Fracture strength of endocrown maxillary restorations using different preparation designs and materials.

PURPOSE: This study investigated the impact of preparation design and material types on fracture strength in maxillary premolars endocrowns after thermodynamic aging. MATERIALS AND METHODS: Eighty two-rooted maxillary premolar crowns underwent endodontic treatment (N = 80, n = 10). The teeth were categorized into ten groups (4-mm deep with no intracanal extension lithium disilicate glass ceramic & multilayer zirconia endocrowns (LE0 & ZE0); 4-mm deep with 4-mm intracanal extension in one canal (LE1 & ZE1); 4-mm deep with 2-mm intracanal extensions in both canals (LE2 & ZE2); flat overlays with no endocore (LO & ZO); glass fiber reinforced post & core and crown (LC & ZC)). After cementation, all specimens were subjected to 1500 thermocycles and 1,200,000 chewing cycles with an axial occlusal load of 49 N. A static loading test was performed at a non-axial 45° loading using a universal testing machine and failure modes (Type I: restoration debonding; Type II: restoration fracture; Type III: restoration/tooth complex fracture above bone level; Type IV: restoration/tooth complex fracture below bone level) were evaluated using a stereoscope. Data were ananalzed using 2-way ANOVA and Tukey's tests (alpha = 0.05). RESULTS: The endocrowns manufactured from multilayered zirconia and pressed lithium disilicate glass ceramic exhibited a fracture load ranging between 1334 ± 332 N and 756 ± 150 N, with ZC presenting the highest and LE2 the lowest values. The differences were not statistically significant (p > 0.05). CONCLUSION: All endocrowns tested in this study performed similar considering the different designs and materials tested. The distribution of fracture modes did not differ significantly depending on the design of the restoration and the type of material used.

Evaluation of Marginal and Internal Fit of Ceramic Laminate Veneers Fabricated with Five Intraoral Scanners and Indirect Digitization.

The long-term success of ceramic laminate veneers (CLVs) is influenced by the marginal and internal fit of the restorations. However, studies comparing the fit of CLVs using different intraoral scanners or the indirect digitization technique are lacking. The purpose of this study was therefore to assess the marginal and internal fit of CAD/CAM-milled CLVs using different intraoral scanners and the indirect digitalization technique. An ivorine typodont maxillary left-central incisor was prepared; the tooth and the neighboring teeth were scanned and used as a template to print ninety 3D partial models. Thereafter, ceramic laminate veneers (CLVs) (N = 90) were milled from IPS-Emax CAD blocks and divided into six equal groups (15 specimens each) according to the type of intraoral scanner (IOS), as follows: Omnicam IOS, SC3600 IOS, Trios 3 IOS, Emerald IOS, I500 IOS. Fifteen further CLVs were fabricated using the conventional indirect digitalization technique. After cementation on the resin dies and embedding in clear epoxy resin, specimens were sectioned inciso-gingivally and mesio-distally. At the incisal and cervical positions, the marginal discrepancy was measured and evaluated in addition to the internal gap at six locations using SEM (200×). Differences between gap measurements among the six groups were determined using ANOVA. Games-Howell multiple comparisons for homogenous variances and LSD multiple comparisons for non-homogenous variances were used with 95% confidence intervals. The significance level was set at 0.05. The lowest mean absolute marginal gap at the incisal margins (AMGI) was recorded for Omnicam group (203.28 ± 80.14) µm, while the highest mean absolute marginal gap at the cervical margins (AMGC) was recorded for Omnicam group (147.16 ± 59.78) µm. The mean AMGC was reported to be significantly different between the conventional technique (146.75 ± 38.43) µm and Trios 3 (91.86 ± (35.51) µm; p = 0.001) and between Emerald (112.37 ± (50.31) µm; p = 0.042) and I500 (86.95 ± (41.55) µm; p < 0.001). The mean MGI was found to be significantly different between the conventional technique (114.11 ± (43.45) µm and I500 group (186.99 ± (73.84) µm) only (p = 0.035). However, no significant differences were found in the mean MGI between all types of IOSs. The means of AMG and MG were significantly different at incisal or cervical areas between the conventional technique and IOSs and within the scanner groups (p > 0.05). Marginal gaps were higher in the incisal region compared to the cervical region with both the indirect digitization technique and the IOSs. Ceramic laminate veneers (CLVs) fabricated using IOSs produced overall internal and marginal fit adaptation results comparable to CLVs fabricated from the indirect digitalization method, and both techniques produced clinically acceptable results.

