Resumo em Inglês:

OBJECTIVE: To investigate potential barriers to the utilisation of the ART approach in a South African public oral health service. METHOD: 7 barriers were identified: patient load/work load, operator opinion, patient opinion, service management, material supply, clinical ART skill, chair-side assistance. Operators were asked to answer a questionnaire one year after completing the ART training. Responses ranged from 1 = no barrier to 5 = highest barrier. Treatment data per operator were collected during 1 year after training, for both dentitions, including: number of extracted teeth, placed traditional restorations, ART restorations. The restoration/extraction (REX) ratio and the proportion of ART restorations (ART%) of the total number of restorations were calculated and correlated with the barrier variables. Pearson correlation, ANOVA and 2-tailed t-tests were used in the statistical analyses. RESULTS: Patient load/work load (mean = 2.80: SE = 0.16) was the strongest barrier (p<0.001) and clinical ART skill was the weakest barrier (p<0.001). A significant correlation between material supply and mean REX score was observed in both dentitions. In primary teeth, the ART% correlated significantly with clinical ART skill (r= -0.63; p<0.01). In permanent teeth, statistically significant correlations were observed between ART% and patient load/work load (r = -0.54; p<0.05), patient opinion (r = -0.76; p<0.01), operator opinion (r = -0.53; p<0.05), chair-side assistance (r = -0.57; p<0.05), oral health service management (r = -0.46; p<0.05). CONCLUSIONS: 1 year after ART training completion high patient load/work load, followed by insufficient provision of materials/instruments, were the two most inhibiting barriers to the use of ART in the public oral health services. Dentists' perceptions of low clinical skill levels in performing ART confidently inhibited the use of ART in primary teeth in children.

Resumo em Inglês:

A group of destructive changes occurring in jaws in patients with maxillary complete dentures and mandibular removable partial dentures (bilaterally) has been described in the literature as the combination syndrome. However, this condition is not clinically observed in all patients. The aim of this study was to establish the prevalence index on signs of combination syndrome and to verify whether these changes also occurred in patients rehabilitated with a mandibular removable partial denture (unilaterally). Sample was composed of 44 patients, completely edentulous in the maxilla. Thirty-two patients had a Kennedy Class I removable partial denture and 12 a Kennedy Class II. Three major alterations were observed in 20.5% of the studied population. Nevertheless, these changes were present only in 25% of patients with Kennedy Class I removable partial denture. Based on the findings of this study, it can be concluded that patients with Kennedy Class II removable partial denture do not have similar signs that lead to the combination syndrome's condition.

Resumo em Inglês:

OBJECTIVES: This study applied a simple method to evaluate the performance of three digital devices (two scanners and one digital camera) using the reproducibility of pixel values attributed to the same radiographic image. METHODS: Using the same capture parameters, a radiographic image was repeatedly digitized in order to determine the variability of pixel values given to the image throughout the digitization process. One coefficient value was obtained and was called pixel value reproducibility. RESULTS: A significant difference in pixel values was observed among the three devices for the digitized images (ANOVA, p<0.00001). There was significant pixel value variability at the same digitization conditions for one scanner and the digital camera. CONCLUSIONS: Digital devices may assign pixel values differently in consecutive digitization depending on the optical density of the radiographic image and the equipment. The pixel value reproducibility was not satisfactory as tested for two devices. It is maybe advisable knowing the digitization variations regarding pixel values whenever using digital radiography images in longitudinal clinical examinations.

Resumo em Inglês:

