Hardness and surface roughness of enamel and base layers of resin denture teeth after long-term repeated chemical disinfection.

AIM: To evaluate the effect of successive cycles of disinfection in different denture cleansers on the surface roughness and the Vickers hardness of two layers of acrylic resin (base-BL and enamel-EL) of two commercial cross-linked artificial teeth. MATERIALS AND METHODS: The occlusal surfaces of 60 acrylic resin denture posterior teeth (Trilux-TLX and SR Orthosit PE-SRO) embedded in autopolymerizing acrylic resin were ground fat with 1200-grit silicon carbide paper. Specimens were stored in distilled water at 37°C and then submitted to the microhardness (VHN) and roughness (µm) tests. Specimens were stored in distilled water at 37°C for 90 days and submitted to 720 disinfection cycles in sodium hypochlorite at 0.5%, 30% vinegar solution or distilled water (control). Afterward, micro-hardness and roughness tests were again performed. Data were analyzed using two-way ANOVA and Tukey's test (α=0.05). RESULTS: Hypochlorite immersion decreased the hardness of BL and EL of SRO teeth, with an average reduction of 10.11% (p<0.008). TLX teeth demonstrated a hardness reduction of 28.96% of both layers for all solutions including water (p<0.0000). The roughness of both teeth was not affected by denture cleansers (p>0.37). CONCLUSION: Hypochlorite promoted deleterious effects on the hardness of both layers of the artificial teeth tested. Immersion in vinegar and water also resulted in reduction of hardness of TLX teeth. CLINICAL SIGNIFICANCE: The surface hardness of the different layers of cross-linked artificial teeth can be altered by daily disinfection in denture cleansers commonly indicated for removable dentures.

Resolution of complex esthetic problems in abnormal anterior teeth: a clinical report.

A conservative treatment is presented for a patient with complex severe esthetic problems related to the presence of anomalous teeth. The patient showed a rare occurrence of macrodontia of the maxillary right lateral incisor and microdontia of the maxillary left lateral incisor. The treatment plan was conservative to avoid tooth extraction, periodontal tissue trauma, and the risk of an unpredictable esthetic outcome. A multidisciplinary treatment involving orthodontic extrusion, endodontic therapy, periodontal therapy, and minimally invasive restorations was performed. A successful outcome was observed after a 2-year follow-up.

Influence of technique and manipulation on self-adhesive resin cements used to cement intraradicular posts.

STATEMENT OF PROBLEM: Resin cements are widely used to cement intraradicular posts, but bond strength is significantly influenced by the technique and material used for cementation. PURPOSE: The purpose of this study was to evaluate the bond strength of 3 self-adhesive cements used to cement intraradicular glass fiber posts. The cements all required different application and handling techniques. MATERIAL AND METHODS: Forty-five human maxillary canines were selected and randomly divided into 3 groups n= 15 by drawing lots: Group BIS - Biscem, Group BRE - Breeze, and Group MAX - Maxcem. Each group was divided into 3 subgroups according to application and handling techniques: Sub-group A - Automix/Point tip applicator, Sub-group L - Handmix/Lentulo, and Sub-group C - Handmix/Centrix. Cementation of the posts was performed according to the manufacturers' instructions. The push-out test was performed with a crosshead speed of 0.5 mm/min, and bond strength was expressed in megapascals. The results were evaluated by 2-way ANOVA and the all pairwise multiple comparison procedures (Tukey test) (α=.05). RESULTS: Breeze cement showed the highest average for the subgroups A, L, and C when compared to the Biscem cement and Maxcem Elite (P<.05). Statistically significant differences among the subgroups were only observed for Biscem. CONCLUSIONS: This study shows that application and handling techniques may influence the bond strength of different self-adhesive cements when used for intraradicular post cementation.

Gingival recession in individuals with cleft lip and palate: prevalence and severity.

