Tooth Preparation Research Articles

Evaluation of the Influence of Acid Etching Technique on Surface Roughness and Fracture Strength of Heat-Pressed Lithium-disilicate Veneers

Abstract Background Metal-free ceramic veneers exhibit many desirable properties. However, low fracture strength is a major disadvantage. The success of the veneers depends on optimal tooth preparation and intaglio surface preparation techniques for bonding porcelain substrates to the tooth to ensure clinical success. This study was conducted to evaluate the influence of acid etching technique on surface roughness and fracture strength of veneers. Methods The in vitro study was conducted on maxillary central incisors that were prepared to receive the veneers; the specimens were divided into two groups—group A and group B. The intaglio surface of veneer in both groups was etched with 4.6 % of the hydrofluoric acid solution for 30 seconds, in group B specimens were further treated with 33% sodium hypochlorite solution treatment following which the surface roughness was measured and calculated with scanning electron microscope at a magnification of 3000X and profilometer, respectively. The fracture strength of the specimens in both groups was determined by subjecting the tooth with veneer to a universal testing machine; the force was applied until the fracture occurred. Results There was a significant difference observed in the surface roughness, fracture strength, and bond strength of the heat-pressed lithium-disilicate veneers treated solely with hydrofluoric acid and samples treated with hydrofluoric acid and phosphoric acid. Conclusion Optimizing porcelain surfaces before treatment with various adhesives and luting resins requires an understanding of the involved substrates and materials, as well as a logical and systematic methodology in their manipulation. The intaglio surface of the veneers treated with hydrofluoric acid followed with phosphoric acid has no significant difference observed in the properties of the veneers but has better bonding with the tooth structure.

VR-haptic and phantom head dental training: Does the order matter? A comparative study from a preclinical fixed prostho-dontics course.

Learning tooth preparation techniques and the finesse required is an important part of preclinical dental education. Being able to practice surgical skills without loss of Frasaco® teeth while being provided with performance analysis data is a boon to students and educators. We investigated the combination of haptics-enhanced virtual reality (Simodont®) and conventional phantom head practice in a preclinical dental course, evaluating the students' performances and perceptions. Forty students were randomized into two groups: Group One began within a VR-haptic setting while Group Two worked with Frasaco® teeth. Halfway through the course the scenarios were switched. A crown preparation test on Frasaco® teeth was conducted at the end of the course. Students' performances and satisfaction were assessed anonymously. Analysis of the students' performances included clinical metrics (occlusal and axial reduction, convergence angle, damage to adjacent teeth). The perceived usefulness of VR-haptic and phantom head simulations was assessed. In Group One, the tooth preparation metrics were more in line with the requested parameters compared to Group Two. All students ranked VR-haptics highly regarding manual dexterity improvement. In conclusion, this study shows that by combining VR-haptics with conventional dental procedures, it is possible to improve important preparation metrics in fixed prosthodontics tooth preparation.

The Effect of Preparation Design on Stress Distribution in Lithium Disilicate Laminate Veneer using 3D Finite Element Analysis.

Background: A layer of ceramic bonded to the facial surfaces of prepared teeth to create a ceramic esthetic veneer, also known as a laminate veneer. Objective: This study aimed to examine the effect of preparation design on the stress distribution in lithium disilicate veneer at different angulations of masticatory loading. Methods: The finite element approach assessed the structure stress distribution. So, Exocad dental CAD was used to obtain the models, which consist of an upper central incisor in three dimensions (3D), and prepare them with the same software for an indirect veneer. The models were imported into software (SolidWorks; Dassault Systems) to construct solid models. The external load used in this study was 100 N at 60 degrees (intercuspal) and 125 degrees (protrusive) in the palatal surface, two mm below the incisal edge. The models were restored using e-max laminate veneers with different tooth preparation designs (palatal chamfer and window preparation designs). Analysis and calculations were performed on the stress distributions and maximum stress values of the tooth structures, cement layer, and laminate veneer. Results: With a window preparation design, the maximum stress values in the tooth and laminate veneer were higher. In the palatal chamfer design, stresses were dispersed more consistently through the cement layer and laminate veneer. Higher stress was generated by protrusive movement than by intercuspal movement. Conclusion: Compared to window preparation, the palatal chamfer design for lithium disilicate laminate veneer showed a more favourable stress distribution. Regardless of the preparation design, maximum stress values were observed in the cervical and incisor areas of the tooth structure.