A Comparison of the Surface and Mechanical Properties of 3D Printable Denture-Base Resin Material and Conventional Polymethylmethacrylate (PMMA).

PURPOSE: To study the surface and mechanical properties of 3D printed denture-base resin materials and compare them with conventional heat-cured polymethylmethacrylate (PMMA). MATERIALS AND METHODS: Three brands of 3D printed denture-base resin materials and one conventional heat-cured PMMA were tested in this study: NextDent 3D printed resin, Dentona 3D printed resin, ASIGA 3D printed resin, and Meliodent conventional PMMA. Sixty specimens (25 × 25 × 3 mm) were fabricated (n=15 per group) to perform the following tests: wettability, surface roughness, and microhardness. One hundred twenty specimens (65 × 10 × 3 mm) were fabricated (n=30 per group) and stored in distilled water at (37 ±1°C) for 7 days. Specimens (N = 15) in each group were subjected to the three-point bending test and impact strength test, employing the Charpy configuration on un-notched specimens. The morphology of the fractured specimens was studied under scanning electron microscope (SEM). Statistical analysis was performed using one-way ANOVA and Tukey-pairwise multiple comparisons with 95% confidence interval. P-values of ≤0.05 were considered significant. RESULTS: The conventional heat-cured specimens demonstrated the highest means of surface roughness (0.23 ± 0.07 µm), Vickers hardness number (18.11 ±0.65) and flexural strength (92.44 ±7.91 MPa), and the lowest mean of contact angle (66.71° ±3.38°). ASIGA group showed the highest mean of contact angle (73.44° ±2.74°) and the lowest mean of surface roughness (0.19 ±0.03 µm). The highest mean of impact strength was recorded in the Dentona group (17.98 ±1.76 kg/m2 ). NextDent specimens showed the lowest means of Vickers hardness number (16.20 ±0.93), flexural strength (74.89 ±8.44 MPa), impact strength (15.20 ±0.69 kg/m2 ), and recorded the highest mean of bending modulus (2,115.80 ±178.95 MPa). CONCLUSIONS: 3D printed resin exhibited noticeable differences in surface and mechanical properties between different brands and with conventional heat-polymerized PMMA.

Durability of cantilever inlay-retained fixed dental prosthesis fabricated from multilayered zirconia ceramics with different designs.

PURPOSE: The purpose of this in-vitro study was to investigate the effect of framework design on fracture resistance and failure modes of cantilever inlay-retained fixed partial dentures (IRFDPs) fabricated from two multilayered monolithic zirconia materials. MATERIALS AND METHODS: Seventy-two natural premolar teeth were prepared as abutments for cantilever IRFDPs using three designs: mesial-occlusal (MO) inlay with short buccal and palatal wings (D1), MO inlay with long palatal wing (D2), MO inlay with long palatal wing and occlusal extension (D3). Full-contoured IRFDPs were fabricated from two monolithic zirconia materials; IPS e.max ZirCAD Prime and Zolid Gen-X. Adhesive surfaces were air-abraded and bonded with MDP-containing resin cement. Specimens were subjected to thermocycling (5-55 °C, 5000 cycles); then, mechanical loading (1.2 × 106 cycles, 49 N). Surviving specimens were loaded until failure in the universal testing machine. All specimens were examined under stereomicroscope, and two samples from each group were evaluated using Scanning Electron Microscope. RESULTS: Mean failure loads were not significantly different between different framework designs or between two materials. However, IPS e.max ZirCAD Prime showed significantly higher failure rate than Zolid Gen-X during dynamic fatigue (p = 0.009). Samples with D1 design showed higher debonding rate, D2 failed mainly by fracture of the palatal wing and debonding, and D3 failed mainly by fracture of the abutment tooth. Debonded restorations showed mainly mixed failures. CONCLUSION: Cantilever IRFDPs with framework designs that maximize adhesion to enamel exhibited promising results. IPS e.max ZirCAD Prime was more susceptible to fractures with the long palatal wing design.

Effect of CAD/CAM Bur Deterioration on the Surface Roughness of Ceramic Crowns.

