O uso de resina composta restauradora preaquecida como agente de cimentação influencia na adaptação de restaurações indiretas? Revisão Sistemática / Does the use of preheated restorative resin composite as luting agent influence on the adaptation of indirect restorations? Systematic review

Uma revisão sistemática foi realizada para responder a seguinte pergunta: O uso de resina composta preaquecida como agente de cimentação influencia na adaptação de restaurações indiretas? Foram selecionados estudos que avaliaram a adaptação das restaurações indiretas, sobre dentes naturais ou artificiais preparados, e que compararam a resina composta restauradora preaquecida, como agente de cimentação com o cimento resinoso. A avaliação do risco de viés foi baseada em uma lista de verificação de 9 itens. MEDLINE via PubMed, EMBASE, Web of Science, Scopus, LILACS e BBO via Virtual Health Library, Cochrane Library e bancos de dados da literatura cinzenta foram pesquisados, sem restrição de idioma ou ano. Dos 2046 estudos potencialmente elegíveis, 4 estudos in vitro foram incluídos nesta revisão. Enquanto em um dos estudos incluídos a resina composta restauradora preaquecida melhorou a adaptação das restaurações indiretas; de acordo com os outros três estudos, o material produziu uma desadaptação significativamente maior em comparação ao cimento resinoso. Todos os estudos incluídos apresentaram médio risco de viés. O elevado nível de heterogeneidade entre os estudos excluiu a realização de meta-análise. Os estudos incluídos nesta revisão sistemática parecem sugerir que a resina composta preaquecida, quando usada como agente cimentante, não influencia favoravelmente a adaptação das restaurações indiretas. A alta heterogeneidade entre os estudos indica a necessidade de mais investigações com um melhor desenho metodológico para concluir esta questão. (AU)

A systematic review was performed to answer the following research question: Does the use of preheated restorative resin composite as luting agent influence on the adaptation of indirect restorations? Studies evaluating the adaptation of indirect restorations in prepared natural and artificial teeth, and compared preheated restorative composite resin as luting agent with resin cement were selected. Assessment of the risk of bias was based on an 9-item checklist. The MEDLINE via PubMed, EMBASE, Web of Science, Scopus, LILACS and BBO via Virtual Health Library, Cochrane Library, and the grey literature databases were searched, without language or year restriction. From 2046 retrieved articles, 4 in vitro studies were included in this review. While in one of the included studies preheated restorative composite resin improved the adaptation of indirect restorations; according to the other three studies, the material produced a significantly greater mismatch compared to resin cement. All included studies were considered to be at medium risk of bias. The high level of heterogeneity across the studies excluded meta-analysis. The studies included in this systematic review seems to suggest that preheated restorative resin composite, used as luting agent, does not influence favorably the adaptation of indirect restorations. The high heterogeneity across the studies indicates the need for further investigations with a better methodological design to conclude this question. (AU)

Influence of Intra-Oral Scanner (I.O.S.) on The Marginal Accuracy of CAD/CAM Single Crowns.

