Reproducibility, Reliability, and Validity of Fuchsin-Based Beads for the Evaluation of Masticatory Performance.

PURPOSE: Rehabilitation of masticatory function is inherent to prosthodontics; however, despite the various techniques for evaluating oral comminution, the methodological suitability of these has not been completely studied. The aim of this study was to determine the reproducibility, reliability, and validity of a test food based on fuchsin beads for masticatory function assessment. MATERIALS AND METHODS: Masticatory performance was evaluated in 20 dentate subjects (mean age, 23.3 years) using two kinds of test foods and methods: fuchsin beads and ultraviolet-visible spectrophotometry, and silicone cubes and multiple sieving as gold standard. Three examiners conducted five masticatory performance trials with each test food. Reproducibility of the results from both test foods was separately assessed using the intraclass correlation coefficient (ICC). Reliability and validity of fuchsin bead data were measured by comparing the average mean of absolute differences and the measurement means, respectively, regarding silicone cube data using the paired Student's t-test (α = 0.05). RESULTS: Intraexaminer and interexaminer ICC for the fuchsin bead values were 0.65 and 0.76 (p < 0.001), respectively; those for the silicone cubes values were 0.93 and 0.91 (p < 0.001), respectively. Reliability revealed intraexaminer (p < 0.001) and interexaminer (p < 0.05) differences between the average means of absolute differences of each test foods. Validity also showed differences between the measurement means of each test food (p < 0.001). CONCLUSIONS: Intra- and interexaminer reproducibility of the test food based on fuchsin beads for evaluation of masticatory performance were good and excellent, respectively; however, the reliability and validity were low, because fuchsin beads do not measure the grinding capacity of masticatory function as silicone cubes do; instead, this test food describes the crushing potential of teeth. Thus, the two kinds of test foods evaluate different properties of masticatory capacity, confirming fushsin beads as a useful tool for this purpose.

Association between prosthetic factors and temporomandibular disorders in complete denture wearers.

OBJECTIVE: The purpose of this study was to investigate the prevalence of temporomandibular disorders (TMD) in denture wearers and the association between prosthetic factors and this condition. BACKGROUND: There is no consensus about the relationship between prosthetic factors and TMD among denture wearers. MATERIALS AND METHODS: The sample was composed of 92 patients wearing both maxillary and mandibular complete dentures. The Research Diagnostic Criteria for TMD (RDC/TMD) were adopted for patient examination. Objective evaluation of denture quality was determined by analysis of retention and stability of mandibular denture, interocclusal distance, articulation and occlusion. Association between denture quality and TMD diagnosis was analysed using chi-square and Fisher's exact tests. RESULTS: 37.4% of the patients presented TMD. Denture quality was not significantly associated with the presence of TMD: mandibular retention (p = 0.466); mandibular stability (p = 0.466); interocclusal distance (p = 0.328); centric relation (p = 0.175); and balanced occlusion (p = 0.56). CONCLUSION: Within the scope of this case-controlled cross-sectional study, no robust association between prosthetic factors and TMD was found.

Bilateral balanced articulation: science or dogma?

For more than a hundred years, it has been supposed that canine guidance should be avoided in conventional complete dentures, since it would result in denture instability. Thus, bilateral balanced articulation has been held by many authors as fundamental for treatment success. However, randomized clinical trials have shown that balanced articulation is not as important as previously thought. The issue about which occlusal concept is the most appropriate for individual needs is clinically and economically relevant for both the dentist and dental technician. Therefore, the purpose of this study is to provide an evidence-based update on complete denture occlusion. Clinical Relevance: The issue about which occlusal concept is the most appropriate for individual needs is clinically and economically relevant.

Relationship between chewing rate and masticatory performance.

The influence of mandibular movement timing on food breakdown remains unclear. The authors, therefore, sought to relate chewing rate with masticatory performance. Chewing rate, defined as the number of masticatory cycles habitually achieved per minute, was measured in 55 healthy dentulous subjects (age, 22.2 +/- 5.0 years). Subjects were grouped according to obtained values (cycles/minute): slower: < 70; middle: 70-90; and faster: > 90. Masticatory performance was determined through the sieve method, and the estimated comminuted median particle size (X50). Data was analyzed using the one-way ANOVA and chi-square tests (alpha = .05). Subjects with slower chewing rates showed higher (p < .05) masticatory performance (X50 = 3.05 +/- 0.77 mm). X50 was associated with chewing rate when subjects were categorized as better or poorer performers (chi-square = 11.25, p < .005). Thus, chewing rate was related to masticatory performance, with smaller food particles being achieved with a slower chewing rate.

