Remaining Tooth Structure Research Articles

Esthetic and Functional Posterior Rehabilitation With Lithium Disilicate Ceramics for the Replacement of Gold Alloy and Metal-Ceramic Restorations: A Clinical Case With a 10-Year Follow-Up.

This case report illustrates a clinical scenario of a patient with insufficient crowns, gold onlays and localized tooth pain in the posterior teeth, treated with partial and full coverage lithium disilicate restorations. A female patient presented in the clinics, complaining about tooth pain and unesthetic metal restorations. After a thorough examination, diagnosis and treatment plan, the existing restorations were removed, and a defect-oriented preparation was done to preserve as much as possible of the remaining tooth structure. Final partial and full coverage lithium disilicate restorations were delivered. After a 10-year follow-up no biological complications were observed. Nevertheless, one major chipping was observed in one of the upper molars. This technical complication was resolved with the fabrication of a new ceramic restoration. Lithium disilicate ceramic posterior full- or partial-coverage restorations are a reliable and predictable treatment option not only for the replacement of tooth structure lost due to caries but also for the replacement of insufficient restorations. The following key factors are to be considered to pursue long-term success with ceramic restorations: patient selection, minimal invasive tooth preparation, appropriate material selection and cementation. Nevertheless, complications are to be expected, and the patient should be informed accordingly.

Post-Endodontic Restorative and Prosthetic Options - A Review

Background- In the past, conventional wisdom in post-endodontic care dictated the application of full coverage restorations to all teeth. However, recently a shift towards minimally invasive dentistry has gained traction among the restorative dentists. This change has been driven by accumulating evidence revealing that full coverage restorations often result in significant loss of healthy tooth structure. Consequently, clinicians and researchers have advocated for more conservative approaches to restoring endodontically treated teeth. These alternatives encompass partial coverage restorations such as inlays, onlays, overlays, and even simpler resin composite cores. While the allure of this minimally invasive strategy is evident, there are cases where greater coverage is necessary. Various factors, including tooth type, occlusal load, number of missing teeth, remaining healthy tooth structure, and tooth position, must be carefully considered before selecting an appropriate post- endodontic restoration.  Conclusion- The purpose of this review is to summarize the post- endodontic restorations, various new materials their indications depending on the remaining tooth structure and the teeth that needs to be restored. Light has been thrown on the recent advances in the prosthetic aspect in post-endodontic cases with minimally invasive dentistry in mind.

DENTAL REHABILITATION BY THE OCCLUSAL MATRIX TECHNIQUE USING PROVISIONAL RESTORATOR: Case report of a pediatric patient from the city of Mato Verde - MG

The occlusal matrix technique allows the recording of anatomical details of the remaining tooth structure before starting cavity preparation, enabling the reestablishment of the original tooth morphology by means of an occlusal matrix. The objective of this study was to report a clinical case of dental rehabilitation by the occlusal matrix technique using a temporary restorative in pediatric dentistry. This research is an observational descriptive study (committee, nº 6.906.292). The work was conducted in the city of Mato Verde, Minas Gerais, at Faculdade Verde Norte (FAVENORTE). A 7-year-old female patient, together with her guardian, attended the FAVENORTE Dentistry clinic for dental care, complaining that her tooth had some “dark spots”. During the clinical examination, it was observed that tooth 46 had an active carious lesion on the occlusal surface in a region of pits and fissures with shadowing in the underlying dentin (ICDAS – Score 4), but with relatively intact occlusal anatomy. Interproximal radiographic examination showed that the carious lesion was in the dentin, but not close to the pulp. Due to the preservation of the occlusal anatomy of the tooth, the proposed treatment for the patient was the use of the occlusal matrix technique, selective removal of carious tissue, and restoration with composite resin, aiming to restore form and function. The occlusal matrix technique has proven to be an effective and efficient approach in the rehabilitation of carious lesions on occlusal surfaces, especially in pediatric patients. The technique allowed the faithful reproduction of the original anatomy of the tooth, which is essential for the maintenance of masticatory function, esthetics and occlusal integrity.

