Effect of preparation design on the fracture resistance and fracture patterns of 3D printed one-piece endodontic crowns.

STATEMENT OF PROBLEM: The impact of various preparation designs on the fracture resistance and fracture type of mandibular premolars restored with 3 dimensionally (3D) printed, 1-piece endodontic crowns remains unclear. PURPOSE: The purpose of this study was to investigate the effect of different preparation designs on the fracture resistance and fracture patterns of mandibular premolars restored with 3D printed 1-piece endodontic crowns after thermal aging. MATERIAL AND METHODS: Forty-five freshly extracted mandibular premolars received 3 different preparation designs: with at least 2 intact cuspal walls (2CW), with only 1 intact cuspal wall (1CW), and no cuspal wall present (NoCW). One-piece endodontic crowns were designed by using a computer-aided design (CAD) software program, 3D printed, cemented to the prepared teeth with self-adhesive resin cement, and thermocycled between 5 °C and 55 °C in artificial saliva. Subsequently, all specimens were subjected to a fracture test. The results were statistically analyzed using 1-way ANOVA (α=.05), and fracture types of all specimens were examined using a light microscope. RESULTS: The analysis of fracture resistance values across separate designs revealed no statistically significant differences (P>.05). Mean fracture resistance values were 724.5 N in 2CW, 713 N in 1CW, and 861 N in NoCW. In 2CW and 1CW, the 1-piece endodontic crowns mostly displayed Type III fractures, whereas those in NoCW exhibited a combination of Type II and Type III fractures. CONCLUSIONS: The mandibular premolar 1-piece endodontic crowns tested in this study exhibited similar fracture resistance and type of fracture with different preparation designs.

Evaluation of the Effect of Different Abutment Materials on the Final Color of the Restoration After Aging: An In Vitro Study.

PURPOSE: To compare the effect of thermomechanical aging on implant abutment color change when using different abutment backgrounds. MATERIALS AND METHODS: In this study, three separate experimental groups (n = 10) with different implant abutment materials were used: zirconia, modified polyether ether ketone (MPEEK), and polyether ketone ketone (PEKK). Equal-sized glass-ceramic incisor crowns were cemented to the abutments using transparent dual-curing resin cement. The specimens were then subjected to the thermomechanical aging process for the clinical equivalent of 5 years of use. The color values of each specimen in the middle third and the incisal third were recorded by a digital spectrophotometer in the CIE L*a*b* color coordinates both before and after the aging process. Color differences between groups were compared using one-way analysis of variance (ANOVA), while Tukey test was used to compare differences within the groups (P = .05). RESULTS: In terms of color change (ΔE00) values, the zirconia group was found to show statistically more color changes only in the middle third (P < .000), but there was no significant difference between the the MPEEK and PEKK groups. In all groups, the ΔE00 value was clinically acceptable (ΔE00 < 1.8). CONCLUSION: After the aging process, high-performance polymer abutments caused less color change than zirconia. Therefore, esthetically satisfying results can be obtained in the anterior region, especially when highly translucent crown materials are used.

The effect of nanocoatings of SiO2, TiO2, and ZrO2 on titanium-porcelain bonding.

STATEMENT OF PROBLEM: Durable titanium-porcelain bonding is challenging because of the formation of a thick oxide layer on the surface during porcelain firing. PURPOSE: The purpose of this in vitro study was to evaluate how atomic layer deposition (ALD) of different oxide coatings affected titanium-porcelain bonding and failure types. MATERIAL AND METHODS: Forty-four airborne-particle abraded Type-2 titanium specimens were coated by ALD with either SiO2, TiO2, or ZrO2 (n=11) at a thickness of 30 nm, whereas control specimens were left uncoated (n=11) (airborne-particle abraded only). The surface roughness of the specimens was analyzed with a profilometer before applying porcelain (Vita Titankeramic). Titanium-porcelain bonding was analyzed by using a 3-point bend test. Surface properties and titanium-porcelain interfaces were examined under scanning electron microscopy combined with energy-dispersive spectroscopy, and failure types were evaluated by using a stereomicroscope. Surface roughness and bond strength data were analyzed by 1-way ANOVA and Tukey HSD tests. Failure type data were analyzed by the Fisher-Freeman-Halton exact test (α=.05). RESULTS: All nanocoatings increased surface roughness values, but only TiO2 and ZrO2 coatings showed statistically significant higher roughness than the control surfaces (P<.001). Specimens coated with SiO2 (28.59 ±4.37 MPa) and TiO2 (26.86 ±3.66 MPa) presented significantly higher bonding strength than control (22.04 ±4.59 MPa) specimens (P<.01). Fracture types of different groups were not statistically different (P>.05). CONCLUSIONS: Nanocoating titanium surfaces with SiO2 and TiO2 by using the ALD technique significantly improved titanium-porcelain bonding.

