Restorations In Premolars Research Articles

Five-year survival of class II restorations with and without base bulk-fill composite: a retrospective cohort study

ObjectiveThis study aimed to determine the survival of class II composite restorations in premolars and molars with and without base bulk-fill composite in general dental practice.Materials and methodsWe collected data from the electronic patient files of the Public Dental Services in the City of Oulu, Finland. The timespan of data collection was from August 15th, 2002, to August 9th, 2018. The data consisted of class II composite restorations both with and without base bulk-fill composite. We compared the survival of these restorations using Kaplan–Meier survival curves, the log-rank test, survival rates, and the Wilcoxon signed ranks test.ResultsWe observed 297 restorations in 96 patients. The five-year survival rates for restorations with and without base bulk-fill composite were comparable in premolars (77.5% and 77.4%, respectively) but different in molars (69.9% and 57.8%, respectively, p = 0.069). In molars, the restorations with base bulk-fill composite exhibited a higher survival rate in 14 patients, whereas in 11 patients the restorations without base bulk-fill composites exhibited a higher survival rate. In 24 patients the survival rates were similar for restorations with and without the base bulk-fill composite (p = 0.246).ConclusionsThe restorations with and without base bulk-fill composite had similar longevity.Clinical relevanceBase bulk-fill composites are safe to use in general practice due to their similar survival rates compared to conventional composites.

Restoration of Bilateral Premolars Using Custom Made Cast Post and Core: A Case Report

When grossly carious teeth need to be restored after endodontic treatment, long term success depends on the choice of the post and core systems. A custom-cast post and core is recommended when the remaining tooth structure is compromised and an insufficient ferrule is present. The following case report depicts the restoration of bilateral grossly carious premolar teeth by using custom-cast posts followed by PFM crowns. The patient presented with bilateral severely carious premolars with pulpal necrosis. The treatment plan included endodontic treatment followed by custom-cast posts and cores with PFM crowns. In this way, aesthetics and function for the patient can be achieved by using cast metal posts and metal ceramic crowns for the restoration of premolars.

Stresses in Premolars Restored Using Different Post-and-Core and Crown Materials: An FEA Study.

The aim of the present study was to investigate the influence of three post-and-core systems and two crown materials on stresses in restored premolars using Finite Element Analysis (FEA). A maxillary second premolar 3D model was created in SolidWorks 2014 (Dassault Systémés). Severe loss of tooth structure was simulated with six restorative options: 1) glass-fiber-reinforced composite post and composite core (GFRC)+CAD/CAM leucite-reinforced glass-ceramic crown (LRC); 2) carbon-fiberreinforced composite post and composite core (CFRC)+LRC; 3) metal cast post-and-core (MPC)+LRC 4) GFRC+CAD/CAM composite resin crown (CC); 5) CFRC+CC; 6) MPC+CC. Three-point occlusal loading (150N) was simulated and von Misses and maximum principal stresses calculated. Although maximum von Mises stresses in the crown and dentin were similar across groups (137.9-139.2MPa crown; 17.2-19.6 dentin), there were important differences in stress distribution in dentin. Only in MPC+CC group the maximum stresses were on the bottom of the post preparation cavity. Stress values within the posts were: CFRC(4.8MPa)>GFRC(6.7MPa)>MPC(10.3MPa). CC-restored models presented higher von Mises stresses within the post-and-core compared to the LRC groups. Maximum principal stresses were lower compared to von Mises stresses, following the same trend, and were distributed similarly in all the groups. Both GFRC and CFRC showed favourable stresses distribution in the dentin and restorative materials, while MPC increased stresses in core, post and post cement. The more rigid crown material seems to transmit less stresses to the underlying core and crown cement compared to CC.

