Estimation of the Risk of Failure for an Endodontically Treated Maxillary Premolar With MODP Preparation and CAD/CAM Ceramic Restorations

IntroductionThis study evaluated the risk of failure for an endodontically treated premolar with mesio occlusodistal palatal (MODP) preparation and 3 different computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic restoration configurations.MethodsThree 3-dimensional finite element (FE) models designed with CAD/CAM ceramic onlay, endocrown, and conventional crown restorations were constructed to perform simulations. The Weibull function was incorporated with FE analysis to calculate the long-term failure probability relative to different load conditions.ResultsThe results indicated that the stress values on the enamel, dentin, and luting cement for endocrown restoration were the lowest values relative to the other 2 restorations. Weibull analysis revealed that the individual failure probability in the endocrown enamel, dentin, and luting cement obviously diminished more than those for onlay and conventional crown restorations. The overall failure probabilities were 27.5%, 1%, and 1% for onlay, endocrown, and conventional crown restorations, respectively, in normal occlusal condition.ConclusionsThis numeric investigation suggests that endocrown and conventional crown restorations for endodontically treated premolars with MODP preparation present similar longevity.     

CAD/CAM or conventional ceramic materials restorations longevity: a systematic review and meta-analysis

PurposeThis systematic review and meta-analysis aimed to evaluate the difference in longevity of tooth-supported ceramic prostheses designed by conventional and computer-aided design/computer-aided manufacturing (CAD/CAM) techniques.Study selectionTwo reviewers searched the Web of Science, PubMed, SCOPUS and LILACS databases between 1966 and October 2017. Clinical studies that compared the survival rate of CAD/CAM against conventional restorations were included.ResultsEleven randomized controlled trials and three prospective studies were included, n = 14. Three types of tooth-supported restorations were searched in the included studies: single crown, multiple-unit and partial ceramic crown. The follow-up of patients in the studies ranged from 24 to 84 months. A total of 1209 restorations had been placed in 957 patients in the included trials, and failures were analyzed by type and material restoration. From a total of 72 restoration failures, the CAD/CAM system resulted in a 1.84 (IC95%: 1.28–2.63) higher risk than conventional manufacturing of ceramic restoration. Nevertheless, when drop-outs were included as a failure risk, the CAD/CAM system resulted in a risk of 1.32 (IC95%: 1.10–1.58). Multilevel analysis of tooth-supported ceramic restorations, considering drop-outs as successes, resulted in rates of 1.48 and 2.62 failures per 100 restoration-years for the controls and CAD/CAM groups, respectively. Considering drop-outs as failures, we found rates of 4.23 and 5.88 failures per 100 restoration-years for the controls and CAD/CAM groups, respectively.ConclusionsThe meta-analysis results suggest that the longevity of a tooth-supported ceramic prostheses made by CAD/CAM manufacturing is lower than that of crowns mad by the conventional technique.     

Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin

Objective

The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM.

Material and Methods

Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group): direct composite resin restoration (Alert) with etch-and-rinse adhesive system (Bond 1 primer/adhesive), Group 2: indirect composite restoration (Estenia) luted with a resin cement (Cement-It) combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond), Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively) onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Student''s t-test. The failure modes of all groups were also evaluated.

Results

The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7) showed better results compared to the other groups (p<0.05). Group 4 showed the weakest bond strength (p>0.05). The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure.

Conclusion

The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces.     