The Effect of Preparation Design on Stress Distribution in Lithium Disilicate Laminate Veneer using 3D Finite Element Analysis.

Background: A layer of ceramic bonded to the facial surfaces of prepared teeth to create a ceramic esthetic veneer, also known as a laminate veneer. Objective: This study aimed to examine the effect of preparation design on the stress distribution in lithium disilicate veneer at different angulations of masticatory loading. Methods: The finite element approach assessed the structure stress distribution. So, Exocad dental CAD was used to obtain the models, which consist of an upper central incisor in three dimensions (3D), and prepare them with the same software for an indirect veneer. The models were imported into software (SolidWorks; Dassault Systems) to construct solid models. The external load used in this study was 100 N at 60 degrees (intercuspal) and 125 degrees (protrusive) in the palatal surface, two mm below the incisal edge. The models were restored using e-max laminate veneers with different tooth preparation designs (palatal chamfer and window preparation designs). Analysis and calculations were performed on the stress distributions and maximum stress values of the tooth structures, cement layer, and laminate veneer. Results: With a window preparation design, the maximum stress values in the tooth and laminate veneer were higher. In the palatal chamfer design, stresses were dispersed more consistently through the cement layer and laminate veneer. Higher stress was generated by protrusive movement than by intercuspal movement. Conclusion: Compared to window preparation, the palatal chamfer design for lithium disilicate laminate veneer showed a more favourable stress distribution. Regardless of the preparation design, maximum stress values were observed in the cervical and incisor areas of the tooth structure.

Non-retentive adhesive restorations

With the advent of adhesive dentistry, tooth preparation can be minimally invasive. An optimal adhesion to the dental tissues is a requirement. Rubberdam isolation, using a gold standard adhesive and bonding to freshly prepared dentin are all factors that improve the adhesion to tooth tissue. For non-retentive restorations, indirect composite and glass-ceramic materials are suitable. To date, several studies have shown a high survival rate of indirect adhesive restorations. The adage "if you can isolate the tooth, you can preserve it" may guide the choice of starting an adhesive procedure.

The removal of three kinds of occlusal veneers by Er: Yag laser.

This study aimed to remove occlusal veneers of varied thicknesses and compositions by Er:Yag laser in vitro and analyze the interfacial microstructure between veneers and tooth that irradiated by laser, by which experimental evidence could be provided to support the non-invasive removal of occlusal veneerby laser. Fresh mandibular premolars extracted for orthodontic requirements were collected for tooth preparation. Three kinds of ceramic materials (Vita Suprinity, Vita Mark Ⅱ, and Upcera Hyramic) were selected to fabricate occlusal veneer with different thicknesses (1.0, 1.5, and 2.0 mm). One week later, Er:Yag laser (2.5 W and 3.5 W) was used to irradiate and remove the occlusal veneer and recorded the timespan. After the removal operation, the micro-morphologies of samples were examined by scanning electron microscope. Upcera Hyramic veneer failed to be removed (>20 min); the operation span at 2.5 W, Vita Suprinity (96.0 s±16.0 s) was longer than Vita MarkⅡ(84.5 s±19.5 s) in the 1.0 mm group (P<0.05), and Vita Suprinity (246.5 s±13.5 s) was longer than Vita MarkⅡ(170.0 s±14.0 s) in the 1.5 mm group (P<0.05). At 3.5 W, Vita Suprinity (381.0 s±24.0 s) was longer than Vita MarkⅡ(341.5 s±26.5 s) in the 2.0 mm group. Increasing laser power could shorten the operation span and facilitate the removal of occlusal veneers with the same thickness and composition. The occlusal veneer was sustained when insufficient laser power was applied. With the same laser power and ceramic thickness, laser penetration could interfere with the integral of the ceramic structure when the laser interacted with the bonding layer. With the same ceramic composition and laser power, the operation span and laser power increased with the thickness of the occlusal veneer. However, the laser was incapable of removing occlusal resin veneer directly.

Near-peer teaching in a psychomotor skills course: Benefits, challenges and solutions.