COMPARATIVE EVALUATION OF FRACTURE RESISTANCE OF ENDODONTICALLY TREATED TEETH USING DIFFERENT TYPES OF ROOT CANAL SEALERS: AN IN-VITRO STUDY

Introduction: Obturation materials are considered the key elements in supporting strength of endodontically treated teeth. Hence, along with gutta percha (GP) use of sealers strengthen the remaining tooth structure, thus increasing fracture resistance. Material and Methods: Eighty extracted single rooted mandibular premolar teeth were decoronated to standardized root length of 13mm. After confirming working length cleaning and shaping upto F2 file along with irrigation using 5ml 3% NaOCl, 5ml 17% EDTA and normal saline was done. Teeth were divided into 5 groups (n=16) depending upon type of sealer used for obturation along with gutta percha (GP) using lateral compaction technique. Group 1: Endoseal sealer, Group 2: AH Plus, Group 3: Apexit Plus, Group 4: Bio C Sealer, Group 5: Instrumented and unobturated (Control). Samples were stored for 7 days at 37 degree and 100% humidity for sealer to set completely. Samples were mounted vertically 3mm into acrylic resin block leaving 9mm of root length exposed. Fracture resistance was tested using Universal Testing Machine (UTM). Amount of force required for fracture was recorded in Newton. Data were analysed using SPSS 22.0 and oneway ANOVA and Post hoc Tukey test were used for statistical analysis. Result: The maximum fracture resistance was obtained in Group 4 Bio C sealer i.e. 418.81±21.06 N, followed by Group 2, Group 3 and Group 1. Least fracture resistance was obtained in Group 5. Conclusion: Bio C sealer provides the best fracture resistance to the endodontically treated teeth when compared with AH Plus, Apexit Plus and Endoseal.

Stress distribution pattern in two different no-post systems in endodontically treated maxillary central incisors: A three-dimensional finite element analysis.

This study aimed to evaluate the stress distribution in an endodontically treated tooth restored with two different reinforcing fibers followed by direct composite restoration using a finite element analysis (FEA). FEA. Two three-dimensional models of endodontically treated maxillary central incisors were restored with two reinforcing fibers: the polyethylene fibers (PFs) and the short fiber-reinforced composite (SFRC), respectively. The restoration was carried out without any intraradicular preparation using direct composite restoration. The models were generated using SolidWorks. The elastic modulus and Poisson's ratio for various structures and materials were installed into the simulation software, Abaqus. A FEA was then conducted. Each model received a mixed-mode loading of 150 N as distributed pressure to the specified region, and stress distribution was evaluated using the von Mises criteria. Both the reinforcing materials, PF and SRFC, showed maximum concentration of stresses in the cervical third of the tooth. The calculated values of the von Mises stresses for the PF and the SFRC models were 1.7 Mpa and 1.9 Mpa, respectively. Moreover, the stresses generated were of low intensity and were uniformly distributed, suggesting that by using this technique, stresses may be very well tolerated by the remaining tooth structure without any fracture. This no-posttechnique, using the two reinforcing fibers, showed minimal stress concentration in the cervical region of the tooth. Thus, using this ultraconservative approach that aims to preserve and reinforce the pericervical dentin and restore the remaining tooth structure with direct composite restoration could be a promising treatment option for the rehabilitation of badly mutilated teeth.

Restorations of Endodontically Treated Teeth

Endodontically treated teeth are fragile compared to vital teeth. The reason for the decrease in fracture resistance and hardness is related to the deterioration of the structural integrity as a result of caries, trauma and cavity preparation. Restorations in endodontically treated teeth are applied considering the remaining tooth structure and functional status. For many years, post core systems that require additional preparation in the root canal, as well as the loss of most of the coronal tooth structures, are used for the final restoration of endodontically treated teeth. Endocrowns are monoblock restorations that attach to the pulp chamber and its walls, providing macro-mechanical and cementation with micro-mechanics, thus requiring no additional preparation. The first study written on ceramic endocrown was published in 1995. In this study, it is defined as a ceramic monoblock production technique for the restoration of endodontically treated teeth. This procedure was later named "endocrown" in 1999.

Clinical Effectiveness of High-viscosity Glass Ionomer Cement and Composite Resin as a Restorative Material in Primary Teeth: A Systematic Review of Clinical Trials.

