Effect of Duplication Techniques on the Fitting Accuracy of CAD-CAM Milled, 3D-Printed, and Injection-Molded Mandibular Complete Denture Bases.

BACKGROUND: Digital technology has been introduced in prosthodontics, and it has been widely used in denture duplication instead of a conventional denture duplication technique. However, research comparing different denture duplication techniques and how they affect the fitting accuracy of the denture base is scarce. OBJECTIVES: The aim was to assess the impact of duplication techniques on the accuracy of the fitting surface of computer-aided design and manufacturing (CAD-CAM) milled, 3D-printed, and injection-molded complete denture bases (CDBs). METHODOLOGY: This study involved fabricating a mandibular complete denture base with three marked dimples as reference marks (A, B, and C at the incisive papilla, right molar, and left molar areas) using a conventional compression molded technique. This denture was then scanned to generate a standard tessellation language (STL) file; after that, it was duplicated using three different techniques (milling, 3D printing, and injection molding) and five denture base resin materials-two milled CAD-CAM materials (AvaDent and IvoBase), two 3D-printed materials (NextDent and HARZ Labs), and one injection-molded material (iFlextm). Based on the denture base type, the study divided them into five groups (each with n = 10). An evaluation of duplication accuracy was conducted on the fitting surface of each complete denture base (CDB) using two assessment methods. The first method was a two-dimensional evaluation, which entailed linear measurements of the distances (A-B, A-C, and B-C) between reference points on both the scanned reference mandibular denture and the duplicated dentures. Additionally, a three-dimensional superimposition technique was employed, involving the overlay of the STL files of the dentures onto the reference denture's STL file. The collected data underwent statistical analysis using a one-way analysis of variance and Tukey's pairwise post hoc tests. RESULTS: Both evaluation techniques showed significant differences in fitting surface accuracy between the tested CDBs (p ˂ 0.001), as indicated by one-way ANOVA. In addition, the milled CDBs (AvaDent and IvoBase) had significantly higher fitting surface accuracy than the other groups (p ˂ 0.001) and were followed by 3D-printed CDBs (NextDent and HARZ Labs), while the injection-molded (iFlextm) CDBs had the lowest accuracy (p ˂ 0.001). CONCLUSIONS: The duplication technique of complete dentures using a CAD-CAM milling system produced superior fitting surface accuracy compared to the 3D-printing and injection-molded techniques.

Effect of Different Occlusal Tooth Forms of Mandibular Overdenture Retained by an Immediate Loaded Single Implant on the Masticatory Efficiency and Oral Health-Related Quality of Life.

Aim: To study the masticatory efficacy and oral health-related quality of life (OHRQoL) of participants wearing a mandibular overdenture retained by an immediate loading single implant with different occlusal tooth forms. Materials and Methods: For this nonrandomized controlled trial study, 27 edentulous participants were selected and randomly divided into three groups (n = 9) based on occlusal tooth forms of the mandibular implant overdenture (MIOD). Group I: participants received an MIOD with an anatomical tooth form; Group II: participants received an MIOD with a semianatomical tooth form; and Group III: participants received an MIOD with a nonanatomical tooth form. For each participant, a single implant (screw root form) was inserted into the midline of the mandibular ridge to support the MIOD. For each group, the masticatory efficiency was evaluated after 3 months, and the OHRQoL of the participants was evaluated after 3 and 6 months. One-way ANOVA and post hoc Tukey's test were used for data analysis (P < 0.05). Results: The masticatory efficiency of the anatomic and semianatomic tooth forms was higher than that of the nonanatomic (P < 0.05). Moreover, the improvement in the participants' OHRQoL in the anatomic group was more significant than that of other groups (P < 0.05). Conclusion: There was a greater improvement in masticatory efficiency and participants' OHRQoL when fitted with an anatomic tooth form mandibular overdenture retained by an immediate loading single implant than with a semianatomic or nonanatomic tooth form.

Impact of different chemical denture cleansers on the properties of digitally fabricated denture base resin materials.