This study evaluates the perceptions and experiences of students in the role of near-peer teachers in a psychomotor skills course. Final year BDS students were invited to participate as near-peer teachers in a 4th-year conventional bridges course. Near-peer teachers attended eight sessions (3 h) of simulation laboratory teaching relating to conventional bridge tooth preparations and provided feedback on near-peer tooth preparations and answered their questions. Interviews were conducted with all near-peer teachers to evaluate their perceptions of this novel teaching and learning experience and a thematic analysis was performed to analyse the data. Near-peer teachers reported this to be a rewarding, enjoyable and challenging experience. They benefited from learning and revising content-related materials as well as gained insights and teaching skills through the peer teaching process. Students felt supported and learned from peers and teaching staff and some used dyad teaching as a strategy to overcome perceived challenges. Students also reported the benefits of social and cognitive congruence in interacting with junior peers. However, students reported the feeling of inadequacy or lack of confidence and suggested the need for a training to prepare them better for the course. This paper reports on the benefits as well as challenges perceived by near-peer teachers during simulation laboratory teaching experience. We provide solutions into how to better prepare students for such teaching experience.

Application of optical scanning systems and 3D modeling algorithms as a method to control the depth of teeth preparation for fixed orthopedic structures

Background. In orthopedic dentistry at the present stage of its development, a chemical technique for preparing teeth for fixed structures of dentures has been developed; however, the state of the pulp in response to preparation is not taken into account. As a result, medical tactics for preserving or extirpating the pulp of abutment teeth, depending on the clinical case, are unreasonable. Given the generally accepted rules for preparing teeth for fixed orthopedic structures, there is a significant percentage of complications. Controlling the depth of tooth preparation makes it possible to carry out this manipulation as rationally as possible, and as a result to ensure the effectiveness of procedure, based on the state of vitality of the prepared teeth. The aim of the study is to determine and control the depth of the studied teeth preparation using digital volumetric scanning technology and algorithms of a digital graphic 3D editor in the CAD/CAM system. Materials and methods. The article presents the results of using digital volumetric scanning of the CAD/CAM system and an integrated algorithm for digital 3D modeling to determine and control the depth of teeth preparation for fixed orthopedic structures. Results. Based on the results of digital volumetric scanning, the working thickness of the tooth preparation in the area of the tooth neck was determined with the formation of various types of chamfer in different study groups. In order to determine the depth of the preparation of hard dental tissues, an artificial crown was modeled in the CAD system — digital volumetric scanner NeWay (Open Technologies) and data on its thickness in the area of the ledge were obtained. Conclusions. Method of digital volumetric scanning to determine and control the depth of preparation of hard dental tissues makes it possible to prevent the development of irreversible morpho-functional changes in the tissues of teeth caused by odontoreparation.

Fracture resistance of monolithic translucent zirconia crown bonded with different self-adhesive resin cement: influence of MDP-containing zirconia primer after aging

ObjectivesSuccessful ceramic restorations depend on the strong bonding with resin cement and even stress distribution. The aim of this study was to evaluate the impact of adding MDP-containing zirconia primer before self-adhesive resin cements with different functional acidic monomers on fracture resistance of monolithic zirconia crown.Materials and methodsEighty defect-free human maxillary premolars were divided according to the cement type and application of MDP-containing zirconia primer into eight groups (n = 10): Calibra Universal (C), Calibra Universal combined with zirconia primer (CZ), RelyX U200 (R), RelyXU200 combined with zirconia primer (RZ), Panavia SA Cement Plus (P), Panavia SA Cement Plus combined with zirconia primer (PZ), Multilink Speed (M), and Multilink Speed combined with zirconia primer (MZ). After teeth preparation and fabrication of zirconia crowns, each crown was bonded to its corresponding tooth. All specimens were subjected to 10,000 thermocycles between 5 and 55°C, followed by cyclic load (50 N) for 240,000 cycles. Each specimen was subjected to a static axial load until fracture using universal testing machine and the fracture load was recorded. The fracture mode studied and recorded. The fracture load results were analyzed using two-way ANOVA test (α = 0.05).ResultsA significant interaction (P = 0.038) of combining MDP-containing zirconia primer and cement type on fracture resistance of monolithic zirconia crown was detected. The mean fracture load values of zirconia crown were significantly influenced by the combined application of the MDP-containing zirconia primer with Calibra Universal (P = 0.01), RelyX U200 (P < 0.001), and Multilink Speed (P = 0.038), while there was no significant difference with Panavia SA Cement Plus (P = 0.660). There was significant difference (F = 20.69, P < 0.001) between the mean fracture loads of groups with self-adhesive cements (C, R, P, and M groups). The highest fracture load was recorded with RZ group (2446.90 ± 126.72 N) while the lowest fracture load was recorded with C group (1623.18 ± 149.86 N).ConclusionsThe self-adhesive resin cement with different acidic functional monomer affects the fracture resistance of monolithic zirconia crown. Application of MDP-containing primer could improve the fracture resistance of monolithic zirconia crown with most self-adhesive cements. The application of an MDP-containing primer had no impact on the fracture resistance of monolithic translucent zirconia crown bonded by MDP-containing self-adhesive resin cement.

