Denture Teeth Research Articles

ASSESSMENT OF MEAN DISTANCE BETWEEN CENTRAL INCISOR AND INCISIVE PAPILLA WITH RESPECT TO STANDARDIZED ARCH FORM IN DENTATE SUBJECTS

BACKGROUND & OBJECTIVE: Edentulous patients require accurate positioning of artificial maxillary anterior teeth in complete dentures to recover the esthetic and phonetic characteristics. This positioning is guided by measuring distance between central incisor (CI) and incisive papilla (IP) in dentate subjects which varies according to the ovoid, square and tapered maxillary arch forms.
 Objectives: 1- To determine the frequency of three different arch forms in dentate patients;
 2- To assess the mean distance between central incisor and incisive papilla in each of the three maxillary arch forms.
 METHODOLOGY: 130 cases were selected by non-probability consecutive sampling, which included both genders and age range of 20-40 years. Impressions of maxillary arches were recorded and their casts photocopied. Arch form template was used to standardize the assessment of arch forms by best-fit method on the photocopies. The distance between mesio-incisal edge of CI and posterior border of IP was measured with digital verniercalipers (SparkFun,Colorado).
 RESULTS: Out of 130 subjects, 54 males and 76 females were present. The ovoid arch form was the most frequent form recorded at 67% (n=87) while the tapered arch was the least at 14% (n=18). The overall mean distance between central incisor (CI) and incisive papilla (IP) was 11.34mm (7.58mm - 16.45mm). The mean distance was the highest for ovoid arch form (11.58mm) and lowest for square (10.49) with a statistically significant difference (p=0.016) between the two arch forms.
 CONCLUSION: The ovoid arch was the most frequent arch form found in dentate subjects. The mean distance recorded was highest for ovoid arch followed by tapering arch and least for square arches.

Effects of conventional and heated tobacco product smoking on discoloration of artificial denture teeth

Statement of problemCigarette smoke can cause discoloration of artificial denture teeth. However, studies on the effects of heated tobacco product smoke on artificial denture teeth are lacking. PurposeThe purpose of this in vitro study was to evaluate the effects of conventional cigarette and heated tobacco product smoke on the color stability of artificial denture teeth. Material and methodsNinety maxillary central incisor denture teeth (Endura Anterior HC5 A3; Shofu) were randomly divided into 3 groups (n=30). Teeth in the control group were exposed to air; those in group CC were exposed to conventional cigarette (Marlboro Medium; Philip Morris) smoke, and those in group HT were exposed to heated tobacco product (IQOS 2.4 plus holder, Marlboro Heets Silver; Philip Morris) smoke. Before the experiment, the shade of the artificial denture teeth was evaluated in accordance with the Commission International de I’Eclairage (CIELab) color system by using a spectrophotometer (Shadepilot; DeguDent GmbH). The average CIELab value was estimated by scanning the entire labial surface of each specimen. To simulate smoking, standard conditions described by the Coresta Recommended Method N°22 were used—the puff duration was 2 seconds, with a 60-second interval between puffs. For each cigarette, 6 puffs and 6 intervals were simulated across 372 seconds. A total of 105 cigarettes were used based on a smoking simulation of 15 cigarettes each day for 7 days. The teeth in the control group were stored in fresh air in the smoke chamber for the same period as those in the experimental groups. After the experiment, L∗, a∗, and b∗ values were measured, and ΔE was calculated to evaluate the color change. All statistical analyses were performed with a statistical software program using a paired t test to determine discoloration after exposure to cigarette smoke. One-way ANOVA and the Tukey test were used to evaluate the significant differences between groups (α=.05). ResultsLightness was significantly lower in the CC and HT groups (P<.001). All CIELab values showed statistically significant differences in the CC group. The greatest color change was observed in the CC group (ΔE=6.93 ±0.59), whereas the HT group showed a clinically imperceptible color change (ΔE=0.79 ±0.21). Discoloration was minimal in the CC group (ΔE=0.34 ±0.13). ConclusionsConventional cigarette and heated tobacco product smoke can change the color of denture teeth. Heated tobacco product smoke causes less discoloration of denture teeth.