Clinical survival and performance of premolars restored with direct or indirect cusp-replacing resin composite restorations with a mean follow-up of 14 years

ObjectivesThe objective is to evaluate the long-term clinical survival and performance of direct and indirect resin composite restorations replacing cusps in vital upper premolars.MethodsBetween 2001 and 2007, 176 upper premolars in 157 patients were restored with 92 direct and 84 indirect resin composite restorations as part of an RCT. Inclusion criteria were fracture of the buccal or palatal cusp of vital upper premolars along with a class II cavity or restoration in the same tooth.ResultsForty patients having 23 direct and 22 indirect composite restorations respectively, were lost to follow-up (25.6%). The cumulative Kaplan-Meier survival rates were 63.6% (mean observation time: 15.3 years, SE 5.6%) with an AFR of 2.4% for direct restorations and 54.5% (mean observation time: 13.9 years, SE: 6.4%) with an AFR of 3.3% for indirect restorations. The Cox regression analysis revealed a statistically significant influence of the patient’s age at placement on the survival of the restoration (HR 1.036, p = 0.024), the variables gender, type of upper premolar, type of restoration, and which cusp involved in the restoration had no statistically significant influence. Direct composite restorations failed predominantly due to tooth fracture, indirect restorations primarily by adhesive failure (p < 0.05).SignificanceThere was no statistically significant difference in survival rates between direct and indirect composite cusp-replacing restorations. Both direct and indirect resin composite cusp-replacing restorations are suitable options to restore compromised premolars. The longer treatment time and higher costs for the indirect restoration argue in favor of the direct technique.     

Fractography of clinical failures of indirect resin composite endocrown and overlay restorations

ObjectivesCompare failure modes and fracture origins using fractography on recovered clinically fractured parts of indirect resin composite endocrowns and overlay restorations on endodontically treated teeth (ETT).MethodsFour endocrowns (3 molars, 1 premolar) and one overlay (molar) adhesively luted on ETT were recovered after fracturing during function. The time in service ranged between 4 and 48 months. The composite materials were (i) CAD/CAM LAVA Ultimate (N = 1), (ii) Premise Indirect (N = 2), and (iii) Colombus (N = 2). Fractography was performed by means of digital microscopy and SEM. Occlusal surfaces were checked for signs of fatigue degradation and contact wear. Cuspal plane angles were measured from profiles obtained from 3D digital microscope images with respect to the horizontal plane of the occlusal central crown groove.ResultsAll five cases showed a wedge-opening mode I fracture, splitting the crown and tooth in two parts through the crown’s central groove. Classic brittle fracture features (arrest lines, twist and wake hackle) were easily identified on the fracture surfaces. Multiple origins were located along the central groove in conjunction with the presence of fatigue cracks. Contact wear surfaces showed pitting and cracking. Cuspal plane angles were around 30–35°, except a 50° palatal cusp slope for the Lava Ultimate overlay.SignificanceFractography on clinical fractures of resin composites was enlightening. Occlusal surface fatigue degradation from cyclic loading, mode I fracture from applied mastication forces on cuspal planes, and stress concentration within the crown’s central groove, indicate limitations of use of these materials for endocrowns in posterior teeth.     

Occlusal stress distribution and remaining crack propagation of a cracked tooth treated with different materials and designs: 3D finite element analysis

ObjectiveHere we used 3D finite element analysis (FEA) to analyze and directly compare stress distribution and crack propagation in identical cracked tooth models after treatment with various materials and designs.MethodsA 3D model of a cracked tooth was generated. We then applied eight restoration models, comprising combinations of three kinds of restoration designs (inlay, onlay, and crown) and four types of restoration materials (direct composite resin, indirect composite resin, ceramic, and gold). A 1000-N occlusal load was applied on the three reference points of the ball-shaped part in the direction of the longitudinal axis, causing crack line separation in the buccolingual direction. Stress distribution was analyzed on the occlusal surface, bottom level of the restoration, and mesiodistal longitudinal section. The stress on the lower margin of the crack surface was measured at 15 points on each model.ResultsCeramic inlay and onlay showed stress concentration at the restoration bottom, and low stress on the lower margin of the crack surface. Direct and indirect resin restorations exhibited low stress on the restoration bottom, and high stress on the proximal end of the lower margin of the crack surface. With a resin-unfilled gold crown, stress was concentrated on the crown bottom and the lower margin of the crack surface. Direct resin filling inside the gold crown yielded significantly decreased stress on both areas.SignificanceOur results suggest that inlay and onlay ceramic restorations, and gold crown with resin filling inside, are advantageous methods for preventing further crack propagation.     