PURPOSE: To evaluate the effect of repetitive milling on the surface roughness of ceramic crowns. MATERIALS AND METHODS: Twenty feldspathic ceramic crowns (VITABLOCS Mark II; Vita Zahnfabrik, Bad Säckingen, Germany) milled with hard milling protocol, and 20 zirconia crowns (5Y-TZP, inCoris TZI; Dentsply Sirona, York, PA) milled with soft milling protocol, using a 5-axis milling machine (inLab MC X5; Dentsply Sirona) were investigated. Atomic force microscopy (SPM SmartSPM™-1000) was used for surface roughness measurements (Ra, RMS). Pearson correlation between bur deterioration percentage as provided by the software of the milling machine and surface roughness was performed with an (r) range between 1 and -1. Trend analysis between the 2-half and among the 4-quarter bur lifetime was performed with linear contrast analysis and partial eta squared (η) for estimate of effect size. Analysis of mean variance between the zirconia and feldspathic ceramic groups was performed with a t-test, with α = 0.05. RESULTS: Correlation analysis showed small correlation for Ra, RMS (r = -0.02, -0.16 for the feldspathic ceramic crowns and r = 0.044, 0.034 for the zirconia crowns), and no significant differences for the 2-half and 4-quarter groups (p > 0.05) for both crown types. Estimate of effect size was rated as medium for the 2-half groups (Ra = 0.420, RMS = 0.395) and large for the 4-quarter groups (RA = 0.22, F = 1.48, RMS = 0.19, F = 1.26) for the feldspathic ceramic crowns, and small effect size for the 2-half groups (Ra = 0.18, RMS = 0.20) and the 4-quarter groups (Ra = 0.035, RMS = 0.037) for the zirconia crowns. There was no significant difference (p = 0.178, F = 0.016. p = 0.088, F = 0.002) between the feldspathic ceramic and zirconia crowns with medium and large effect size (0.45, 0.57) for RA and RMS. CONCLUSIONS: Milling zirconia and feldspathic ceramic crowns had small correlation between bur deterioration and surface roughness when the burs were used within their recommended lifetime. However, hard milled feldspathic ceramic crowns had higher surface roughness than the soft milled zirconia crowns. Bur deterioration had a larger effect on the surface roughness of the feldspathic ceramic crowns than the zirconia crowns.

A Comparison of the Flexural and Impact Strengths and Flexural Modulus of CAD/CAM and Conventional Heat-Cured Polymethyl Methacrylate (PMMA).

PURPOSE: The introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) technology to the field of removable prosthodontics has recently made it possible to fabricate complete dentures of prepolymerized polymethyl methacrylate (PMMA) blocks, which are claimed to be of better mechanical properties; however, no published reports that have evaluated mechanical properties of CAD/CAM PMMA. The purpose of this study was to compare flexural strength, impact strength, and flexural modulus of two brands of CAD/CAM PMMA and a conventional heat-cured PMMA. MATERIALS AND METHODS: 45 rectangular specimens (65 mm × 10 mm × 3 mm) were fabricated (15 CAD/CAM AvaDent PMMA specimens from AvaDent, 15 CAD/CAM Tizian PMMA specimens from Shütz Dental, 15 conventional Meliodent PMMA specimens from Heraeus Kulzer) and stored in distilled water at (37  ± 1°C) for 7 days. Specimens (N = 15) in each group were subjected to the three-point bending test and impact strength test, employing the Charpy configuration on unnotched specimens. The morphology of the fractured specimens was studied under a scanning electron microscope (SEM). Statistical analysis was performed using one-way ANOVA and Tukey pairwise multiple comparisons with 95% confidence interval. RESULTS: The Schütz Dental specimens showed the highest mean flexural strength (130.67 MPa) and impact strength (29.56 kg/m2 ). The highest mean flexural modulus was recorded in the AvaDent group (2519.6 MPa). The conventional heat-cured group showed the lowest mean flexural strength (93.33 MPa), impact strength (14.756 kg/m2 ), and flexural modulus (2117.2 MPa). Differences in means of flexural properties between AvaDent and Schütz Dental specimens were not statistically significant (p > 0.05). CONCLUSIONS: As CAD/CAM PMMA specimens exhibited improved flexural strength, flexural modulus, and impact strength in comparison to the conventional heat-cured groups, CAD/CAM dentures are expected to be more durable. Different brands of CAD/CAM PMMA may have inherent variations in mechanical properties.

Effect of length of LOCATOR abutment and cement type on retention to intraradicular dentin in overdentures.