Mode of bond failure between 3D-printed denture teeth and printed resin base material: effect of fabrication technique and dynamic loading. An in-vitro study.

To evaluate the failure load of 3D-printed denture resin material and teeth before and after dynamic loading. A total of 40 specimens were fabricated following ISO/TS 19736 and were divided into two equal groups. In the test group, the cylindrical base and denture teeth were 3D printed separately and then luted together. In the control group, the specimens were fabricated from conventional heat-cured polymethyl methacrylate (PMMA) and commercially available denture teeth using the compression-molding technique. Ten specimens from each group were subjected to dynamic load of 50 N for 250,000 cycles in a chewing simulator. All specimens were subjected to static load of 50 N using Instron machine with a crosshead speed of 1 mm/minute until fracture. The fractured surfaces were analyzed using field emission scanning electron microscopy. The failure loads were calculated and compared using analysis of variance (P < .05). All specimens survived the loading, undergoing 250,000 cycles without fracture. The mean failure load was influenced by fabrication technique and was significantly higher for the 3D-printed test group (P = .028). 3D-printed teeth showed a mixed mode of fracture, whereas in the control group, the specimens showed cohesive fracture within the teeth. The fabrication technique has an influence on the mode of failure between acrylic teeth and resin base material. Cohesive failure in teeth was predominant in the conventional group, suggesting possibly higher bond strength between the teeth and resin base in this group. The observed failure modes reveal that both fabrication techniques exhibited satisfactory bond strength. Chewing simulation did not significantly influence the bond strength of any of the tested groups.

Wear Resistance of 3D Printed and Prefabricated Denture Teeth Opposing Zirconia.

To evaluate the wear resistance of a recently developed three-dimensional (3D) printed denture teeth resin compared to three commercially available prefabricated denture teeth. A total of 88 maxillary first molar denture teeth were evaluated: C (Classic; Dentsply Sirona, York, PA), DCL (SR Postaris DCL; Ivoclar Vivadent, Schaan, Liechtenstein), IPN (Portrait IPN; Dentsply Sirona, York, PA), and F (Denture Teeth A2 Resin 1 L; Formlabs, Somerville, MA). The 3D printed denture tooth specimens were fabricated from a methacrylate-based photopolymerizing resin using stereolithography (SLA). Denture teeth were subjected to a three-body wear test with a poly(methylmethacrylate) (PMMA) abrasive slurry. A Leinfelder-style four station wear apparatus with custom bullet-shaped milled zirconia styli was utilized with a load force of 36-40 N at 1.7 Hz for 200,000 cycles. Maximum depth of wear was measured using a lab grade scanner and analyzing software program. Data were analyzed using a one-way ANOVA followed by the Tukey's Multiple Comparisons post hoc test (α = 0.05). A statistically significant difference in depth of wear was found between denture tooth materials (p < 0.001). The mean vertical depth of wear for the 3D printed denture teeth (0.016 ± 0.010 mm) was statistically significantly less than the prefabricated denture teeth. The highly cross-linked denture teeth, DCL (0.036 ± 0.011 mm) and IPN (0.035 ± 0.014 mm), exhibited statistically significantly less wear than the conventional acrylic denture teeth. The conventional acrylic denture teeth demonstrated the greatest wear (0.058 ± 0.014 mm). No significant difference in depth of wear was found between DCL and IPN (p > 0.001). Denture tooth material significantly influences the depth of wear. The 3D printed denture teeth demonstrated superior wear resistance compared to the commercially available prefabricated denture teeth when opposed to zirconia. Denture teeth fabricated with SLA technology may have a promising future in prosthetic dentistry.