The direct composite crown

The direct composite crown is a restoration replacing the original toothcrown in form and function. It can be an alternative for indirect gold or porcelain restorations if the oral health condition is not stable, if indirect restorations require a high biological price or if financial resources are limited. The longterm durability of these restorations is still unknown. As a direct composite crown can be considered as minimally invasive and can be easily replaced by an indirect restoration if needed, there are hardly any contra-indications for its use.     

Influence of the preparation design on the survival probability of occlusal veneers

ObjectivesThe fracture resistance of ultrathin computer-aided design and computer-aided manufacturing (CAD/CAM) occlusal veneers with different preparation designs was investigated under cycling mechanical loading and via finite element analysis (FEA).MethodsEighty molars were prepared with a circular enamel ring until complete exposure of the occlusal dentin occurred. Forty were prepared via additional circular chamfer preparation. The teeth were restored with 0.5 mm-thick occlusal veneers. Each group received a CAD/CAM fabricated occlusal veneer with a low modulus of elasticity (composite, CeraSmart) and a high modulus of elasticity material (ceramic, Celtra Duo). The restorations were adhesively luted and underwent 2000 thermocycling cycles. The samples were loaded at 50 N under 1,000,000 cycles in a chewing simulator and were checked for failure after various cycles. A visible crack was defined as failure, and the Kaplan-Meier survival rate was used for data analysis.One sample per group was digitized using microcomputed tomography, and FEA was performed using open-source software. The comparative stresses were analyzed for specimens with and without chamfer preparation.ResultsThe survival probabilities were 60% for occlusal ceramic veneers without preparation and 40% for veneers with chamfer preparation, with no statistically significant differences. Composite veneers achieved 95% survival probability regardless of the preparation method.The main principal stress in ceramic restoration was visualized via FEA. In composite veneers, stress was also visible in the luting composite and dentin.SignificanceThe preparation method had no influence on mechanical fatigue. Minimally invasive preparation can be recommended. The restoration material is crucial for survival.     

Defective restoration repair or replacement: An American Dental Association Clinical Evaluators Panel survey

BackgroundClinicians often encounter defective restorations and are faced with the difficult decision of whether to repair the existing restoration or replace it.MethodsAn electronic survey on repairing or replacing defective restorations was developed to assess how clinicians are making these decisions and the technical aspects considered when making a repair. E-mails containing the survey link were sent to the American Dental Association Clinical Evaluators (ACE) Panel on August 14, 2019, and the survey remained open for 2 weeks. Nonrespondents were sent reminders 1 week after deployment.ResultsApproximately 4 of every 5 respondents repair defective restorations. The top 3 conditions for making these repairs were noncarious marginal defects (87%), partial loss or fracture of the restoration (79%), and crown margin repair due to carious lesions (73%). Among respondents who repair defective restorations, almost all repair direct resin composite (98%), whereas approximately one-third do not repair the other restorative materials (that is, amalgam, glass ionomer, and fractured indirect all-ceramic crowns). Resin composite is used most often to repair resin direct composite restorations, and likewise, glass ionomer is used most often to repair glass ionomer restorations. Only 54% of respondents use amalgam to repair amalgam restorations. Surface treatments varied among the 3 available restorations types.ConclusionsMany dentists are actively making restoration repairs, but choosing clinical scenarios to make these repairs is material dependent.Practical ImplicationsThe repair of defective restorations is an acceptable and more conservative alternative than restoration replacement, and its success depends on proper case selection, material, and technique.     

Microleakage of indirect composite inlays. An in vitro comparison with the direct technique.

