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.

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.

Fracture Resistance of Zirconia, Polyetheretherketone, and Polyetherketoneketone Implant Abutments After Aging.

PURPOSE: This study aimed to assess the fracture resistance of zirconia (Zr), reinforced polyetheretherketone (PEEK), and polyetherketoneketone (PEKK) implant abutments restored with glass-ceramic crowns after thermomechanical aging. MATERIALS AND METHODS: Zr, reinforced PEEK, and PEKK titanium base abutments were divided into three groups (n = 10). CAD/CAM maxillary central incisor crowns were fabricated using monolithic lithium disilicate and luted to the abutments using resin cement. The specimens were thermomechanically aged (1.2 × 106 cycles, 49 N, 5°C to 55°C). After testing fracture strength and determining fracture patterns, statistical analyses were made using the one-way analysis of variance (ANOVA) and Tukey post hoc tests (α = .05). RESULTS: Fracture resistance of the PEKK abutments (541.90 ± 68.49 N) was significantly lower than the Zr (780.65 ± 105.77 N) and reinforced PEEK (741.09 ± 99.84 N) abutments (P = .000). A significant discrepancy was not detected between the reinforced PEEK and Zr abutments. Failures usually formed due to crown or abutment fracture, plastic deformation of the titanium base or screw fracture in the Zr group, crown fracture or separation of the abutment-crown complex from the titanium base in the reinforced PEEK group, and abutment fracture without crown deformation in the PEKK group. CONCLUSION: After thermomechanical aging, the reinforced PEEK abutments exhibited similar fracture resistance to the Zr abutments. All abutment types withstood the physiologic occlusal forces typical for the oral anterior region. Before considering them as alternative esthetic implant abutment materials, further in vitro and clinical studies are needed to determine their long-term performance.

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.

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.

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.

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.

Effects of silica coating and silane surface conditioning on the bond strength of metal and ceramic brackets to enamel.

OBJECTIVE: To evaluate the effect of tribochemical silica coating and silane surface conditioning on the bond strength of metal and ceramic brackets bonded to enamel surfaces with light-cured composite resin. MATERIALS AND METHODS: Twenty metal and 20 ceramic brackets were divided into four groups (n = 10 for each group). The specimens were randomly assigned to one of the following treatment conditions of the metal and ceramic brackets' surface: (1) tribochemical silica coating combined with silane and (2) no treatment. Brackets were bonded to the enamel surface on the labial and lingual sides of human maxillary premolars (20 total) with a light-polymerized resin composite. All specimens were stored in water for 1 week at 37 degrees C and then thermocycled (5000 cycles, 5 degrees C to 55 degrees C, 30 seconds). The shear bond strength values were measured on a universal testing machine. Student's t-test was used to compare the data (alpha = 0.05). The types of failures were observed using a stereomicroscope. RESULTS: Metal and ceramic brackets treated with silica coating with silanization had significantly greater bond strength values (metal brackets: 14.2 +/- 1.7 MPa, P < .01; ceramic brackets: 25.9 +/- 4.4 MPa, P < .0001) than the control groups (metal brackets: 11.9 +/- 1.3 MPa; ceramic brackets: 15.6 +/- 4.2 MPa). Treated specimens of metal and ceramic exhibited cohesive failures in resin and adhesive failures at the enamel-adhesive interface, whereas control specimens showed mixed types of failures. CONCLUSIONS: Silica coating with aluminum trioxide particles coated with silica followed by silanization gave higher bond strengths in both metal and ceramic brackets than in the control group.

Neonatal line on fetus and infant teeth: An indicator of live birth and mode of delivery.