STATEMENT OF PROBLEM: In clinical practice, loss of adhesion between the silicone-based denture liner and the denture base resin is always an undesirable event that might cause loss of material softness, water sorption, bacterial colonization and functional failure of the prosthesis. PURPOSE: This study evaluated the effect of thermocycling on tensile and shear bond strengths of three soft liner materials to a denture base acrylic resin. MATERIAL AND METHODS: Three resilient liners (Mucopren-Soft, Mollosil-Plus and Dentusil) and a heat-polymerized acrylic resin (QC-20) were processed according to manufacturers' directions. Sixty specimens (14 x 14 mm cross-sectional area) per bond strength test (20 for each liner) were fabricated and either stored in water at 37ºC for 24 hours (control groups; n=10) or thermocycled 3,000 times in water between 5ºC and 55ºC (test groups; n=10). The specimens were tested in tensile and shear strength in a universal testing machine until fracture. Bond strength means were compared between water-stored and thermocycled groups for each material, as well as among materials for each treatment (water storage or thermocycling). Failure mode (adhesive, cohesive and mixed) after debonding was assessed. Data were analyzed statistically by paired Student's t-test and ANOVA at 5% significance level. RESULTS: The water-stored groups had statistically significant higher bond strengths than the thermocycled groups (p<0.05). Without thermocycling, Mucopren-Soft (2.83 ± 0.48 MPa) had higher bond strength than Mollosil-Plus (1.04 ± 0.26 MPa) and Dentusil (1.14 ± 0.51 MPa). After thermocycling, Mucopren-Soft (1.63 ± 0.48 MPa) had the highest bond strength (p<0.05). CONCLUSION: The bond strength of the three soft denture liners tested in this study changed with their chemical composition and all of them exhibited higher bond strengths than those usually reported as clinically acceptable. CLINICAL IMPLICATIONS: All soft lining materials tested in this study showed a significant decrease in the bond strength to an acrylic denture base resin after thermocycling. In spite of thermocycling, though, the silicone-based liners had satisfactory bond strengths for clinical application.

Resumo em Inglês:

OBJECTIVE: The aim of this study was to assess the existence of myofunctional alterations before and after first premolar extraction in Class II/1 malocclusion patients that could endanger the long-term dental arch stability. MATERIAL AND METHODS: The study was performed by means of morphological, functional and electromyographic analyses in 17 Class II/1 malocclusion patients (group T) and 17 Class I malocclusion patients (group C), both groups with 12-30-year age range (mean age: 20.93 ± 4.94 years). RESULTS: Data analyzed statistically by Student's t-test showed a significant decrease in the maxillary and mandibular dental arch perimeters after orthodontic treatment (p<0.05). The Kruskal-Wallis test analyzed data from tongue posture at rest and during swallowing, not showing significant differences after treatment (groups Tb and Ta) (p>0.05). However, group T differed significantly from group C (p<0.05). The electromyographic data showed that the anterior right and left suprahyoid muscles acted synergistically in both groups, while having a lower myoelectric activity in group T during swallowing. CONCLUSIONS: Myofunctional alterations observed after the orthodontic treatment in Class II/1 malocclusion seemed to jeopardize the long-term orthodontic stability, making recurrence possible. Further research should be conducted to compare electromyographic data before and after orthodontic treatment in order to corroborate the results of the present investigation.

Resumo em Inglês:

OBJECTIVE: This study evaluated the fracture strengths of endodontically treated teeth restored with prefabricated posts with different post lengths. MATERIAL AND METHODS: Thirty freshly extracted canines were endodontically treated. They were randomly divided into groups of 10 teeth and prepared according to 3 experimental protocols, as follows; Group 1/3 PP: teeth restored with prefabricated post and composite resin core (Z250) with post length of 5.0mm; Group 1/2 PP and Group 2/3 PP: teeth restored with prefabricated post and composite resin core (Z250) with different combinations of post length of 7.5mm and 10mm, respectively. All teeth were restored with full metal crowns. The fracture resistance (N) was measured in a universal testing machine (crosshead speed 0.5mm/min) at 45 degrees to the tooth long axis until failure. Data were analyzed by one-way analysis of variance (alpha=.05). RESULTS: The one-way analysis of variance demonstrated no significant difference among the different post lengths (P>.05) (Groups 1/3 PP = 405.4 N, 1/2 PP = 395.6 N, 2/3 PP = 393.8 N). Failures occurred mainly due to core fracture. CONCLUSIONS: The results of this study showed that an increased post length in teeth restored with prefabricated posts did not significantly increase the fracture resistance of endodontically treated teeth.