Microleakage occurring around directly and indirectly made class-II composite restorations was evaluated on extracted human premolars. Before the evaluation was made, the teeth were thermocycled and stained with an organic dye. Direct class-II composite restorations demonstrated extensive microleakage at their dentin cavosurface margins. Indirect class-II composite inlays luted with a dual-curing composite cement displayed much less microleakage than restorations made using the direct technique. The use of glass-ionomer cement rather than composite cement as the luting material resulted in more microleakage. Rather than being a true microleakage, the leakage of glass-ionomer cement might be the result of a diffusion of the water-soluble organic dye in the water-based cement. The results suggest that the indirect composite technique is superior to the direct technique when it comes to reducing microleakage.     

Restoration of the endodontically treated posterior tooth

ObjectivesTo analyse the key factors of the restoration in the posterior endodontically treated teeth, through a literature review and clinical cases presentation. To focus on the clinical advantages of the adhesive indirect restorations, describing the basic principles for long-term success.Materials and methodsThe biomechanical changes due to the root canal therapy and the degree of healthy dental tissue lost because of pathology and iatrogenic factors are the critical points leading the clinician to the restorative treatment planning. The full crown is considered by the literature as the gold standard and is indicated in case of teeth heavily weakened by dental caries, fractures or previous conservative-prosthetic preparations. The improvement of the adhesion and the composite materials, with mechanical properties close to those of dental tissues, offers to the clinician the option of a conservative restoration, able to seal, reinforce and protect the tooth and to delay the execution of a full crown, with the subsequent sacrifice of dental tissue. Although in the presence of small-sized cavity, direct bonded restoration is considered an effective short and medium-term restoration, cuspal coverage with indirect restoration is the treatment of choice in case of mesio-occlusal-distal cavities. Adhesive overlays preserve coronal structure, avoid contamination of the root canal system, reinforce residual dental tissues, guarantee optimal form, function, aesthetics and offer ergonomic and economic undoubted clinical advantages.Results and conclusionsDirect adhesive restorations, indirect bonded restorations and traditional full crown are three therapeutic options for the single posterior endodontically treated teeth. The amount of remaining sound tooth structure is the most significant factor influencing the therapeutic approach. The clinician's operative skill is a determining aspect for long-term success of adhesive inlays.     

Saturation reduces in-vitro leakage of monomers from composites

Objective

Accurate knowledge of the quantity of released monomers from composites is important. To evaluate the elution of monomers, polymerized composites are typically immersed in an extraction solvent. The objective was to determine whether the volume of extraction solvent and the immersion time influences monomer leachability from dental composite materials.

Two-year clinical evaluation of direct and indirect composite restorations in posterior teeth.

STATEMENT OF PROBLEM: Few long-term clinical studies have reported data of modern posterior composites as direct and indirect restorations. PURPOSE: This prospective, long-term clinical trial (1) evaluated direct and indirect composite restorations for clinical acceptability as posterior restoratives in single or multisurface carious teeth and (2) provided a survey on the 2-year results. MATERIAL AND METHODS: Nine dental students placed 88 composite restorations (Tetric, blend-a-lux, Pertac-Hybrid Unifil), 43 direct composite restorations and 45 indirect inlays, under the supervision of an experienced dentist. The first clinical evaluation was performed 11 to 13 months after placement by 2 other experienced dentists, using modified USPHS criteria. A second follow-up of 60 restorations took place within 20 to 26 months after placement. RESULTS: A total of 93% of indirect and 90% of direct composite restorations were assessed to be clinically excellent or acceptable. Two restorations (1 indirect composite inlay and 1 margin of a direct composite restoration) failed during the second year because of fracture. Indirect inlays demonstrated a significantly better "anatomic form of the surface" than direct composite restorations. Premolars revealed a significantly better margin integrity and postoperative symptoms than molars. CONCLUSION: Posterior composite restorations provided a satisfactory clinical performance over a 2-year period when placed by relatively inexperienced but supervised students.     

Materials for chairside CAD/CAM restorations

Chairside computer-aided design/computer-aided manufacturing (CAD/CAM) systems have become considerably more accurate, efficient, and prevalent as the technology has evolved in the past 25 years. The initial restorative material option for chairside CAD/CAM restorations was limited to ceramic blocks. Restorative material options have multiplied and now include esthetic ceramics, high-strength ceramics, and composite materials for both definitive and temporary restoration applications. This article will review current materials available for chairside CAD/CAM restorations.     