Occlusal Thickness and Cement-Type Effects on Fracture Resistance of Implant-Supported Posterior Monolithic Zirconia Crowns.

PURPOSE: To evaluate the factors that could influence the fracture resistance of implant-supported posterior monolithic zirconia crowns. MATERIALS AND METHODS: Sixty zirconia molar crowns with three different occlusal thicknesses of 0.5, 1.0, and 1.5 mm (20 samples per group) were prepared for implant abutments using a CAD/CAM system. In each group, 10 crowns were luted on the abutment with resin cement (Panavia F), and the other 10 crowns were luted with resin-modified glass-ionomer cement (Ketac Cem Plus). Dynamic loading (1.2 × 106 cycles; 70 N) and thermal cycling were applied to the samples using a chewing simulator before evaluating their fracture resistance with a universal testing machine and examining their fracture type using a stereomicroscope. One-way analysis of variance (ANOVA), the Duncan test, and two-way ANOVA were used for data evaluation (α = .05). RESULTS: The occlusal thickness (P < .001) and cement type (P < .01) affected the fracture load of the monolithic zirconia crowns. The highest fracture resistance was found in 1.5-mm-thick crowns luted with resin cement (4,212 ± 501 N), and the lowest fracture resistance was found in 0.5-mm and 1-mmthick crowns luted with resin-modified glass-ionomer cement (1,198 ± 116 N and 1,197 ± 66 N). A significant difference was not found in the mean maximum fracture load between the 1.5-mm-thick crowns cemented with resin cement and glass-ionomer resin cement. CONCLUSION: Both the occlusal thickness and cement type remarkably affected the fracture resistance of the crowns, but occlusal thickness was more significant. Implant-supported posterior zirconia crowns can withstand physiologic occlusal forces even with a thickness as low as 0.5 mm. Resin luting cement is recommended for implant-supported posterior zirconia crowns with reduced occlusal thickness.

Endodontic management of a patient with dystrophic epidermolysis bullosa: A case report.

Epidermolysis bullosa is a congenital genetic disease that causes blistering and erosion of the skin and mucosa. The main known forms include simple, junction, dystrophic and mixed subtypes. This case report presents the endodontic management and 1-year follow-up of a 27-year-old female patient with epidermolysis bullosa who was referred to the Faculty of Dentistry, Kirikkale University, Turkey. An extraoral examination showed that the patient had multiple scars and blisters. The intraoral examination revealed ankyloglossia, microstomia, shallow buccal and vestibular sulci, enamel hypoplasia, gingival inflammation, mouth ulcers, symptomatic and asymptomatic deep caries, a tooth with an apical lesion and a tooth with pulpitis. The dental treatment was divided into four stages: (i) oral hygiene motivation and elimination of gingival bleeding, (ii) restorative and/or endodontic procedures, (iii) extractions and prosthetic treatments and (iv) recall appointments. A 1-year follow-up radiographic examination of the periapical status of the root canal treatments was clear.

Oral parafunctions, personality traits, anxiety and their association with signs and symptoms of temporomandibular disorders in the adolescents.