The aim of this in vitro study was to compare the quality of digital workflows generated by different scanners (Intra-oral digital scanners (I.O.S.s)) focusing on marginal fit analysis. A customized chrome-cobalt (Cr-Co) implant abutment simulating a maxillary right first molar was fixed in hemi-maxillary stone model and scanned by eight different I.O.S.s: Omnicam® (Denstply Sirona, Verona, Italy) CS3500®, CS3600®, (Carestream Dental, Atlanta, GA, USA), True Definition Scanner® (3M, St. Paul, MN, USA), DWIO® (Dental Wings, Montreal, Quebec, Canada), PlanScan® (Planmeca Oy, Helsinki, Finland), 3D PROGRESS Plus® (MHT, Verona, Italy), TRIOS 3® (3Shape, Copenhagen, Denmark). Nine scans were performed by each tested I.O.S. and 72 copings were designed using a dental computer-assisted-design/computer-assisted-manufacturing (CAD/CAM) software (exocad GmbH, Darmstadt, Germany). According to CAD data, zirconium dioxide (ZrO2) copings were digitally milled (Roland DWX-50, Irvine, CA, USA). Scanning electron microscope (SEM) direct vision allowed for marginal gap measurements in eight points for each specimen. Descriptive analysis was performed using mean, standard deviation, and median, while the Kruskal⁻Wallis test was performed to determine whether the marginal discrepancies were significantly different between each group (significance level p < 0.05). The overall mean marginal gap value and standard deviation were 53.45 ± 30.52 µm. The minimum mean value (40.04 ± 18.90 µm) was recorded by PlanScan®, then 3D PROGRESS Plus® (40.20 ± 21.91 µm), True Definition Scanner® (40.82 ± 26.19 µm), CS3500® (54.82 ± 28.86 µm) CS3600® (59,67 ± 28.72 µm), Omnicam® (61.57 ± 38.59 µm), DWIO® (62.49 ± 31.54 µm), while the maximum mean value (67.95 ± 30.41 µm) was recorded by TRIOS 3®. The Kruskal⁻Wallis tests revealed a statistically significant difference (p-value < 0.5) in the mean marginal gaps between copings produced by 3D PROGRESS Plus®, PlanScan, True Definition Scanner, and the other evaluated I.O.S.s. The use of an I.O.S. for digital impressions may be a viable alternative to analog techniques. Although in this in vitro study PlanScan®, 3D PROGRESS Plus® and True Definition Scanner® may have showed the best performances, all I.O.S.s tested could provide clinically encouraging results especially in terms of marginal accuracy, since mean marginal gap values were all within the clinically acceptable threshold of 120 µm.

Fits of Implant Zirconia Custom Abutments and Frameworks: A Systematic Review and Meta-Analyses.

PURPOSE: The aim of this systematic review and meta-analyses was to evaluate fits of zirconia custom abutments and frameworks on implants and to identify the factors that influence their fits. MATERIALS AND METHODS: An electronic search was conducted through PubMed (MEDLINE), Google Scholar, and Cochrane Central Registrar of Controlled Trials. The search was completed in August 2017. Series of meta-analyses were conducted to compare fits of zirconia custom abutments and frameworks on implants with metal abutments and frameworks. The interest variables were the interface gap and the rotational misfit of abutments and the vertical fit of frameworks. RESULTS: Initially, a total of 672 articles were identified from the electronic search. After applying the inclusion criteria, 17 suitable articles were selected, including 9 studies on the fit of zirconia custom abutments and 8 studies on the fit of zirconia frameworks. There is a tendency for zirconia abutments to exhibit greater interface gaps and rotational misfits than metal abutments. Abutments produced by manual-aided designs/manual-aided manufacturing (MAD/MAM) exhibited inferior fits compared with those produced by computer-aided design/computer-aided manufacturing (CAD/CAM). Proprietary abutments had superior fits compared with non-proprietary abutments. Milled zirconia frameworks had insignificantly inferior fits compared with milled metal frameworks. CONCLUSION: Within the limitations of this study, custom zirconia abutments and non-proprietary abutments appeared to exhibit slightly inferior fits compared with metal abutments or abutments produced by the same implant company. However, the clinical significance of this difference is yet to be determined. The fit of milled zirconia frameworks is generally comparable to milled metal frameworks.

Reliability of light microscopy and a computer-assisted replica measurement technique for evaluating the fit of dental copings.

The aim of this in vitro study was to assess the reliability of two measurement systems for evaluating the marginal and internal fit of dental copings. Sixteen CAD/CAM titanium copings were produced for a prepared maxillary canine. To modify the CAD surface model using different parameters (data density; enlargement in different directions), varying fit was created. Five light-body silicone replicas representing the gap between the canine and the coping were made for each coping and for each measurement method: (1) light microscopy measurements (LMMs); and (2) computer-assisted measurements (CASMs) using an optical digitizing system. Two investigators independently measured the marginal and internal fit using both methods. The inter-rater reliability [intraclass correlation coefficient (ICC)] and agreement [Bland-Altman (bias) analyses]: mean of the differences (bias) between two measurements [the closer to zero the mean (bias) is, the higher the agreement between the two measurements] were calculated for several measurement points (marginal-distal, marginal-buccal, axial-buccal, incisal). For the LMM technique, one investigator repeated the measurements to determine repeatability (intra-rater reliability and agreement). For inter-rater reliability, the ICC was 0.848-0.998 for LMMs and 0.945-0.999 for CASMs, depending on the measurement point. Bland-Altman bias was -15.7 to 3.5 µm for LMMs and -3.0 to 1.9 µm for CASMs. For LMMs, the marginal-distal and marginal-buccal measurement points showed the lowest ICC (0.848/0.978) and the highest bias (-15.7 µm/-7.6 µm). With the intra-rater reliability and agreement (repeatability) for LMMs, the ICC was 0.970-0.998 and bias was -1.3 to 2.3 µm. LMMs showed lower interrater reliability and agreement at the marginal measurement points than CASMs, which indicates a more subjective influence with LMMs at these measurement points. The values, however, were still clinically acceptable. LMMs showed very high intra-rater reliability and agreement for all measurement points, indicating high repeatability.