PURPOSE: To compare the impact of three different chemical denture cleansers (CDCs) (Corega, chlorhexidine, and hydrogen peroxide) on the surface roughness, microhardness, and color stability of 3D-printed, computer-aided design and computer-aided manufacturing (CAD-CAM) milled, and heat-polymerized denture base material (DBM). MATERIALS AND METHODS: A total of 420 disc-shaped specimens (10 ± 0.1 × 2 ±0.1 mm) were fabricated using three different construction techniques: three-dimensional (3D) printing (n = 140), CAD-CAM milling (n = 140), and heat-polymerization (n = 140). Sixty specimens (20 of each DBM) were used for baseline (pre-immersion) measurements (T1 ) for the tested surface properties (hardness [n = 10/material] and roughness [n = 10/material]). The remaining 360 specimens (n = 120/material) were investigated for surface roughness, microhardness, and color change after immersion for 1 year (T2 ) in distilled water or CDCs (n = 30/solution and n = 10/test). The data were analyzed using two-way ANOVA, one-way ANOVA followed by post-hoc Tukey's test at a significance level of less than 0.05. RESULTS: Significant differences were observed in the effects of the tested CDCs on the surface roughness, micro-hardness, and color stability of varying DBM specimens (p < 0.05). Corega showed the highest surface roughness and color change in all DBMs while H2 O2 resulted in the lowest microhardness for all DBMs. The lowest changes in all tested properties were seen with distilled water followed by chlorhexidine. A significant effect of type of cleanser, denture base material, and the interaction between the two was seen on all measured properties (p < 0.05). CONCLUSIONS: The tested CDCs significantly affected the surface properties of all DBMs but at varying degrees. Corega produced the highest negative effect on roughness and color change while H2 O2 dramatically affected the microhardness. Prolonged use of CDCs should be cautiously followed.

Efficacy of Occlusal Splints and Low-Level Laser Therapy on the Mandibular Range of Motion in Subjects with Temporomandibular Joint Disc Displacement with Reduction.

Aims and Objectives: The study was carried out to evaluate the efficacy of four conservative therapeutic modalities on the mandibular range of motion (MRM) in subjects with anterior disc displacement with reduction (ADDwR) of the temporomandibular joint (TMJ). Materials and Methods: One hundred patients (64 women and 36 men) were selected, and randomly distributed into four groups. Group I: Subjects receiving behavioral therapy (BT). Group II: Subjects receiving low-level laser therapy (LLLT). Group III: Subjects receiving maxillary anterior repositioning splint (MARS). Group IV: Subjects receiving stabilization splint (SS). The MRM was evaluated for each patient before treatment and after 6 months. Paired t test and one-way analysis of variance (ANOVA) tests were used for statistical analysis followed by a post hoc Tukey test (P ≤ 0.05). Results: All groups showed significant improvement in MRM after 6 months of treatment (P ≤ 0.05) except for BT. There was a significant improvement for SS and MARS on the different movements of MRM, more than for LLLT and BT (P ≤ 0.05). Conclusion: The MARS and the SS are effective in increasing the MRM for patients with ADDwR.

Comparison of Dimensional Changes Between CAD-CAM Milled Complete Denture Bases and 3D Printed Complete Denture Bases: An In Vitro Study.

PURPOSE: This study compared the dimensional changes between computer-aided design and computer-aided manufacturing (CAD-CAM) milled complete denture bases (CDBs) and three-dimensional (3D) printed CDBs. MATERIALS AND METHODS: One maxillary completely edentulous stone model was fabricated with three reference points at the incisive papilla, right molar, and left molar areas marked as X, Y, and Z, respectively. It was scanned to produce a standard tessellation language (STL) file, which was imported to a metal milling machine software to produce the metal model. This metal model was used to fabricate 30 CDBs for analysis. The CDBs were divided into three groups (n = 10 each) according to the fabrication method used as follows: Group 1, CAD-CAM milled CDBs; Group 2, 3D printed CDBs; and Group 3, conventional compression molded CDBs. The CDBs of all groups were scanned after fabrication, and the dimensional changes in each were evaluated by two methods. The first was the two-dimensional evaluation method that involved linear measurement of the distances between the reference points (X-Y, X-Z, and Y-Z) of the scanned reference cast and dentures. The second method was the 3D evaluation method that involved the superimposition of the STL files of the dentures on the STL file of the reference cast. Data were calculated and were statistically analyzed using one-way analysis of variance and Tukey's pairwise post hoc tests. RESULTS: There was a significant difference in the dimensional accuracy between the CAD-CAM milled, 3D printed, and conventional compression molded CDBs (p < 0.05). CONCLUSION: The dimensional accuracy of the CAD-CAM milling system in complete denture fabrication is superior to that of the compression molding and 3D printing systems.