This systematic review was designed to compare the clinical effectiveness of high-viscosity glass ionomer cement (HVGIC) restorations to direct composite resin (CR) restorations in single- or multisurface cavities in primary teeth. Restorative procedures are typically used to treat caries in primary teeth. Due to their improved preservation of the natural tooth structure and their adhesion to the remaining tooth structure, CR and GIC have drawn attention as the preferred restorative materials. In the literature, over the past 20 years, the term HVGIC has developed. Compared to C-GICs, HVGICs appear to have a higher survival rate. However, isolated studies provide contradictory findings regarding the durability of restorations in primary teeth. Major electronic databases were thoroughly searched to find publications from the years 2000 to 2021. Studies included were randomized and nonrandomized clinical trials on children aged 3-13 years, in which restoration of primary teeth using HVGIC and CR was performed. This systematic review includes four studies [three randomized controlled trials (RCTs) and one nonrandomized controlled trial]. No statistically significant difference between these materials was seen in any of the included studies. This systematic review of findings supports the assertion that both HVGIC and CR restorations deliver satisfactory outcomes in terms of clinical efficacy and overall survivability. It was found that, for both materials, class I restorations had statistically higher survival rates than class II restorations. Long-term studies are essential to evaluate the clinical efficacy of both restorations. This systematic review outlines the application of HVGIC and CR as restorative materials for pediatric dentists to use in their everyday dental practices. Krishnakumar K, Kalaskar R, Kalaskar A, et al. Clinical Effectiveness of High-viscosity Glass Ionomer Cement and Composite Resin as a Restorative Material in Primary Teeth: A Systematic Review of Clinical Trials. Int J Clin Pediatr Dent 2024;17(2):221-228.

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.

Restoration of Teeth with Severely Compromised Tooth Structure using Digital Planning Combined with Orthodontic Magnetic Extrusion—A Report of 2 Cases

This report outlines 2 digitally planned cases in which the teeth underwent magnetic extrusion to preserve the supracrestal tissue attachment and regain the ferrule, followed by their restoration. Case 1: A 42-year-old man with the chief concern of a fractured right maxillary second premolar. Following the completion of root canal treatment, the remaining tooth structure was insufficient to create a ferrule for tooth restoration. For this scenario, a rapid magnetic extrusion technique was performed on tooth #4 to obtain an approximate 3-mm ferrule. The condition of both the dentition and the restorative margin was acceptable 18 months following treatment. Case 2: A 62-year-old man with the chief complaint of mobility on both sides of the maxillary arch in relation to a tooth-supported fixed partial denture (FPD). Following removal of the FPD, multiple extractions were carried out and tooth #6 was subjected to magnetic extrusion in 3 stages to a maximum of 4 mm to obtain a ferrule. At the 18-month and 3-year follow-up appointments, the tooth had no symptoms and the gingiva around the restorations had optimal architecture and margins. The 3-dimensional digital planning was helpful in precisely positioning the magnets within the tooth and the provisional restorations to facilitate axial extrusion. The extruded teeth were restored with zirconia crowns in both cases. The beneficial outcomes observed from these cases provides evidence that the integration of digital planning and magnetic extrusion holds promise as a method for reconstructing teeth with crowns that are significantly compromised.

A microcomputed tomography analysis of adaptation in premolars with flared root canals restored with different digitally custom fabricated post materials