Complete denture occlusion: an evidence-based approach.

PURPOSE: This study involved an extensive search for randomized controlled clinical trials comparing bilateral balanced and canine-guided dentures, and questioned whether a bilateral balanced occlusion is imperative for successful denture treatment. MATERIALS AND METHODS: Studies were identified by searching electronic databases (PubMed/MEDLINE, ISI Web of Science, LILACS, and BBD). The keywords "denture" and "occlusion" were used. The minimum inclusion requirements were (1) randomized controlled trials with patients of any age wearing both maxillary and mandibular conventional complete dentures (CDs), (2) comparison between bilateral balanced and canine-guided dentures, and (3) assessment of masticatory function and/or patients' satisfaction. RESULTS: The search resulted in the identification of 5166 articles. Subsequently, 5156 articles were excluded on the basis of title and abstract. By the end of the search phase, seven randomized controlled trials were considered eligible. CONCLUSIONS: Current scientific evidence suggests that bilateral balanced occlusion is not imperative for successful treatment with conventional CDs in average patients. More studies are necessary to identify if specific clinical conditions may benefit from a balanced occlusion.

The influence of double flask investing on tooth displacement in dentures processed by microwave irradiation.

OBJECTIVE: This study evaluated the influence of the bimaxillary flask (BMF) and two different investing materials on first molar inclination in dentures processed by microwave irradiation. BACKGROUND: The BMF may minimise tooth displacement, saving time and improving occlusion. METHODS AND MATERIALS: Forty pairs of dentures were randomised into four groups: stone wall in monomaxillary flask; silicone wall in BMF; stone wall in BMF; acrylic resin retentions and silicone in BMF. Dentures were processed by microwave irradiation. Two referential points were established on tooth surface. A microscope and a digital pachymeter were used to measure the distance between these points, and the angles α (right maxillary molar), ß (left maxillary molar), α' (right mandibular molar) and ß' (left mandibular molar) were calculated by the law of cosines. Data were submitted to Kruskal-Wallis (5% significance). RESULTS: No difference was observed among the groups (p > 0.05). In the intra-group analysis, α was significantly different for groups I, II and III; α', for groups II and IV; ß, for all groups; ß', for groups III and IV. CONCLUSION: First molar inclination was similar for monomaxillary and BMFs. The use of stone or silicone as investing materials presented the same effect on tooth inclination.

The influence of mandibular implant-retained overdentures in masticatory efficiency.

OBJECTIVE: To evaluate the masticatory efficiency of patients rehabilitated with conventional dentures (CDs) or implant-retained mandibular overdentures. BACKGROUND: Despite the evident benefits of implants on mastication as assessed by subjective patient-based outcomes, the extent of implant overdenture treatment effect on food comminution is not well established. MATERIALS AND METHODS: A randomised clinical trial was carried out with 29 completely edentulous patients divided into two groups. The first group was rehabilitated with a mandibular overdenture retained by two splinted implants with bar-clip system, while the second group was rehabilitated with a mandibular CD. Both groups also were rehabilitated with maxillary CDs. Masticatory efficiency and patient satisfaction were assessed 3 months after denture insertion. Masticatory efficiency was evaluated through the colorimetric method with the beads as the artificial test-food. Comparisons for masticatory efficiency and patient satisfaction were performed using Student's t-test (α = 0.05). RESULTS: No significant statistical difference was found for masticatory efficiency (p = 0.198). Patient overall satisfaction was significantly higher for the mandibular overdenture (p < 0.001). In addition, mandibular overdenture patients were significantly more satisfied with chewing experience (p < 0.05) and retention of the lower denture (p < 0.005). CONCLUSION: The results of this study suggest that mandibular overdenture significantly improves chewing experience, although limited effect on masticatory efficiency has been observed.

Tooth preparation for ceramic veneers: when less is more.

Historically, preparations for ceramic veneers have varied from extremely aggressive to a minimal reduction or a lack of preparation. Today, we are moving toward minimally invasive dentistry with the philosophy that less is more. Less tooth reduction means more adhesion and clinical longevity. What must be considered when performing minimally invasive preparations is that in a significant number of cases the dental element will receive a veneer that will modify its final contour. This is quite common in cases of conoid teeth, diastemas or loss of dental structure by abrasion, erosion or attrition. The aim of this article is to present a step-by-step protocol to achieve conservative preparations for ceramic veneers, called the mock-up driven technique. This technique takes into account the final contour desired for the veneer, and results in considerably less invasive dental preparations.