STATEMENT OF PROBLEM: Limited information is available on the effect of LOCATOR abutment length and luting cement type on retention to intraradicular dentin in overdentures. PURPOSE: The purpose of this in vitro study was to evaluate the effect of the length of a commercially available LOCATOR abutment and cement type on retention in the root canal. MATERIAL AND METHODS: Eighty LOCATOR abutments with a standard length of 6 mm were obtained. Half of them were shortened to 3 mm. Eighty recently extracted single-rooted teeth were divided into 2 groups. The post space was prepared to 6 mm in the first group and 3 mm in the second. After preparation, the LOCATOR abutments were luted with one of the following cements: dual-polymerized glass-reinforced resin cement (Parapost Paracore), dual-polymerized resin cement (Variolink II), self-adhesive resin cement (RelyX Unicem), and conventional cement (zinc phosphate). The tensile force required for the removal of the LOCATOR abutments from their corresponding roots was recorded. Data were statistically analyzed with 2-way ANOVA and the Tukey multiple comparison test. RESULTS: Both the cement type (P<.001) and the length of the LOCATOR abutment (P<.001) significantly affected the mean tensile forces. Dual-polymerized glass-reinforced resin cement (Parapost Paracore) presented significantly higher mean tensile forces for the LOCATOR abutment retention among all cements (P<.05). CONCLUSIONS: Regardless of the length, LOCATOR abutments luted with Parapost Paracore resin cement presented higher mean resistance to tensile forces compared with those luted with the other cements. LOCATOR abutments of 6 mm in length were more resistant to tensile forces than those of 3 mm in length in combination with all cements.

A Comparison of the Surface Properties of CAD/CAM and Conventional Polymethylmethacrylate (PMMA).

PURPOSE: To compare surface properties of 2 brands of pre-polymerized resin blocks for complete dentures (CAD/CAM PMMA) to conventional heat-polymerized PMMA. MATERIALS AND METHODS: A total of 45 rectangular specimens (25 × 25 × 3 mm) were fabricated from 3 brands of PMMA (n = 15/group): AvaDent CAD/CAM PMMA, Tizian-Schütz CAD/CAM PMMA, Meliodent conventional PMMA. Specimens were examined for wettability using the sessile drop method, surface roughness using a digital contact profilometer, and microhardness using Vickers hardness number. Statistical analysis was performed using one-way ANOVA and Tukey pairwise multiple comparisons. p-Values of ≤0.05 were considered significant. RESULTS: AvaDent specimens demonstrated the highest mean contact angle (72.87 ± 48°) and the highest mean Vickers hardness number (20.62 ± 0.33). The conventional heat-polymerized specimens showed the highest mean surface roughness (0.22 ± 0.071 µm). Tizian-Schütz specimens showed the lowest mean surface roughness (0.12 ± 0.02 µm). CONCLUSIONS: As CAD/CAM PMMA groups exhibited significantly more favorable surface properties in comparison to the conventional heat-polymerized groups, CAD/CAM dentures are expected to be more durable. Different brands of CAD/CAM PMMA may have inherent variations in surface properties.

A comparison of the marginal and internal fit of porcelain laminate veneers fabricated by pressing and CAD-CAM milling and cemented with 2 different resin cements.

STATEMENT OF PROBLEM: The marginal and internal adaptations of porcelain laminate veneers (PLVs) are key elements in their long-term success. However, the marginal and internal fit obtained with a pressable material compared with computer-aided design and computer-aided manufacturing (CAD-CAM) needs further investigation as does the choice of cement used. PURPOSE: The purpose of this in vitro study was to evaluate the marginal and internal fit of PLVs fabricated using pressing and CAD-CAM milling and cemented using 2 types of composite resin cement. MATERIAL AND METHODS: Twenty PLVs were fabricated from VITA PM9 pressable material, and 20 veneers were milled using VITA Blocs Mark II. Veneers were cemented to composite resin dies using either RelyX Veneer cement or Variolink-N cement. Specimens were embedded in clear resin and sectioned incisogingivally and mesiodistally. Marginal discrepancy at the incisal and cervical positions and the internal gap at 6 different locations were evaluated by using a scanning electron microscope. Two-way ANOVA followed by Tukey multiple comparisons were used to examine difference among groups (α=.05). RESULTS: The cement and fabrication methods did not show any significant effect for absolute marginal gap (AMG) at the incisal edge, AMG at the cervical margin or marginal gap at the incisal edge. However, both had a significant effect on marginal gap at the cervical margin (P=.038 for the fabrication method and P=.050 for the cement used). Also, both cement and fabrication methods had a significant effect on internal gap average (P<.001). The lowest gap values were reported for veneers fabricated from VITA PM9 by using the press technique and cemented with RelyX Veneer cement. When the position of gap measurements was taken into consideration, it was the only significant factor (P<.001 for the effect of position on AMG and P<.001 for the effect of position on marginal gap). Gaps at the cervical position were significantly lower than gaps at the incisal position. CONCLUSIONS: Smaller marginal and internal discrepancies were recorded for PLVs fabricated by using the pressing technique and cemented using RelyX Veneer cement compared with milled veneers and Variolink-N cement. Larger discrepancies were present incisally than cervically.