Cox Regression Analysis of Prognostic Factors in Full Crown Restoration of Premolars with Cervical Defect

Objective: To study the prognostic factors in Full crown restoration of Premolars with cervical defect by analyzing long-term survival. Methods: A total of 432 Premolars with cervical defect, selected from 2012 Jan to 2014 Dec, were restored by Full crown. According to different repair methods, they were divided into resin repair group and post core repair group. The effect was analyzed by Cox regression analysis in 5-year follow-up. Results: Different repair methods (RR=0.567, 95% CI: 0.355~0.907), Teeth contact (RR=0.033, 95% CI: 0.016~0.840), Abutment teeth (RR=0.494, 95% CI: 0.308~0.793), Dentin shoulder collar (RR=11.465, 95% CI: 6.653~19.759), Defect size RR=0.386, 95% CI: 0.187~0.798) were the isolated factor influencing the prognosis. Further subgroup analysis shows that, the survival rate of the affected teeth as abutments restored with single crown fixed dentures is higher than that restored with fixed bridge dentures (χ²=4.141, P =0.0419). The survival rate of reinforced abutments restored with fiber posts is higher than that of reinforced abutments restored with metal posts (χ²=18.12, P =0.0001)。The C-index of the nomogram for prognosis was 0.838. Conclusion: In order to improve the long-term preservation rate, different restoration methods for Premolars with cervical defect should be selected according to different situations.

Endocrown restorations in premolars: influence of remaining axial walls of tooth structure and restorative materials on fatigue resistance.

To evaluate the effect of the remaining tooth structure and different CAD/CAM materials on the fatigue performance and failure mode of endodontically treated premolars restored with endocrowns. Ninety maxillary premolars were endodontically treated and assignedinto 6 groups (n = 15) according to the number of remaining axial walls (four, three, and two) and restorative materials (ultra-translucent zirconia 5Y-PSZ [KATANA UTML] and lithium disilicate [IPS e.max-CAD]). The specimens were subjected tocyclic fatigue loading test(initial load 200 N; 20Hz). An incremental step load of 100N per 10,000 cycles was applied until failure. The fatigue failure load (FFL) and number of failure cycles (CFFs) datawere statistically analyzed with two-way ANOVA and Kaplan-Meier test (α = 0.05). Failedspecimens were examined under a stereomicroscope 25 × and failure modes were determined. FFL and CFF were significantly influenced by restorative material (p < 0.05). 5Y-PSZ endocrowns showed significantly higher FFL when compared with lithium disilicate. The number of remaining walls did not affect the fatigue behavior or failure mode of the specimens. Of the lithium disilicate restorations, 51% had repairable failures, while 95% 5Y-PSZ restorations had non-repairable failures. Zirconia endocrowns showed better FFL than lithium disilicate endocrowns, regardless of the number of remaining axis walls. Lithium disilicate and 5Y-PSZ endocrowns showed FFL higher than the normal masticatory loads. Restoring endodontically treated premolars with endocrown could be a promising treatment, regardless of the remaining axial walls. However, precaution should be taken in material selection since it affects the fatigue resistance and failure mode.

Clinical longevity of extensive direct resin composite restorations after amalgam replacement with a mean follow-up of 15 years

ObjectivesThe aim of this retrospective clinical study was to determine the survival of extensive direct resin composite restorations after amalgam replacement on vital molars and premolars after a mean observation period of 15 years. MethodsBetween January 2007 and September 2013, a total of 117 extensive cusp replacing direct resin composite restorations were placed in 88 patients in a general dental practice. These were indicated for replacement of existing amalgam restorations. Tooth vitality, the absence of at least one cusp in premolars, and at least two cusps in molars were considered for inclusion. The long-term follow-up of the restorations, re-evaluated after up to 17 years using the original evaluation criteria is reported. Results81 of 88 patients (92.1%) and 106 of 117 restorations (90.6%) were available for follow-up. The cumulative success rate was 62.0% (95% CI: 47.3–76.2, AFR 2.79%) after a mean observation time of 163.4 months, the cumulative survival rate was 74.7% (95% CI: 59.8–89.6%, AFR: 1.70%) after a mean observation time of 179.1 months. The number of cusps replaced in premolars had a statistically significant influence on the success and survival rate of the restorations (HR of respectively, 2.974 and 3.175, p = <0.0005). Premolars with two cusps replaced had 297% more chance of failure than premolars with one cusp replaced. ConclusionsExtensive direct resin composite restorations placed after amalgam replacement showed good survival after a mean observation period of 15 years. The number of cusps involved had a statistically significant influence on the longevity of the restorations in premolars. Clinical SignificanceWith good survival and low annual failure rates, direct resin composite restorations are a suitable treatment for repairing extensive defects in posterior teeth involving multiple cusps and surfaces, provided that they are placed by a dentist who has long experience and is skilled in the placement of direct composite materials.