Changes in patient satisfaction and masticatory efficiency during adaptation to new dentures.

Because adapting to new conventional dentures is highly variable, there is uncertainty as to how long dissatisfied patients should wait before choosing a treatment with dental implants. The authors investigated whether changes in patient satisfaction and masticatory efficiency may be observed between 3 and 6 months after the insertion of new conventional complete dentures. The study included 24 edentulous patients requiring new complete dentures. Masticatory efficiency and patient satisfaction were evaluated at 3 and 6 months post-insertion. Masticatory efficiency was evaluated through the colorimetric method, with the beads as the artificial test food. A method for quantifying overall satisfaction of complete-denture wearers was used. Subjects were asked to respond to questions with three-grade answers concerning 12 factors: chewing, tasting, speech, esthetics, pain, fit, retention, and comfort (maxillary and mandibular evaluations were done for each of the last four factors). The results of patient satisfaction and masticatory efficiency at 3 and 6 months post-insertion were compared using the paired-samples t test (α = 0.05). Significant reductions in mandibular pain (P less than 0.05) and improvements in mandibular fit (P less than 0.05) were observed at 6 months. No difference was found for patient overall satisfaction, chewing, tasting, speech, maxillary pain, esthetics, maxillary fit, retention, comfort, and masticatory efficiency. The authors concluded that reduction in pain and improvements in adaptation of the lower denture may be observed between 3 and 6 months after insertion of new conventional complete dentures. This period of adaptation should be considered before choosing a treatment with dental implants.

Conventional Complete Denture in Patients with Ectodermal Dysplasia.

Ectodermal dysplasia is described as heritable conditions that involve anomalies of structures derived from the ectoderm, including hypodontia. In the cases of edentulous young patients, who did not finish their craniofacial growth, treatment with conventional complete denture is a suitable alternative. The aim of this study was to report a case of mandibular edentulism treated with conventional complete denture in a thirteen-year-old patient diagnosed with hidrotic ectodermal dysplasia. Typical features, such as frontal bossing, depressed nasal bridge, protuberant lips, scarce hair, and brittle nails, were visualized during the extraoral examination. The intraoral inspection and radiographic analysis revealed oligodontia, dental malformation, and prolonged retention of deciduous teeth at maxilla and total edentulism at mandible. A conventional complete denture was planned and constructed following the same steps of technique as recommended in adults. Although this option is not a definitive treatment, the patient and his parents were satisfied with his improvement in chewing and speech, as well as with the aesthetic benefits.

Esthetic Rehabilitation of the Smile with No-Prep Porcelain Laminates and Partial Veneers.

Rehabilitation of patients with anterior conoid teeth may present a challenge for the clinician, especially when trying to mimic the nature with composite resins. This clinical report exemplifies how a patient with conoid upper lateral incisors was rehabilitated with minimally invasive adhesive restorations. Following diagnostic wax-up and cosmetic mock-up, no-prep veneers and ceramic fragments (partial veneers) were constructed with feldspathic porcelain. This restorative material presents excellent reproduction of the optical properties of the dental structure, especially at minimal thicknesses. In this paper, the details about the treatment are described. A very pleasing outcome was achieved, confirming that minimally invasive adhesive restorations are an excellent option for situations in which the dental elements are healthy, and can be modified exclusively by adding material and the patient does not want to suffer any wear on the teeth.

The relationship between occlusal support and maxillary development: An animal study.

OBJECTIVE: To test the hypothesis that maxillary development may be affected by occlusal support. MATERIALS AND METHODS: The sample was composed by Wistar rats (5 weeks old) divided into three groups: Control (n = 10), extraction of mandibular molar teeth - left side (n = 10), extraction mandibular molar teeth - left and right sides (n = 10). The rats were sacrificed 8 weeks postextraction. Cone beam computed tomography scan images were taken for posterior measurement of maxillary length and width. Data were analyzed by one-way analysis of variance (Tukey test as post-hoc test). RESULTS: Maxillary length was significantly shorter (P < 0.005) in both groups after tooth extraction. No difference was observed regarding maxillary width and body weight. CONCLUSION: Reduced occlusal support may impair the development of the maxilla in rats.

Reproducibility of a silicone-based test food to masticatory performance evaluation by different sieve methods.