The marginal fit of lithium disilicate crowns: Press vs. CAD/CAM.

This study aimed to compare the vertical marginal gap of teeth restored with lithium disilicate crowns fabricated using CAD/CAM or by pressed ceramic approach. Twenty mandibular third molar teeth were collected after surgical extractions and prepared to receive full veneer crowns. Teeth were optically scanned and lithium disilicate blocks were used to fabricate crowns using CAD/CAM technique. Polyvinyl siloxane impressions of the prepared teeth were made and monolithic pressed lithium disilicate crowns were fabricated. The marginal gap was measured using optical microscope at 200× magnification (Keyence VHX-5000, Japan). Statistical analysis was performed using Wilcoxon test. The lithium disilicate pressed crowns had significantly smaller (p = 0.006) marginal gaps (38 ± 12 µm) than the lithium disilicate CAD/CAM crowns (45 ± 12 µm). This research indicates that lithium disilicate crowns fabricated with the press technique have measurably smaller marginal gaps compared with those fabricated with CAD/CAM technique within in vitro environments. The marginal gaps achieved by the crowns across all groups were within a clinically acceptable range.

The marginal fit of lithium disilicate crowns: Press vs. CAD/CAM

Abstract: This study aimed to compare the vertical marginal gap of teeth restored with lithium disilicate crowns fabricated using CAD/CAM or by pressed ceramic approach. Twenty mandibular third molar teeth were collected after surgical extractions and prepared to receive full veneer crowns. Teeth were optically scanned and lithium disilicate blocks were used to fabricate crowns using CAD/CAM technique. Polyvinyl siloxane impressions of the prepared teeth were made and monolithic pressed lithium disilicate crowns were fabricated. The marginal gap was measured using optical microscope at 200× magnification (Keyence VHX-5000, Japan). Statistical analysis was performed using Wilcoxon test. The lithium disilicate pressed crowns had significantly smaller (p = 0.006) marginal gaps (38 ± 12 μm) than the lithium disilicate CAD/CAM crowns (45 ± 12 μm). This research indicates that lithium disilicate crowns fabricated with the press technique have measurably smaller marginal gaps compared with those fabricated with CAD/CAM technique within in vitro environments. The marginal gaps achieved by the crowns across all groups were within a clinically acceptable range.

Reliability of light microscopy and a computer-assisted replica measurement technique for evaluating the fit of dental copings

Abstract The aim of this in vitro study was to assess the reliability of two measurement systems for evaluating the marginal and internal fit of dental copings. Material and Methods: Sixteen CAD/CAM titanium copings were produced for a prepared maxillary canine. To modify the CAD surface model using different parameters (data density; enlargement in different directions), varying fit was created. Five light-body silicone replicas representing the gap between the canine and the coping were made for each coping and for each measurement method: (1) light microscopy measurements (LMMs); and (2) computer-assisted measurements (CASMs) using an optical digitizing system. Two investigators independently measured the marginal and internal fit using both methods. The inter-rater reliability [intraclass correlation coefficient (ICC)] and agreement [Bland-Altman (bias) analyses]: mean of the differences (bias) between two measurements [the closer to zero the mean (bias) is, the higher the agreement between the two measurements] were calculated for several measurement points (marginal-distal, marginal-buccal, axial-buccal, incisal). For the LMM technique, one investigator repeated the measurements to determine repeatability (intra-rater reliability and agreement). Results: For inter-rater reliability, the ICC was 0.848-0.998 for LMMs and 0.945-0.999 for CASMs, depending on the measurement point. Bland-Altman bias was −15.7 to 3.5 μm for LMMs and −3.0 to 1.9 μm for CASMs. For LMMs, the marginal-distal and marginal-buccal measurement points showed the lowest ICC (0.848/0.978) and the highest bias (-15.7 μm/-7.6 μm). With the intra-rater reliability and agreement (repeatability) for LMMs, the ICC was 0.970-0.998 and bias was −1.3 to 2.3 μm. Conclusion: LMMs showed lower interrater reliability and agreement at the marginal measurement points than CASMs, which indicates a more subjective influence with LMMs at these measurement points. The values, however, were still clinically acceptable. LMMs showed very high intra-rater reliability and agreement for all measurement points, indicating high repeatability.