Effect of Splinting of Tilted External Hexagon Implants on 3-Unit Implant-Supported Prostheses in the Posterior Maxilla: A 3D Finite Element Analysis.

To assess the effects of tilted external hexagon implants and splinted restorations in terms of stress distribution on the bone tissue, implants, and prosthetic screws, using three-dimensional finite element analysis. Six models were used to simulate a posterior maxilla bone block (type IV) from the first premolar to the first molar. Each model included three 4.1-mm-diameter external hexagon implants with varying inclinations (0°, 17°, and 30°) and crown designs (splinted and nonsplinted restorations). The forces applied were as follows: 400 N axially (50 N for each slope of the cusp) and 200 N obliquely (45° only on the buccal slope of the cusp). Stress distribution on the implants and prosthetic screw was evaluated using Von Mises stress, while the maximum principal stress was used to evaluate the stress distribution in the bone tissue. The oblique load increased the stress on all the structures in all the models. Increased inclination of the implants resulted in higher stress concentration in the bone tissue, implants, and prosthetic screws. However, splinted restorations contributed to reduction of the stress for the oblique loading, mainly in the bone tissue and prosthetic screw of the first molar, as the stress was shared between the first and second premolar restorations. Tilted implants increased proportionally the stress on bone tissue and prosthetic screws of models. Additionally, splinting restorations reduced the stress concentration area in the simulated bone tissue, implants, and prosthetic screws in the first molar, as the stress was shared with the adjacent implants.

Assessing Fracture Resistance of Restored Premolars with Novel Composite Materials: An In Vitro Study.

During restorative treatment, premolars restored with resin filling materials using the conventional incremental-fill technique take longer restoration time and undermine the integrity of the tooth. The aim of this study was to assess fracture resistance of premolars restored by various types of novel bulk-fill composite resin materials. Forty-eight (n = 48) freshly extracted sound maxillary first premolars were used in this in vitro study. The teeth were divided into six groups, each having 8 specimens. Group A (positive control) was allocated for the intact teeth. For specimens in Groups B to F, a large cavity (Class-II MOD) was prepared with a standardized dimension of cavity (3 mm depth on the pulpal floor, 4 mm at the gingival seat, and 3 mm cavity width). Group B represented prepared teeth without any restoration. Group C, Group D, Group E, and Group F were restored with Tetric EvoCeram® incremental-fill (conventional), Beautifil bulk-fill, Filtek posterior bulk-fill, and SonicFill 2 bulk-fill restorative materials, respectively. All samples were finished and polished with an enhanced finishing kit and stored in distilled water for a month before the fracture resistance testing. All the samples were exposed to the axial loading (the speed of crosshead was 1 mm/min) in a computer-controlled universal testing machine (LARYEE, China) via a steel bar (6 mm in diameter) and the maximum applied force in Newton was recorded as the fracture resistance. One-way analysis of variance (SPSS 21) was used to compare the fracture resistance within the groups, and Tukey's post hoc test was used to determine the difference between the groups. The lowest value of fracture resistance was recorded for Group B, and the highest value was recorded for Group A followed by the values of Group D, Group C, Group F, and Group E. One-way ANOVA revealed a statistically significant difference between the groups (P < 0.05). Nonsignificant difference was found between the premolars restored by bulk-fill and conventional composites. Among the bulk-fill restored specimens, Beautifil restorative demonstrated significantly higher fracture resistance in comparison with the other two bulk-fill restored specimen groups (SonicFill 2 and Filtek). Bulk-fill composite such as Beautifil could be an alternative option to conventional incremental-fill composite for premolar restoration.

The effect of pre-treatment levels of tooth wear and the applied increase in the vertical dimension of occlusion (VDO) on the survival of direct resin composite restorations.