OBJECTIVE: To analyze the prevalence and severity of gingival recession in individuals with cleft lip and alveolus with or without cleft palate. DESIGN: Cross-sectional. SETTING: Tertiary referral hospital. PARTICIPANTS: A total of 400 individuals with cleft lip and alveolus with or without cleft palate, aged 15 to 49 years, without any previous periodontal treatment. MAIN OUTCOME MEASURES: Gingival recession was evaluated by measuring the distance from the cementoenamel junction to the most coronal point on the gingival margin, analyzing the prevalence and scoring its severity as mild (<3 mm), moderate (3 to 4 mm), or severe (4 mm). The prevalence and severity of gingival recession was compared between sextant 2 (cleft sextant) and the mean of the other sextants (1, 3, 4, 5, and 6: noncleft sextants). The relationship between gingival recession in the cleft area and gender was evaluated and data were analyzed statistically. The correlation between gingival recession and age was assessed also. RESULTS: There was no statistically significant gender difference in gingival recession. The prevalence and severity of gingival recession increased with age, and most of the affected teeth were premolars and molars. The cleft area did not present a higher prevalence and severity of gingival recession. CONCLUSIONS: Individuals with cleft lip and alveolus with or without cleft palate presented the same prevalence and severity of gingival recession compared with other populations. The area adjacent to the cleft (sextant 2) did not show greater risk of gingival recession than other areas (sextants 1, 3, 4, 5, and 6).

Influence of the composition and shades of ceramics on light transmission and degree of conversion of dual-cured resin cements.

OBJECTIVE: Since the transmittance of ceramics can influence the degree of conversion (DC) of resin cements, ceramics composition and shade should be considered in the selection of resin cement. This in vitro study aimed to evaluate the effect of the transmittance of different composition, opacities and shades of ceramics on the degree of conversion of two dual-cured resin cements. METHODOLOGY: Sixty discs were prepared from low translucency (LT) and medium opacity (MO) lithium disilicate ceramic, and zirconia ceramic (Z). Each group was subdivided into 5 subgroups (n=4) in shades A2, A3.5, B2, C2 and D3. The transmittance measurement was performed in a spectrophotometer. The Variolink II and Rely X U200 resin cements were photoactivated by LED (1400 mW/cm2) for 40 s through the ceramic discs and without the discs (control group). The DC was measured with infrared FTIR spectroscopy, immediately after light activation. Data were analyzed with Kruskall-Wallis and one-way ANOVA, following post-hoc comparisons by Tukey test and Pearson's correlation test (P<0.05). RESULTS: LT ceramic exhibited higher transmittance values compared to MO and Z ceramics. LTA2 and LTB2 showed statistically higher transmittance values compared to MOA2, MOA3.5 and ZA3.5. For Variolink II, the ceramic interposition did not influence the DC, since there were no statistical differences between groups with ceramic interposition and the control group. For Rely X U200 cement, the interposition of some ceramics types/shades (LTA3.5, MOA2, MOA3.5 and ZA3.5) significantly decreased the DC values compared to control group. A positive correlation was found between the ceramic transmittance and DC values of both tested cements. Conclusions. The transmittance and DC values of the cements were influenced by composition and shades of the ceramics. The higher the transmittance of ceramics, the higher the DC values for both cements.

Effect of aging and testing method on bond strength of CAD/CAM fiber-reinforced composite to dentin.