BACKGROUND: The neonatal line (NL) is an important issue in forensic odontology. It is the sign of a developmental birth defect, which is caused by the effect of metabolic stress on tooth structures when the fetus passes to extrauterine life. AIMS: The aim of this research is to determine the existence and thickness of NL in teeth, as it is a legal necessity to indicate the signs of viability at birth in a forensic examination of a fetus or infant case. STUDY DESIGN AND SUBJECTS: This research was conducted on 48 lower left and right lateral teeth, which were taken from 24 autopsy cases (46% female and 54% male). Left lateral teeth were sectioned in a vertical plane and right lateral teeth were sectioned in a horizontal plane. The NL thickness was measured with a scanning electron microscope (SEM). These cases comprised three conditions as: 70.3% normal birth, 16.7% caesarean sections, and 12.5% still birth cases under the legal and ethical permission. OUTCOME MEASURES: The mean NL thickness of normal birth cases was higher than caesarean cases as 7.7µm and 2.5µm, respectively. RESULTS AND CONCLUSIONS: The results showed a statistical significance between all birth conditions. NL does not exist in still birth cases (p<0.001). Not only is the presence of NL a sign of live birth, but also its thickness is an indicator of the delivery mode where NL thickness of normal birth was found thicker than the caesarean cases.

A surgical guide for dental implant placement in edentulous posterior regions.

Proper implant placement is crucial for successful implant-supported restorations. This article describes a simple technique for fabricating a vacuum-formed surgical guide to assist in dental implant placement in edentulous posterior regions.

The coexistence of temporomandibular disorders and styloid process fracture: a clinical report.

This clinical report describes the diagnosis and treatment of a patient with both temporomandibular disorders (TMD) and styloid process fracture. The presence of tender muscles of mastication, facial pain, especially upon awakening, frequent grinding sounds, and tooth attrition indicated a diagnosis of TMD with bruxism as a possible etiological factor. However, the preliminary diagnosis of styloid process fracture based on the patient's sensation of a foreign body in the throat and some discomfort when turning the head was confirmed using radiography. The styloid process fracture was treated using conservative nonsurgical therapy, and an occlusal splint was used to treat the TMD. The patient's symptoms were significantly reduced at the 12-month follow-up visit.

Temporomandibular disorders seen in rheumatology practices: A review.

Temporomandibular disorders are recognized as the most common nontooth-related chronic orofacial pain conditions. This article reviews the recent temporomandibular disorders literature and summarizes the temporomandibular disorders seen in rheumatology practices. Arthritis is a common condition affecting the temporomandibular joint. Although degenerative and rheumatoid arthritis are the most frequently encountered infectious arthritis, metabolic arthritis, spondyloarthropathies and the traumatic arthritis have also been reported. Distinguishing between different temporomandibular disorders is as important as the clinical course, long-term prognosis, and therapy. Diagnostic criteria are generally based on signs and symptoms of the patient. The American Academy of Orofacial Pain established the first well-defined diagnostic classification. In addition, Research Diagnostic Criteria for Temporomandibular Disorders have been developed using similar classification. In the treatment of temporomandibular disorders, conservative and noninvasive treatments are endorsed for the initial care of nearly all TMD patients because the majority of patients with TMD achieve good relief of symptoms with conservative treatment.

Effect of zirconium-oxide ceramic surface treatments on the bond strength to adhesive resin.