Effect of dental technician disparities on the 3-dimensional accuracy of definitive casts.

STATEMENT OF PROBLEM: Studies that evaluated the effect of dental technician disparities on the accuracy of presectioned and postsectioned definitive casts are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the accuracy of presectioned and postsectioned definitive casts fabricated by different dental technicians by using a 3-dimensional computer-aided measurement method. MATERIAL AND METHODS: An arch-shaped metal master model consisting of 5 abutments resembling prepared mandibular incisors, canines, and first molars and with a 6-degree total angle of convergence was designed and fabricated by computer-aided design and computer-aided manufacturing (CAD-CAM) technology. Complete arch impressions were made (N=110) from the master model, using polyvinyl siloxane (PVS) and delivered to 11 dental technicians. Each technician fabricated 10 definitive casts with dental stone, and the obtained casts were numbered. All casts were sectioned, and removable dies were obtained. The master model and the presectioned and postsectioned definitive casts were digitized with an extraoral scanner, and the virtual master model and virtual presectioned and postsectioned definitive casts were obtained. All definitive casts were compared with the master model by using computer-aided measurements, and the 3-dimensional accuracy of the definitive casts was determined with best fit alignment and represented in color-coded maps. Differences were analyzed using univariate analyses of variance, and the Tukey honest significant differences post hoc tests were used for multiple comparisons (α=.05). RESULTS: The accuracy of presectioned and postsectioned definitive casts was significantly affected by dental technician disparities (P<.001). The largest dimensional changes were detected in the anterior abutments of both of the definitive casts. The changes mostly occurred in the mesiodistal dimension (P<.001). CONCLUSIONS: Within the limitations of this in vitro study, the accuracy of presectioned and postsectioned definitive casts is susceptible to dental technician differences.

Evaluation of the marginal and internal discrepancies of CAD-CAM endocrowns with different cavity depths: An in vitro study.

STATEMENT OF PROBLEM: The marginal and internal discrepancies of computer-aided design and computer-aided manufacturing (CAD-CAM) endocrowns are unknown. PURPOSE: The purpose of this in vitro study was to evaluate the marginal and internal discrepancies of endocrowns with different cavity depths by measuring them with microcomputed tomography (µCT). MATERIAL AND METHODS: Endocrowns (n=48) of 2 different cavity depths (2 mm and 4 mm) were fabricated in 2 different chairside CAD-CAM systems (CEREC AC and E4D). A µCT scan was made before and after cementation. For analysis of the marginal and internal discrepancies, reference points were selected in 2-dimensional views of 3 buccolingual cross-sections and 3 mesiodistal cross-sections. To calculate the total discrepancy volume, the µCT sections were reconstructed 3-dimensional views, and changes in volume and surface area were examined. Statistical analysis was performed using 2-way ANOVA with Bonferroni correction (α=.05). RESULTS: An endocrown with a 4-mm cavity showed a larger marginal and internal volume than one with a 2-mm cavity. Cementation did not show significant differences in total discrepancy thickness. Discrepancies on the pulpal floor were largest in other sites. Both chairside CAD-CAM systems showed similar discrepancy in the endocrowns. CONCLUSIONS: Based on the present study, marginal and internal discrepancies increased depending on cavity depth. Cementation did not increase the dimension of the discrepancy between the restoration and the cavity wall. The discrepancy on the pulpal floor appeared to affect these results.

Clinical performance of aesthetic restorative materials in primary teeth according to the FDI criteria.