The aim of this study was to evaluate the reproducibility of the condensation silicone Optosil Comfort® as an artificial test food for masticatory performance evaluation. Twenty dentate subjects with mean age of 23.3±0.7 years were selected. Masticatory performance was evaluated using the simple (MPI), the double (IME) and the multiple sieve methods. Trials were carried out five times by three examiners: three times by the first, and once by the second and third examiners. Friedman's test was used to find the differences among time trials. Reproducibility was determined by the intra-class correlation (ICC) test (α=0.05). No differences among time trials were found, except for MPI-4 mm (p=0.022) from the first examiner results. The intra-examiner reproducibility (ICC) of almost all data was high (ICC≥0.92, p<0.001), being moderate only for MPI-0.50 mm (ICC=0.89, p<0.001). The inter-examiner reproducibility was high (ICC>0.93, p<0.001) for all results. For the multiple sieve method, the average mean of absolute difference from repeated measurements were lower than 1 mm. This trend was observed only from MPI-0.50 to MPI-1.4 for the single sieve method, and from IME-0.71/0.50 to IME-1.40/1.00 for the double sieve method. The results suggest that regardless of the method used, the reproducibility of Optosil Comfort® is high.

The influence of mandibular ridge anatomy on treatment outcome with conventional complete dentures.

Since prognostic indicators are likely to take on increasing importance as a diagnostic tool for selection of patients for implant provision, this study investigated the influence of the shape and resiliency of the mandibular alveolar ridge on the retention and stability of conventional complete dentures. Ninety- three edentulous patients wearing both maxillary and mandibular conventional complete dentures composed the sample. Data were collected regarding shape and resiliencyof the mandibular residual ridge. Dentures were assessed for retention and stability using an objective and reproducible tool.The associations between the clinical characteristics of the mandibular alveolar ridge and denture retention and stability were analyzed using chi-square and Fisher exact tests (a = 0.05). A significant association between ridge shape and denture stability (p < 0.05) was found, while ridge resiliency was significantly associated to denture retention (p < 0.001). Based on the results, mandibular ridge shape and resiliency influenced the retention and stability of conventional complete dentures.

Marginal microleakage of class V resin-based composite restorations bonded with six one-step self-etch systems.

This study compared the microleakage of class V restorations bonded with various one-step self-etching adhesives. Seventy class V resin-based composite restorations were prepared on the buccal and lingual surfaces of 35 premolars, by using: Clearfil S3 Bond, G-Bond, iBond, One Coat 7.0, OptiBond All-In-One, or Xeno IV. The Adper Single Bond etch-and-rinse two-step adhesive was employed as a control. Specimens were thermocycled for 500 cycles in separate water baths at 5°C and 55°C and loaded under 40 to 70 N for 50,000 cycles. Marginal microleakage was measured based on the penetration of a tracer agent. Although the control showed no microleakage at the enamel margins, there were no differences between groups (p = 0.06). None of the adhesives avoided microleakage at the dentin margins, and they displayed similar performances (p = 0.76). When both margins were compared, iBond® presented higher microleakage (p < 0.05) at the enamel margins (median, 1.00; Q3-Q1, 1.25-0.00) compared to the dentin margins (median, 0.00; Q3-Q1, 0.25-0.00). The study adhesives showed similar abilities to seal the margins of class V restorations, except for iBond®, which presented lower performance at the enamel margin.

The effect of loss of occlusal support on mandibular morphology in growing rats.

OBJECTIVE: To evaluate the effects of unilateral and bilateral premature loss of posterior occlusal support on mandibular bone dimensions in growing rats. MATERIALS AND METHODS: Thirty female Wistar rats (5 weeks old) were randomized into three groups: control, unilateral mandibular molar teeth extraction, and bilateral mandibular molar teeth extraction. After 8 weeks, animals were sacrificed and acrylic rapid-prototyped templates of the mandibles were constructed. Mandibular length, ramus height, intercondylar distance, and body weight were measured and analyzed by one-way analysis of variance (Tukey test as post hoc test; α  =  .05). RESULTS: Mandibular length and intercondylar distance were significantly shorter in experimental animals, while no difference was observed for ramus height and body weight. CONCLUSIONS: Unilateral and bilateral premature loss of posterior occlusal support in growing rats results in a smaller mandible at skeletal maturity.

Altered mandibular growth under functional posterior displacement in rats.