STATEMENT OF PROBLEM: Surface treatment methods used for resin bonding to conventional silica-based dental ceramics are not reliable for zirconium-oxide ceramics. PURPOSE: The aim of this study was to compare the effects of airborne-particle abrasion, silanization, tribochemical silica coating, and a combination of bonding/silane coupling agent surface treatment methods on the bond strength of zirconium-oxide ceramic to a resin luting agent. MATERIAL AND METHODS: Sixty square-shaped (5 x 5 x 1.5 mm) zirconium-oxide ceramic (Cercon) specimens and composite resin (Z-250) cylinders (3 x 3 mm) were prepared. The ceramic surfaces were airborne-particle abraded with 125-microm aluminum-oxide (Al(2)O(3)) particles and then divided into 6 groups (n = 10) that were subsequently treated as follows: Group C, no treatment (control); Group SIL, silanized with a silane coupling agent (Clearfil Porcelain Bond Activator); Group BSIL, application of the adhesive 10-methacryloyloxydecyl dihydrogen phosphate monomer (MDP)-containing bonding/silane coupling agent mixture (Clearfil Liner Bond 2V/ Porcelain Bond Activator); Group SC, silica coating using 30-microm Al(2)O(3) particles modified by silica (CoJet System); Group SCSIL, silica coating and silanization (CoJet System); and Group SCBSIL, silica coating and application of an MDP-containing bonding/silane coupling agent mixture (Clearfil Liner Bond 2V/Porcelain Bond Activator). The composite resin cylinders were bonded to the treated ceramic surfaces using an adhesive phosphate monomer-containing resin luting agent (Panavia F). After the specimens were stored in distilled water at 37 degrees C for 24 hours, their shear bonding strength was tested using a universal testing machine at a crosshead speed of 0.5 mm/min. Debonded specimen surfaces were examined with a stereomicroscope to assess the mode of failure, and the treated surfaces were observed by scanning electron microscopy. Bond strength data were analyzed using 1-way analysis of variance and the Duncan test (alpha = .05). RESULTS: The bond strengths (mean +/- SD; MPa) in the groups were as follows: Group C, 15.7 +/- 2.9; Group SIL, 16.5 +/- 3.4; Group BSIL, 18.8 +/- 2.8; Group SC, 21.6 +/- 3.6; Group SCSIL, 21.9 +/- 3.9; and Group SCBSIL, 22.9 +/- 3.1. The bond strength was significantly higher in Group SCBSIL than in Groups C, SIL, and BSIL (P<.001), but did not differ significantly from those in Groups SC and SCSIL. Failure modes were primarily adhesive at the interface between zirconium and the resin luting agent in Groups C and SIL, and primarily mixed and cohesive in Groups SC, SCSIL, and SCBSIL. CONCLUSION: Tribochemical silica coating (CoJet System) and the application of an MDP-containing bonding/silane coupling agent mixture increased the shear bond strength between zirconium-oxide ceramic and resin luting agent (Panavia F).

Age-related changes in tooth enamel as measured by electron microscopy: implications for porcelain laminate veneers.

STATEMENT OF PROBLEM: Available information on the dimensions of the enamel and pulp tissues of tooth structure, as well as their correlation with chronologic age, is limited. However, this information is a significant determinate in planning the tooth reduction for a porcelain laminate veneer (PLV) restoration. PURPOSE: This study examined variations in tooth enamel thickness and its correlation with chronologic age as it relates to available tooth substrate for PLV restorations. MATERIAL AND METHODS: Forty human maxillary central incisors extracted from patients within the age range of 30 to 69 years were used to evaluate the thickness of tooth layers. Measurements were made for the following tooth areas using scanning electron microscopy (SEM): facial enamel thickness at 1, 3, and 5 mm above the cemento-enamel junction (CEJ), palatal enamel thickness at 5 mm above the CEJ, facial and palatal enamel thickness at the incisal edge, maximum facial-palatal (MFP) width at incisal edge, physiologic secondary dentin (PSD) height, facial-cervical enamel-pulp (FCEP) distance, and the incisal edge enamel-pulp (IEP) distance. The relationship between thickness and age was evaluated with a regression analysis (alpha=.05). RESULTS: Significant differences (P<.001) were observed in all of the relationships between tooth thicknesses and chronological age. Outcome variables of enamel thickness related to age showed a steady decrease, beginning at approximately age 50. Mean values of facial enamel thickness at 1, 3, and 5 mm above the CEJ were 0.31 +/- 0.01, 0.54 +/- 0.01, and 0.75 +/- 0.02 mm, respectively, for the age range of 30 to 69 years. The thickness of maximum incisal width (R(2) = 0.95), PSD height (R(2) = 0.76), and IEP distance (R(2) = 0.99) indicated that all are subject to an increase in relation to age. CONCLUSION: Facial enamel thickness above the CEJ decreases, while MFP increases in relation to age. The PSD height and IEP distance also increased with age.