OBJECTIVES: To evaluate and compare the outcomes of shear (S) and microtensile (µT) bond strength tests of CAD/CAM fiber-reinforced composite (FRC) to dentin. Aging with either fatigue or thermocycling were conducted for comparison with baseline microtensile group. METHODS: CAD/CAM FRC (Trinia, Bicon LLC, Boston, USA) blocks were milled to 3-mm diameter cylinders for shear and to blocks (5×5×5mm) for µT. Sixty extracted human molars were flattened to obtain dentin surfaces and randomly divided in four groups (n=15): (1) SC: samples tested in shear 24h after bonding; (2) µTC: samples tested in µT 24h after bonding); (3) µTF: samples submitted to mechanical fatigue prior to µT test, and; (4) µTT: thermocycling prior to µT test. Bonding system was applied onto the FRC material (Cera-Resin Bond, CRB, Shofu Dental, Kyoto, Japan). A conventional three-step adhesive system (All-bond 3, Bisco, Schaumburg, USA) was use with a self-cure resin cement (C&B resin cement, Bisco, Schaumburg, USA). Bond strength tests were conducted at 0.75mm/min and data analyzed using Weibull distribution (p<0.05). RESULTS: Weibull contour plots showed a significantly lower characteristic strength (η) and Weibull modulus (m) for SC (η=6.9MPa and m=1.4) compared to µTC (η=20.9MPa and m=4.5). Fatigued and thermocycled µT groups presented significantly reduced characteristic strength (η=3.1MPa and η=4.1MPa, respectively) compared to µTC. Weibull modulus was significantly reduced only for SC and µTF groups compared µTC. Failure predominantly occurred at the cement/FRC interface. SIGNIFICANCE: FRC bonded to dentin samples presented lower Weibull modulus and characteristic bond strength when immediately tested in shear compared to microtensile. Aging through thermocycling or mechanical fatigue significantly reduced the characteristic strength in microtensile testing, with the majority of failures emerging between restoration material and cement interface.

Measurement properties of gingival biotype evaluation methods.

BACKGROUND: There are numerous methods to measure the dimensions of the gingival tissue, but few have compared the effectiveness of one method over another. OBJECTIVE: This study aimed to describe a new method and to estimate the validity of gingival biotype assessment with the aid of computed tomography scanning (CTS). MATERIALS AND METHODS: In each patient different methods of evaluation of the gingival thickness were used: transparency of periodontal probe, transgingival, photography, and a new method of CTS). Intrarater and interrater reliability considering the categorical classification of the gingival biotype were estimated with Cohen's kappa coefficient, intraclass correlation coefficient (ICC), and ANOVA (P < .05). The criterion validity of the CTS was determined using the transgingival method as the reference standard. Sensitivity and specificity values were computed along with theirs 95% CI. RESULTS: Twelve patients were subjected to assessment of their gingival thickness. The highest agreement was found between transgingival and CTS (86.1%). The comparison between the categorical classifications of CTS and the transgingival method (reference standard) showed high specificity (94.92%) and low sensitivity (53.85%) for definition of a thin biotype. CONCLUSION: The new method of CTS assessment to classify gingival tissue thickness can be considered reliable and clinically useful to diagnose thick biotype.

Cements for use in esthetic dentistry.

Dental cements are designed to retain restorations, appliances, and post and cores in a stable and, presumably, long-lasting position in the oral environment. Conventional glass ionomer and zinc phosphate cements are among the most popular materials for luting metallic restorations and posts, whereas resin-based cements are preferred for esthetic applications. Successful cementation of esthetic restorations is largely dependent on the appropriate treatment and silane application to the internal surface of the restoration. Clinicians are frequently advised to use three-step total-etch or two-step self-etch adhesive for luting purposes to avoid problems of incompatibility between adhesives and chemical- or dual-cure cements. A reliable cementation procedure can only be achieved if the operator is aware of the mechanisms involved and the material limitations.

Influence of curing protocol and ceramic composition on the degree of conversion of resin cement.

OBJECTIVE: Due to increasing of aesthetic demand, ceramic crowns are widely used in different situations. However, to obtain long-term prognosis of restorations, a good conversion of resin cement is necessary. To evaluate the degree of conversion (DC) of one light-cure and two dual-cure resin cements under a simulated clinical cementation of ceramic crowns. MATERIAL AND METHODS: Prepared teeth were randomly split according to the ceramic's material, resin cement and curing protocol. The crowns were cemented as per manufacturer's directions and photoactivated either from occlusal suface only for 60 s; or from the buccal, occlusal and lingual surfaces, with an exposure time of 20 s on each aspect. After cementation, the specimens were stored in deionized water at 37°C for 7 days. Specimens were transversally sectioned from occlusal to cervical surfaces and the DC was determined along the cement line with three measurements taken and averaged from the buccal, lingual and approximal aspects using micro-Raman spectroscopy (Alpha 300R/WITec®). Data were analyzed by 3-way ANOVA and Tukey test at =5%. RESULTS: Statistical analysis showed significant differences among cements, curing protocols and ceramic type (p<0.001). The curing protocol 3x20 resulted in higher DC for all tested conditions; lower DC was observed for Zr ceramic crowns; Duolink resin cement culminated in higher DC regardless ceramic composition and curing protocol. CONCLUSION: The DC of resin cement layers was dependent on the curing protocol and type of ceramic.