Resumo em Inglês:

In addition to an initial socket discomfort, ocular prosthesis (OP) installation may allow the adherence of fungi and/or bacteria due to the superficial characteristics of the prosthesis' material, use of inadequate cleansing solutions and methods, or because the void located between the internal portion of the prosthesis and the anophthalmic cavity (AC) mucosa. Objective: The aim of this study was to evaluate OP biofilm formation and the level of contamination of the internal portion of the OP and the AC in 24 patients. Material and Methods: Material was collected from the AC at the beginning of the study and 15 days after cleansing of the OP with 3 cleansing solutions: a neutral liquid soap, a multiuse solution for contact lens (Complete) and 0.12% chlorhexidine (Periogard). The collected materials were sowed in Petri dishes containing selective media for aerobic and facultative microorganisms, specifically staphylococci (Hipersalt agar with egg yolk), aerobic microorganisms (Brain Heart Infusion Blood Agar), streptococci (Mitis salivarius Agar), gram-negative bacilli (MacConkey Agar) and yeasts (Chromagar CandidaTM), incubated at 35ºC or 37ºC and the number of colony forming units were counted. Data were analyzed statistically by ANOVA, Friedman's test and Spearman's correlation. Results: Aerobic microorganisms, gram-negative bacilli and S. aureus were found in the OP biofilm and in the AC. There was statistically significant difference (p<0.05) between the number of microorganisms before and after the use of the cleansing solutions. Conclusion: There was positive correlation with respect to the microorganisms present in the OP biofilm and AC for the 4 proposed treatments, indicating that the decrease of OP contamination leads to AC contamination as well.

Resumo em Inglês:

The aim of this study was to compare the efficacy of three denture brushes (Bitufo-B; Medic Denture-MD; Colgate-C) on biofilm removal from upper and lower dentures using a specific dentifrice (Corega Brite). The correlation between biofilm levels on the internal and external surfaces of the upper and lower dentures was also evaluated. A microbiological assay was performed to assess the growth of colony-formed units (cfu) of Candida yeasts on denture surface. Thirty-three patients were enrolled in a 10-week trial divided in two stages: 1 (control) - three daily water rinses within 1 week; 2 - three daily brushings within 3 weeks per tested brush. Internal (tissue) and external (right buccal flange) surfaces of the complete dentures were disclosed (neutral red 1%) and photographed. Total denture areas and disclosed biofilm areas were measured using Image Tool 3.00 software for biofilm quantification. Dentures were boxed with #7 wax and culture medium (CHROMagarTM Candida) was poured to reproduce the internal surface. Statistical analysis by Friedman's test showed significant difference (p<0.01) between control and brushing stages. No difference was found among the brushes with respect to their efficacy on biofilm removal (p>0.01). Analysis by the Correlation test showed higher r values (B=0.78; MD=0.8341, C=0.7362) for the lower dentures comparing the surfaces (internal and external) and higher r values (B=0.7861, MD=0.7955, C=0.8298) for the external surface comparing the dentures (upper and lower). The results of the microbiological showed no significant difference (p>0.01) between the brushes with respect to the frequency of the species of yeasts (chi-square test). In conclusion, all denture brushes evaluated in this study were effective in the removal of biofilm. There was better correlation of biofilm levels between the surfaces for the lower dentures, and between the dentures for the external surface. There was no significant difference among the brushes regarding the frequency of yeasts.

Resumo em Inglês:

The aim of the work was to evaluate the influence of the temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy casting. Were obtained for the tensile strength test dumbbell rods that were invested in the Rematitan Plus investment and casting in the Discovery machine cast. Thirty specimens were obtained, fiftten to the CP Titanium and fifteen to the Ti-6Al-4V alloy, five samples to each an of the three temperatures of investment: 430ºC (control group), 480ºC and 530ºC. The tensile test was measured by means of a universal testing machine, MTS model 810, at a strain of 1.0 mm/min. After the tensile strenght test the specimens were secctioned, embedded and polished to hardness measurements, using a Vickers tester, Micromet 2100. The means values to tensile tests to the temperatures 430ºC, 480 and 530: CP Ti (486.1 - 501.16 - 498.14 -mean 495.30 MPa) and Ti-6Al-4V alloy (961.33 - 958.26 - 1005.80 - mean 975.13 MPa) while for the Vickers hardness the values were (198.06, 197.85, 202.58 - mean 199.50) and (352.95, 339.36, 344.76 - mean 345.69), respectively. The values were submitted to Analysis of Variance (ANOVA) and Tukey,s Test that indicate differences significant only between the materials, but not between the temperature, for both the materias. It was conclued that increase of the temperature of investment its not chance the tensile strength and the Vickers hardness of the CP Titanium and Ti-6Al-4V alloy.