Hall technique for the management of carious primary molar teeth among African children - a review

Background: Hall technique involves cementing preformed metal crowns or stainless steel crowns on the tooth with the use of luting glass ionomer cements, without the use of local anaesthesia, caries removal and tooth preparation of any kind. It can be an intervention to stop the progression of active untreated carious lesion in primary molar teeth among African children. This article reviews the available studies on Hall technique used for the management of carious primary molar teeth among African children. Method: An electronic literature search in Web of science, Scopus, PubMed, Google Scholar, African journals online, ResearchGate and Google was conducted in June, 2023 using the Population-Concept-Context framework. Search terms and keywords were combined by Boolean operators. Three independent investigators (research assistants) screened titles, abstracts and full text of publications. The inclusion criteria were original research articles, case report, case series related to Hall technique for the management of carious primary molar teeth studies conducted in African continent, published in English language and in electronic databases. Results: Four articles were included as they were assessed to meet the aim of the review. The study design of the articles was three randomised controlled clinical trial and one case report. One study was identified each from Egypt, Morocco, Nigeria and Sudan respectively. All the identified studies in African continent were hospital based. Conclusion: Hall technique can be an intervention for management of carious primary molar teeth in resource poor locality in Africa and globally. Studies on Hall technique for the management of carious primary molar teeth identified in Africa were few and restricted to few countries. IMC J Med Sci. 2024; 18(1):003. DOI: https://doi.org/10.55010/imcjms.18.003 *Correspondence:Obehi. O Osadolor, University of Nigeria Teaching Hospital, Ituku- ozalla, Enugu State, Nigeria. E-mail: osadolorobehi@yahoo.com

Fracture Resistance of Laboratory Composite Versus All-Ceramic Restorations in Class II Inlay Cavity Preparations: An In Vitro Study.

A posterior tooth's occlusal surfaces and the proximal surface can be restored by using an inlay, which is an intra-crown cast reconstruction without affecting the cusps of the tooth. When an inlay is prepared using an indirect approach, issues with traditional filling approaches, including poor morphology of the occlusal aspect or proximal aspect, inadequate resistance to wear, or subpar mechanical qualities of the directly inserted filler substance, are overcome. The current study was conducted in order to compare and assess the resistance to fracture of dental materials used in the preparation of inlay restorations indirectly, like composite restorations prepared by laboratories indirectly, inlays formed indirectly of monolithic translucent ceramic derived from zirconia, and inlays formed indirectly of traditional monolithic ceramic derived from zirconia. For the investigation, 100 human premolars of the maxilla that were extracted recently were chosen. A self-polymerizing acrylic resin was used to incorporate the tooth roots in a band made up of polyvinyl chloride up to 2 mm below the cement-enamel junction. The dimension of the band was 1.3 cm by 1.9 cm. Five categories of 20 specimens of such teeth were formed. Category one, featuring teeth in good condition, acted as the positive control category. The remaining four categories of teeth received inlay tooth preparation. The research samples underwent thermocycling after having been preserved for a full week following the cementation of inlay replacements. Then, in a universal testing apparatus, every sample endured axial compressive force with a metal globe delivered vertically at a crosshead rate of 1 mm/minute. The amount of force necessary to cause a fracture was measured in Newtons (N). The mean values of resistance against fracture in specimens in categories 1-5 were 1208.87 N, 614.89 N, 733.05 N, 1179.14 N, and 1148.49 N, respectively. The values of fracture resistance in specimens where an inlay cavity preparation was done but not filled were lower than those in traditional monolithic ceramic derived from zirconia and tooth specimens with inlays formed of monolithic translucent ceramic derived from zirconia, and the difference was significant statistically (p=0.001). The values of fracture resistance in composite inlay restorations prepared by laboratories were indirectly lower than those of monolithic ceramic derived from zirconia and tooth specimens with inlays formed of monolithic translucent ceramic derived from zirconia, and the difference was significant statistically (p=0.004). Within the constraints of the current investigation, we can state that indirect zirconia-based ceramic products offer adequate fracture resistance, but additional research is needed to determine how well these materials hold up under different types of pressures before employing them in clinical tooth restoration.