Seven-Year Follow-up of Full-Arch Prostheses Supported by Four Implants: A Prospective Study.

PURPOSE: To evaluate biologic and prosthetic outcomes of implant-supported mandibular full-arch fixed prostheses treated with the All-on-4 treatment concept after 7 years. MATERIALS AND METHODS: Patients were selected to receive full-arch fixed immediate prostheses supported by four implants up to 72 hours after surgery. The following biologic aspects were evaluated: Plaque Index (PI) and Bleeding Index (BI), implant stability by resonance frequency, and marginal bone loss (MBL) measured with the aid of periapical radiographs. The prosthetic complications evaluated were related to screw loosening, framework or acrylic teeth fractures, or fractures of implants. The means of implant stability and MBL were subjected to analysis of variance and the Tukey test (P < .05). For PI and BI, the Friedmann test was used (P < .05). RESULTS: Sixteen patients (12 women and 4 men; mean age: 59.1 years) received 64 implants, and in all patients, two implants were positioned axially at the incisor region and two distally tilted implants at the region of the second premolars or molars. Patients were evaluated immediately after surgery and at 1, 2, and 7 years. Fifteen patients attended the recall after 2 years; one patient could not attend the scheduled follow-up visit and was excluded from the sample. In the 7-year evaluation, the sample size decreased to 12 patients; one could not attend because of a severe disease, and two were deceased. The cumulative implant survival rate was 100%. There was a significant (P < .0162) decrease in PI at the 1- and 7-year evaluations (71.87% and 47.92%, respectively), while the BI was the same at 1 and 7 years (43.75%). There was no statistical difference in MBL (P = .12) and implant stability (P = .48) between axial and tilted implants (P = .48). The survival rate of prostheses was 100%. The following technical complications were observed: tooth fracture occurred in one patient (6.25%); loosening of prosthetic screws and abutments were observed in three patients (18.75%); after 5 years, three patients (18.75%) had changed the denture acrylic teeth because of the replacement of the removable total maxillary prostheses with fixed implant prostheses. CONCLUSION: For the 12 patients who attended the recall after 7 years, implant loss was not found, the implant stability was high, MBL was low, and prosthetic complications were easily solved. Thus, it can be concluded that rehabilitation with implant-supported mandibular full-arch fixed prostheses with four implants has proved to be a treatment with a high survival rate.

Noncarious cervical lesions in adults: prevalence and occlusal aspects.

BACKGROUND: The factors that induce the formation of noncarious lesions are not understood fully, particularly those that are related to occlusal aspects. The authors conducted a study to evaluate the prevalence of noncarious cervical lesions in adults and their association with occlusal aspects. METHODS: The authors examined 70 people (35 men and 35 women) aged 25 to 45 years to determine the presence and type of noncarious cervical lesions, wear facets, tooth contacts in maximal intercuspal position, and lateral and protrusive movements. The assessment involved a questionnaire and clinical examination. RESULTS: Among the teeth the authors evaluated, 17.23 percent had cervical lesions, 80.28 percent of which had wear facets (P < .01). The authors found a significant difference between the prevalence of noncarious lesions and the presence of wear facets (P = .0484). CONCLUSIONS: The authors found that cervical lesions were related significantly to wear facets. These findings strengthen evidence for the role of occlusal forces as an etiologic factor for noncarious lesions. CLINICAL IMPLICATIONS: The presence of wear facets should be considered in the treatment of noncarious cervical lesions.

Effect of conventional water-bath and experimental microwave polymerization cycles on the flexural properties of denture base acrylic resins.

