Clinical evaluation of light-cured composite resin inlays in primary molars

A study was carried out to evaluate the clinical potential of a visible light-cured composite resin inlay (P-30) cemented with an adhesive resin cement (Panavia-EX) in primary molars. The inlays were placed in Class I complex, Class II MO, DO, MOD and more extensive cavity preparations in primary molars. Fifty restorations were placed in 40 patients and evaluated at baseline, 3 months, 6 months, 1 year and 2 years. The evaluations were carried out according to the U.S. Public Health Service Clinical Rating System. The results showed the composite resin inlay cemented with an adhesive resin cement to be a highly effective combination.     

Fracture risk of lithium-disilicate ceramic inlays: A finite element analysis

Objectives

In the present study, lithium-disilicate ceramic inlays should be analyzed biomechanically according to their thickness and dimension, and it should be clarified as to whether there is a significant relationship between the inlay volume and the induced tensile stress level.

Methods

Using a new parametric CAD modeling procedure, 27 lithium-disilicate ceramic inlays with various parameters of “depth”, “width”, “angle” and restoration volume were generated. These inlays were integrated into the CAD model of a lower molar created from the CT data of an anatomical preparation. The resulting CAD models were, finally, three-dimensionally cross-linked to FEM models. After applying a compressive force of 200 N, Principal Tensile Stresses (PTSs) could be measured in the inlay. The values were subject to statistical analysis afterwards.

Results

The volume of the inlay restorations varied between 35.7 mm³ and 82.5 mm³. The maximum PTS values (n = 10) only showed a slight negative correlation with the inlay volume. The correlation coefficient according to Spearman was −0.082 (p ≤ 0.001). If the highest 1000 PTS values of each inlay were considered (n = 1000), the correlation coefficient was further reduced to +0.068 (p ≤ 0.001). No significant correlation between the inlay volume and the induced PTS level could be detected.

Significance

Under the conditions and limitations of the present FEM study, the inlay volume did not significantly influence the tensile stress level of ceramic inlays. The results may support the thesis that volume-reduced all-ceramic inlays might not have an increased fracture risk. Further studies are needed to confirm this.     

不同大小MO洞型复合树脂嵌体修复应力分布的有限元分析

目的 探讨复合树脂嵌体修复后,近中邻（meiso-occlusal,MO）洞型面深度及宽度变化对牙体抗力的影响。方法采用锥形束CT（cone beam computed tomography,CBCT）扫描,结合Mimics、Geomagic Studio逆向工程等软件,建立不同大小邻（II类）MO洞型树脂嵌体修复的三维有限元模型,用ANSYS Workbench软件网格划分并求解分析各模型内部牙体及嵌体在垂直、舌向45°加载下主应力峰值及Von-mises应力分布情况。结果大小不同的MO洞型以复合树脂嵌体修复时,龈壁对应处是嵌体的主要应力所在,洞底部近髓腔处是牙体的主要应力集中区。随着面洞型深度、宽度增加,牙体、修复体的最大应力峰值及Von-mises应力集中区分布范围加大;牙体Von-mises应力受洞型宽度的影响更大,嵌体的Von-mises应力受洞型深度增加影响更大。侧向加载大大增加了牙体和修复体的应力峰值。结论MO洞型以树脂嵌体修复后,洞深、洞宽度加大及侧向加载增加了牙体与嵌体的应力峰值,改变了应力集中区分布范围。     

Bond strengths and pulpal response of light-cured composite resin inlays in primary molars

The purpose of this study was to: 1) determine the most effective combination of composite resin and adhesive resin cement in the cementation process when fabricating esthetic inlays in severely broken down posterior primary teeth; 2) evaluate the pulpal response to adhesive resin cement in the primary teeth of young dogs. In Part I of the study, P-30 and Dentacolor composite resin inlays were evaluated with regard to their bonding strengths with Panavia-EX and Chemiace adhesive resins. Test samples of the composite resin inlays were prepared in molds according to the manufacturer's instructions. Each sample was polished on a flat, wet surface of 320 grit carborundum until a uniformly flat surface, perpendicular to the long axis of the cylinder was attained. Composite resin plugs, similarly fabricated, were bonded to the test samples using either Panavia-EX or Chemiace adhesive resin cements. A total of 160 samples were divided into four groups. Three of the groups were tested for bonding strength at intervals of 24 hours, 7 days and 30 days. The fourth group was thermocycled through 4 degrees C and 60 degrees C immersion periods. The results were analyzed using Tukey's studentized range test with an alpha (significance level) of 0.05. In Part II of the study, the pulpal response to Panavia-EX as a luting medium was compared with that of HY-Bond polycarboxylate cement. Cavities were prepared in 92 teeth from 8 young dogs and contralateral pairs of teeth were restored with Panavia-EX and HY-Bond polycarboxylate cement respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Three-dimensional finite element analysis of stress distribution in composite resin cores with fiber posts of varying diameters