The influence of the tooth preparation finish line position on the expression of matrix metalloproteinase-9 and the presence of periodontopathogens in the gingival crevicular fluid.

The objective of the study was to determine the concentration of matrix metalloproteinase 9 (MMP-9) and changes in the presence of periodontopathogens in the gingival crevicular fluid before and after tooth preparation with the subgingival and equigingival finish line position. The clinical prospective study included 20 subjects with an indication for upper canine preparation, with the subgingival (group 1) and equigingival finish line (group 2). Samples were taken in four observation intervals: 5 minutes before (control samples), as well as 15 minutes, 24 and 72 hours after tooth preparation (experimental samples). Measurement of MMP-9 was done using Enzyme-linked Immunosorbent Assay (ELISA). The presence of bacteria in the gingival fluid was proven by the Polymerase chain reaction (PCR) analysis. The MMP-9 values did not differ statistically significantly between the groups (p=0.524). The MMP-9 values showed a statistically significant difference in the given observation period (p<0.001) with a significant linear increase in values (p<0.001). A significant quadratic trend recorded a decrease in the MMP-9 values 15 minutes after preparation, and an increase 24 hours after preparation, without a significant difference in the interaction between groups (p=0.392). After preparation, a significant difference in the presence of periodontopathogens was confirmed, i.e., a decrease in the presence of Prevotella intermedia (p=0.025) and Tannerella forsythia (p=0.016) in group 1, and an increase in the presence of Aggregatibacter actinomycetemcomitans in both groups (p=0.029, p=0.026). The study is a good basis for determining the influence of tooth preparation on gingival inflammation, with therapeutic (choice of preparation technique) and preventive significance regarding the protection of the periodontal tissue from possible iatrogenic damage.

Effect of resin cement selection on fracture resistance of chairside CAD-CAM lithium disilicate crowns containing virgilite: A comparative in vitro study

Studies on the fracture performance of a recently introduced computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate ceramic containing virgilite with different cements are lacking. The purpose of this in vitro study was to evaluate the fracture resistance of crowns made of a recently introduced chairside CAD-CAM lithium disilicate containing virgilite cemented with different types of adhesive luting cement. Sixty complete coverage crowns for a maxillary right central incisor were milled out of a lithium disilicate with virgilite (CEREC Tessera) (n=48) and a traditional lithium disilicate (e.max CAD) (n=12) using a chairside CAD-CAM system (Primescan). The central incisor tooth preparation included a 1.5-mm incisal reduction, a 1.0-mm axial reduction, and a 1.0-mm chamfer finish line. The restorations were bonded with different types of resin cement to 3D printed dies of the tooth preparation and were divided into 5 groups (n=12 per group): e.max CAD with Multilink Automix (E.Mu); Tessera with Multilink Automix (T.Mu); Tessera with Calibra (T.Ca); Tessera with Unicem (T.Un); and Tessera with Speedcem (T.Sp). The cemented restorations were stored in water for 30 days and then loaded until they were fractured in compression. The load at fracture was analyzed with a 1-way analysis of variance (ANOVA) and the honestly significant difference (HSD) Tukey test (α=.05). The mean fracture resistance of traditional lithium disilicate and virgilite lithium disilicate anterior crowns significantly differed depending on the type of resin cement used (P<.05). Group E.Mu displayed the highest values (946.35 ±155N), followed by group T.Un (819.59 ±232N), group T.Sp (675.52 ±153N), and group T.Mu (656.95 ±193N). The lowest values were displayed by group T.Ca (567.94 ±184N). The fracture resistance of lithium disilicate containing virgilite and traditional lithium disilicate crowns cemented with the same cement displayed statistically similar values. However, significant differences were observed when the virgilite lithium disilicate crowns were cemented with different types of adhesive luting cement. The crowns in the T.Ca group displayed the lowest fracture resistance.