ObjectivesTo investigate the effects of the level of pre-treatment tooth wear and increasing the VDO on the performance of direct resin composite restorations for the rehabilitation of pathological tooth wear. MethodsFull-mouth (pre-treatment) grading was performed on digital greyscale scan records for 34 participants (35.3 ± 8.4 years) with signs of moderate-to-severe generalised tooth wear, using the Tooth Wear Evaluation System and the Basic Erosive Wear Examination. Each participant received full-mouth direct resin composite restorations, with increased VDO. The post-treatment increase in the VDO was determined. Recalls were planned after 1 month, and after 1, 3, and 5 years. Three ‘levels’ of restoration failure were described. The effects of the variables on the frequencies of restoration failure were calculated with a multivariable Cox regression, (p < 0.05). Results1269 restorations were placed with a mean observation period of 62.4 months. Increasing the VDO by 1 mm significantly reduced the risks of all levels of anterior restoration failure (HR ≤ 0.62, p ≤ 0.025). A higher anterior BEWE surface score was associated with increased risks of Level 2- & 3- failures, (HR ≥ 1.29, p ≤ 0.019). Premolar restorations showed lower risks of Level 2- & 3- failure, compared to the molar restorations, (HR ≤ 0.5, p ≤ 0.005). ConclusionLevels of pre-treatment wear and the applied change in the VDO significantly affected failure risk. Clinical relevanceDirect resin composite restorations for the rehabilitation of wear should be made as voluminous as possible, respecting the presenting biological, functional, and esthetic constraints.

Evaluation of Remineralization Potential of ACTIVA Bioactive Restorative Material Versus Resin Modified Glass Ionomer in Restoration of Premolars: In Vitro Study

Evaluation of Remineralization Potential of ACTIVA Bioactive Restorative Material Versus Resin Modified Glass Ionomer in Restoration of Premolars: In Vitro Study

Current status and perspective of CAD/CAM-produced resin composite crowns: a review of clinical effectiveness.

The purpose of the present review was to survey the available literature on computer-aided design/computer-aided manufacturing (CAD/CAM)-produced resin composite materials to provide clinicians with a current overview of the key components necessary for daily clinical use. An electronic search was conducted in the PubMed database. Peer-reviewed articles in English language on the use of resin composites in CAD/CAM dental crowns were included. A total of 122 full-text articles were identified, 15 of which were selected during the initial review. Two additional articles were also discovered through a manual search, to obtain a final total of 17 articles included in the present review. Of these, 16 were to in vitro studies, and one was an in vivo study. Findings from the in vitro studies indicate that resin composite block materials for CAD/CAM applications demonstrate excellent physical properties and are appropriate for the clinical restoration of premolars and molars. However, the in vivo study reported a low 3-year success rate, but high survival rate for resin composite CAD/CAM crowns placed in the premolar region. The key to ensuring the successful prognosis of a resin composite CAD/CAM crown is to ensure that all steps—such as proper case selection, abutment tooth preparation, occlusal adjustment, and bonding—are accurately performed.

Association of age and gender of patients who underwent amalgam restoration in mandibular premolars with class 1 dental caries

The presence of dental caries is the main reason for the placement and replacement of restorations. Maintaining restorations to a satisfactory clinical condition is a big challenge for the practitioners. The aim of the study is to associate the age and gender of the patients who underwent amalgam restorations in mandibular premolars with class 1 dental caries. This was a descriptive study, where all the patients data were collected by reviewing patients records and analysing the data of 86000 patients reported from June 2019 to March 2020 to the Department of conservative dentistry and endodontics, Private Dental college and hospitals, Chennai. Data was collected and tabulated, statistical analysis was done by SPSS – IBM. In this study, we observed that there is a significant difference between the age, gender and tooth number of patients who underwent amalgam restoration in mandibular premolar with class 1 dental caries. Amalgam restoration has served the profession well, and it is very useful in restorative dentistry. Thus the use of amalgam can be continued as a material of choice if esthetics is not a concern.