The effect of polymerization cycles on flexural properties of conventional (Vipi Cril(®)-VC) or microwave-processed (Vipi Wave(®)-VW) denture base acrylic resins was evaluated. Specimens (n=10) were submitted to the cycles: WB=65ºC for 1 h+1 h boiling water (VC cycle); M630/25=10 min at 270 W+5 min at 0 W+10 min at 360 W (VW cycle); M650/5=5 min at 650 W; M700/4=4 min at 700 W; and M550/3=3 min at 550 W. Specimens were submitted to a three-point bending test at 5 mm/min until fracture. Flexural strength (MPa) and elastic modulus (GPa) data were analyzed by 2-way ANOVA/Tukey HSD (α=0.05). Overall, VC showed higher values than VW. The results obtained with microwave polymerization did not differ from those obtained with water-bath for both acrylic resins. The results observed when polymerization cycles using medium power and shorter time were used did not differ from those when manufacturer's recommended microwave cycle was applied. Conventional VC might be microwave-processed without compromising its flexural properties.

Digitally produced fiber-reinforced composite substructures for three-unit implant-supported fixed dental prostheses.

PURPOSE: This study aimed to evaluate the probability of survival, Weibull modulus, characteristic strength, and failure modes of computer-aided design/computer-assisted manufacture (CAD/CAM) fiber-reinforced composite (FRC) substructures used for implant-supported fixed dental prostheses (ISFDPs). MATERIALS AND METHODS: Three-unit ISFDPs (first molar pontic) fabricated as a monolithic composite piece or as composite veneered on a CAD/CAM FRC substructure with either a 12-mm² or 3-mm² connector area (n = 18 each) were subjected to step-stress accelerated life testing in water. Use-level probability Weibull curves and the probability of survival were calculated. Fractographic analysis was performed under polarized light and scanning electron microscopy. RESULTS: Fatigue did not accelerate the failure of any group, whereas prosthesis strength was the main factor in increased failure (ß < 1). The probability Weibull contour plot showed no differences between the ISFDPs with 12 mm² and the monolithic composite ISFDP in characteristic strength (η = 643.5 N and 742.7 N, respectively) or Weibull modulus (6.7 and 5.8, respectively), whereas both were significantly higher than 3 mm² (444.91 N and 9.57). The probability of survival was not statistically different between groups at 100,000 mission cycles at 300 N. Differences were observed in fatigue failures above 800 N; monolithic composite ISFDPs failed catastrophically, whereas those with CAD/CAM FRC substructures presented veneer/composite cohesive or adhesive failures. Cracks evolved from the occlusal contact toward the margins of the cohesively failed composite, and in CAD/CAM FRC prostheses, competing failure modes of cracks developing at the connector area with those at the indentation contact were observed. CONCLUSION: The probability of survival did not differ between CAD/CAM FRC with either 3-mm² or 12-mm² connector areas, monolithic composite, or metal-ceramic ISFDPs previously tested under the same methodology. However, differences in failure modes were detected between groups.

Effects of coronal substrates and water storage on the microhardness of a resin cement used for luting ceramic crowns.

UNLABELLED: Composite resin and metallic posts are the materials most employed for reconstruction of teeth presenting partial or total destruction of crowns. Resin-based cements have been widely used for cementation of ceramic crowns. The success of cementation depends on the achievement of adequate cement curing. OBJECTIVES: To evaluate the microhardness of Variolink® II (Ivoclar Vivadent, Schaan, Liechtenstein), used for cementing ceramic crowns onto three different coronal substrate preparations (dentin, metal, and composite resin), after 7 days and 3 months of water storage. The evaluation was performed along the cement line in the cervical, medium and occlusal thirds on the buccal and lingual aspects, and on the occlusal surface. MATERIAL AND METHODS: Thirty molars were distributed in three groups (N=10) according to the type of coronal substrate: Group D- the prepared surfaces were kept in dentin; Groups M (metal) and R (resin)- the crowns were sectioned at the level of the cementoenamel junction and restored with metallic cast posts or resin build-up cores, respectively. The crowns were fabricated in ceramic IPS e.max® Press (Ivoclar Vivadent, Schaan, Liechtenstein) and luted with Variolink II. After 7 days of water storage, 5 specimens of each group were sectioned in buccolingual direction for microhardness measurements. The other specimens (N=5) were kept stored in deionized water at 37ºC for three months, followed by sectioning and microhardness measurements. RESULTS: Data were first analyzed by three-way ANOVA that did not reveal significant differences between thirds and occlusal surface (p=0.231). Two-way ANOVA showed significant effect of substrates (p<0.001) and the Tukey test revealed that microhardness was significantly lower when crowns were cemented on resin cores and tested after 7 days of water storage (p=0.007). CONCLUSION: The type of material employed for coronal reconstruction of preparations for prosthetic purposes may influence the cement properties.