Statement of problemPreserving and strengthening the remaining tooth structure of compromised flared root canals after endodontic treatment is challenging. PurposeThe purpose of this in vitro study was to compare the adaptation of milled polymer- infiltrated ceramic, fiber-reinforced composite resin, and high-performance semicrystalline thermoplastic resin posts as used to restore mandibular premolars with flared root canals. Material and methodsForty sound mandibular premolars were randomly divided into 4 groups: custom Vita Enamic (CV), custom fiber-reinforced composite resin (CF), custom polyetherketoneketone (CP), and prefabricated fiber (RF) posts. After endodontic treatment, each tooth was sectioned 1.5 mm occlusal to the cementoenamel junction. Then, the post space was prepared and flared, except the RF group, to a depth of 9 mm. The post space in RF group was prepared with a post drill. For the CV, CF, and CP groups, the posts were milled, finished, and cemented to their corresponding teeth. Each tooth was scanned using a microcomputed tomography device, and the reconstructed images were analyzed in mesiodistal, buccolingual, and horizontal planes. The cement thickness, cement volume, and volume of voids were measured. The data were analyzed using 3-way ANOVA (cement thickness) and 2-way ANOVA (cement volume and voids volume) tests followed by the post hoc Tukey test (α=.05). ResultsThe 3-way ANOVA test revealed a significant interaction (P<.001) between material type, section, and surface on the cement thickness. The mean cement thickness in the RF group was significantly higher than in the CV group (P=.001) and CF group (P=.005). The least mean cement thickness was at the apical section followed by the cervical and middle sections. Regarding cement volume, the 2-way ANOVA test showed statistically significant interaction between material type and section. The mean cement volume in the RF group was significantly lower than in the CV group (P=.001), CF group (P=.001), and CP group (P=.001). The highest mean cement volume was in the cervical section followed by the middle and apical sections. The 2-way ANOVA test showed statistically significant interaction (P<.001) between material type and section on the volume of voids. Significant differences were found between the mean volume of voids at the cervical and middle sections (P=.001) and the cervical and apical sections (P=.002). ConclusionsCompared with prefabricated fiber posts, digitally fabricated polymer-infiltrated ceramic and fiber-reinforced composite resin posts had a thinner cement layer with minimal thickness at the apical section. The digitally fabricated posts had higher cement volume, especially at the cervical section, than prefabricated fiber posts. High volumes of voids were related to the cervical section of all tested posts.

Impact of Conservative Access Cavity Designs and Remaining Tooth Structure on Fracture Resistance of Maxillary First Premolars(In Vitro Study)

Impact of Conservative Access Cavity Designs and Remaining Tooth Structure on Fracture Resistance of Maxillary First Premolars(In Vitro Study)

Assessment of Occlusal Load Strength of Glass Ionomer Cement and Composite in Class V Cavities: An In-Vitro Study.

Glass ionomer cement (GIC) is widely used in dentistry due to its chemical adhesion to dental tissues, biocompatibility, and anti-cariogenic potential but they have relatively weak mechanical properties. Resin composites have been widely regarded as the first choice for direct restorations but their polymerization shrinkage has remained a major problem. It has the potential to cause tooth debonding. The composite interface leads to postoperative sensitivity, secondary caries, enamel cracks, and microleakage. A restorative material's capacity to withstand occlusal stresses and support the remaining tooth structure depends on this property. Although class V restorations are predominantly done with GIC, this study was done to compare the strength ofcomposite with the same. The GIC restore glass which is commonly used was tested against restofill composite. The main objective of conducting the study was to compare the compressive strengthof the composite vsGIC in cervical cavities. So the aimof the study isto assess the occlusal load strength of GIC and composite in class V cavities using the universal testing machine. This study was employed as an in vitro study involving 20 natural central incisor teeth without any carious lesions. Class V cavity preparation was done and the selected teeth were divided into two groups of ten each. The cavities were filled with D Tech RestoreGICand composite restorations (restofill), respectively, polished, and then subjected to testing. An eccentric load was applied to the tooth structure using an Instron (Instron E3000 Electropuls, Instron, Norwood, United States) - Universal testing machine with a cross-head speed of 1mm per minute, and the stresses were further analyzed in the presence of an occlusal loading test using a stainless steel jig of 1mm diameter which led to the sectioning of the tooth buccolingually under the applied load. An independent t-test was used to assess the results, and it was concluded that the results were statistically significant (p<0.05) at p=0.034. Conclusively, the results suggested that the occlusal load strength of the composite is greater when compared to GIC.