Clinical Performance of Posterior Microhybrid Resin Composite Restorations Applied Using Regular and High-Power Mode Polymerization Protocols According to USPHS and SQUACE Criteria: 10-Year Randomized Controlled Split-Mouth Trial.

This randomized, split-mouth clinical study evaluated the marginal quality of direct class-I and class-II restorations made of microhybrid composite that were applied using two polymerization protocols and two marginal evaluation criteria. A total of 50 patients (mean age: 33 years) received 100 direct class-I or class-II restorations in premolars or molars. Three calibrated operators made the restorations. After conditioning the tooth with 2-step etch-and-rinse adhesive, restorations were made incrementally using microhybrid composite. Each layer was polymerized using a polymerization device operated either in regular mode (600-650 mW/cm2 for 20 s) (RM) or high-power (1200-1300 mW/cm2 for 10 s) mode (HPM). Two independent, calibrated operators evaluated the restorations 1 week (baseline) and 6 months after restoration placement, and thereafter annually up to 10 years using modified USPHS and SQUACE criteria. Data were analyzed using the Mann-Whitney U-test (α = 0.05). Alpha scores (USPHS) for marginal adaptation (76% and 74% for RM and HPM, respectively) and marginal discoloration (70% and 72%, for RM and HPM, respectively) did not show significant differences between the two polymerization protocols (p > 0.05). Alpha scores (SQUACE) for marginal adaptation (78% and 74% for RM and HPM, respectively) and marginal discoloration (70% for both RM and HPM) were also not significantly different at the 10-year year follow-up (p > 0.05). Regular and high-power polymerization protocols had no influence on the stability of marginal quality of the microhybrid composite tested up to 10 years. Both modified USPHS and SQUACE criteria confirmed that regardless of the polymerization mode, marginal quality of the restorations deteriorated significantly compared to baseline (p < 0.05).

A comparison of the marginal fit and mechanical properties of a zirconia dental crown using CAM and 3DSP

PurposeThis study aims to compare the marginal fit, flexural strength and hardness for a ceramic premolar that is constructed using dental computer aided machining (CAM) and three-dimensional slurry printing (3DSP).Design/methodology/approachDental CAM and 3DSP are used to fabricate a premolar model. To reduce the fabrication time for 3DSP, a new composition of solvent-free slurry is proposed. Before it is fabricated, the dimensions of the green body for the premolar model are enlarged to account for the shrinkage ratio. A two-stage sintering process ensures accurate final dimensions for the premolar model. The surface morphology of the green body and the sintered premolars that are produced using the two methods is then determined using scanning electronic microscopy. The sintered premolars are seated on a stone model to determine the marginal gap using an optical microscope. The hardness and the flexural strength are also measured for the purpose of comparison.FindingsThe developed solvent-free slurry for 3DSP can be used to produce a premolar green body without micro-cracks or delamination. The maximal marginal gap for the sintered premolar parts that are constructed using the green bodies from dental CAM is 98.9 µm and that from 3DSP is 72 µm. Both methods produce a highly dense zirconia premolar using the same sintering conditions. The hardness value for the dental CAM group is 1238.8 HV, which is slightly higher than that for the 3DSP group (1189.4 HV) because there is a difference in the pre-processing of the initial ceramic materials. However, the flexural strength for 3DSP is 716.76 MPa, which is less than the requirement for clinical use.Originality/valueThis study verifies that 3DSP can be used to fabricate a zirconia dental restoration device that is as good as the one that is produced using the dental CAM system and which has a marginal gap that is smaller than the threshold value. The resulting premolar restoration devices that are produced by sintering the green bodies that are produced using 3DSP and dental CAM under the same conditions have a similar hardness value, which is four times greater than that of enamel. The flexural strength of 3DSP does not meet the requirement for clinical use.