Influence of the composition and shades of ceramics on light transmission and degree of conversion of dual-cured resin cements

Abstract Objective Since the transmittance of ceramics can influence the degree of conversion (DC) of resin cements, ceramics composition and shade should be considered in the selection of resin cement. This in vitro study aimed to evaluate the effect of the transmittance of different composition, opacities and shades of ceramics on the degree of conversion of two dual-cured resin cements. Methodology Sixty discs were prepared from low translucency (LT) and medium opacity (MO) lithium disilicate ceramic, and zirconia ceramic (Z). Each group was subdivided into 5 subgroups (n=4) in shades A2, A3.5, B2, C2 and D3. The transmittance measurement was performed in a spectrophotometer. The Variolink II and Rely X U200 resin cements were photoactivated by LED (1400 mW/cm2) for 40 s through the ceramic discs and without the discs (control group). The DC was measured with infrared FTIR spectroscopy, immediately after light activation. Data were analyzed with Kruskall-Wallis and one-way ANOVA, following post-hoc comparisons by Tukey test and Pearson's correlation test (P<0.05). Results LT ceramic exhibited higher transmittance values compared to MO and Z ceramics. LTA2 and LTB2 showed statistically higher transmittance values compared to MOA2, MOA3.5 and ZA3.5. For Variolink II, the ceramic interposition did not influence the DC, since there were no statistical differences between groups with ceramic interposition and the control group. For Rely X U200 cement, the interposition of some ceramics types/shades (LTA3.5, MOA2, MOA3.5 and ZA3.5) significantly decreased the DC values compared to control group. A positive correlation was found between the ceramic transmittance and DC values of both tested cements. Conclusions. The transmittance and DC values of the cements were influenced by composition and shades of the ceramics. The higher the transmittance of ceramics, the higher the DC values for both cements.

O impacto positivo na promoção de saúde bucal em jovens adolescentes / The Positive Impact on Oral Health Promotion in Young Adolescents

Introdução: o conhecimento da importância dos cuidados em saúde bucal é deficiente em âmbito escolar, ressalta-se que jovens capacitados, partilham o aprendizado assumindo papel importante na sociedade. Objetivos: capacitação de estudantes para difusão do conhecimento sobre cuidados em saúde bucal. Os temas de higienização dentária/prótese dentária e/ou implantossuportadadas e manejo após o traumatismo dentário foram abordados em escola pública. Métodos: Inicialmente, houve avaliação do conhecimento prévio dos alunos (n=25) por meio de questionários de saúde bucal, os questionários (GOHAI, higienização oral e de prótese dentária e manejo de traumatismo dentário) foram aplicados na sala de aula com supervisão. Em um próximo momento houve o treinamento dos discentes por palestras e material didático. Finalmente, após 2 meses do ciclo de formação os questionários foram aplicados novamente. Os dados foram tabulados e e análise estatística considerou o valor significativo para p<0,05, a fim de verificar o conhecimento adquirido durante o treinamento de todos os estudantes. Resultados: Identificou se pós-oficina que os jovens estavam mais satisfeitos com a aparência da boca (p<0,05). Nos questionários de higienização de próteses dentárias houve a conscientização do tempo para substituição das mesmas. Para o reimplante dentário, houve significativa percepção dos alunos como possibilidade de terapia real (p=0,016), após a realização das oficinas. Conclusão: com base nos dados, a proposta de promoção em saúde bucal para os adolescentes foi eficiente, e mais eventos (oficinas) com esta finalidade devem ser realizados em escolas de ensino médio.