AIM: The purpose of this study is to evaluate the clinical performance of three different restorative materials in primary teeth according to the FDI criteria. MATERIALS AND METHODS: Resin-modified glass ionomer cement, compomer and composite resin restorations (n=93) were made in 31 patients. The restorations were clinically evaluated at baseline, 6th, 12th and 18th month with the FDI criteria. RESULTS: The cumulative survival rate after 18 months was found to be 90.3% for resin modified glass ionomer cement restorations, 100% for compomer restorations and 80.6% for composite resin restorations. Statistically significant increase in surface roughness, colour mismatch, anatomic form loss and marginal deterioration were detected in resin- modified glass ionomer group (p<0.05). The most frequent reason for restoration failure in composite resin group was restoration fractures. CONCLUSIONS: The resin-modified glass ionomer restorations necessitates close follow-up because of the risk of increase in surface roughness, changes in colour and loss in anatomic form and marginal adaptation. The clinical performance of compomer restorations is superior to resin-modified glass ionomer and composite resin restorations in primary teeth.

In vitro evaluation of marginal, axial, and occlusal discrepancies in metal ceramic restorations produced with new technologies.

STATEMENT OF PROBLEM: Marginal and axial discrepancies of metal ceramic restorations are key to their long-term success. Little information is available for metal ceramic restorations fabricated with soft metal milling and laser sintering technologies. PURPOSE: The purpose of this in vitro study was to compare the marginal, axial, and occlusal discrepancies in single-unit metal ceramic restorations fabricated with new production techniques with those in a single-unit restoration fabricated using a conventional technique. MATERIAL AND METHODS: After the artificial tooth was prepared, impressions were made, and 40 dies were obtained. Dies were randomly divided into 4 groups (n=10). Cobalt-chromium (Co-Cr) cast (C), hard metal milled (HM), laser sintered (LS), and soft metal milled (SM) copings were fabricated. Marginal, axial, and occlusal discrepancies of these copings were measured using the silicone replica technique before and after the application of veneering ceramic. Data were analyzed with repeated measurements 2-way ANOVAs and Bonferroni post hoc tests (α=.05). RESULTS: Significant differences were found in the increase of marginal discrepancy after the application of veneering ceramic in the LS group (P=.016). However, no significant differences in marginal discrepancy were found whether veneering ceramic was applied to copings before or after in the other groups (P>.05). With regard to marginal and occlusal discrepancies, significant differences were found among the production techniques (P<.001 and P<.05, respectively). No significant differences in axial discrepancies were found among the groups (P>.05). CONCLUSION: This in vitro study showed that metal ceramic restorations produced with HM and newly introduced SM techniques exhibited better marginal adaptations than those produced with the LS or C technique.

Evaluation of the marginal fit of single-unit, complete-coverage ceramic restorations fabricated after digital and conventional impressions: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: In existing published reports, some studies indicate the superiority of digital impression systems in terms of the marginal accuracy of ceramic restorations, whereas others show that the conventional method provides restorations with better marginal fit than fully digital fabrication. Which impression method provides the lowest mean values for marginal adaptation is inconclusive. The findings from those studies cannot be easily generalized, and in vivo studies that could provide valid and meaningful information are limited in the existing publications. PURPOSE: The purpose of this study was to systematically review existing reports and evaluate the marginal fit of ceramic single-tooth restorations after either digital or conventional impression methods by combining the available evidence in a meta-analysis. MATERIAL AND METHODS: The search strategy for this systematic review of the publications was based on a Population, Intervention, Comparison, and Outcome (PICO) framework. For the statistical analysis, the mean marginal fit values of each study were extracted and categorized according to the impression method to calculate the mean value, together with the 95% confidence intervals (CI) of each category, and to evaluate the impact of each impression method on the marginal adaptation by comparing digital and conventional techniques separately for in vitro and in vivo studies. RESULTS: Twelve studies were included in the meta-analysis from the 63 identified records after database searching. For the in vitro studies, where ceramic restorations were fabricated after conventional impressions, the mean value of the marginal fit was 58.9 µm (95% CI: 41.1-76.7 µm), whereas after digital impressions, it was 63.3 µm (95% CI: 50.5-76.0 µm). In the in vivo studies, the mean marginal discrepancy of the restorations after digital impressions was 56.1 µm (95% CI: 46.3-65.8 µm), whereas after conventional impressions, it was 79.2 µm (95% CI: 59.6-98.9 µm) CONCLUSION: No significant difference was observed regarding the marginal discrepancy of single-unit ceramic restorations fabricated after digital or conventional impressions.