Reducing the need to maintain fixed complete dentures by providing gold occlusal surfaces: A clinical report

The excessive occlusal wear of complete-arch implant-supported prostheses made with metal and acrylic resin is a clinical complication that can require repeated maintenance in certain patients. A patient who presented with moderate occlusal wear of the prosthetic teeth and substantial fracture of the maxillary anterior acrylic resin base only 2 years after a previous replacement of the acrylic resin base and denture teeth is described. Because of the patient’s history and existing wear, both the maxillary and mandibular prostheses were repaired by replacing the acrylic resin bases and resin denture teeth but with the addition of cast gold occlusal surfaces on the posterior prosthetic teeth. The provided treatment helped this patient, who was likely to need more frequent maintenance visits in the future because of his history of accelerated occlusal wear and increased occlusal force.

Comparison of artificial tooth position in dentures fabricated by heat curing and additive manufacturing.

The purpose of this study was to compare the displacement of tooth arrangement in dentures fabricated by additive manufacturing (AM) and heat curing. Three-dimensional (3D) scanning was performed for edentulous jaw models. After the teeth were arranged, 3D scanning for the wax denture was performed. Heat-cured dentures were fabricated with heat-cure polymer resin. Based on data obtained by subtracting the model data from wax denture data, AM dentures were fabricated from ultraviolet-cured acrylic resin. Accuracy was verified by superimposing heat-cured and AM dentures on the tooth region data from the wax dentures and measuring displacement of the tooth arrangement. In the maxillary dentures, the amount of tooth displacement for the heat-cured dentures and for the AM dentures ranged from -0.08 to +0.06mm and from -0.25 to +0.06mm respectively. A significant difference was observed between two dentures. In the mandibular dentures, the amount of tooth displacement for the heat-cured dentures and for the AM dentures ranged from -0.09 to +0.07mm and from -0.03 to +0.07mm respectively. No significant difference was observed between two dentures. The artificial teeth of the maxillary dentures fabricated by AM showed a greater displacement compared to those by heat curing.

Is there a role for casein phosphopeptide–amorphous calcium phosphate (cpp-acp) in paediatric dentistry?

In the age of minimally invasive dentistry, products with the ability to prevent and reverse common dental diseases are becoming increasingly popular. Casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) contains the compounds casein, phosphate and calcium, which all have the ability to remineralize enamel. Dental caries, visible demineralization following removal of orthodontic appliances, non-carious tooth surface loss and dentine hypersensitivity due to structural anomalies are frequently seen in children and young people. The evidence for CPP–ACP and fluoride-containing CPP–ACP is positive for managing dental caries and non-carious tooth surface loss, specifically erosion, but is less clear in the management of visible demineralization following orthodontic appliance removal and dentine hypersensitivity owing to structural anomalies. When recommending CPP–ACP-containing products, dental practitioners should be aware of medical and social contra-indications that preclude its use. CPD/Clinical Relevance: CPP–ACP may have a role in the management of common paediatric dental conditions.

Morphological Changes in Dental Surfaces Suggest Health Status and Alimentary Habits in the Subjects Belonging to the Copper Age in Sardinia Island (III Millennium BC)

The aim of this multidisciplinary study, which involved a team of archaeologists, odontologists, biologists, is to examine a set of dental health indicators, including caries, tooth wear, and enamel hypoplasia of a III millennium BC sample from the burial site of Scaba ’e Arriu (Siddi, South Sardinia), in order to evaluate the dental health status and the diet. Our purpose is to depict a timeline of dental health in Sardinia from prehistory to the present day, starting with a focus on a Copper Age population. Caries, dental wear, and enamel hypoplasia of 259 permanent teeth were evaluated. It was not possible to assign sex and age of each tooth because of the lack of bony support, lost due to taphonomy factors. 14,7% of Scaba‘e Arriu’s samples were affected by carious lesions, with greater involvement of the posterior teeth (12,7% against 1,9% of anterior ones). Interproximal caries was the most frequent. Dental wear affected 77,8% of the teeth, and its presence is preponderant over caries’ rate. The high percentage of dental wear suggests a diet based on abrasive foods. Further studies are necessary to delineate more accurately the modus vivendi, the nutrition, and, consequently, the health status of this sample.