Comparative evaluation of post operative sensitivity in etch and rinse and self etch adhesives: A longitudinal study

Introduction: It is presumed that self- etch adhesives are prevent post operative sensitivity in posterior restorations. In this study author tested a hypothesis: a self etch adhesives would results in postoperative sensitivity than etch and rinse. Methods patients were recruited on the basis of class I and class II restorations in molars and premolars. The author placed 60 restorations with self etch adhesive [Adper Easy Bond, 3M ESPE, Germany] and 72 restorations with Tetric N-Bond [Ivoclar-Vivadent, India], which uses 34% phosphoric acid to etch enamel and dentine simultaneously. Cavity preparations were of established design for composite restoration, with no beveling on occlusal surface with supported enamel margins. Restoration done with corresponding composite materials under rubber dam isolations. The restored teeth were evaluated preoperatively and a 15 days, 2 months and 6 months postoperatively for sensitivity to cold [ice], air and masticatory forces. Results analysis of variance reveled no statically significant difference in postoperative sensitivity between the self etch and etch and rinse at any recall time. Conclusion of study was that the self adhesive did not differ from the etch and rinse in terms of sensitivity. Keywords: Self etch adhesive, Total etch, Sensitivity, Beveling.

Direct Restorations, Endodontics, and Bleaching: Materials and Techniques Used by General Dentists of New Zealand.

Background To investigate the selection and use of direct restorative materials, endodontic techniques adopted, and approaches to bleaching by general dentists in New Zealand. Methods A questionnaire comprising 19 sections and 125 questions was distributed via mail to 351 general dentists in New Zealand who were selected, at random, from the Dental Council of New Zealand's 2016 register. Results A total of 204 questionnaires were returned, of which 188 were usable. Direct resin composite was the most commonly used material for occlusoproximal cavity restorations in premolars (93.7%) and permanent molars (85.2%). Resin-modified glass ionomer cements (34%) and resin composite materials (31.4%) were more commonly used in the restoration of deciduous molars. Home-based vital bleaching was provided by a significant number of dentists (86%), while only 18% provided practice-based bleaching. Cold lateral condensation was the most commonly used obturation technique (55.8%), and 83% of respondents reported using rubber dam for treatments. Conclusions The findings from this study indicate that dentists in New Zealand are adapting to new materials and technologies to provide high quality care to their patients. Aesthetic treatments such as bleaching have become an integral part of general dental practice.

Fracture Resistance of Endodontically Treated Maxillary Premolars Restored With Different Methods.

The purpose of this in vitro study was to evaluate the resistance and patterns of fracture of endodontically treated maxillary premolars (ETPs) restored with different methods. Mesio-occluso-distal cavities were prepared in 50 extracted caries-free human maxillary premolars after endodontic treatment. The teeth were divided into five groups (n=10), according to the restorative method. G1: intact teeth (control group); G2: conventional composite resin; G3: conventional composite resin with a horizontal glass fiber post inserted between buccal and palatal walls; G4: bulk-fill flowable and bulk-fill restorative composites; and G5: ceramic inlay. For direct restorations, Filtek Z350 XT, Filtek Bulk Fill Flowable Restorative, and Filtek Bulk Fill Posterior Restorative were used. Indirect restorations were fabricated from a pressable lithium disilicate glass-ceramic (IPS e-max Press) and adhesively cemented (RelyX Ultimate). All specimens were subjected to thermocycling (5°C to 55°C/5000 cycles) and additionally submitted to cyclic loading 50,000 times in an Electro-Mechanical Fatigue Machine. Next, the specimens were subjected to a compressive load at a crosshead speed of 1 mm/min until fracture. The fractured specimens were analyzed to determine the fracture pattern using a stereomicroscope, and then representative specimens were carbon coated to allow for the studying of the fracture surface under scanning electron microscopy. One-way analysis of variance (ANOVA) was used to compare fracture resistance of the groups. The results of fracture patterns were submitted to the Fisher exact test (α=0.05). All specimens survived fatigue. Mean (standard deviation) failure loads (N) for groups were as follows: G1: 949.6 (331.5); G2: 999.6 (352.5); G3: 934.5 (233.6); G4: 771.0 (147.4); and G5: 856.7 (237.5). The lowest fracture resistance was recorded for G4, and the highest ones were recorded for G2, followed by that of G1 and G3. One-way ANOVA did not reveal significant differences between groups ( p>0.05). The highest repairable fracture rates were observed in G1 (100%) and G3 (80%). ETPs restored with conventional composite resin with or without horizontal fiber post, bulk-fill composite, and ceramic inlay showed fracture resistance similar to that of sound teeth. Conventional composite resin restorations exhibited the highest prevalence of unrepairable fractures, and the insertion of a horizontal fiber post decreased this prevalence. Intact teeth showed 100% of repairable fractures. It is difficult to extrapolate the results directly to a clinical situation due to the limitations of this study.