Trueness of 4 sectional-cast digital methods for transferring the interocclusal relationship in complete mouth rehabilitation

An accurate digital workflow for transferring the interocclusal relationship from complete arch diagnostic interim restorations to complete arch tooth preparations is essential in complete mouth rehabilitation. However, research on the accuracy of digital cross-mounting methods is lacking. The purpose of this in vitro study was to compare the trueness of 4 sectional-cast digital cross-mounting methods in transferring the interocclusal relationship for complete mouth rehabilitation. Maxillary and mandibular anatomic typodonts were used to build complete arch tooth preparations and diagnostic interim restorations for complete mouth rehabilitation in vitro. Four sectional casts were designed: an anterior cast (AR), a posterior cast (PO), a unilateral cast (UL), and a tripod cast (TR). Both extraoral scanning (EOS) and intraoral scanning (IOS) were used to obtain intermediate digital sectional casts, which were cross-registered with diagnostic interim restorations and definitive casts to transfer the interocclusal relationship. Trueness was determined by assessing tooth distance deviation and mandibular 3-dimensional (3D) deviation. Differences among the 4 sectional-cast methods were analyzed with the Kruskal-Wallis test, and differences between the 2 scanning methods were analyzed with the Mann-Whitney U test (α=.05). Significant differences in the trueness of interocclusal relationship transfer were observed among the 4 sectional-cast methods (P<.05). Regarding tooth overall distance deviation, TR-EOS found no statistically significant difference compared with PO-EOS (P>.05), but TR-EOS had half the overall distance deviation of PO-EOS. Both TR-EOS and PO-EOS had smaller deviations than the AR-EOS and UL-EOS groups (P<.05). TR-IOS had a smaller distance deviation than the AR-IOS, PO-IOS, and UL-IOS groups (P<.05). The overall distance deviation of EOS was significantly smaller than that of IOS in the TR and PO groups (P<.05). Regarding mandibular 3D deviation, TR-EOS found no statistically significant difference but had half the root mean square (RMS) of 3D deviation compared with the PO-EOS groups (P>.05). Both TR-EOS and PO-EOS groups had a smaller RMS than the AR-EOS and groups (P<.05). The TR-IOS group had a smaller RMS than the AR-IOS, PO-IOS, and UL-IOS groups (P<.05). The 3D deviation of EOS was significantly smaller than that of IOS in the PO group (P<.05). Both EOS and IOS with the tripod sectional-cast digital method accurately transferred the interocclusal relationship for complete mouth rehabilitation.

A Study to Evaluate the Effect of Cleaning Solutions on Shear Bond Strength of Resin Cement to Saliva-Contaminated Lithium Disilicate (LDS) Ceramic.