Association between oral tori, occlusal force, and mandibular cortical index.

OBJECTIVE: To assess possible associations between torus palatinus (TP), torus mandibularis (TM), occlusal force (OF), Klemetti's classes, mandibular cortical index (MCI), and sociodemographic variables in a selected sample of Jordanians. Previous studies have suggested that oral tori are benign anatomical variations probably related to several factors such as functional stress, gender predisposition, number of teeth present, and nutritional factors. METHOD AND MATERIALS: A total of 130 Jordanian adults were included. Shape, location, and appearance of tori were recorded from study casts. Size was measured using digital calipers. OF was recorded in Newtons. MCI and Klemetti's classification were assessed using panoramic radiographs. Data were statistically analyzed, and level of significance was set at P < .05. RESULTS: The mean ± SD recorded OF was 524 ± 183 N in the tori group, compared to 417 ± 172 N in controls (P = .001). OF was significantly higher in males compared to females (P < .001), and was significantly higher in subjects with TM only (543 ± 201 N) (P < .001). TP and TM were predominantly more than 6 mm in size. The average OF in subjects with Klemetti class 3 was 418 ± 174 N, while OF in Klemetti class 1 subjects amounted to 535 ± 187 N (P = .043). CONCLUSION: Average OF was significantly higher in tori subjects and in males (if compared to controls and female subjects, respectively). The presence of oral tori, Klemetti's classification, and MCI ratio seems to be positively correlated with OF.

Heat Generation on Implant Surface During Abutment Preparation at Different Elapsed Time Intervals.

PURPOSE: The purpose of this study was to evaluate heat generation at the implant surface caused by abutment preparation using a diamond bur in a high-speed dental turbine in vitro at 2 different water-coolant temperatures. MATERIALS AND METHODS: Thirty-two titanium-alloy abutments were connected to a titanium-alloy implant embedded in an acrylic resin placed within a water bath at a controlled temperature of 37°C. The specimens were equally distributed into 2 groups (16 each). Group 1: the temperature was maintained at 20 ± 1°C; and group 2: the temperature was maintained at 32 ± 1°C. Each abutment was prepared in the axial plane for 1 minute and in the occlusal plane for 1 minute. The temperature of the heat generated from abutment preparation was recorded and measured at 3 distinct time intervals. RESULTS: Water-coolant temperature (20°C vs 32°C) had a statistically significant effect on the implant's temperature change during preparation of the abutment (P < 0.0001). CONCLUSION: The use of water-coolant temperature of 20 ± 1°C during preparation of the implant abutment decreased the temperature recorded at the implant surface to 34.46°C, whereas the coolant temperature of 32 ± 1°C increased the implant surface temperature to 40.94°C.

Pull-out retentive strength of fiber posts cemented at different times in canals obturated with a eugenol-based sealer.

STATEMENT OF PROBLEM: Currently, no standard luting protocol exists for fiber posts. In addition, no agreement has been reached on the time interval between canal obturation and post space preparation and cementation. PURPOSE: The purpose of this in vitro study was to evaluate the retention of fiber posts cemented with 3 different types of cement: Paracore, Variolink II, and RelyX Unicem cement after 24 hours or 2 weeks in root canals obturated with gutta percha and a eugenol-based sealer. MATERIAL AND METHODS: Seventy-two caries-free, freshly extracted, single-rooted human mandibular first premolar teeth with straight root canals were prepared and obturated with gutta percha and Endofil sealer. Specimens were divided into 2 groups (n=36): post spaces prepared 24 hours after obturation and post spaces prepared 2 weeks after obturation. Posts in both groups were luted with 1 of 3 different luting agents (n=12), ParaCore, Variolink II, or RelyX Unicem cement. Each tooth specimen was vertically secured in a universal testing machine, and a constant pull-out loading rate of 0.5 mm/min was applied until cement failure occurred. Data were statistically analyzed with 2-way and 1-way ANOVAs and t tests. RESULTS: Two-way ANOVA indicated statistically significant differences in mean post retention among the 3 cement types (P<.001) and among the means of the different time intervals investigated (P<.001). Significant differences were noted among all cement types tested between the 24-hour and 2-week time intervals (P<.05). CONCLUSIONS: Time elapsed between canal obturation and post cementation significantly influenced fiber post retention, regardless of the type of resin cement. Fiber posts showed significantly higher retention if cemented after 24 hours of obturation than if cementation occurred after 2 weeks.

