The baseline standards for minimally acceptable science are improving as the understanding of the scientific method improves. Journals publishing research papers are becoming more and more rigorous. For example, in 2001 a group of authors evaluated the quality of clinical trials in anesthesia published over a 20 year period [Pua et al., Anesthesiology 2001;95:1068–73]. The authors divided the time into 3 subgroups and analyzed and compared the quality assessment score from research papers in each group. The authors reported that the scientific quality scores increased significantly in this time, showing more randomization, sample size calculation and blinding of studies. Because every journal strives to have a high scientific impact factor, research quality is critical to this goal. This means novice researchers must study, understand and rigorously avoid the common mistakes described in this review. Failure to do so means the hundreds and hundreds of hours of effort it takes to conduct and write up a clinical trial will be for naught, in that the manuscript with be rejected or worse yet, ignored. All scientists have a responsibility to understand research methods, conduct the best research they can and publish the honest and unbiased results.

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Purpose: An objective assessment of speech would benefit the prosthetic rehabilitation of maxillectomy patients. This study aimed to establish a simple, objective evaluation of monosyllable /sa/ utterances in maxillectomy patients by using a psychoacoustic system typically used in industry.
Materials and methods: This study comprised two experiments. Experiment 1 involved analysis of the psychoacoustic parameters (loudness, sharpness and roughness) in monosyllable /sa/ utterances by 18 healthy subjects (9 males, 9 females). The utterances were recorded in a sound-treated room. The coefficient of variation (CV) for each parameter was compared to identify the most suitable parameter for objective evaluation of speech. Experiment 2 involved analysis of /sa/ utterances by 18 maxillectomy patients (9 males, 9 females) with and without prosthesis, and comparisons of the psychoacoustic data between the healthy subjects and maxillectomy patients without prosthesis, between the maxillectomy patients with and without prosthesis, and between the healthy subjects and maxillectomy patients with prosthesis.
Results: The CV for sharpness was the lowest among the three psychoacoustic parameters in both the healthy males and females. There were significant differences in the sharpness of /sa/ between the healthy subjects and the maxillectomy patients without prosthesis (but not with prosthesis), and between the maxillectomy patients with and without prosthesis.
Conclusion: We found that the psychoacoustic parameters typically adopted in industrial research could also be applied to evaluate the psychoacoustics of the monosyllable /sa/ utterance, and distinguished the monosyllable /sa/ in maxillectomy patients with an obturator from that without an obturator using the system.

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Purpose: The aim of this study was to evaluate the effect of different levels of unilateral angular misfit on preload maintenance of retention screws of single implant-supported prostheses submitted to mechanical cycling.
Materials and methods: Premachined UCLA abutments were cast with cobalt–chromium alloy to obtain 48 crowns divided into four groups (n = 12). The crowns presented no misfit in Group A (control group) and unilateral misfits of 50 μm, 100 μm and 200 μm in the groups B, C and D, respectively. The crowns were attached to external hexagon implants with a titanium retention screw with torque of 30 N/cm. Oblique loading of 130 N at 2 Hz was applied on each replica, totalizing 5 × 10⁴ and 1 × 10⁶ cycles. Detorque values were measured initially and after each cycling period. Data were evaluated by analysis of variance and Tukey's HSD test (p < 0.05).
Results: All groups presented reduced initial detorque values (p < 0.05) in comparison to the insertion torque (30 ± 0.5 N/cm) and Group A (25.18 N/cm) exhibited the lowest reduction. After mechanical cycling, all groups presented detorque values from 19.5 N/cm to 22.38 N/cm and the mechanical cycling did not statistically influence the detorque values regardless the misfit level of the replicas.
Conclusion: The unilateral misfit influenced the preload maintenance only before mechanical cycling. The mechanical cycling did not influence the torque reduction.

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Purpose: The aim of this study was to evaluate the effect of occlusal splint treatment on the temperature of masseter (inferior, intermediate and superior), anterior temporal, digastric and trapezius muscles in patients with temporomandibular disorder (TMD).
Materials and methods: Thirty patients (6 male and 24 female) aged from 16 to 57 years (mean 37.8 ± 11.4 years) were selected. The patients were diagnosed with muscular TMD by clinical examination (application of Research Diagnostic Criteria questionnaire and physical examination). Occlusal splints in acrylic resin were inserted in all patients with a weekly follow-up. The superficial thermography (°C) on the both sides of the muscles was performed using a digital thermometer in a controlled temperature room. This procedure was performed before occlusal splint insertion (patient with pain) and after the completion of the treatment (patient without pain). The data were analyzed by 2-way repeated-measures ANOVA and means were compared by Tukey HSD test (P < .05).
Results: After occlusal splint treatment a significant increase in temperature was observed in each muscle, both in the right and left sides. When the muscles were compared in the same period (before or after therapy) there was no significant difference among them.
Conclusion: It can be concluded that the use of occlusal splint promoted a significant increase on the muscles temperature. There was symmetry in the temperature of muscles on the right and left sides both before and after the treatment.