Effect of software version and parameter settings on the marginal and internal adaptation of crowns fabricated with the CAD/CAM system.

OBJECTIVE: This study investigated the marginal and internal adaptation of individual dental crowns fabricated using a CAD/CAM system (Sirona's BlueCam), also evaluating the effect of the software version used, and the specific parameter settings in the adaptation of crowns. MATERIAL AND METHODS: Forty digital impressions of a master model previously prepared were acquired using an intraoral scanner and divided into four groups based on the software version and on the spacer settings used. The versions 3.8 and 4.2 of the software were used, and the spacer parameter was set at either 40 µm or 80 µm. The marginal and internal fit of the crowns were measured using the replica technique, which uses a low viscosity silicone material that simulates the thickness of the cement layer. The data were analyzed using a Friedman two-way analysis of variance (ANOVA) and paired t-tests with significance level set at p<0.05. RESULTS: The two-way ANOVA analysis showed the software version (p<0.05) and the spacer parameter (p<0.05) significantly affected the crown adaptation. The crowns designed with the version 4.2 of the software showed a better fit than those designed with the version 3.8, particularly in the axial wall and in the inner margin. The spacer parameter was more accurately represented in the version 4.2 of the software than in the version 3.8. In addition, the use of the version 4.2 of the software combined with the spacer parameter set at 80 µm showed the least variation. On the other hand, the outer margin was not affected by the variables. CONCLUSION: Compared to the version 3.8 of the software, the version 4.2 can be recommended for the fabrication of well-fitting crown restorations, and for the appropriate regulation of the spacer parameter.

Effect of software version and parameter settings on the marginal and internal adaptation of crowns fabricated with the CAD/CAM system

Objective This study investigated the marginal and internal adaptation of individual dental crowns fabricated using a CAD/CAM system (Sirona’s BlueCam), also evaluating the effect of the software version used, and the specific parameter settings in the adaptation of crowns.Material and Methods Forty digital impressions of a master model previously prepared were acquired using an intraoral scanner and divided into four groups based on the software version and on the spacer settings used. The versions 3.8 and 4.2 of the software were used, and the spacer parameter was set at either 40 μm or 80 μm. The marginal and internal fit of the crowns were measured using the replica technique, which uses a low viscosity silicone material that simulates the thickness of the cement layer. The data were analyzed using a Friedman two-way analysis of variance (ANOVA) and paired t-tests with significance level set at p<0.05.Results The two-way ANOVA analysis showed the software version (p<0.05) and the spacer parameter (p<0.05) significantly affected the crown adaptation. The crowns designed with the version 4.2 of the software showed a better fit than those designed with the version 3.8, particularly in the axial wall and in the inner margin. The spacer parameter was more accurately represented in the version 4.2 of the software than in the version 3.8. In addition, the use of the version 4.2 of the software combined with the spacer parameter set at 80 μm showed the least variation. On the other hand, the outer margin was not affected by the variables.Conclusion Compared to the version 3.8 of the software, the version 4.2 can be recommended for the fabrication of well-fitting crown restorations, and for the appropriate regulation of the spacer parameter.

Evaluation of marginal and internal fit of ceramic and metallic crown copings using x-ray microtomography (micro-CT) technology.

STATEMENT OF PROBLEM: Prosthetic crown fit to the walls of the tooth preparation may vary depending on the material used for crown fabrication. PURPOSE: The purpose of this study was to compare the marginal and internal fit of crown copings fabricated from 3 different materials. MATERIAL AND METHODS: The selected materials were zirconia (ZirkonZahn system, group Y-TZP), lithium disilicate (IPS e.max Press system, group LSZ), and nickel-chromium alloy (lost-wax casting, group NiCr). Five specimens of each material were seated on standard dies. An x-ray microtomography (micro-CT) device was used to obtain volumetric reconstructions of each specimen. Points for fit measurement were located in Adobe Photoshop, and measurements were obtained in the CTAn SkyScan software environment. Marginal fit was measured at 4 points and internal fit at 9 points in each coping. Mean measurements from the 3 groups were compared by analysis of variance (ANOVA) at the 5% significance level, and between-group differences were assessed with the Tukey range test. RESULTS: The nickel-chromium alloy exhibited the best marginal fit overall, comparable with zirconia and significantly different from lithium disilicate. Lithium disilicate exhibited the lowest mean values for internal fit, similar to zirconia and significantly different from the nickel-chrome alloy. CONCLUSIONS: The marginal and internal fit parameters of the 3 tested materials were within clinically acceptable range.

