groups (p>0.05). The fracture analysis showed the prevalence of mixed fractures (cement partially attached to the dentin and/or post). Experimental groups showed inexpressive amount of adhesive fractures (complete detachment of the cement from dentin and/or post). The ARC_Sco and U200 groups presented higher prevalence of dentin cohesive fracture.

Conclusion: Bonding had no influence on the immediate bond strength between cast metal posts and root canal dentin.

Background: Different treatment protocols for teeth affected by fluorosis have been applied. Among them, microabrasion associated with tooth bleaching has presented satisfactory results in the treatment of intrinsic and/or extrinsic staining.

Case Presentation: A 22-year-old female patient attended the Dental Clinic of FOP/UNICAMP, reporting dissatisfaction with her smile due to the presence of white striations contrasting with the yellowish hue of the other teeth. Initially, the adequacy of the oral environment was performed by supragingival scraping and prophylaxis. Due to the characteristics of the staining, fluorosis TF3, the treatment plan consisted of teeth whitening with 35% hydrogen peroxide (Whiteness HP, AutoMixx 35% FGM) and microabrasion (Whiteness RM, FGM).

Conclusion: The association of tooth bleaching and microabrasion techniques provided the harmonization of the smile and resolution of the clinical case of the main complaint.