Impact of thermocycling on surface roughness, microhardness and optical properties of three different lithium disilicate ceramics.

Objectives: This investigation was carried out to examine the influence of thermocycling aging on the surface roughness (Ra, µm), color parameters (L*, a*, b*), lightness change (ΔL*), chroma change (ΔC*ab), color change (ΔE), and microhardness (VH) of three lithium disilicate ceramics. Materials and methods: Forty-five specimens were prepared from three lithium disilicate materials (n = 15)-e.max CAD (EC), e.max Press (EP), and GC Initial LiSi Press (LP) ceramics-with dimensions of 6.0 × 1.2 × 16.0 ± 0.2 mm following the manufacturers' instructions. All specimens were exposed to 5000 thermal cycles with bath temperatures ranging between 5 °C and 55 °C. Data of surface roughness, color parameters, and microhardness were obtained using an optical profiler, a spectrophotometer, and a Vickers hardness tester, respectively. One-way ANOVA, a post-hoc Tukey's test, and a paired sample t-test were implemented for statistical analysis (p ≤ 0.05). Results: For surface roughness, insignificant differences were reported between the materials either before or after thermocycling (p > 0.05) while each material displayed a significant increase after being subjected to thermocycling (p < 0.05). For color parameters, LP showed significantly lower L* and b* after thermocycling while EC presented a significant reduction in a* in comparison with other materials (p < 0.05). EP showed a significant decrease in ΔL*, ΔC*ab and ΔE compared with other materials (p < 0.05). Regarding microhardness, LP showed significantly increase value in comparison with other materials (p < 0.05). Conclusions: Thermocycling had a major impact on the surface roughness, microhardness and optical characteristics of the tested materials. E.max Press displayed less changes in (ΔL*), (ΔC*ab) and (ΔE), while GC LiSi Press had better behavior in terms of microhardness.

Impact of Nanoparticles Additions on the Strength of Dental Composite Resin.

Objective: This study aimed to evaluate the effect of nanoparticles, zirconium dioxide (ZrO2), titanium dioxide (TiO2), and silicon dioxide (SiO2), on flexural strength (FS), hardness, and wear resistance of light cured dental composite resin. Materials and Methods: 210 rectangular and disc-shaped composite resin specimens were fabricated with dimensions (25 × 2 × 2 ± 0.03 mm) and (6×4 ± 0.03 mm) for FS, hardness, and wear resistance, respectively (70/test). Specimens of each test were divided according to nanofillers into four groups, unmodified as control, ZrO2 (Z), TiO2 (T), and SiO2 (S) groups; each one was further subdivided into two subgroups according to nanoparticles concentration, 3wt.% and 7wt.% (Z3, Z7, T3, T7, S3, and S7), 10 specimens of each subgroup. A3-point bending test and Vickers hardness test were used for FS and hardness measurements, respectively. Wear resistance was evaluated by the differences in surface roughness of tested specimens before and after wear test. Two-way and 1-way ANOVA and Bonferroni's post hoc tests were done for data analysis (α = 0.05). Results: Two-way ANOVA for FS and wear resistance showed that there was a significant interaction between type of nanoparticles and concentration of nanoparticles (p < 0.001) while two-way ANOVA for hardness showed that both type of nanoparticles and concentration of nanoparticles had a significant effect (p < 0.001), while the effect of their interaction was not statistically significant (p=0.142). 1-way-ANOVA test showed significant increase in FS and wear resistance for all tested groups (p < 0.001 and p < 0.001, respectively) except T7 and S7. Also, there was a significant enhancement in hardness for all tested groups (p < 0.001). Conclusion: Modification of light cured composite resin with certain amounts of nanoparticles (3% and 7% of ZrO2 and 3% of TiO2 and SiO2) can be beneficial in improving flexural strength and wear resistance while hardness of composite resin was increased with all NPs additions.