Direct technique premolar coronal restorations: From metallic material to "complete adhesive restoration".

Introduction:The choice of restorative materials has for a long time been determined by the tooth position. Thus, premolar restoration depended on the practitioner's clinical assessment and practical experience in regard to the material to be handled.Aim:The objective of this study was to assess, in the students' practice, the change in the choice of materials used for premolars restoration.Materials and Methods:This was a retrospective study based on the available care records in the department of conservative dentistry and endodontics of a dental school. Variables analyzed included the year of restoration, the type of material, the premolar position in the arch, and the coronal restoration site (occlusal, proximal, and cervical). Data collected were processed with the SPSS software version 22 (SPSS Inc., Chicago, IL, USA; 2013). The statistical significance threshold was set at 5% for Pearson's Chi-square test.Results:Between 1994 and 2017, 1738 restored premolars were identified. Over the years, amalgam restorations declined from 99.2% in 1994 to 1.3% in 2017, contrary to composite whose frequency increased from 0.6% to 88.6%. Maxillary premolars were exclusively restored with composite in 2017 when amalgam was still, somewhat, used for mandibular premolars.Conclusion:The reversal in the choice of materials in favor of composites reflects the global trend. This seems to be related to the current awareness of the prohibition, among others, of medical devices containing mercury.

Treatment Outcome of Posterior Composite Indirect Restorations: A Retrospective 20-Year Analysis of 525 Cases with a Mean Follow-up of 87 Months.

The purpose of this study was to evaluate the survival of 525 composite indirect restorations in premolars and molars after a follow-up of 20 years. For each patient, the following variables were recorded and analyzed: age, sex, smoking status, presence of plaque according to O'Leary index, and presence of bruxism. For each restoration, the following variables were collected: restoration class, tooth type (premolar or molar), and restoration material. Mean 20-year survival rate of composite restorations was 57%, ranging from 44% to 75%. The Kaplan-Meier method demonstrated a probability of survival at 10 years of 80% and 90%. Surviving restorations kept their clinical characteristics extremely well, as assessed on the basis of the United States Public Health Service criteria. The results of this study demonstrate the efficacy of indirect composite restorations, confirming their reliability as a posterior prosthetic clinical option.

Fracture Resistance of CAD/CAM-Fabricated Lithium Disilicate MOD Inlays and Onlays with Various Cavity Preparation Designs.

To examine the fracture resistance of premolars restored with CAD/CAM lithium disilicate mesio-occlusal-distal (MOD) inlays and onlays of different cavity designs. Two widths of occlusal isthmus (75%, 100% of intercuspal distance) and three designs of cuspal coverage (none, palatal, complete) were used for the preparation of MOD inlays and onlays in the extracted maxillary premolars. Sixty lithium disilicate restorations were milled and bonded into the cavities. After 24 hours of water storage, the specimens were loaded until fracture, and the fracture loads (N) were measured. Any evidence of cracks and fractures on the tested specimens were examined to classify failure patterns. Mean fracture load values for the tested groups were as follows: 664.4 ± 214.7 N (group A), 659.3 ± 391.2 N (B), 681.9 ± 258.1 N (C), 938.1 ± 862.0 N (D), 841.7 ± 375.4 N (E), and 994.2 ± 486.3 N (F). The width of occlusal isthmus did not significantly affect the fracture loads among all the groups. Within groups with identical isthmus width, the fracture loads showed no significant difference depending on the designs of cuspal coverage. The majority of specimens showed either type III or IV fracture mode. Within limitations of this study, the bonded restorations of premolars with CAD/CAM-generated lithium disilicate were reliable, regardless of cavity preparation design.