OBJECTIVE: To test the null hypothesis that there is no difference in mandibular growth between growing rats with posterior functional mandibular displacement and growing rats without functional mandibular displacement. MATERIALS AND METHODS: Twenty female Wistar rats (5 weeks old) were randomized into two groups: (1) control and (2) mandible posterior displacement in the occluded condition induced by an occlusal guiding appliance. After 8 weeks all animals were sacrificed, cone beam computed tomography scan images of the heads were taken using the classic I-CAT, and acrylic rapid-prototyped templates of the mandibles were constructed. Mandibular length, ramus height, and intercondylar distance were measured. Mandibular length and ramus height were submitted to the two-way analysis of variance, while intercondylar distance was analyzed by nonpaired Student's t-test. RESULTS: Mandibular length was bigger (P < .0001) in the control than in the experimental group, but no significant difference was found between the left and right sides (P  =  .9380). No significant differences were observed for ramus height and intercondylar distance. CONCLUSIONS: The results of this study demonstrated that functional posterior displacement of the mandible in growing rats resulted in shorter mandibular length.

The effect of posterior tooth loss on the expression of type II collagen, IL-1ß and VEGF in the condylar cartilage of growing rats.

OBJECTIVE: The aim of this study was to evaluate the effect of unilateral and bilateral loss of posterior occlusal support on the expression of type II collagen, interleukin-1ß and VEGF in the condylar cartilage of growing rats. DESIGN: Thirty female Wistar rats (5 weeks old) were randomized into three groups: control, unilateral extraction of mandibular molar teeth, bilateral extraction of mandibular molar teeth. Animals were sacrificed 8 weeks after tooth extraction and the temporomandibular joints were prepared for immunohistochemical analysis. RESULTS: Bilateral molar extraction increased the expression of interleukin-1ß (P<0.01) and VEGF (P<0.01), while unilateral extraction increased the expression of interleukin-1ß (P<0.05) and type II collagen (P<0.01). The expression of VEGF was higher on the extracted than on the non-extracted side (P<0.01) after unilateral extraction. CONCLUSION: Loss of posterior occlusal support alters the expression of type II collagen, interleukin-1ß and VEGF in the condylar cartilage of rats. The expression pattern of these proteins is different when loss of occlusal support was bilateral or unilateral, including differences between extracted and non-extracted sides.

Evaluation of complete denture quality and masticatory efficiency in denture wearers.

PURPOSE: This study aimed to investigate (1) the influence of complete denture quality and years of denture use on masticatory efficiency and (2) the relationship between complete denture quality and years of use. MATERIALS AND METHODS: A cross-sectional study was conducted with 93 edentulous patients (mean age: 65.6 years) wearing both mandibular and maxillary dentures. Patients were classified into two categories according to years of denture use: ≤ 2 years and ≥ 5 years. Masticatory efficiency was evaluated via the colorimetric method with beads as the artificial test food. A reproducible method for objective evaluation of the technical quality of complete dentures was employed. The association between denture quality and years of denture use was analyzed using chi-square and Fisher exact tests. The results of masticatory efficiency testing were analyzed using two-way analysis of variance (with the Tukey post hoc test) in terms of years of denture use (≤ 2 years, ≥ 5 years) and denture quality (poor, average, good). RESULTS: A significant relationship was found between denture quality and years of denture use (P < .05). Masticatory efficiency differed significantly (P < .05) between patients with ≤ 2 years of denture use (0.101 ± 0.076 absorbance) and ≥ 5 years of use (0.068 ± 0.076 absorbance). Masticatory efficiency was not influenced by denture quality. CONCLUSIONS: Complete denture quality and masticatory efficiency significantly decreased over time. However, complete denture quality did not influence masticatory efficiency.

Masticatory efficiency in denture wearers with bilateral balanced occlusion and canine guidance.

The maintenance of masticatory function is especially important for patients wearing complete dentures due to their limitations. Thus, the bilateral balanced occlusal concept is used to achieve greater masticatory efficiency. However, a critical review of the literature reveals that there is not sufficient scientific evidence to support bilateral balanced occlusion as the most appropriate occlusal concept in complete dentures. Therefore, the aim of this study was to evaluate the masticatory efficiency in complete dentures wearers with bilateral balanced occlusion and canine guidance. A double-blinded controlled crossover clinical trial was conducted. The sample was composed by 24 edentulous patients who wore sets of complete dentures with both occlusal concepts during equal periods of 3 months. Objective data were collected through the masticatory efficiency test performed by the colorimetric method with the beads, in which capsules of a synthetic material enclosing fuchsine-containing granules were used. Subjective data were recorded by patient's ratings of their chewing function. No significant statistical difference was found for masticatory efficiency (p=0.095) between the two occlusal concepts studied. The results suggest that bilateral balanced occlusion does not improve the masticatory efficiency in complete denture wearers.