Comparative Effect of Incorporation of ZrO2, TiO2, and SiO2 Nanoparticles on the Strength and Surface Properties of PMMA Denture Base Material: An In Vitro Study.

Objective: This study aimed to investigate the effects of nanoparticles (zirconium dioxide (ZrO2), titanium dioxide (TiO2), and silicon dioxide (SiO2)) on the flexural strength, impact strength, hardness, and wear resistance of the acrylic resin denture base material. Materials and Methods: Acrylic resin specimens were fabricated in dimensions according to American Dental Association (ADA) specifications per test. Specimens were divided according to nanofiller into four groups; unmodified as control, ZrO2 (Z), TiO2, (T), and SiO2 (S) groups. Each one was subdivided into two subgroups according to nanoparticle concentrations; 3% and 7% (Z3, Z7, T3, T7, S3, and S7). A 3-point bending test, Charpy impact test, and Vickers hardness test were used for flexural strength, impact strength, and hardness measurements, respectively. Wear resistance was measured by the differences in surface roughness of tested specimens before and after the wear test. A scanning electron microscope was used to assess nanoparticle specifications and distributions and for fracture surfaces analysis. ANOVA, Bonferroni's post hoc test, and the Kruskal-Wallis test were applied for data analysis (α = 0.05). Results: Regarding the flexural and impact strength, there was a statistically remarkable increase for all tested groups compared with the control group, except for the T7 and S7 groups (P value <0.001, effect size = 0.893) and (P value <0.001, effect size = 0.759), respectively. There was a statistically significant improvement in the hardness of all tested groups compared with the control group (P value <0.001, effect size = 0.67) except T3 and S3. Regarding wear, a statistically significant enhancement was noticed in the wear resistance of all tested groups (P value <0.001, effect size = 0.685), except for the T7 and S7 groups. Conclusion: The flexural strength, impact strength, and wear resistance improved with both concentrations of ZrO2 and low TiO2 and SiO2 concentrations. The hardness increased with both concentrations of ZrO2 and high TiO2 and SiO2 concentrations.

Evaluation of Surface Properties and Elastic Modulus of CAD-CAM Milled, 3D Printed, and Compression Moulded Denture Base Resins: An In Vitro Study.

Objectives: This study evaluated the surface roughness, surface hardness, and elastic modulus of CAD-CAM (Computer-aided design/computer-aided manufacturing) milled, three-dimensional printed and conventional compression-moulded denture base resins. Materials and Methods: Thirty specimens (65*10*3 mm) were fabricated and divided into 3 groups (10 for each group) according to the type of denture base resin, Group I contained specimens of milled denture base resin, Group II contained specimens of 3-dimensional printed denture base resin, Group III contained specimens of polymethyl methacrylate heat cured denture base resin. The surface roughness of all specimens was evaluated using an atomic force microscope. Then by using the three-point bending test, the elastic modulus of the 30 specimens was evaluated. Finally, after fracturing the specimens from the bending test, the fractured specimens of the 3 groups were used to evaluate hardness using the Vickers hardness test. Data were analyzed using one-way ANOVA and Tukey's pair-wise post hoc tests. Results: There were significant differences between the tested groups (P< 0.05). The milled denture base resins showed the lowest surface roughness (27.46 ± 5.45 nm) when compared with printed (47 ± 7.01 nm) and conventional (39.72 ± 4.72 nm) denture base resins (P< 0.05); however, there was a significant increase in elastic modulus and hardness of milled (3240.06 ± 61.23 MPa and 29.18 ± 3.44 Vickers hardness number) and conventional (3017.16 ± 215.32 MPa and 22.44 ± 0.98 Vickers hardness number) denture base resins when compared with printed denture (576.65 ± 37.73 MPa and 2.64 ± 0.37 Vickers hardness number) base resins (P< 0.05). Conclusions: Milled denture base resins showed the lowest surface roughness, and highest hardness and elastic modulus among the three groups.