One of the greatest benefits of contemporary restorative dentistry is the creation of fixed partial dentures. The retention and durability of the fixed partial dentures may be improved by using a variety of tooth preparation methods, surface treatments, and luting resins. To measure the shear binding strength of resin cement to saliva-contaminated lithium disilicate (LDS) ceramicafter being exposed to various cleaning treatments. Over 30 LDS samples were examined. In Group 1, a cleansing solution comprising 15% zirconium oxide (Ivoclean) was employed for a duration of 20 s. This was succeeded by a rinsing phase lasting 15 s utilizing deionized water, followed by a 15-s period for drying. Subsequently, a final stage of air drying was conducted over a span of 15 s.In contrast, Group 2 underwent a washing procedure of 20 s involving a cleansing solution containing 30% sodium silicate. This was then ensued by a rinsing interval of 15 s with deionized water, succeeded by an air-drying process spanning 15 s. After applying cleaning solutions to the surface and adhering the specimens to the composite blocks using resin cement Multilink Automix (Ivoclar Vivadent, Schaan, Liechtenstein), the shear bond strength was assessed. Using a 30% sodium silicate solution (Group 2), we were able to get the highest mean shear bond strength value after saliva-contaminated LDS. Group 1, 15% zirconium oxide (Ivoclean) had the weakest decontamination agents as measured by mean shear bond strengths. The shear bond strength values of the two groups were found to vary significantly between individuals using the independent sample t-test. LDs ceramic cleaned with a 30% sodium silicate solution had a higher shear bond strength than ceramic cleaned with Ivoclean (p<0.05). The application of a 30% sodium silicate solution rendered the highest shear bond strength for saliva-contaminated LDS ceramic. In comparison, ceramic cleaned with Ivoclean exhibited notably lower shear bond strength values. The outcome of this investigation highlights the potential of diverse cleaning agents in influencing the adhesive qualities of resin cement, thereby contributing to the enhancement of fixed partial denture durability and efficacy.

Patient-specific virtual simulation in the clinical training for prosthetic dentistry.

Dental education always involves live patient treatment, and clinical training for each patient is different for students. Using an intraoral scanner and Simodont Dental Trainer, we can provide students with an opportunity to train on actual patient cases in a virtual environment before real preparation. This study aimed to develop, implement and test patient-specific virtual simulation training in prosthetic dentistry curriculum. Before the actual preparation, the students' patients were scanned using 3Shape intraoral scanner. Thereafter, the .stl file was uploaded to Simodont Dental Trainer (Nissin dental products) where all the scanned teeth were prepared virtually. The 'prepared' .stl file was downloaded and submitted to the teacher. Instruction manuals for virtual simulation patient-specific tasks were provided. The students were asked to voluntarily complete the survey, at the end of the course. Forty-two 4th year students from the Faculty of Dentistry performed a patient-specific virtual simulation training task and completed a survey. The created training materials served as guidelines for students to perform all the steps on their own without teacher assistance, except in the final step, where the teacher evaluated the digital preparation. Students appreciated the amount of information provided regarding the technologies used and patient-specific tasks. Students admitted that the patient-specific task was more interesting than standard tasks. However, they were not satisfied with the technical performance of Simodont Dental Trainer or the reflection of reality. Patient-specific virtual simulation can be accepted by students for training before actual teeth preparation in the clinic. However, technical improvements are required in this regard.

Assessment the impact of operator experience on cyclic fatigue resistance in reciprocating and rotary NiTi files: a comparative study between dental students and pediatric dentistry specialists

Introduction: Devices reducing clinical practice time, and which get minimally affected by user experience are invaluable in pediatric dentistry. Additionally, knowing the fracture resistance of different nickel-titanium (NiTi) files for root canal preparation of primary teeth is important for treatment success. Thus, the present study aimed to compare the instrumentation time (IT) and fracture resistance of reciprocating T-endo MUST (TEM) and continuously rotating AF Baby File (ABF) NiTi files according to the use of pediatric dentistry specialists.Methods: According to their clinical experience level, 3 experimental groups (EG)s were formed namely: no experience, 2-years (less-experienced), and 10-years experienced pediatric dentistry specialists' groups. The fourth group was the control group (CG). In each EGs, 10 TEM (25/.06) and 10 ABF 20/.04, and 10 ABF 25/.04 NiTi file systems were used in 20 artificial resin teeth. Instrumentation time was recorded for each tooth. In the CG, the same number of files were not used for instrumentation. The files in all groups were subjected to a dynamic cyclic fatigue test, and the data were analyzed using the Kruskal–Wallis test at 5% significance level.Results: In all groups, TEM files showed a significant higher fatigue resistance as compared to ABF files. However, fatigue resistances were significantly lower in (EG)s both in TEM and ABF compared to (CG)s. The instrumentation time was found to be significantly lower in TEM compared to the ABF. Also, for both file systems, the experience level did not affect the fatigue resistance, and instrumentation time.Discussion: The experience level of the pediatric dentist did not affect the cyclic fatigue resistance of the reciprocating and rotating NiTi files, but the instrumentation time was lower for the reciprocating NiTi files.