Bond strength of artificial teeth to thermoplastic denture base resin for injection molding.

This research was conducted to investigate the bond strength between artificial teeth and a thermoplastic denture base resin for injection molding with different surface preparations for use in flexible resin removable partial dentures. Composite resin denture teeth and acrylic denture resin teeth were bonded to three types of thermoplastic denture base resins for injection molding (polyamide, polyester, and polycarbonate) and a conventional heat-polymerized polymethyl methacrylate (PMMA) resin (control). The ridge lap surfaces of the artificial teeth were classified into four groups based on the type of ridge lap surface treatment applied (n=10): no treatment, ethyl acetate, small T-shaped tunnel, and large T-shaped tunnel. The specimens were tested for bond strength. The results showed that the ethyl acetate treatment was ineffective for enhancing the bond strength (p>0.05) between the artificial teeth and thermoplastic denture base resin for injection molding, whereas the T-shaped tunnel was quite effective in this regard (p<0.05).

Bond Strength of Acrylic Denture Tooth to a Novel Thermo-Polymerized Denture Base Copolymer Containing Cycloaliphatic Comonomer after Mechanical and Thermal Aging.

Background:There are numerous artificial denture tooth materials available of which acrylic resin teeth were used widely. The resin teeth bond chemically to the denture base resin, and this bonding is affected by numerous intrinsic and extrinsic factors. The type of cross-linker in the denture base monomer is one such factor which has a questionable influence on the bond strength. Recently, cycloaliphatic comonomer was added in the methyl methacrylate monomer and the resultant novel copolymer possessed good physico-mechanical and biological properties.Purpose:The purpose of this study was to evaluate the shear bond strength (SBS) between acrylic denture tooth and resultant novel copolymer after cyclic loading and thermal aging.Materials and Methods:Sixty central incisor denture teeth were bonded to three types of acrylic denture base resin groups (n = 20 per group) categorized based on the presence of the cycloaliphatic comonomer – Control group (G0): denture bases without cycloaliphatic comonomer and trial groups G10 and G20 contain 10 vol.% and 20 vol.% comonomer, respectively, substituted in the denture base monomer component. The specimens were processed and subjected to cyclic loading and thermal aging which was then followed by SBS testing.Results:G20 possessed the highest SBS followed by G10. G0 had the least SBS. All the specimens of the control and trial groups exhibited adhesive–cohesive mixed failure at the resin tooth–base resin interface.Conclusion:The addition of cycloaliphatic comonomer increased the SBS between the resultant novel copolymer and the resin teeth after cyclic loading and thermal aging.

Loss of abutment teeth for double crown-retained removable partial dentures compared to clasp-retained removable partial dentures: a systematic review and meta-analysis.