Microbiological evaluation for antifungal activity of some metal oxides nanofillers incorporated into cold cured soft lining materials: clinical based study / Avaliação microbiológica da atividade antifúngica de algumas nanopartículas de óxidos metálicos incorporadas em materiais de revestimento macio curados a frio: estudo clínico

Objetivo: O objetivo do presente estudo foi avaliar a eficácia da adição de nanopartículas de óxido de zircônio (ZrO2), óxido de titânio (TiO2) e óxido de sílica (SiO2) a um material de revestimento macio curado a frio na adesão de Candida albicans (CA). Material e Método: Cinquenta e quatro pacientes foram selecionados e divididos em três grupos de acordo com a modificação do revestimento com nanopartículas de ZrO2, TiO2 e SiO2 (18 cada). Cada paciente recebeu prótese total maxilar com três cavidades, as cavidades foram revestidas com forro macio curado a frio modificado com diferentes concentrações (0%, 3% e 7%) de nanopartículas de óxido metálico. Nos dias 14 e 28, as trocas foram retiradas do local de realinhamento e imediatamente cultivadas para avaliação fúngica. O número de colônias foi contado, os dados coletados e explorados para normalidade usando o teste de Shapiro-Wilk e a transformação logarítmica da contagem de CA foi realizada. ANOVA para medidas repetidas e de uma via (one-way) foram usados, seguidos por teste de Tukey (HSD). O teste t independente foi usado para comparar as contagens de CA em diferentes períodos. Resultados: A adesão do CA foi significativamente diminuída pela adição de nanopartículas de ZrO2, TiO2 e SiO2 em comparação com o grupo controle, também a cobertura antifúngica aumentou com o aumento da concentração de nanopartículas (p <0,005). A maior contagem de CA foi identificada no grupo SiO2 seguido por ZrO2, enquanto TiO2apresentou a menor contagem de CA (p <0,001). Conclusão: Adição de diferentes nanopartículas; ZrO2, TiO2 e SiO2para revestimento macio curado a frio é um método eficaz para reduzir a adesão de CA (AU)

Objective: The aim of the current study was to evaluate the efficacy of addition of zirconium oxide (ZrO2), titanium oxide (TiO2), and silica oxide (SiO2) nanoparticles to cold-cured soft liner on adhesion of Candida albicans (CA). Material and Methods: Fifty-four patients had been selected and divided into three groups according to the modification of soft liner with ZrO2, TiO2, and SiO2 nanoparticles (18 each of). Each patient received maxillary complete denture having three cavities, the cavities were lined using cold cured soft liner modified with different concentration (0%, 3%, and 7%) of metal oxide nanoparticles. On days 14 and 28, swaps were taken out from relining site and immediately cultured for fungal evaluation. The number of colonies were counted, data collected and explored for normality using Shapiro-Wilk test, logarithmic transformation of CA count was performed. Repeated and one-way ANOVA were used followed by Tukey HSD. Independent-t test used to compare between CA counts at different periods. Results: The CA adhesion was significantly decreased by the addition of ZrO2, TiO2 and SiO2 nanoparticles in comparison with control group, also the antifungal coverage increased with nanoparticles concentration increased (P<0.005). The highest CA count was identified in group SiO2 followed by ZrO2, while TiO2 showed the lowest CA count (P <0.001). Conclusion: Addition of different nanoparticles; ZrO2, TiO2 and SiO2 to cold-cured soft liner is an effective method for reducing CA adhesion. (AU)

Influence of Different Beverages on the Color Stability of Nanocomposite Denture Base Materials.