Comparative Evaluation of Marginal Microleakage of a Bioactive Composite Resin Using Three Different Bonding Agents in Non-Carious Cervical Lesions– An In Vitro Study

Background and objectives: Increasing prevalence of non-carious cervical lesions makes it imperative to overcome challenges in tooth preparation, isolation and restoration. Bio-active restorative materials are relatively new concepts in dentistry having the potential to prevent secondary caries, a major cause of failure of restorations. Composite resins have the disadvantage of polymerization shrinkage leading to marginal gap formation. This study evaluated the marginal microleakage properties of Activa bio-active composite resin using three different adhesives in non- carious cervical lesions. Materials and method: Forty extracted maxillary &amp; mandibular premolars for the study were collected. The specimens were divided into groups (n= 10). Box type class V cavities, 2mm inciso-gingivally, 3mm mesio-distally &amp; 2mm in depth was prepared on the buccal surfaces. Group 1: Activa bio-active resin +No bonding agent, Group 2: Activa bio-active resin +Tetric N-bond, Group 3: Activa bio-active resin +Single bond Universal, Group 4: Activa bio-active resin + G Premio bond. Restorations were done and samples subjected to thermocycling. They were immersed in Rhodamine B dye solution for 24 hours. The samples were longitudinally sectioned in a bucco-lingual direction with diamond discs, examined under a stereo-microscope with 30x magnification and depth of penetration analyzed. The statistical analysis for microleakage was performed using the Kruskal Wallis test followed by the Mann Whitney U-tests with the Wilcoxon correction for pair-wise comparisons at a significance level of p &lt; 0.05. Results: Activa bio-active resin + G Premio bond showed lesser micro-leakage compared to other groups and the difference was statistically significant. Conclusion: Activa bioactive resin with G Premio bond, 8th generation bonding agent showed lesser micro-leakage when compared with 5th and 7th generation bonding agents.

Procedure for Making Snap On Smiles Using Acetyl Thermoplastic Resin Materials to Improve Aesthetics in Upper Anterior Teeth

Snap on smile is a denture prosthesis made using high-tech dental resin, namely acetyl thermoplastic resin. Acetyl thermoplastic is a thermoplastic material, rigid, and not easily broken. This study aims to find out how the procedure for making a snap on smile with acetyl thermoplastic material can improve aesthetics and function in aesthetic cases of upper anterior teeth. This study uses a descriptive method that will describe the procedure for making a snap on smile using acetyl thermoplastic resin to improve the esthetics of the upper anterior teeth. The procedure for making a snap on starts with the acceptance of the model, duplicating the working model, fixing the working model, implanting it in the ocludator, waxing up, flasking the top cuvette, installing sprue, flesking the top cuvette, boiling out, preheating, injecting, deflasing, sprue cutting, fitting, finishing and polishing. The conclusion of this study is the snap on smile on prosthesis that is made without tooth preparation or reduction of the teeth and without the use of cementation on the teeth or glue and can also be removed by the patient.

Root Canal Preparation of a Commercial Artificial Tooth versus Natural Tooth—A MicroCT Study

This study aimed to evaluate by microCT the preparation of the artificial teeth (ATs), TrueTooth®, versus natural teeth (NTs): (1) the time and number of pecking movements needed for preparation; (2) the root canal volume increase; (3) if the pulp-colored medium has any effect on the 3D analysis. Material and Methods: Artificial and natural maxillary molars were used. Fourteen AT distobuccal canals and fourteen NT buccal canals were used for the first and second aim and fourteen AT mesiobuccal canals for the third aim. Results: No statistically significant differences were observed regarding the time and number of pecking movements (p &gt; 0.05); for the root canal volume increase, a statistically significant difference was observed (p &lt; 0.05) with a higher mean value for NTs; however, in the group of ATs, there was a volume decrease in three cases. The AT mesiobuccal root canal mean volume increase was also negative. Conclusions: There are no differences between the time and number of pecking movements between NTs and ATs, so TrueTooth® can potentially be used in endodontic training. The volume increase between ATs and NTs was higher in NTs. However, some samples showed negative values, also seen in the AT mesiobuccal canal, confirming that the pulp-colored medium has an effect on the 3D analysis.