97例CAD/CAM氧化锆基底冠桥修复体制作效果评价

目的评价运用CAD/CAM技术制成的氧化锆修复体的制作效果,探讨影响效果的相关因素。方法选择97例CAD/CAM氧化锆冠桥基底修复的临床病例,观察修复体制作的过程,分析其边缘适合性、颜色、固位、折断或破损情况,综合评价制作效果。以70例贵金属烤瓷冠作为对照组进行研究。结果 97例修复体的制作过程中,发现有1例在切削加工时从包埋蜡中脱落,1例上前牙4单位桥在完成烧结后有小幅度翘动,1例上前牙3单位桥体在切削过程中破裂,上述3例修复体通过返工重做解决问题。所有制作的氧化锆支架,通过饰面瓷的堆塑可使修复体获得较好的美观效果。两种修复方式在边缘适合性、固位和破损率上均无统计学差异(P>0.05),而CAD/CAM氧化锆基底冠的颜色良好率要优于贵金属基底冠(P<0.05)。结论高强度氧化锆全瓷修复体的制作效果能符合临床要求,可以考虑用于全瓷修复。     

三维有限元分析在纤维桩力学研究中的应用进展

纤维桩自推出以来以其良好的生物相容性、优良的机械性能、耐疲劳、耐腐蚀以及易拆除、根折发生率低等优点,在残根残冠的修复治疗中逐渐得到广泛的应用。有限元分析能对复杂形态、结构物体在各种载荷下的应力应变进行分析比较,是口腔生物力学研究中的重要手段。其中三维有限元分析因其模型的几何相似性和力学相似性,成为了纤维桩力学研究中的一种高效、精确、直观的方法。     

间接法树脂高嵌体修复磨牙残冠的临床评价

目的:评价间接法树脂高嵌体修复磨牙残冠的临床效果。方法:分别应用HRi美塑树脂通过间接法制作树脂高嵌体和直接法树脂充填修复68颗磨牙残冠的邻牙合面龋损,分别在修复后6、24、36个月随访,对边缘密合、邻接关系、牙周健康及修复体完整性等临床修复效果进行统计学分析并给予评价。结果:第6个月时两组无差别;第24个月时,两组除了在邻接关系方面嵌体组要优于直接组外(P<0.05),其余方面并没有明显差别;但在36个月时,用间接法树脂高嵌体修复的患牙在边缘密合、邻接关系及牙周健康方面与直接法修复有显著性差异(P＜0.05)。结论:应用间接法树脂高嵌体修复磨牙残冠能获得更好的临床修复效果,更能符合不同层次患者的功能及美学需求。     

Microleakage of thin-walled monolithic zirconia and polymer-containing CAD-CAM crowns