Objective: To analyze the loss of abutment teeth for double crown-retained removable partial dentures (DC-RPDs) compared to clasp-retained removable partial dentures (C-RPDs). Method and materials: A search was conducted in the Ovid MEDLINE, Embase, Web of Science databases, and a manual search. The search was conducted based on the PICO framework with inclusion and exclusion criteria. After extracting the data of selected studies, a meta-analysis was performed to estimate abutment loss with 95% confidence interval (CI). The statistical significance was defined as P < .05, and the heterogeneity of the data was assessed based on the chi-squared test and I2 statistics. Risk of bias assessment was conducted using Cochrane Risk of Bias tool and Newcastle-Ottawa Scale. Results: A total of 4,692 records were identified from electronic databases and 38 studies were included for quantitative synthesis of 3,393 subjects with 13,552 abutment teeth. A total of 1,226 abutment teeth were lost with &gt; 4,016 RPDs. Seven studies were compounded for &gt; 668 C-RPDs (mean follow-up time ≤ 5 years) and six studies for 893 C-RPDs (mean follow-up time < 5 years), where the estimates of abutment loss were 5% (95% CI 2% to 8%) and 8% (95% CI 5% to 13%), respectively. The data were not significantly different (P = .1), and were heterogenous between the studies (τ2 ≥ 0.34, I2 ≥ 87.38%). Thirteen studies were compounded for 1,223 DC-RPDs (mean follow-up time ≤ 5 years) and eight studies for 1,033 DC-RPDs (mean follow-up time &gt; 5 years), where the estimates of abutment loss were 6% (95% CI 5% to 8%) and 12% (95% CI 8% to 18%), respectively. The data were heterogenous (τ2 ≥ 0.17, I2 ≥ 75.86%), and were significantly different between the studies (P = .005). Overall, C-RPDs were not significantly different from DC-RPDs in abutment loss (P ≥ .3). A significant predictor for abutment loss was follow-up time with DC-RPDs (P = .005), where the risk of abutment loss per year was 18% (P = .0001). In contrast, follow-up time was not a significant factor for C-RPDs (P = .1). None of the included studies were at high risk of bias. Conclusion: Within the limitations of the current systematic review and meta-analysis, abutment loss was not significantly different between C-RPDs and DC-RPDs. A significant predictor was follow-up time for DC-RPDs, whereas this factor was not significant for C-RPDs. Further research is needed to investigate critical factors for abutment loss with RPDs.

A finite element optimization of the design variables of a dental implant screw based on the Mechanostat Theory

Background and Objective: Dental implants, as one of the most frequently used medical prostheses, are widely utilized as a replacement for the lost teeth in dentistry, which can provide the patients with comfort and utility in mastication and digestion purposes. However, there is a demanding requirement for the implant mechanical quality improvements carried out by optimizing the implant size and material characteristics. The improvements made to the design variables of a dental implant can benefit the supporting bone viability and reduce the risk of bone injury and loosening implants. Therefore, the purpose of the present finite element-based study was to optimize the design variables of an implant screw in a geometrically developed implant-mandible assembly for minimizing the resultant difference of the maximum equivalent strain value in the mandible to an as possible admissible, safe limit compared with pre-implantation state, based on the Mechanostat Theory. The usage of the Mechanostat Theory as the criterion for which the difference of mandible maximum equivalent strain value after implantation was considered as an objective function to be minimized from before-implantation state, was newly addressed in this study. Methods: In order to form the 3D geometry of the mandible, a patient-specific CT image dataset was used, and a 3D model of a dental implant with relevant parts was extracted based on a literature design, after which the assembly of the mandible and implant was imported to a finite element software to analyze the biomechanical behavior of the mandible bone under a mechanical pressure load exerted on the implant crown, as the mastication equivalence. The same procedure was conducted for importing the 2nd premolar tooth geometry with the same boundary conditions of the mandible to compare the results. Results: The results indicated that there was 50.2% decline in the maximum equivalent strain difference from 44.2 με to 22.2 με as the consequence of the optimized sizes of the implant screw length and radius. Furthermore, there was a sensible amount of sensitivity for the maximum equivalent strain to the alterations in the screw radius rather than length. Conclusions: Finally, the proposed, optimized geometry for the implant screw improved the baseline design and provided a useful basis for further research.

A digital approach to robust and esthetic implant overdenture construction.

Overdenture therapy is an important option for implant rehabilitation. However, numerous reports suggest that mechanical/technical complications and failures can limit therapeutic success. The goal of this report is to illustrate a digital approach to design and construction of a robust overdenture with high-esthetic value. Beginning with new denture design to establish esthetic parameters, 3D modeling of a metal framework and the denture teeth are completed in a connected manner. This enables connection of rapidly printed, prototype dentition that is attached directly to the framework without intervening wax or acrylic components. Following evaluation of the dentition and required adjustments, the final dentition is milled from resin and processed to the selective laser sintered framework. The advantages of the digital workflow include the control of dimensions and strength of the framework, the esthetic relationship of the framework to the dentition and the facilitation of esthetic try-in of the dentition. Enhancing a robust overdenture can be readily achieved using a digital workflow. The use of digital technology enables the clinical team to plan and produce prostheses with dimensions and contours that support long-term function and esthetics. The clinical chair time can be potentially reduced by use of digital design that facilitates try-in and reduces major errors by improved communication between the patient, dentist, and technician.