Sealing composite with defective margins, good care or over treatment? Results of a 10-year clinical trial.

PURPOSE: The objective of this study was to clinically evaluate sealed composite restorations after 10 years and compare their behavior with respect to controls. METHODS AND MATERIALS: The cohort consisted of 20 patients aged 18 to 80 years with 80 composite restorations. All participants in the sealing and no-treatment groups presented with clinical features for the marginal adaptation that deviated from the ideal and were rated Bravo (United States Public Health Service criteria). Composites with Alfa values for the marginal adaptation were used as the positive control. RESULTS: The marginal adaptation behavior was similar between the sealing and control (+) groups, with a high frequency of Bravo values in the 10th year (80% and 51%, respectively). Most of the no-treatment (-) group maintained the Bravo values (91%) for 10 years, although some restorations (9%) progressed to Charlie values. The anatomy parameter differed significantly between the first and 10th years, with deterioration in all three groups (p<0.05). The secondary caries parameter had a similar behavior in the three groups (p>0.05). CONCLUSIONS: Sealing the margins of the composite resin restorations had no significant effect compared with the control groups, under the conditions of this study. Sealing the restorations substantially improved the marginal staining and marginal adaptation parameters, although by the tenth year they were similar to the group without intervention.

[Scanning electron microscopy analysis of marginal adaptation of composite resines to enamel after using of standard and gradual photopolimerization].

INTRODUCTION: Bonding between composite and hard dental tissue is most commonly assessed by measuring bonding strength or absence of marginal gap along the restoration interface. Marginal index (MI) is a significant indicator of the efficiency of the bond between material and dental tissue because it also shows the values of width and length of marginal gap. OBJECTIVE: The aim of this investigation was to estimate quantitative and qualitative features of the bond between composite resin and enamel and to determine the values of MI in enamel after application of two techniques of photopolymerization with two composite systems. METHODS: Forty Class V cavities on extracted teeth were prepared and restored for scanning electron microscope (SEM) analysis of composite bonding to enamel. Adhesion to enamel was achieved by Adper Single Bond 2 - ASB (3M ESPE), or by Adper Easy One--AEO (3M ESPE). Photopolymerization of Filtek Ultimate--FU (3M ESPE) was performed using constant halogen light (HIP) or soft start program (SOF). RESULTS: Quantitative and qualitative analysis, showed better mikromorphological bonding with SOF photopolymerization and ASB/FU composite system. Differences in MI between different photopolymerization techniques (HIP: 0.6707; SOF: 0.2395) were statistically significant (p < 0.001), as well as differences between the composite systems (ASB/FU: 0.0470; AEO/ FU: 0.8651) (p < 0.001) by two-way ANOVA test. CONCLUSION: Better marginal adaptation of composite to enamel was obtained with SOF photopolymerization in both composite systems.

A comparison of the accuracy of polyether, polyvinyl siloxane, and plaster impressions for long-span implant-supported prostheses.