Using three-dimensional finite element analysis (3D-FEA), stress distributions in the remaining radicular tooth structure were investigated under the condition of varying diameters of fiber post for fiber post-reinforced composite resin cores (fiber post and core) in maxillary central incisors. Four 3D-FEA models were constructed: (1) fiber post (?1.2, ?1.4, and ?1.6 mm) and composite resin core; and (2) gold-cast post and core. Maximum stresses in the tooth structure for fiber post and core were higher than that for gold-cast post and core. In the former models, stresses in the tooth structure as well as in the composite resin were slightly reduced with increase in fiber post diameter. These results thus suggested that to reduce stress in the remaining radicular tooth with a large coronal defect, it is recommended to accompany a composite resin core with a fiber post of a large diameter.     

Longevity of ceramic inlays and onlays luted with a solely light-curing composite resin

OBJECTIVES: To determine the longevity of heat-pressed glass ceramic inlays and onlays luted with solely light-curing composite resin. METHODS: The records of patients who had received a ceramic inlay or onlay at the Heidelberg University Department of Conservative Dentistry from 1993 to 2002 were evaluated. The mean observation time and the survival probability of the ceramic inlays and onlays was calculated with the aid of the Kaplan-Meier algorithm. This was done for the total number of all restorations as well as for various subgroups (number of surfaces, tooth type, endodontic condition at the time that the ceramic restoration was incorporated, experience of operator). The log-rank test was used to compare groups and look for significant differences, and p<0.05 was set to be statistically significant. In addition, 95% confidence intervals of the survival probability values were computed. RESULTS: At the time of the last observation, 783 (96.7%) of these restorations were still in place. The mean observation period for all ceramic restorations was 17.3 months (SD 20.2), with an observation interval of between 0 and 116 months. The last loss of a ceramic restoration was observed 45 months after it had been placed, so that the survival probability of all ceramic restorations amounted to p=0.90 (95% confidence interval 0.86-0.94) from this time onward. Factors such as endodontic condition of tooth, type of tooth, position of tooth, extent of restoration, experience of operator or gender of patient had no significant influence on the survival probability of the ceramic restorations. CONCLUSIONS: Heat-pressed glass ceramic inlays and onlays can be used successfully in routine clinical therapy. In addition, this type of inlays and onlays can be placed successfully with solely light-curing composite resin.     

Evaluation of internal adaptation in ceramic and composite resin inlays by silicon replica technique

This study was aimed at investigating the internal adaptation of a ceramic (Ceramco II) and two composite resin inlay materials (SureFil and 3M Filtek Z 250) using silicon replica technique as an indicator. Forty-five standard mesial-occlusal-distal (MOD) cavities were prepared into brass moulds by using computer numerically controlled system. Inlays were prepared according to manufacturers' instructions with indirect methods. Replicas of the prepared cavities and inlays were produced with a polyvinyl siloxane material (Elite H-D). The spaces between inlays and cavities were filled by different coloured light-body polyvinyl siloxane material. Two parallel slices (mesio-distally) were obtained from the replicas with a sharp blade. Different coloured polyvinyl siloxane material thickness between cavity and inlay was measured at seven points (mesial, occlusal and distal). The data were evaluated with anova and Tukey's honestly significantly different (HSD) statistical tests. In the SureFil and Ceramco II groups, the sizes of the contraction gaps at mesial and distal gingival floors were greater than that of the occlusal marginal walls. In comparison of gap formation at occlusal regions, while the 3M composite group showed highest gap values (204.33 +/- 75.45 microm), the Ceramco II group revealed the lowest (141.17 +/- 23.66 microm) (P < 0.05). At the gingival floors, gap formation of Ceramco II group was the highest (227.08 +/- 51.95 microm). Neither the 3M Filtek Z250 nor SureFil group showed any statistical difference between gap values of their self-occlusal and gingival floors (P > 0.05). In conclusion, our results showed that ceramic inlays did not confer any big advantage for internal adaptation over the composite inlays.     

