Newton Sesma

Effect of denture surface glazing on denture plaque formation

This study evaluated, in vivo, the efficacy of a denture glazing material (Palaseal) in modifying plaque colonization of dentures. Ten subjects were selected and received maxillary temporary partial removable dentures, with complete acrylic palatal coverage. The right half of the fitting surface of the denture bases were glazed with Palaseal, whereas the other half was not glazed. One month after insertion, two fragments of the resin base of all dentures were removed (one from the glazed side and another from the non-glazed side). These samples were prepared and examined by scanning electron microscopy. Three months after insertion, other fragments were obtained and analyzed. Microscopic observation at 1 month revealed that, for all patients, the plaque film was thinner on the treated side in comparison to the non-treated side. However, at the 3-month evaluation, some areas of the glaze showed cracking, and both glazed and non-glazed sides were covered by a dense bacterial plaque film. In conclusion, the findings of this clinical experiment showed that glazing dentures fitting surface did not prevent bacterial colonization, but favored plaque removal while the glaze layer remained intact. After three months, glaze cracks created microretentive areas that increased plaque accumulation.

Fracture strength of teeth restored with ceramic inlays and overlays

This study evaluated the fracture strength of teeth restored with bonded ceramic inlays and overlays compared to sound teeth. Thirty sound human maxillary premolars were assigned to 3 groups: 1- sound/unprepared (control); 2- inlays and 3- overlays. The inlay cavity design was Class II MOD preparation with an occlusal width of 1/2 of the intercuspal distance. The overlay cavity design was similar to that of the inlay group, except for buccal and palatal cusp coverage The inlay and overlay groups were restored with feldspathic porcelain bonded with adhesive cement. The specimens were subjected to a compressive load until fracture. Data were analyzed statistically by the Kruskal-Wallis test at 5% significance level. The fracture strength means (KN) were: Sound/unprepared group = 1.17, Inlay group= 1.17, and Overlay group = 1.14. There were no statistically significant differences (p>0.05) among the groups. For inlays and overlays, the predominant fracture mode involved fragments of one cusp (70% of simple fractures). The fracture strength of teeth restored with inlay and overlay ceramics with cusp coverage was similar to that of intact teeth.

Facially generated and cephalometric guided 3D digital design for complete mouth implant rehabilitation: A clinical report

Harmony among the teeth, lips, and facial components is the goal of prosthodontic treatment, whether performed by conventional or digital workflow methods. This clinical report describes a facial approach to planning computer-guided surgery and immediate computer-aided designed and computer-aided manufactured (CAD-CAM) interim complete-arch fixed dental prostheses on immediately placed dental implants with a digital workflow. A single clinical appointment for data collection included dentofacial documentation with photographs and videos. On these photographs, facial reference lines were drawn to create a smile frame. This digital smile design and sagittal cephalometric analysis were merged with 3-dimensional scanned casts and a cone beam computed tomographic file in virtual planning software, thus guiding virtual waxing and implant positioning. Computer-guided implant surgery and CAD-CAM interim dental prostheses allowed esthetic and functional rehabilitation in a predictable manner and integrated with the patients face.

Photoelastic stress analysis in mandibular bone surrounding bar-clip overdenture implants

The aim of this in vitro study was to evaluate, using the photoelastic analysis method, the stress distribution in mandibular bone surrounding a bar-clip overdenture when 2 implant angulations were simulated. Two mandibular photoelastic models were manufactured, with 2 implants embedded in the interforaminal region: model 1-PAPI, a photoelastic analysis model with parallel implants; and model 2-PAAI, a photoelastic analysis model with angled implants. A bar-clip retention system and an overdenture were positioned over the implants, and loads of 1.0, 2.0 and 3.0 bars were applied. The resultant stresses that developed in the supporting structure were photoelastically monitored and were recorded photographically. The results showed that there were no similarities in the areas of stress among the photoelastic resin models when the angulation of the implants was evaluated. Model 1-PAPI presented a higher stress concentration at the implant apex, while in model 2-PAAI, there were higher stress concentrations on the mesial and distal implant faces. Within the limitations of this study, it was concluded that the PAPI photoelastic model demonstrated better stress transfer compared to the PAAI model, since the forces oriented along the axis were better absorbed by the bone.

Effectiveness of Denture Cleanser Associated With Microwave Disinfection and Brushing of Complete Dentures: In Vivo Study

Complete dentures acts as a reservoir for microbial colonization, which may lead to systemic infections. Microwave irradiation has been used as an efficient method of denture disinfection. Even though current methods eliminate denture-base microorganisms, a recurrence rate of denture stomatitis (DS) is still observed among denture-wearing patients. It was hypothesized that microwave disinfection kills microorganisms but do not remove dead bacteria from the denture surface. To test this hypothesis, the biofilm found in the dentures of 10 patients with DS was evaluated. In addition, the effects of microwave irradiation plus brushing (MW+B) on the denture biofilm and the combination of denture cleanser with microwave irradiation and brushing (MW+DC+B) for the removal of denture-accumulating microorganisms were investigated. Microbiological data were analyzed statistically by nonparametric analysis (Friedman/Wilcoxon, α=0.05). MW+B and MW+DC+B were effective in reducing the rate of microorganisms (99.2% and 99.5% respectively), but without significant difference between them (p=0.553). However, it was observed that the complete removal of microorganisms from denture surface was only possible when all regimens were combined (MW+DC+B). Microwave irradiation in combination with soaking in denture cleanser and brushing effectively disinfected the dentures and removed denture biofilm.

Connecting accuracy of interchanged prosthetic abutments to different dental implants using scanning electron microscopy.