Biomechanical behavior and Weibull survival of CAD-CAM endocrowns with different marginal designs: A 3D finite element analysis

ObjectivesTo evaluate and compare the effect of tooth preparation designs and different CADCAM. materials on stress distribution and Weibull survival probability of endocrowns. applied to root canal-treated lower first permanent molar using the 3D finite element. analysis method. MethodsA root canal-treated lower first permanent molar was prepared for endocrowns with a. butt joint or with a ferrule design by placing, circumferentially, a 1-mm wide shoulder. finish line. The prepared molar was scanned for the two designs and modeled on a 3D. Finite element model. Monolithic zirconia (IPS e.max ZirCAD MT, FCZ), lithium. disilicate (IPS e.max CAD, EX), and nano-ceramic resin composite (Lava Ultimate, LU). CAD-CAM materials were used for each preparation to design the virtual endocrown. A. total of six models were built according to the different tooth preparation designs and. endocrown materials. An occlusal load of 600 N and a transverse load of 20 N in. magnitude that simulates the average occlusal load was directed toward the occlusal. surfaces. von Mises and maximum principle values were evaluated Weibull risk-ofrupture. analysis was used to analyze the survival probability of the restorations and. tooth in the different models. ResultsThe highest von Mises were found in the butt joint design for FCZ, EX, and LU (45.3. MPa, 35.2 MPa, and 24.2 MPa, respectively) compared to the ferrule design for the. same materials (42.6 MPa, 31.2 MPa, and 23.6 MPa, respectively). For von Mises. stress distribution in the remaining part of tooth structure (dentin), the highest stresses. were found in LUFerrule which was closely similar to LUButt joint (135.4 MPa and. 134.7 MPa, respectively), followed by EXFerrule and FCZFerrule (132.2 MPa and. 131.7 MPa, respectively), while the lowest stresses were found in EXButt joint and. FCZButt joint (129.0 MPa and 128.4 MPa, respectively). Shear stresses within the. resin cement were the highest in FCZ and EX compared to LU. EX was found to be the. most reliable material with the highest survival probability, while FCZ showed the. lowest survival probability according to the Weibull risk-of-fracture results. SignificanceMaterials with high elastic modulus transfer more stresses to the endocrown and less. to the remaining tooth structure. Endocrown tooth preparation with ferrule design has. better stress distribution and magnitude compared to the butt joint design.

In vitro assessment of bonding of the total-etch adhesive to carious dentin in molars treated with and without 38% silver diamine fluoride: a study protocol

Background: The aim will be to evaluate and compare the bonding of the total-etch adhesive to carious dentin in molars treated with and without 38% silver diamine fluoride using the universal testing machine and scanning electron microscope. Methods: 30 extracted teeth samples will be been randomly distributed into 2 groups (n=15). The test group will receive the intervention of 38% SDF whereas the control group will not receive any such intervention. Samples in both groups will be restored with resin composite. Assessment will be done based on the primary outcome, which will be determined by microtensile bond strength whereas the secondary outcome will be determined by fracture modes, i.e., cohesive, adhesive, or mixed fracture. Descriptive statistics will be used for the results of each group. Intergroup comparison will be done on the basis of independent sample t-test to detect the mean difference between the two groups. Independent t-test will be run to analyse the type of failure. In all tests, p-values below 0.05 will be considered statistically significant. Conclusion: The study may provide us with a new restorative technique that will not only be less invasive by preserving the remaining tooth structure but will also prevent the risk of caries progression beneath the restoration. Thus, this will contribute to the longevity of the tooth life by the maintenance of its pulpal health which will contribute to the durability and long-term successful outcome of the direct restoration procedure.

Restoration of a Vital Tooth With Extensive Crown Destruction Using Glass Fiber and Polyethylene Fiber-reinforced Composite Resin: A Clinical Case.

Conservative restorative dentistry has been evolving in the last 25 years, focusing mainly on the development of direct restorative materials. Resin-based composites remain an excellent conservative alternative for restoration of teeth with extensive caries lesions. Over time, several strategies have been proposed to improve the mechanical properties of these composites so that they can adequately withstand masticatory forces. Glass fiber-reinforced resin-based composites and their use in situations where there is great loss of tooth structure have gained popularity due to their favorable mechanical properties. Combined techniques with polyethylene fibers can further enhance their clinical performance. This study presents a brief review of their most important qualities and potential use in direct restorative procedures. In addition, a clinical case is described where a vital tooth with extensive coronal destruction was restored using polyethylene fibers embedded in glass fiber-reinforced flowable resin under resin-based composite. The reinforcement of both the remaining tooth structure and the restoration with fibers is a valid treatment option since the network structure formed by the fiber reinforcement can increase the longevity of the direct composite restorations. There are few reports in the literature describing the use of a combined technique using polyethylene fibers embedded in glass fiber-reinforced flowable resin under resin-based composite. Thus, clinical follow-up of this case is required.