Resumo em Inglês:

OBJECTIVE: The purpose of this in vitro study was to evaluate the internal adaptation of Class V composite restorations to the cavity walls using three different techniques of polymerization. METHODS: Standard cavities were prepared on the buccal and lingual surfaces of 24 extracted human third molars with margins located above and below the cementoenamel junction. Restorations were placed in one increment using two restorative systems: 3M Filtek A110/ Single Bond (M) and 3M Filtek Z250/ Single Bond (H) in the same tooth, randomly in the buccal and lingual surfaces. Resin composites were polymerized using three techniques: Group 1 - Conventional (60 s - 600 mW/cm²); Group 2 - Soft-start (20 s - 200 mW/cm² , 40 s - 600 mW/cm²); Group 3 - Pulse Activation (3 s - 200 mW/cm², 3-min hiatus, 57 s - 600 mW/cm²). Buccolingual sections were polished, impressions taken and replicated. Specimens were assessed under scanning electron microscopy up to X1000 magnification. Scores were given for presence or absence of gaps (0 - no gap; 1 - gap in one wall; 2 - gap in two walls; 3 - gap in three walls). RESULTS: The mean scores of the groups were (±SD) were: G1M-3.0 (± 0.0); G2M-2.43 (± 0.8); G3M- 1.71 (± 0.9); G1H- 2.14 (± 1.2); G2H- 2.00 (± 0.8); G3H- 1.67 (± 1.1). Data were analyzed using Kruskal-Wallis and Dunnet's tests. No statistically significant difference (p>0.05) was found among groups. Gaps were observed in all groups. CONCLUSIONS: The photocuring technique and the type of resin composite had no influence on the internal adaptation of the material to the cavity walls. A positive effect was observed when the slow polymerization techniques were used.

Resumo em Inglês:

INTRODUCTION: The production of sufficient saliva is indispensable for good chewing. Recent research has demonstrated that salivary flow rate has little influence on the swallowing threshold. OBJECTIVES: The hypothesis examined in the present study was that adding fluids to foods will influence chewing physiology. Materials and METHODS: Twenty subjects chewed on melba toast, cake, carrot, peanut and Gouda cheese. They also chewed on these foods after addition of different volumes of water or alpha-amylase solution. Jaw muscle activity, number of chewing cycles until swallowing and chewing cycle duration were measured. Repeated measures analysis of variance was applied to test the null hypothesis that there would be no statistically significant difference among the results obtained for the various food types and fluids. Subsequently, contrasts were determined to study the levels of intra-subjects factors (food type and fluid volume). Linear regression was used to determine the changes in muscle activity and cycle duration as a function of the chewing cycles. RESULTS: Fluid addition significantly decreased muscle activity and swallowing threshold for melba, cake and peanut (p<0.05). The effect of alpha-amylase in the solutions was similar to that of water (p>0.05). Doubling the volume of tap water had a greater effect. CONCLUSIONS: Fluid addition facilitated chewing of dry foods (melba, cake), but did not influence the chewing of fatty (cheese) and wet products (carrot). This study is relevant to improve patients' life quality and the management of chewing and feeding disorders caused by hyposalivation.

Resumo em Inglês:

This study evaluated, in vitro, the effect of iron (previously exposed with enamel powder or added directly to the beverage) on the erosive potential of carbonated or decarbonated beverage. Four sets of experiments were done. For groups E1 and E3, a solution containing 30 mmol/L FeSO4 was added to bovine enamel powder (particles between 75-106 mm) before exposure to the carbonated or decarbonated beverage (Sprite Zero®), respectively. For groups E2 and E4, 15 mmol/L FeSO4 was added directly to the carbonated or decarbonated beverage, respectively. Control groups were included for comparison. In controls C1 and C3, the experiments E1 and E3 were repeated, but the iron solution was replaced by deionized water. For controls C2 and C4, the carbonated and decarbonated beverage, respectively, was used, without addition of iron. After addition of the beverage to the powdered enamel (40 mg enamel powder/400 mL of final volume), the sample was vortexed for 30 s and immediately centrifuged for 30 s (11,000 rpm). The supernatant was removed after 1 min 40 s. This procedure was repeated in quintuplicate and the phosphate released was analyzed spectrophotometrically. The results were analyzed by Student's t-test (p<0.05). E2 presented the best results with a significant inhibition (around 36%) of phosphate released. For E3 and E4 a non-significant inhibition (around 4 and 12%, respectively), was observed. For E1 an increase in phosphate loss was detected. Thus, the protective effect of iron seems to be better when this ion is directly added to the carbonated beverage.

Resumo em Inglês:

OBJECTIVE: The aim of this study was to evaluate the biomechanical preparation of flattened root canals using the following systems: Endo-Eze AET stainless steel oscillatory instruments (Ultradent) and RaCe rotary NiTi instruments (FKG Dentaire). MATERIAL AND METHODS: Twenty extracted human mandibular incisors were randomly assigned to two groups: Group 1 - Instrumentation with oscillatory Endo-Eze AET files (oscillatory technique); Group 2 - Instrumentation with rotary NiTi RaCe files (rotary technique). The teeth were decoronated, had their apices and coronal openings sealed with sticky wax and were embedded in crystal-clear orthophtalic polyester resin. The roots were sectioned transversally with diamond discs at 10 mm (middle third) and 5 mm (apical third) from the apex and the segments were reassembled for instrumentation. The sections were photographed before and after root canal instrumentation and evaluated with respect to whether the original root canal shape was modified by instrumentation. To evaluate the differences in the root canal shape before and after biomechanical preparation, scores were given regarding the instruments touch on the intracanal walls. RESULTS: In middle third of the root canals instrumented with the rotary system, there was a change in the original canal anatomy (p<0.05), with formation of a protuberance in the mesiodistal direction. This protuberance did not occur when the oscillatory instrumentation was used. The oscillatory system had better results in the middle and apical thirds as evaluated by Dunn's multiple-comparison test (p>0.05). CONCLUSION: Under the tested conditions, Endo-Eze oscillatory system yielded the instrumentation of all flattened root canal walls, maintaining the canal original shape throughout the biomechanical preparation, and was more effective than RaCe rotary system.

Resumo em Inglês:

Oral forces applied to human teeth during biting and mastication are normally described in the literature only in terms of their axial components. The purpose of this study was to fully determine the spatial characteristics of the oral resultant force - its normal and tangential components - for a given individual. A load cell was especially manufactured to measure oral force and was temporarily implanted as a prosthetic device in the dental arch of a volunteer, replacing his missing upper first molar. The mastication and occlusion tests were carried out in such a way the cell should withstand the loads applied to the molar, and its state of strain was recorded by strain gauges attached to it. Based on the results of these tests and using balance equations, normal and tangential components of the resultant oral force were determined. For direct occlusion, without interposition any obstacle between cusps, a peak normal force of 135 N was recorded simultaneously to a tangential force of 44 N. For mastication of biscuits, a peak normal force of 133 N and a tangential force of 39 N were obtained.

Resumo em Inglês:

The possible association between orthodontic treatment and temporomandibular disorders (TMD) is a topic of great interest in the current literature. The true role of orthodontic therapy on the etiology of TMD, however, is still uncertain. From the clinical prospective, a thorough examination of the stomatognathic system is always necessary in order to detect possible TMD signs and symptoms prior to the beginning of the orthodontic therapy. Caution should be exercised when planning, performing and finalizing orthodontics, especially in patients who with history of signs and symptoms of TMD. The clinician must always eliminate patient's pain and dysfunction before initiating any type of orthodontic mechanics. Muscle incoordination, unstable disc-condyle relationship and bone alterations are usual TMD conditions that can interfere with the presenting occlusal relationship. This article reviews these aspects and presents a detailed clinical guide for the examination of the orthodontic patient, considering aspects related to facial pain and dysfunction.