Microtensile bond strength of zirconia nanofillers reinforced acrylic resin to denture teeth after thermocycling

Abstract Statement of problem: Addition of zirconium oxide nanofillers to PMMA had improved the mechanical properties of heat polymerized acrylic resin, but it’s effect on bond strength to acrylic teeth hadn’t been evaluated yet. Purpose: The purpose of the study was to evaluate the effect of Zirconium oxide (ZrO2) nanofillers powder with different concentrations (1.5%, 3%, 5%) on bond strength of resin denture base to acrylic teeth before and after thermocycling. Material and methods: Zirconium oxide nanoparticles powder were added to heat cured (PMMA) with different concentrations (0, 1.5% ,3%, 5%). The base surfaces of 16 molar acrylic teeth were flattened, and zirconia reinforced heat-polymerized acrylic resin was applied to them. Thereafter, bar specimens were produced for the microtensile bond strength testing either before or after thermocycling. Results: The results showed that 5% ZrO2 conc. recorded the highest value of microtensile bond strength. The lowest value was recorded in 1.5%, followed by 3%. Regarding thermocyling, the non-thermocycled groups always recorded higher values of microtensile bond strength either significant (1.5% & 5%) or insignificant (0% & 3%) than thermocycled ones at p < 0.05. Conclusions: Within the limitation of this study, it was concluded that reinforcement of acrylic denture base with zirconia nanofillers had significantly decreased bond strength with acrylic denture teeth in 1.5 % and 3% concentration; however, 5% had increased the bond strength values insignificantly. Thermocycling had reduced the bond strength in all concentrations.

Implante imediato com provisionalização imediata para estabilidade tecidual pós-extração – relato de caso

The aim of this article is to present a clinical case report where a female patient, 62 years old, presented with element 14 poorly positioned and mobility. The initial planning was immediate implantation with immediate provisionalization. The case described was carried out with a minimally invasive extraction, implant placement of the 3.75 x 11.5 mm (Helix, GrandMorse, Acqua, Neodent®, Brazil), immediate loading with a universal healing abutment (3.3 x 2.5 mm, Neodent®, Brazil) and a provisional cylinder of the universal healing abutment click (3.3 x 6.0 mm, Neodent®, Brasil) to approach of capture from a denture teeth and thus, the cementation of provisional implant crown. For modification of the gingival area, a subepithelial connective tissue graft was performed through the tunneling technique to improve peri-implant tissue conditioning. A 6-month postoperative follow-up was performed, showing satisfactory clinical and radiographic conditions during the most important phase of healing, and finally, a final follow-up of 12 months with the definitive cemented prosthesis. According to the literature and clinical experience, rehabilitation with immediate implant placement is one of the most challenging procedures when associated with immediate loading, where many criteria must be evaluated before the surgical phase, it means, and excellent initial planning.

Reabilitação total com porcelanas em paciente acometido por amelogênese imperfeita

Amelogenesis imperfecta (AI) is a disorder of genetic origin, linked to the amelogenin gene, which presents developmental abnormalities in the quantity and quality of tooth enamel. The main clinical problems are the extensive loss of dental tissue, occlusal problems, impaired aesthetics, tooth sensitivity and gingival inflammation. This study described a clinical case and the approach in the treatment of a patient with AI, with gingival plastic surgery, porcelain crowns on the posterior teeth, porcelain veneers on the anterior teeth and application of botulinum toxin to correct the gingival smile. AI is an anomaly with complex development and early diagnosis is essential for the conduct and success of the case, to improve aesthetics and function, preserving the characteristic tooth wear.