An In vitro Comparative Evaluation of the Fracture Resistance of Teeth with Mesio-Occluso-Distal Preparations Restored with Different Esthetic Materials by Bulk-Fill and Incremental Methods

Introduction: One of the most popular restorative materials today is resin-based composite. Volumetric shrinkage is brought on by polymerization, which can cause contraction stress, microleakage, and adhesion failure. Adhesive restorations have several benefits, including the ability to preserve more healthy tissue and “reinforce” the remaining tooth structure. These benefits go beyond just being attractive. Materials and Methods: Eighty extracted human maxillary premolars were entrenched in a self-cured acrylic resin in a rubber mold cylinder (2.5 cm width-3 cm height). These were arbitrarily divided into 5 groups: 2 control groups (positive control group and negative control group) (n = 10) and 3 experimental (n = 20) groups (microhybrid composite, nanocomposite, and Giomer). The mesio-occluso-distal (MOD) cavities were prepared in 70 samples. After MOD cavities preparation, groups were further subdivided into two subgroups for bulk-fill and incremental methods. Universal Tofflemire Retainer and band were placed on the prepared cavities. The self-etch adhesive was applied on all aspects of the preparations and then it was light-cured using a light-curing unit for 15 s. Now, cavities were restored with different esthetic materials and methods. In the bulk-fill method, the MOD cavity was restored with a solitary increase of restorative material and light cured from all directions of tooth for 20 s each. In the incremental technique, the proximal box on both sides was reconstructed first in a gradual manner, in which two oblique increments and one horizontal increment were restored and treated for 20 s. Then, two oblique increments of material were used to reestablish the occlusal component, and it was once more light-cured for 20 s. Fracture resistance was checked using a steel bar with a diameter of 4.5 mm that was positioned in the middle of the occlusal surface and a crosshead speed of 3 mm/min, all of the samples were compressed axially loaded. Results: The fracture resistance of microhybrid composite resins in bulk technique was significantly higher than that of nanocomposites and Giomer. However, the fracture resistance of nanocomposite in the incremental method was significantly higher than the other two restorative materials. Conclusion: The quality of restoration depends both on the material and method used during the restoration procedure. Both factors are dependent on each other. Superior fracture resistance was shown by microhybrid composites when restored with the bulk-fill technique and nanohybrid composites when restored with the incremental technique.

Impact of different CAD/CAM materials on internal and marginal adaptations and fracture resistance of endocrown restorations with: 3D finite element analysis

PurposeTo assess and compare the impact of various computers aided design/manufacturing (CAD/CAM) materials on internal and marginal discrepancies, fracture resistance and failure probability of Endocrown restorations with 3D Finite Element analysis.Material and methodsForty devitalized human maxillary first molars were collected. After endodontic treatment, they classified into 4 groups (n = 10) based on the materials used for endocrown fabrication. Group V (Vita-Enamic), Group N (Nacera Hybrid), Group T (Translucent Prettau Zirconia) and Group P (Pekkton ivory). All samples were exposed to artificial aging method simulating one year of clinical service. Silicone replica technique and stereomicroscope (25X) utilized to evaluate the marginal and internal gaps of endocrowns at different areas. Fracture resistance test used for cemented specimens followed by qualitative investigation utilizing Stereomicroscopy. Four models representing four endocrown systems used for restoration of severely-damaged endodontically treated upper first molar were generated for finite element analysis (FEA). Axially and centrally static occlusal compressive load was applied. Modified Von Mises and maximum principal stress values on the remaining tooth structure, cement lines and restorative materials were assessed independently. Resulted data were statistically analyzed at P-value ≤ 0.05.ResultsIn the current study, the highest mean values of internal and marginal discrepancies (μm) among studied groups were reported for Zirconia group (100.300 and 102.650) respectively, while the lowest mean value of internal discrepancy (μm) was observed for Nacera group (69.275) and the lowest mean value of marginal discrepancy (μm) was observed for PEKK group (78.4750). Regarding internal discrepancy, Vita-Enamic and PEKK groups did not exhibit any statistically significant differences (P = 0.293), however zirconia and the other tested groups exhibited statistically significant differences in the mean values of the marginal gap region (p 0.05).On the other hand, PEKK group showed the highest mean value of fracture resistance (1845.20 N) and the lowest value was observed for Vita-Enamic group (946.50 N). Regarding to stress distributions through 3D FEA, and according to modified von Mises (mvM) analysis, the greatest possible stress values were noticed in PEKK model in relation to tooth structure, cement line, and flowable composite as the following: (93.1, 64.5, 58.4 MPa) respectively, while Zirconia revealed lower maximum stress values (11.4, 13.6, 11.6 MPa) respectively.ConclusionsStatistically excellent marginal and internal fit was observed for PEKK in relation to other used endocrown materials. Also, PEKK material explained fracture resistance comparable to zirconia value while the lowest value was detected for Vita Enamic material.