Statement of problemMonolithic restorations facilitate computer-aided design and computer-aided manufacturing (CAD-CAM) processability and provide thin-walled restorations, which require less tooth reduction. For the long-term success of these restorations, their durable sealing is important. However, data in this regard are sparse.PurposeThe purpose of this in vitro study was to investigate the microleakage of monolithic complete crowns made from current CAD-CAM materials after mastication simulation.Material and methodsSixty-four identical test specimens (crown and tooth) were milled based on corresponding standard tessellation language data sets: one for the crowns and another for the human molar teeth. Four CAD-CAM restoration materials were investigated: 2 polymer-containing materials, Brilliant Crios (BC) and Vita Enamic (VE), and 2 zirconia materials, ultra-high-translucent Nacera Pearl Q³ Multi-Shade (ultraHT) and high-translucent Nacera Pearl Multi-Shade (HT). The crowns were adhesively luted to the CAD-CAM milled human molars with 1 of 3 luting systems: OneCoat7Universal and DuoCem (BC); A.R.T.Bond and DuoCement (VE); or EDPrimer/Panavia F2.0 (ultraHT and HT). The specimens were divided in 2 subgroups, and 2 different mastication simulations were applied: normal function (NF) and bruxism (B). A dye penetration test was used to detect microleakage, and the specimens were sectioned. A digital microscope (Zeiss) was used for analysis and to calculate the percentage of leakage in relation to the height of the tooth. Data were subjected to the Mann-Whitney and Kruskal-Wallis tests (α=.05).ResultsMicroleakage was identified in all groups. VE reported the highest leakage with a mean of 13.0%, followed by ultraHT (4.8%), HT (3.6%), and BC (3.0%). No significant difference was detected between the 2 simulation programs (normal function and bruxism). However, VE and the zirconia group HT exhibited a significant difference (P<.014), whereas no significant difference was noted among the zirconia groups or the polymer-containing groups BC and VE.ConclusionsThin-walled restorations made of CAD-CAM composite resin and zirconia exhibited reduced microleakage compared with the polymer-containing ceramic. Thus, from the specific viewpoint of microleakage, CAD-CAM composite resins and zirconia seem to be suitable materials for thin-walled complete crowns.     

Marginal adaptation of four tooth-coloured inlay systems in vivo.

This study investigates the margin quality of four different tooth-coloured inlay systems using computer-aided quantitative margin analysis under scanning electron microscopy. Three types of restorations involved chairside procedures using a commercial CAD-CAM apparatus: one type of inlay restoration was milled from preformed glass ceramic blocks, the other two inlay types were milled from preformed porcelain blocks. The fourth system was based on an experimental indirect composite inlay system. Each inlay type was luted with its respective dual-curing luting composite, which was supplied with the system. After 6 months of clinical service, all four systems revealed a significant percentage of submargination indicating occlusal wear of the luting composite. The porcelain inlays and the composite inlays luted with their respective experimental luting composite showed the best marginal adaptation. Luted glass ceramic inlays, in particular, suffered from a significantly higher percentage of inlay margin fractures (9 per cent) and marginal openings (4 per cent) than the other systems. A possible explanation is that the glass ceramic subsurface structure at the inlay-lute interface was weakened by etching with ammonium bifluoride.     

Clinical performance of large, all-ceramic CAD/CAM-generated restorations after three years: a pilot study

BACKGROUND: Adhesively luted all-ceramic restorations preserve and stabilize weakened tooth structure, but there is little published information about the clinical performance of large, all-ceramic restorations. METHODS: In this pilot study, the authors placed 58 large, single-tooth, all-ceramic restorations in 26 patients using a computer-aided design/computer-aided manufacturing, or CAD/CAM, system (CEREC 2, Sirona Dental Systems GmbH, Bensheim, Germany). They documented the maximum height of the restoration and remaining cementoenamel junction, or CEJ. In 21 cases, rubber dam isolation was not possible during adhesive luting. They re-evaluated the restorations after three years according to the U.S. Public Health Service criteria. RESULTS: After three years, the authors rated 56 (97 percent) of the 58 restorations as Bravo or better in regard to marginal integrity, secondary caries (four could not be rated), discoloration and anatomical form. One restoration was rated as Charlie because of poor marginal integrity, and one restoration had to be replaced owing to a bulk fracture. The authors rated the adequacy of proximal contact and occlusal relationships as acceptable-to-good for all restorations. Neither the extent of the remaining enamel at the cavity margin nor application of a rubber dam had any statistically significant influence (chi2 test, P > .05) on the clinical performance of the restorations after three years. CONCLUSIONS: At the three-year recall appointment, the authors found that the adhesively luted all-ceramic restorations had successfully repaired large coronal defects, irrespective of the cavity margin location (that is, coronal or apical to the CEJ). CLINICAL IMPLICATIONS: Tooth-colored, all-ceramic CAD/CAM-generated restorations are an alternative to conventional restorations if large coronal defects need to be treated.