BACKGROUND: The effect of beverages on nanocomposite denture base materials is neglected. Therefore, this study aimed to investigate the influence of different beverages (coffee, tea, cola, and mineral water) on the color stability of nanoparticles-modified denture base materials (DBMs). MATERIALS AND METHODS: A total of 280 specimens (n = 10/group) were prepared from heat-polymerized acrylic resin modified with different concentrations (3% and 7%) of zirconium dioxide (nano-ZrO2), titanium dioxide (nano-TiO2), and silicon dioxide (nano-SiO2) nanoparticles, while 0% was taken as a control. Color change (∆E) of the specimens was evaluated after simulating 6-month immersion time in four commonly used beverages, coffee, tea, cola, and mineral water, as experimental groups. Color stability was measured using a spectrophotometer, and then values were converted to National Bureau of Standards units (NBS units). The one-way ANOVA test was applied to compare color change (ΔE) results followed by Bonferroni's post hoc test (α = 0.05). RESULTS: The results showed that the heat-polymerized acrylic resin modified with different types of nanoparticles showed lower color changes after being immersed in beverage solutions compared to the unmodified group (P < 0.001), so the color stability of heat-polymerized acrylic resin was significantly enhanced by the addition of several nanoparticles; nano-ZrO2 showed the lowest ΔE followed by nano-TiO2 and then nano-SiO2. Regardless of the filler type, 3% concentration showed lower mean ΔE than 7% concentration. Regarding the beverage solutions, the greatest color change was found in the coffee group followed by tea and cola, while water showed the least changes. CONCLUSION: Modification of heat-polymerized acrylic resin with certain amounts of nano-ZrO2, nano-TiO2, and nano-SiO2 may be useful in improving color stability.

Effect of using Photobiomodulation, stabilization, and anterior repositioning splints on the pain level of subjects with temporomandibular joint disc displacement with reduction / Efeito do uso da terapia a laser de baixa potência, placas planas e placas reposicionadoras anterior, no nível de dor de indivíduos com deslocamento anterior do disco articular com redução

Objective: was to evaluate the effect of four conservative treatment modalities on the pain level of patients with temporomandibular joint (TMJ) anterior disc displacement with reduction (ADDwR). Material and methods:100 subjects (64 females and 36 males) were selected, divided into four groups, 25 patients of each. Subjects of Group I have been treated with behavioral therapy. Subjects of Group II had been treated with Photobiomodulation therapy (PBMT). Subjects of Group III had been treated by anterior repositioning splint (ARS). Subjects of Group IV had been treated by a stabilization splint. The pain was evaluated by visual analog score (VAS) from 0 to 10. Statistical analysis was done using one-way ANOVA test for comparison between groups. Within each group, a comparison between baseline and after treatment was done using paired t-test (p<0.05). Results: There was a statistical difference between the pain scores of the different groups after treatment (p≤0.05). Also, there were statistical differences between all groups (p≤0.05) except that between group II and group III (p˃0.05). Conclusion: The use of stabilization splint and ARS are effective non-invasive methods for reducing the pain level in the treatment of TMJ ADDwR cases.(AU)

Objetivo: avaliar o efeito de quatro modalidades de tratamento conservador no nível de dor de pacientes com deslocamento anterior do disco articular com redução. Material e Métodos: foram selecionados 100 indivíduos(64 mulheres e 36 homens), divididos em quatro grupos, 25 pacientes cada. Os indivíduos do Grupo I foram tratados com terapia comportamental. Os indivíduos do Grupo II foram tratados com terapia de fotobiomodulação. Os indivíduos do Grupo III foram tratados com placa de reposicionamento anterior. Os indivíduos do Grupo IV foram tratados com uma placa de estabilização. A dor foi avaliada pelo escala visual analógica (EVA) de 0 a 10. A análise estatística foi feita usando o teste ANOVA de uma via para comparação entre os grupos. Dentro de cada grupo, uma comparação entre a linha de base e após o tratamento foi feita usando o teste t pareado (p <0,05). Resultados: Houve diferença estatística entre os escores de dor dos diferentes grupos após o tratamento (p ≤ 0,05). Além disso, houve diferenças estatísticas entre todos os grupos (p ≤0,05), exceto entre o grupo II e o grupo III (p˃0,05). Conclusão: O uso de placa de estabilização e reposicionadora anterior são métodos não invasivos eficazes para reduzir o nível de dor no tratamento de casos de deslocamento anterior de disco articular sem redução.(AU)