Introduction: the knowledge of the importance of oral health care is deficient in the school environment, it is emphasized that empowered young people share learning, assuming an important role in society. Objectives: This study aimed to enable the training of students to disseminate knowledge about oral health care. The subjects of dental hygiene / dental prosthesis and / or implant supported and management after dental trauma were addressed in a public school. Methods: Initially, the students' prior knowledge (n = 25) was assessed through oral health questionnaires, the questionnaires (GOHAI, oral and dental hygiene and dental trauma management) were applied in the classroom with supervision. In a next moment there was the training of the students by lectures and didactic material. Finally, after 2 months of the training cycle, the questionnaires were applied again. Data were tabulated and statistical analysis considered the value significant for p students. Results: It was identified after the workshop that young people were more satisfied with the appearance of the mouth (p<0,05).In the dental prosthesis cleaning questionnaires, there was a time awareness for their replacement. For dental replantation, there was significant perception of students as a possibility of real therapy (p = 0.016), after the workshops. Conclusion: Based on the data, the proposal for oral health promotion for adolescents was efficient, and more events (workshops) for this purpose should be held in high schools.

Effects of curing protocol and storage time on the micro-hardness of resin cements used to lute fiber-reinforced resin posts.

OBJECTIVES: To determine the micro-hardness profile of two dual cure resin cements (RelyX-U100, 3M-eSPe and Panavia F 2.0, Kuraray) used for cementing fiberre inforced resin posts (Fibrekor-Jeneric Pentron) under three different curing protocols and two water storage times. MATERIAL AND METHODS: Sixty 16 mm long bovine incisor roots were endodontically treated and prepared for cementation of the Fibrekor posts. The cements were mixed as instructed, dispensed in the canal, the posts were seated and the curing performed as follows: (a) no light activation; (b) light-activation immediately after seating the post, and; (c) light-activation delayed 5 minutes after seating the post. The teeth were stored in water and retrieved for analysis after 7 days and 3 months. The roots were longitudinally sectioned and the microhardness was determined at the cervical, middle and apical regions along the cement line. The data was analyzed by the three-way ANOVA test (curing mode, storage time and thirds) for each cement. The Tukey test was used for the post-hoc analysis. RESULTS: Light-activation resulted in a significant increase in the microhardness. This was more evident for the cervical region and for the Panavia cement. Storage in water for 3 months caused a reduction of the micro-hardness for both cements. The U100 cement showed less variation in the micro-hardness regardless of the curing protocol and storage time. CONCLUSIONS: The micro-hardness of the cements was affected by the curing and storage variables and were material-dependent.

Influence of curing protocol and ceramic composition on the degree of conversion of resin cement

Abstract Due to increasing of aesthetic demand, ceramic crowns are widely used in different situations. However, to obtain long-term prognosis of restorations, a good conversion of resin cement is necessary. Objective: To evaluate the degree of conversion (DC) of one light-cure and two dual-cure resin cements under a simulated clinical cementation of ceramic crowns. Material and Methods: Prepared teeth were randomly split according to the ceramic's material, resin cement and curing protocol. The crowns were cemented as per manufacturer's directions and photoactivated either from occlusal suface only for 60 s; or from the buccal, occlusal and lingual surfaces, with an exposure time of 20 s on each aspect. After cementation, the specimens were stored in deionized water at 37°C for 7 days. Specimens were transversally sectioned from occlusal to cervical surfaces and the DC was determined along the cement line with three measurements taken and averaged from the buccal, lingual and approximal aspects using micro-Raman spectroscopy (Alpha 300R/WITec®). Data were analyzed by 3-way ANOVA and Tukey test at =5%. Results: Statistical analysis showed significant differences among cements, curing protocols and ceramic type (p<0.001). The curing protocol 3x20 resulted in higher DC for all tested conditions; lower DC was observed for Zr ceramic crowns; Duolink resin cement culminated in higher DC regardless ceramic composition and curing protocol. Conclusion: The DC of resin cement layers was dependent on the curing protocol and type of ceramic.