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Purpose: There are no entire maxillary finite element analysis models available, as a base of reference for the dimensions of conventional segment finite element analysis models. The objectives of this study were: (1) to construct a maxillary model derived from a human skull and to investigate the strain distribution around a posterior implant embedded in it; (2) to investigate the usability of conventional segment maxillary models.
Methods: CT DICOM data of a human dried skull maxilla was imported into the Mesh Generation Tools (ANSYS AI environment) and a computer-generated implant-abutment unit was bicortically embedded into it. In this Large model, Von Mises strains under axial and buccolingual loads were then calculated by a finite element program. Moreover, two simplified maxillary segments (Simplified models) were computer-generated and their Von Mises strains were similarly calculated.
Results: Although absolute values differed markedly, strain distribution patterns in the cortical bone were similar to those in the Simplified models: high Von Mises strains in the cortical bone concentrated in the sinus floor around the implant apex under axial load, and in the alveolar crest around the implant neck under buccolingual load.
Conclusions: The simplified and segmented three-dimensional finite element models of the human maxilla showed the same locations of the highest equivalent strains as the full maxilla model created from CT DICOM data. If absolute strain values are not of interest, the Simplified models could be used in strain analyses of simulated posterior maxilla for diagnostic suggestions in implant placement.

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Purpose: The purpose of this study was to temporally and spatially analyze movements of lower facial skin during left- and right-side chewing in order to examine, from the viewpoint of kinematics, whether functional differences existed between these movements on the two sides.
Methods: Ten healthy young subjects (aged 24–32 years, mean age 26.7 years) were included in this study. The test bolus used in this study was sufficiently softened chewing gum. The cycle time, mean square error value and mean difference vector value of chewing paths were used as parameters.
Results: Cycle times of movements of lower facial skin during gum chewing were invariant and stable on each chewing side, and showed no significant differences between the sides. The similarities of chewing paths and directions of movements of lower facial skin during gum chewing showed mirror-image relationships between the sides. Furthermore, these relationships during gum chewing were stable on both sides.
Conclusions: Based on these findings, it was found that movements of lower facial skin during left- and right-side chewing in healthy subjects were temporally and spatially invariant, stable and similar on both sides. Moreover, the present results suggest, from the viewpoint of kinematics, that a functional difference may not exist between these movements on the two sides.

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Purpose: Marginal and internal gaps of NobelProcera crown zirconia were clinically evaluated using silicone materials.
Materials and methods: Ninety-one crowns were examined before final cementation, and white and black silicone materials were used to record the marginal and internal fit. The silicone materials were sectioned bucco-lingually and mesio-distally, and the thickness of the silicone layers was measured using a microscope. Sixteen reference points were measured on each specimen, and mean marginal and internal gaps were obtained. Mean marginal gaps among anterior, premolar, and molar tooth groups, in addition to mean gaps at the reference points within the groups, were compared using two-way ANOVA and Games-Howell analysis.
Results: The marginal mean values were the smallest among all tooth groups, and the largest were at the rounded shoulders. There were no significant differences in the mean marginal gaps among the three tooth groups, while there were significant differences in the mean marginal and internal gaps of each tooth group.
Conclusions: The mean marginal gap of the NobelProcera crown zirconia was 44.2 μm, which is within clinically accepted standards.

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Purpose: To indentify buccal design criteria for retainer on polyamide resin removable partial dentures.
Methods: A left upper distal extension model was used for this study. Undercut was given on the buccal side of first and second premolars. Four different retainer designs were created. Undercuts of 0.5 and 0.75 mm were used. All 4 retainer designs started from distal surface of second premolar. The retainer extended to Design 1: covering to the mesial surface of second premolar; Design 2: covering to the distal surface of first premolar; Design 3: covering to the mesial surface of first premolar; and Design 4: covering to the distal surface of canine. For the 0.75 mm undercut experiment, only Design 1 and Design 3 were used. Each experimental denture was pulled and the force maximum required to remove the denture measured.
Results: On 0.5 mm undercut, no significant difference was found between Designs 1 and 2 or between Designs 3 and 4. Significant differences were found between all other combinations, however. On 0.75 mm undercut, a significant difference was found between the two.
Conclusion: The retentive force of a design for the buccal part of retainers in polyamide resin using large undercut was more effective than that of a design covering to the anterior abutment tooth.

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In many cases, dentists try to manage denture pain by adjusting dentures. However, some patients complain of oral discomfort over a long period even after appropriate denture adjustments. In some of these situations, simple denture adjustment does not alleviate the discomfort of these patients. It is known that denture stomatitis may occur in response to plaque accumulation on dentures. One of the chief pathogenic microorganisms causing this type of inflammation is Candida albicans. A common symptom of oral candidiasis is pain in the oral mucosa complicated by angular stomatitis. In this paper, we report a case of oral candidiasis that was diagnosed and managed based on the patient's complaints.

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Purpose: The purpose of this study was to evaluate the fracture resistance of human maxillary premolars restored with 2 ceramic systems (Vitadur Alpha and In Ceram) comparing 3 preparation designs and 2 luting agents.
Methods: Seventy sound teeth were prepared to receive ceramic restorations (Vitadur Alpha; n = 14) as follows: (1) control, sound premolars, with no preparation, (2) inlays, (3) partial onlays (palatal cuspid coverage), (4) total onlays (both cuspids coverage), and (5) total onlays with an In Ceram core. The ceramic restorations were cemented using Enforce or RelyX ARC (half restorations with each cement), placed into the cavity and held under pressure, except for the control group. The teeth were subjected to compressive axial loading at 0.5 mm min⁻¹ using a 9 mm steel ball until fracture. Data were analyzed by 3-way ANOVA and post hoc Tukey's test (α = .05).
Results: There was a significant difference between cements and among preparation designs (P < .05). All restorations cemented with Enforce exhibited significantly higher fracture resistance (P < .05). Inlay restorations showed similar fracture resistance when compared to control group (P > .05). Partial and total onlays did not statistically differ and showed the weakest performance. The use of an In Ceram core did not produce higher fracture resistance.
Conclusions: Within the limitations of this study, the cements tested had different mechanical properties, while cuspid coverage did not result in improved fracture resistance of the restored teeth.

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