Management of internal derangement of temporomandibular joint disc displacement with reduction using two different lines of treatment / Manejo do desarranjo interno do deslocamento de disco temporomandibular com redução utilizando dois tipos diferentes de tratamento

Objetive: This study was to compare the effectiveness of arthrocentesis versus the insertion of anterior repositioning splint (ARS) in improving the mandibular range of motion (MRM) for patients with the temporomandibular joint (TMJ) anterior disc displacement with reduction (ADDwR). Methods: 36 patients diagnosed as ADDwR were recruited and divided randomly into two groups. The first group (G1) was treated by arthrocentesis, and the second (G2) was treated using ARS. All patients were reexamined after six months. Results: Except that for protrusive movement, there were significant differences between the two groups for the percentage changes of the MRM as measured by the amount of pain free opening, unassisted opening, maximum assisted opening, right lateral and left lateral movements (p < 0.05). Conclusion: Within the context of the current study, the non-invasive, lower cost ARS, provided better results in improving the MRM when managing ADDwR cases. (AU)

Objetivo: O presente estudo comparou a eficácia da Artrocentese em relação à inserção da Placa Reposicionadora Anterior (PRA) na melhoria da Amplitude de Movimento Mandibular (AMM) para pacientes que apresentam Deslocamento de Disco Anterior com Redução (DDAcR) da Articulação Temporomandibular (ATM). Método: 36 pacientes diagnosticados como DDAcR foram recrutados e divididos aleatoriamente em dois grupos. O primeiro grupo (G1) foi tratado através da Artrocentese e o segundo (G2), tratado com a PRA. Todos os pacientes foram reexaminados após seis meses. Resultados: Com exceção do movimento protrusivo, houve diferenças significativas entre os dois grupos para as mudanças percentuais das medidas de AMM pela quantidade de abertura sem dor, abertura sem assistência, abertura máxima com assistência, movimentos laterais direitos e laterais esquerdos (p < 0,05). Conclusão: Dentro do contexto do estudo atual, a PRA, não invasiva e de menor custo, proporcionou melhores resultados na melhoria da AMM no gerenciamento de casos de DDAcR (AU)

Comparative study of some mechanical properties of cobalt chromium and polyether ether ketone thermoplastic removable partial denture clasps: an In-vitro Study / Estudo comparativo de algumas propriedades mecânicas dos grampos parciais removíveis termoplásticos removíveis termoplásticos de cobalto cromo e éter cetona: um estudo in vitro

Objective: was to evaluate the retentive force, fatigue resistance and deformity of clasps made from two materials cobalt chromium and poly ether ether ketone (PEEK). Material and Methods: sixteen models were fabricated,each one having lower 1st molar. Models were divided into two groups according to materials,group I (GI) for cobalt chromium (Co-Cr) and group II (GII) for PEEK. Each testing models and its clasps were mounted inside universal testing machine, the retention was measured by applying withdrawal force to it by this machine at 5 mm/min. The Fatigue resistance is measured by the reduction in retention through repeated insertion and removal cycles using robota chewing simulator. Removal and insertion cycling of clasps was carried out for 360, 730, 1080, 1,440, 2,116 and 2,880 cycles (corresponding to 3, 6, 9, 12, 18 and 24 months of simulated clinical use of a RPD) to simulate the fatigue resistance test. Deformity was measured before and after each cycling using a digital micrometer. Statistical analysis was done by 2-way-ANOVA test to detect significance effects of each variable. Results: Retention and fatigue resistance, after 360, 730, 1080, 1,440, 2,116 and 2,880 cycles totally the difference between Co-Cr and PEEK groups was statistically non-significant (P = 0.0980> 0.05) where (Co-Cr > PEEK). Deformation results, regardless to evaluation time, Co-Cr group recorded statistically significant higher deformation mean value than PEEK group (P = 0.008 < 0.05).Regardless to material group, deformation mean value changed nonsignificantly by time (P = 0.2882> 0.05). Conclusion: PEEK clasps (1.0 mm in cross section diameter) engage 0.50 mm undercut provide sufficient retention nearly similar that of Co-Cr clasps.(AU)