复合树脂嵌体修复磨牙缺损的临床疗效观察

目的观察复合树脂嵌体修复磨牙缺损的临床疗效。方法选择163例磨牙缺损患者的200颗患牙，将其分为2组，每组患牙100颗。分别采用直接法复合树脂嵌体和复合树脂直接充填修复患牙。于修复完成6个月和5年复诊。采用美国公共卫生署修复体临床评价标准对患者口内充填体进行疗效评价。结果修复后6个月，嵌体修复成功率为91．8％（90／98），树脂直接充填成功率为91．8％（89／97），经Х^2检验两者临床疗效差异无统计学意义（P〉0．05）。修复后5年，嵌体修复成功率为87．9％（80／91），树脂直接充填修复成功率为67．4％（60／89），Х^2检验显示嵌体的临床疗效优于树脂直接充填，差异有统计学意义（P〈0．05）。结论复合树脂嵌体修复磨牙缺损临床疗效良好，其长期临床疗效显著优于传统复合树脂直接充填。     

Interfacial gaps of resin cemented ceramic inlays

A method was developed for measuring presence, location and extent of interfacial contraction gaps of resin-cemented ceramic inlays in dentin cavities. Cylindrical ceramic inlays were cemented using one of 12 commercially available resin composite cements to make film thickness of 200-μm. Cross-sections revealed absence of marginal gaps but contraction gaps occurred at all dentin-cement interfaces at the cavity floors and ranged from 1.6 to 7.1 μm. This was equivalent to 0.8-3.5% of the cement film thickness and was 3-10 times greater than the wall-to-wall contraction in percent observed when resin composites are used as filling materials in 3-5 mm butt-joint dentin cavities. The results support the theory that contraction gaps developing adjacent to thin films of resin cements reach size equivalent to the cement film thickness multiplied by the volumetric polymerization shrinkage of the cement.     

Influence of surface roughness on mechanical strength of resin composite versus glass ceramic materials.

OBJECTIVES: Clinical polishing leads to reduction of surface flaws sizes and thus to increased mechanical strength. The aim of the present work was to assess fracture strength of a resin composite and of a glass ceramic as a function of surface roughness and to relate the strength data to flaw sizes, microstructural and fractographic examinations. METHODS: Specimens have manufactured out of a resin composite (Tetric EvoCeram, TEC) and out of glass ceramic material (IPS E.max Press, EMP). Different surface roughness levels have been induced using cutting, grinding and polishing techniques and quantified under CLSM. Fracture strength was measured in four-point bending and analyzed using Weibull statistics. Indentation fracture method was used to calculate fracture toughness. Critical flaw sizes were calculated and related to microstructure. Microstructural and fractographic examinations have been performed under SEM. RESULTS: Fracture strength upon the glass ceramic material decreased from 441.4 to 303.3 MPa (R(a)=150 nm-1.5 microm) and upon the resin composite from 109.8 to 74.0 MPa (R(a)=300 nm-50 microm). EMP exhibited a fracture toughness of K(Ic)=4.14 MPam(0.5) and TEC of K(Ic)=1.89 MPam(0.5). Calculated crack lengths for EMP ranged from 28.1 microm (441.4 MPa) to 59.6 microm (303.3 MPa) and for TEC from 94.3 microm (109.8 MPa) to 207.0 microm (74.0 MPa). SIGNIFICANCE: Dependency of fracture strength on surface roughness is neither determined by crystallite size of the glass ceramic material nor by filler sizes of the resin composite. No significant increase in fracture strength has been observed below 0.65 microm (1000 grit) in EMP. For TEC a threshold value might be determined below 2.1 microm (320 grit). Optimal polishing of a restoration right after placement is strongly recommended to keep an optimum strength performance through the whole clinical lifetime.     

A 5-year clinical study of indirect and direct resin composite and ceramic inlays.

OBJECTIVE: The aim of this investigation was to evaluate the clinical performance of 4 types of tooth-colored inlays. METHOD AND MATERIALS: Fifteen direct ceramic inlays (Cerec Cos 2.0), 15 direct resin composite inlays (Brilliant Direct Inlay), 14 indirect ceramic inlays (Vita Dur N), and 14 indirect resin composite inlays (Estilux) were made in 37 patients, according to the manufacturers' instructions. The inlays were evaluated 1 week (baseline) and 6, 12, 36, 48, and 60 months after cementation (modified CDA Quality Evaluation System). RESULTS: Two Vita Dur N inlays fractured after 1 and 4 years in function, and one Cerec inlay fractured after 4.5 years. Two Brilliant DI inlays needed replacement because of secondary caries (after 1 and 5 years), and one inlay (Estilux) needed replacement due to persisting hypersensitivity. Three inlays (1 Estilux and 2 Brilliant DI) were repaired due to chipping or minor fractures. During the observation period, the surface texture of Brilliant DI and Vita Dur N inlays became significantly rougher. After 5 years, the Estilux inlays had significantly lower ratings for morphology compared to baseline ratings. In general, the occlusal marginal adaptation did not show further disintegration of the luting cement after 1 year. CONCLUSION: Eighty-eight percent of the inlays were in function after 5 years. No significant differences were revealed among the survival rates of the different types of inlays.     