Evaluation Of Bond Strength On Surface Treated Denture Teeth To Injection Molded PMMA Denture Base

Evaluation Of Bond Strength On Surface Treated Denture Teeth To Injection Molded PMMA Denture Base

Comparative evaluation of shear bond strength of acrylic teeth with heat polymerized acrylic resins using different surface treatments and curing cycles – An in vitro study

Purpose: This study evaluated the bond strength of acrylic resin denture teeth to heat cure denture base resin processed under different curing cycles and after various surface treatments on the bonding surface area of acrylic denture teeth.Materials and Methods: A two-piece metal mold of 35 mm length and 12 mm diameter was fabricated to standardize the attachment of teeth at 45°. Ninety such wax cylinders were obtained and were randomly divided and coded into three groups of 30 samples each: Group “A” – the “Control” group, Group “B” – the “MMM” group, and Group “C” – the “Acetone” group with Subgroup 1 – processing with short curing cycle and Subgroup 2 – processing with long curing cycle in each group. These 90 wax cylinder specimens were then flasked, dewaxed as per the standard protocol and surface treatment of teeth, and curing was done. The samples were tested in a universal testing machine.Results: ANOVA analysis inferred that there was a statistically significant difference between the mean bond strength values among the groups.Conclusion: Analysis of mean bond strength values reveals that the mean bond strength values of acetone were significantly higher (P < 0.05) when compared to the other groups.

Resistência de união ao cisalhamento entre a resina composta e dentes artificiais de resina acrílica

Acrylic denture teeth may suffer fracture or wear requiring the need for repair. This study aimed to evaluate the shear bond strength between acrylic resin artificial teeth restored with composite resin (with two different surface treatments) and acrylic resin (AR), simulating repair with these materials. Thirty artificial incisors were included by the palatal side in a circular microwave-polymerized AR base and polished on their buccal side with 120 and 320 grit sandpaper in a metallographic polisher and, then, divided into three groups: (I) restoration with self-cured AR; (II) conventional restoration with Z-100 composite resin with application of acid etching and Single Bond-3M adhesive; and (III) restoration with Z-100 composite resin with submersion for 30 seconds in acetone and application of Single Bond-3M adhesive. Shear bond strength tests were performed in a Universal Testing Machine (Instron). The results were submitted to ANOVA and Tukey (p&lt;0.05) tests, in which Group I (33.26MPa ±10.76) and Group III (22.24MPa ±13.13) showed no statistically significant difference, but both were superior to Group II (10.31MPa ±5.62), which showed a lower value of shear bond strength. It can be concluded that composite resin restoration with acetone pretreatment can be a viable alternative for repair.

Comparative laboratory evaluation of dimensional accuracy for 3D-printed complete maxillary denture

Purpose: The objective of the research was to investigate dimensional accuracy concerning denture teeth deviation and vertical dimensional changes for three-dimensional printed, monolithic dentures relative to heat-cured, acrylic resin dentures. Materials and methods: A waxed-up reference maxillary denture was constructed on an educational master cast, and then duplicated to produce ten simulated waxed-up dentures. The planned virtual denture was designed by subtracting the scanned cast from the scanned waxed-up denture with the cast. This virtual denture was considered as a reference and saved alone in 3D- Standard Tessellation Language (STL) format. From this reference (CAD maxillary denture) ten DLP dentures were fabricated. Each fabricated heat-cured, and 3D-printed denture was scanned separately, and the scanned data was saved in an STL file. Each STL file of scanned maxillary dentures was superimposed on a reference virtual maxillary denture to evaluate the degree of denture teeth deviation. An electronic digital caliper was used to measure the occlusal vertical dimension (OVD) of the waxed-up denture and after denture fabrication for both groups to evaluate the change in OVD. Results: A paired t-test was used to compare the recorded data between both groups. It was reported that the higher mean values for either denture teeth deviation or vertical dimensional changes after dentures fabrication were noticed in heat-cured acrylic resin dentures. These values were highly statistically significant between the tested groups for both items of investigations at p ≤ 0.01.