Objetivo: o objetivo foi avaliar a força de retenção, a resistência à fadiga e a deformidade dos grampos fabricados com dois materiais diferentes: cromo-cobalto (Co-Cr) e poliéter-éter-étercetona (PEEK). Materiais e métodos: dezesseis modelos foram confeccionados, cada um com 1º molar inferior. Os modelos foram divididos em dois grupos de acordo com o material: grupo I Co-Cr e grupo II para PEEK. Cada modelo de teste universal e seus grampos foram montados em uma máquina de teste universal. A retenção foi medida aplicando força de retirada por esta máquina a 5 mm/min. A resistência à fadiga foi medida pela redução na retenção através de ciclos repetidos de inserção e remoção usando um simulador do ciclo de mastigação. O ciclo de remoção e inserção dos grampos foi realizado por 360, 730, 1080, 1.440, 2.116 e 2.880 ciclos (correspondendo a 3, 6, 9, 12, 18 e 24 meses de uso clínico simulado de um RPD) para simular o teste de resistência à fadiga. A deformidade foi medida antes e após cada ciclo, usando um micrômetro digital. A análise estatística foi realizada pelo teste ANOVA de 2 fatores para detectar os efeitos de significância de cada variável. Resultados: A retenção e a resistência à fadiga após 360, 730, 1080, 1.440, 2.116 e 2.880 ciclos entre os grupos Co-Cr e PEEK não mostrou diferença estatisticamente significativa (p = 0,0980> 0,05), onde (Co-Cr> PEEK). Para os resultados da deformação, independentemente do tempo de avaliação, o grupo Co-Cr registrou um valor médio de deformação maior, com diferença estatística significativa, quando comparado com o grupo PEEK (p= 0,008 < 0,05). Independentemente do grupo de material, o valor médio da deformação foi alterado de forma não significativa pelo tempo (p= 0,2882> 0,05). Conclusão: os grampos PEEK (1,0 mm de diâmetro da seção transversal) engatam 0,50 mm retenção quase semelhante à dos grampos Co-Cr (AU)

Evaluation of lower facial heights as related to different anthropometric measurements in dentate and completely edentulous subjects.

OBJECTIVE: The aim was to compare two measurements of lower facial height (base of chin-subnasale and base of chin- tip of the nose) as related to different anthropometric measurements in dentate and completely edentulous subjects. METHOD AND MATERIALS: This cross-sectional study was conducted on 132 male subjects (group 1 [G1], 120 dentate subjects; and group 2 [G2], 12 completely edentulous subjects). Base of chin-subnasale measurement (FM1), base of chin-tip of the nose measurement (FM2), Willis' measurement (FM3), glabella-subnasale measurement (FM4), length of the index finger measurement (AM1), and tip of thumb-tip of index finger measurement (AM2) of subjects of G1 and G2 were measured by using a modified caliper while the subjects in G1 closed in centric occlusion, and the subjects of G2 were asked to close the maxillary and mandibular complete dentures in centric relation. Statistical analysis was carried out by using paired t test, Pearson's correlation (PC), and regression analysis. RESULTS: There were no significant differences between G1FM1 and G1FM3, G1FM1 and G1FM4, G1FM1 and G1AM2 (P > .05), and PCs were R = 0.74, R = -0.35, and R = -0.32 respectively. However, there were significant differences between G1FM2 and G1FM3, G1FM2 and G1FM4, G1FM2 and G1AM2 (P ≤ .05), and there were significant differences between G2FM2 and different measurements of G2 (P ≤ .05). CONCLUSION: The use of the linear equation to predict the possible base of chin-subnasale measurement through the Willis' measurement was recommended and could be used as a guide during restoration of the vertical dimension of occlusion when it has been lost.