OBJECTIVES: To investigate the association between oral parafunctions, personality traits, anxiety and signs and symptoms of temporomandibular disorders in the adolescents. METHODS: Two hundred and seventy adolescents were examined clinically for the signs and symptoms of temporomandibular disorders. Participants completed questionnaires about demographic variables, medical history, symptoms of temporomandibular disorders, parafunctional oral habits, Minnesota Multibasic Personality Inventory, and Spielberger State-Trait Anxiety Inventory. RESULTS: Logistic regression analyses revealed that bruxism was associated with joint tenderness (Odds ratio (OR)=6.38, p < 0.01), joint noises (OR=6.02, p < 0.01) and masticatory muscle tenderness (OR=4.19, p < 0.05) to palpation. State anxiety showed increased risk of joint tenderness (OR=2.47, p < 0.05) and muscle tenderness (OR=3.25, p < 0.05) to palpation. CONCLUSION: Within the limitations of this study, it was concluded that oral parafunctions, especially bruxism, state anxiety, depression and hysteria were associated with signs and symptoms of temporomandibular disorders in adolescents.

Fracture Resistance of Titanium, Zirconia, and Ceramic-Reinforced Polyetheretherketone Implant Abutments Supporting CAD/CAM Monolithic Lithium Disilicate Ceramic Crowns After Aging.

PURPOSE: The purpose of this study was to compare the fracture resistances and the fracture types of titanium, zirconia, and ceramic-reinforced polyetheretherketone (PEEK) implant abutments supporting CAD/CAM monolithic lithium disilicate ceramic crowns after in vitro dynamic loading and thermocycling aging. MATERIALS AND METHODS: Three implant abutment (SKY Implant) groups-titanium (group Ti, control); zirconia with titanium base (group Zr); and ceramic-reinforced PEEK (BioHPP) with titanium base (group RPEEK); n = 12 each-were used. Thirty-six CAD/CAM monolithic lithium disilicate crowns (IPS e.max CAD) in the form of a maxillary central incisor were cemented with Panavia V5 on the abutments. The specimens were subjected to dynamic loading and thermocycling. Fracture resistances of the restorations were tested with a universal testing machine (0.5 mm/min), and their fracture patterns were analyzed. One-way ANOVA and Tukey post-hoc test were used for statistical analyses (α = .05). RESULTS: All samples survived after aging. The fracture strength values (mean ± standard deviation) of the groups were as follows: group Ti, 787.8 ± 120.9 N; group Zr, 623.9 ± 97.4 N; and group RPEEK, 602.9 ± 121 N. The fracture strengths were significantly higher in group Ti compared to groups Zr and RPEEK (P = .001). No significant difference was observed between groups Zr and RPEEK. Failures generally occurred due to fracture of the screw in group Ti, abutment and crown in group Zr, and crown in group RPEEK. CONCLUSION: Ceramic-reinforced PEEK abutments may be an alternative to zirconia abutments with a titanium base for single-implant restorations in the anterior region. However, there is need for further in vitro and clinical studies to evaluate the long-term performance of ceramic-reinforced PEEK abutments.

The effect of repeated bonding on the shear bond strength of different resin cements to enamel and dentin.

PURPOSE: Cementation failures of restorations are frequently observed in clinical practice. The purpose of this study is to compare the effect of initial and repeated bonding on the bond strengths of different resin cements to enamel and dentin. MATERIALS AND METHODS: Ninety human maxillary central incisors were bisected longitudinally. The 180 tooth halves were divided into 2 groups (n = 90) for enamel and dentin bonding. The enamel and dentin groups were further divided into 3 groups (n = 30) for different resin cement types. Composite resin (Filtek Ultimate) cylinders (3 × 3 mm) were prepared and luted to enamel and dentin using Variolink II (Group V), RelyX ARC (Group R), or Panavia F 2.0 (Group P) resin cement. After 24 hours, initial shear bond strengths of the resin cements to enamel and dentin were measured. Using new cylinders, the specimens were de-bonded and re-bonded twice to measure the first and the second bond strengths to enamel and dentin. Failure modes and bonding interfaces were examined. Data were statistically analyzed. RESULTS: Initial and repeated bond strengths to enamel were similar for all the groups. The first (15.3 ± 2.2 MPa) and second (10.4 ± 2.2 MPa) bond strengths to dentin were significantly higher in Group V (P<.0001). Second bond strengths of dentin groups were significantly lower than initial and first bond strengths to dentin (P<.0001). CONCLUSION: All resin cements have similar initial and repeated bond strengths to enamel. Variolink II has the highest first and second bond strength to dentin. Bond strength to dentin decreases after the first re-bonding for all resin cements.