Three-year comparison of fired ceramic inlays cemented with composite resin or glass ionomer cement

Ceramic inlays offer a good alternative to posterior composites, which still show a high polymerization shrinkage. The thin cement layer will reduce the total amount of shrinkage and probably result in a better marginal adaptation and decreased marginal leakage. Fired feldspathic ceramic inlays cemented with either a glass ionomer cement or a dual-cured composite resin luting cement were compared intraindividually. During a 3-year period 118 inlays, 59 in each group, were examined. Eleven inlays were evaluated as non-acceptable during the period: two (3.4%) in the composite resin group and nine (15.3%) in the glass ionomer cement group. In the composite group one inlay fractured partially and one inlay was replaced because of postoperative sensitivity. In the glass ionomer group four inlays were totally lost, and partial fractures occurred in five inlays. In the fractured glass ionomer cemented inlays the cement was still in place in the cavities. Eight patients reported postoperative sensitivity. No secondary caries was detected around the inlays even though 46% of the patients were considered high caries risk patients.     

复合树脂嵌体修复儿童第一恒磨牙缺损的临床观察

[摘要] 目的 观察复合树脂嵌体修复儿童第一恒磨牙牙体缺损的临床效果。方法 对儿童第一恒磨牙牙体缺损分别采用复合树脂嵌体技术和复合树脂直接充填术,复合树脂嵌体技术组75颗,复合树脂直接充填组78颗,1年后复诊检查,评价标准采用改良USPHS评价标准。结果 复合树脂嵌体技术组的临床成功率在固位情况、边缘密合度、继发龋、牙龈指数指标上高于复合树脂直接充填修复组,并且存在显著差异(P<0.05)。在色泽协调性和磨耗程度指标上,临床成功率虽高于复合树脂直接充填修复组,但统计学上无显著差异(P>0.05)。结论 复合树脂嵌体修复术组临床效果优于复合树脂直接充填术。     

Dentin bond strength and marginal adaptation: direct composite resins vs ceramic inlays.

The aim of this in vitro study was to compare the dentin bond strength and marginal adaptation of directly and indirectly inserted restorations. A conically modified push-out test was designed to consider polymerization shrinkage and facilitate inlay placement. A total of 260 cavities were prepared into disks of freshly extracted human third molars and filled with direct composite resins or with adhesively luted ceramic inlays. Dentin adhesives of the third--(with self-etching primer: ART Bond, Syntac Classic), fourth--(with total etching: Scotchbond Multi-Purpose Plus), and fifth-generation (one-bottle adhesives: Syntac Single Component, Prime & Bond 2.1) were used in combination with one hybrid composite (Tetric) or luting composite (Variolink Low). Control groups did not use an adhesive. Polymerization of the bonding agent was carried out prior to insertion of the filling/inlay or afterwards simultaneously with the composite/luting composite. The thickness of the adhesive layer and luting composite was recorded, and after 7 days of storage and 24 hours of thermocycling (1150 cycles) replicas were made and extrusion testing performed. Fracture modes were determined and replicas were examined regarding marginal adaptation using SEM (X200 magnification). Precuring of the bonding resin increased dentin bond strength independent of the material combination or insertion mode (P < 0.05). In general, third- and fourth-generation dentin adhesives produced better results in bond strength and marginal adaptation than one-bottle systems (P < 0.05). In the third generation, ART Bond achieved significantly higher push-out values than Syntac (P < 0.05), but no better marginal adaptation. Cohesive fractures within the dentin were only observed in the inlay groups with precured resin. Precuring of the bonding resin is an important factor for both direct and indirect restorations. Nevertheless, precuring of the bonding resin prior to insertion of adhesive inlays cannot be recommended clinically, because the 120-micron luting spaces were too large. In simulated cavities, direct composite fillings with precuring achieved bond strengths similar to inlays without precuring. One-bottle adhesive systems performed poorly compared with multi-step adhesives of the third and fourth generation.