The present study evaluated the interchangeability of prosthetic components for external hexagon implants by measuring the precision of the implant/abutment (I/A) interface with scanning electron microscopy. Ten implants for each of three brands (SIN, Conexão, Neodent) were tested with their respective abutments (milled CoCr collar rotational and non-rotational) and another of an alternative manufacturer (Microplant) in randomly arranged I/A combinations. The degree of interchangeability between the various brands of components was defined using the original abutment interface gap with its respective implant as the benchmark dimension. Accordingly, when the result for a given component placed on an implant was equal to or smaller then that gap measured when the original component of the same brand as the implant was positioned, interchangeability was considered valid. Data were compared with the Kruskal-Wallis test at 5% significance level. Some degree of misfit was observed in all specimens. Generally, the non-rotational component was more accurate than its rotational counterpart. The latter samples ranged from 0.6-16.9 µm, with a 4.6 µm median; and the former from 0.3-12.9 µm, with a 3.4 µm median. Specimens with the abutment and fixture from Conexão had larger microgap than the original set for SIN and Neodent (p<0.05). Even though the latter systems had similar results with their respective components, their interchanged abutments did not reproduce the original accuracy. The results suggest that the alternative brand abutment would have compatibility with all systems while the other brands were not completely interchangeable.

Dynamic Documentation of the Smile and the 2D/3D Digital Smile Design Process

Medical and dental histories, clinical examination, study models, and photographs provide the data for a proper diagnosis and the treatment plan for esthetic dentistry. However, they do not offer all the information necessary to analyze the smile and create harmony with the lips and face without excessive intraoral adjustments. Dentolabial parameters vary according to lip dynamics and are influenced by both a static posed smile and a smile in motion as captured in video. This article describes a documentation protocol using smartphone videos to improve the analysis, smile design decisions, and elaboration of a 2D smile frame that will guide the 3D digital smile design project. The use of dynamic documentation of the smile (DDS) allows esthetic rehabilitative planning from a facial perspective, improvement of communication with the patient, integration between the specialists, and the predictable quality of the treatments.

Incisal coverage or not in ceramic laminate veneers: A systematic review and meta-analysis

BACKGROUND There is no consensus on whether incisal coverage is a risk or a protective factor in preparations for ceramic veneers. OBJECTIVE The aim of this systematic review and meta-analysis was to evaluate the survival rates of preparation designs for ceramic veneers with and without incisal coverage. METHODS Primary clinical studies with the following characteristics were included: 1) studies related to ceramic laminate veneers and 2) prospective or retrospective studies conducted in humans. From the selected studies, the survival rates and failures rates for ceramic veneers were extracted according to preparation design, with or without incisal coverage. The Cochran Q test and the I(2) statistic were used to evaluate heterogeneity. Metaregression, meta-analysis were performed. Two reviewers searched in the MEDLINE (Pubmed) and Cochrane Central Register of Controlled Trials (Central) electronic databases, from 1977 to June 5, 2016, without language restrictions. RESULTS Eight studies out of 1145 articles initially identified were included for risk of bias and systematic assessment. No study was identified for crystalline ceramic veneers. The estimated survival rate for laminate veneers with incisal coverage was 88% and 91% for those without incisal coverage. Incisal coverage presented an OR of 1.25. CONCLUSIONS Irrespective of the preparation designs, with or without incisal coverage, ceramic veneers showed high survival rates. As regard implications for future clinical research studies, randomized clinical studies are necessary to compare preparation designs with and without incisal coverage, and to provide clear descriptions of these preparation designs.

Patient outcomes and procedure working time for digital versus conventional impressions: A systematic review

Statement of problem. Limited evidence is available comparing digital versus conventional impressions from the point of view of patient preference. Purpose. The purpose of this systematic review was to identify and summarize the available literature related to patient‐centered outcomes for digital versus conventional impression techniques. Material and methods. The databases Medline, Cochrane, Science Direct, Scopus, and Embase were electronically searched and complemented by hand searches. All published papers available on the databases from 1955 to July 2016 were considered for title and abstract analysis. Results. A total of 2943 articles were initially identified through database searches, of which only 5 met the inclusion criteria for qualitative analysis. Four studies comparing patient‐reported outcome measures (PROMs) between conventional and digital impressions revealed that the digital technique was more comfortable and caused less anxiety and sensation of nausea. Only 1 study reported no difference between the techniques regardless of patient comfort. Two studies reported a shorter procedure for the conventional technique, whereas 3 studies reported a shorter procedure for the digital technique. Conclusions. A lack of clinical studies addressing patient outcomes regarding digital prosthodontic treatments was observed among the included articles. However, current evidence suggests that patients are more likely to prefer the digital workflow than the conventional techniques.

The influence of tooth color on preparation design for laminate veneers from a minimally invasive perspective: case report.

Various types of dental preparations for laminate veneers have been proposed,depending on factors such as the properties of the ceramic material, remaining dental structure color, need for altering the dental contour, laboratory fabrication technique, and occlusal relationships. Clinical observations of successes and failures associated with the development of techniques and materials have allowed some safe parameters to be delineated for effectively performing dental preparations for ceramic veneers or even placing veneers without any preparation. This article describes the use of an additive diagnostic wax-up that is transferred to the mouth by means of an intraoral mock-up (aesthetic pre-evaluative temporary) with associated mathematic parameters to guide dental preparations. This technique, called Do the Math and presented here in the form of a clinical case report, aims to avoid excessive or incorrect tooth preparation by indicating the exact amount and location of the tooth reduction necessary to attain the desired color and shape.