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.

Online Questionnaire-Based Study to Evaluate the Attitudes and Use of Rubber Dental Dams by Saudi Dental Practitioners.

BACKGROUND A dental dam is a protective sheet with an aperture and is used to prevent the spread of infection during dental procedures. This study aimed to use a 2-part online questionnaire to evaluate the attitudes and use of rubber dental dams by 300 Saudi dental interns, general dental practitioners, residents, specialists, and consultants in prosthodontics, endodontics, and restorative dentistry. MATERIAL AND METHODS The 17-item validated questionnaire consisted of 5 questions on demographics, 2 on knowledge, 6 on attitudes, and 4 on perceptions. It was distributed through Google Forms. The chi-square test was used to determine the associations between the study variables and perception questions. RESULTS A total of 41.67% participants were specialists/consultants, among which 59.2% were in the prosthodontics specialty, 12.8% in endodontics, and 28% in restorative dentistry. Most participants (84.67%) stated the necessity of using rubber dams during post and core procedures. A total of 53.67% had received enough training for using rubber dams during their undergraduate/residency education. The majority of participants (41%) also preferred using rubber dams during the prefabricated post and core procedures, and 28.33% stated that the remaining tooth structure was one of the major reasons for not using rubber dams during the post and core procedures. CONCLUSIONS Workshops and hands-on training should be conducted among dental graduates to instill a positive attitude regarding the use of rubber dams.

One Year Clinical Evaluation Of Translucent Zirconia Crowns In Dental Esthetic Zone With Biologically Oriented Preparation Technique Versus Conventional Preparation (RCT)

Statement of the problem: Tooth preparation with horizontal finish line requires removal of reasonable amount of tooth structure at the cervical area which affects the remaining tooth structure at this area. Therefore, more conservative preparation design such as biologically oriented preparation technique (BOPT) might be needed to save tooth structure at the cervical area. The Purpose: To Evaluate the effect of Conventional preparation design (horizontal), and Biologically Oriented Preparation Technique (BOPT), on Marginal adaptation, fracture and gingival inflammation score of the translucent zirconia crown in dental esthetic zone. Methodology:, 44 monolithic translucent zirconia single crowns were fabricated inn dental esthetic zone . The patients were separated randomly into two groups. Group1: (horizontal preparation design) Group2: BOPT. After final cementation. The Modified United States Public Health Service (MUSPH) criteria for restoration clinical evaluations were used to assess marginal adaption. Gingival inflammation was assessed using gingival inflammation index. Evaluation of the restoration was at intervals of three, six, nine, and twelve months. Results: Comparison between two groups at different intervals regarding marginal adaptation, fracture and gingival inflammation score revealed statistically insignificant difference. Conclusions: Within limitations of the present one year follow up randomized clinical trial, the following conclusions could be drawn: 1.The conventional and BOPT preparation designs both clinically accepted to provide successful dental restoration The lower gingival inflammation score of the restored teeth with the conventional preparation design compared to that of the BOPT, may not be conclusive as regard the study time frame, indicating that increasing the follow-up period might alter the present finding. Clinical implications: Beyond of all the prosthodontic preparation techniques, knowledge of B.O.P.T. (Biological Oriented Preparation Technique) allows us to achieve predictable and consistent results in terms of periodontal health and gingiva architecture surrounding ceramic restoration. Nevertheless, long term studies are necessary to ensure the benefits of this techniques.