Polylactic/polyglycolic acid copolymer is a good carrier for bmp-2 on bone regeneration? / Copolímero do ácido polilático/poliglicólico é um bom carreador para bmp-2 na regeneração óssea?

The aim of this work was to evaluate the role of polylactic /polyglycolic acid copolymer as carrier for BMP-2 on bone regeneration in rat calvarium. Forty five adult male rats underwent 5-mm critical defects in bone calvaria to be divided into three groups according to the filling materials: Control-blood clot; PLGA-polylactic acid Polyglycolic/copolymer; PLGA + BMP-2 -polylactic acid Polyglycolic/copolymer associated with BMP-2. Sacrifice of animals occurred at 5, 15 and 30 days after surgery The evaluation of new bone formation was obtained by histomorphometry, while OPG and RANKL proteins were observed by immunohistochemistry. Statistical analysis was performed by means of nonparametric tests based on quantitative variables of independent samples. Considering the amount of newly formed bone, significant difference was detected between PGLA (178,2±137,5µm) and the other groups, at day 30. In PLGA + BMP-2 and control groups, the expression of RANKL was prevalent on the OPG in the periods of 15 and 30 days, suggesting a favorable condition for bone reabsorption in these periods. Therefore, immunoexpression of RANKL and OPG and bone formation observed in different groups and periods of analysis showed that the polylactic/polyglycolic acid copolymer does not act as a good carrier for BMP-2.

O objetivo deste estudo foi avaliar o copolímero do ácido polilático/poliglicólico como carreador para BMP-2 na regeneração óssea da calvária de ratos. Foram utilizados 45 ratos adultos machos. Defeitos ósseos críticos de 5mm de diâmetro foram realizados com uma broca trefina na calvária dos animais. Os animais foram divididos em três grupos, de acordo com o material de notas para preenchimento dos defeitos: Controle - coágulo; PLGA - copolímero ácido polilático/poliglicólico; PLGA + BMP-2 - copolímero do ácido polilático/poliglicólico associado a BMP-2. O sacrifício ocorreu aos 5, 15 e 30 dias após a cirurgia. A avaliação da neoformação óssea foi obtida por histomorfometria, enquanto a análise de marcação para as proteínas OPG e RANKL foi observada por imunohistoquímica. Análises estatísticas foram realizadas por meio de testes não paramétricos de variáveis quantitativas em amostras independentes. Com relação à quantidade de tecido ósseo neoformado, observou-se diferença estatística significante entre o grupo PLGA (178,2±137,5µm) e os demais, no período de 30 dias. Nos grupos PLGA+BMP-2 e Controle, a marcação de RANKL foi predominante sobre a marcação de OPG nos períodos de 15 e 30 dias, evidenciado uma condição favorável para a reabsorção óssea nestes períodos. Portanto, a marcação de RANKL e OPG, e a formação óssea observada nos diferentes grupos e tempos de análise mostrou que o copolímero de ácido polilático/poliglicólico não atua como um bom carreador para BMP-2.

Cements and adhesives for all-ceramic restorations.

Dental cements are designed to retain restorations, prefabricated or cast posts and cores, and appliances in a stable, and long-lasting position in the oral environment. Resin-based cements were developed to overcome drawbacks of nonresinous materials, including low strength, high solubility, and opacity. Successful cementation of esthetic restorations depends on appropriate treatment to the tooth substrate and intaglio surface of the restoration, which in turn, depends on the ceramic characteristics. A reliable resin cementation procedure can only be achieved if the operator is aware of the mechanisms involved to perform the cementation and material properties. This article addresses current knowledge of resin cementation concepts, exploring the bonding mechanisms that influence long-term clinical success of all-ceramic systems.