PURPOSE: The purpose of this study was to compare the capacity of different impression materials to accurately reproduce the positions of five implant analogs on a master model by comparing the resulting cast with the stainless steel master model. The study was motivated by the knowledge that distortions can occur during impression making and the pouring of casts and that this distortion may produce inaccuracies of subsequent restorations, especially long-span castings for implant superstructures. MATERIALS AND METHODS: The master model was a stainless steel model with five implant analogs. The impression materials used were impression plaster (Plastogum, Harry J Bosworth), a polyether (Impregum Penta, 3M ESPE), and two polyvinyl siloxane (PVS) materials (Aquasil Monophase and Aquasil putty with light-body wash, Dentsply). Five impressions were made with each impression material and cast in die stone under strictly controlled laboratory conditions. The positions of the implants on the master model, the impression copings, and the implant analogs in the subsequent casts were measured using a coordinate measuring machine that measures within 4 µm of accuracy. RESULTS: Statistical analyses indicated that distortion occurred in all of the impression materials, but inconsistently. The PVS monophase material reproduced the master model most accurately. Although there was no significant distortion between the impressions and the master model or between the impressions and their casts, there were distortions between the master model and the master casts, which highlighted the cumulative effects of the distortions. The polyether material proved to be the most reliable in terms of predictability. The impression plaster displayed cumulative distortion, and the PVS putty with light body showed the least reliability. CONCLUSIONS: Some of the distortions observed are of clinical significance and likely to contribute to a lack of passive fit of any superstructure. The inaccuracy of these analog materials and procedures suggested that greater predictability may lie in digital technology.

The evaluation of marginal gap with and without optical aids: clinicians versus technicians.

PURPOSE: This study investigated the reliability of visual assessment of marginal gaps in relation to the use of magnification and the operator's profession. MATERIALS AND METHODS: A titanium bar was notched, simulating 40 marginal gaps, and 35 operators performed a quantitative evaluation of the incisions. RESULTS: Visual examination was neither sensitive nor specific, as an extreme variability of data was recorded. The precision of readers improved with magnification aids only for clinicians; technicians were significantly more accurate in evaluating the incision's width. CONCLUSION: The visual examinations were inadequate to decide the clinical acceptability of a restoration with regard to its marginal fit.

An in vitro comparison of the accuracy of implant impressions with coded healing abutments and different implant angulations.

STATEMENT OF PROBLEM: Fabricating implant definitive casts with CAD/CAM technology (Robocasts) from coded healing abutment impressions represents a simpler and innovative alternative to conventional implant impression techniques. However, information about the accuracy of the impressions and the resultant definitive casts is limited. PURPOSE: The purpose of the study was to evaluate the accuracy of the Robocasts and compare them to those definitive casts fabricated with conventional implant impression techniques (open tray with splinted impression copings technique). MATERIAL AND METHODS: A reference epoxy resin cast was fabricated and shaped to simulate a dental arch. Two regular platform implant replicas (Biomet 3i Certain, 4.1 mm diameter and 15 mm length) with internal connections were placed 10 mm apart with a 10-degree convergence for one side of the reference resin cast and a 30-degree convergence for the other. Coded healing abutments (Encode) were placed at 3 different heights above the level of the soft tissue replication material (approximately 1, 2, and 4 mm) and served as test groups (E1, E2, and E4), and open trays with splinted impression copings (OTSC) served as a control group. The control group was compared to the impressions of the coded healing abutments by using a standardized measurement protocol. Impressions were made for each group (n=18) and poured with vacuum mixed (100 g powder/20 mL water) Type IV dental stone. The vertical discrepancy (Z axis) between 2 prefabricated passively fitting titanium reference frameworks and the platforms of the implant replicas was measured with an optical comparator applying the 1 screw test. Data were analyzed with Kruskal-Wallis and post-hoc Mann-Whitney U tests, as well as the Wilcoxon signed-rank tests. The Bonferroni correction was used to account for multiple comparisons. The significance level (α) used in a given set of tests was equal to .05 divided by the number of tests performed in that set. RESULTS: The median vertical discrepancy of each coded healing abutment impression group was higher than the corresponding median of the control group (OTSC) for every combination of angulation and position. Kruskal-Wallis tests indicated a statistically significant difference (P<.001) between groups for each angulation/position combination. All post hoc Mann-Whitney U tests indicated statistically significant differences (all P≤.002) between OTSC and the other groups. Differences between the angulations and positions were not statistically significant when accounting for multiple comparisons. CONCLUSIONS: The implant definitive casts fabricated from the coded healing abutment impressions were found to be less accurate than those fabricated from the open tray with splinted impression copings technique for restoring 2 paired (10 or 30 degrees) convergent internal connection implants with nonengaging screw-retained splinted 2-unit implant restorations. Accuracy of fit was not influenced by the implant angulation or position for either impression technique or by the Encode healing abutment height for the Encode impression technique.