Assessment of Posterior Teeth Preparations for Metal-Ceramic Crowns.

OBJECTIVES: To evaluate teeth preparation designs for metal-ceramic crowns in private dental practice in Jordan. MATERIALS AND METHODS: One-hundred and seventy two dies were included. Different aspects of tooth preparations were quantified, analyzed and compared with the recommended guidelines. RESULTS: Almost 64% of preparations finish lines were positioned subgingivally. Shoulder finish lines were observed in 74.4% where-as 22.7% showed chamfer finish lines. Total occlusal convergence angles were 29.8 degrees in BL plane, 247 degrees in MD plane. CONCLUSIONS: Dental practitioners in private practice in Jordan did not fully adhere to the recommendedguidelines for tooth preparations for MCRs.

Studying the relationships between the outlines of the face, maxillary central incisor, and maxillary arch in Jordanian adults by using Fourier analysis.

STATEMENT OF THE PROBLEM: The outline shapes of the dental arch, face, and tooth are esthetic factors used to determine the proper form of artificial teeth when selected for artificial prostheses. PURPOSE: The purpose of this study was to investigate the quantitative relationships between the outlines of the face, the maxillary central incisor, and the maxillary arch by using Fourier analysis. MATERIAL AND METHODS: Frontal facial photographs and irreversible hydrocolloid impressions of the maxilla were obtained from 200 young, dentate individuals (100 men, 100 women) ages 22 to 28 years. On the resultant casts, standardized photographs were made for the dental arch and the maxillary central incisor. The outlines of the face, dental arch, and tooth were digitally traced and the digitized curved outlines were converted into X-Y coordinates with special software, which, in turn, were imported into Fourier Shape Descriptor software for harmonic analysis. The quantitative outputs of Fourier analyses were analyzed and tested with statistical software to investigate the differences across the shapes of the 3 outlines under study. RESULTS: Facial and tooth outlines were similar for each sex, although the similarity was stronger among the men. By contrast, no relationship was found between tooth and maxillary arch outlines or between face and maxillary arch outlines. CONCLUSIONS: Face and tooth forms were quantitatively related. Therefore, face form may reliably guide the selection of artificial anterior tooth form in complete denture prostheses or any complex anterior restorations.

Effect of endodontic sealers on push-out bond strength of cemented fiber posts.

OBJECTIVE: The purpose of this study was to compare the effect of eugenol-based and resin-based endodontic sealers on the push-out bond strengths of prefabricated fiber posts luted with different resin cements. METHOD AND MATERIALS: Ninety prefabricated fiber posts were luted into extracted singlerooted teeth with one of three resin cements (Variolink II, ParaCore, or Rely X Unicem). Each group was subdivided into three groups with 10 teeth each. The first two groups were obturated with gutta percha and one of two eugenol-based endodontic sealers (Endofil or TubliSeal) each. The third group was obturated with gutta percha and (AH26) resin-based root canal sealer. Push-out tests were performed in a universal testing machine by applying a load speed at 0.5 mm/min by using a 1-mm-diameter metallic plunger which induced a load in an apical to coronal direction. The maximum value for post dislodgement (in Newtons) was recorded. Data were collected and statistically analyzed using two-way ANOVA and Tukey multiple comparison tests (α = .05). RESULTS: The highest mean bond strength values were recorded for the AH26 sealer group (non-eugenol sealer) luted with Rely X Unicem resin cement (mean ± SD = 326.1 ± 66.1 N), while the lowest mean bond strength values were observed with posts luted with Variolink II resin cement into canals obturated with gutta-percha and Endofil (eugenol-based) sealer (90.3 ± 25.2 N). There was no significant difference between the means of push-out strengths for the Endofil and TubliSeal groups (P = .745). CONCLUSION: Eugenol-based sealers (Endofil and TubliSeal) significantly reduced the push-out bond strength of prefabricated fiber posts luted with resin cement.

Implant Fixture Heat Transfer During Abutment Preparation.

The purpose of the study was to evaluate the effect of water flow rate on the heat transmission in implants during abutment preparation using a diamond bur in a high-speed dental turbine. Titanium-alloy abutments (n = 32) were connected to a titanium-alloy implant embedded in an acrylic resin within a water bath at a controlled temperature of 37°C. The specimens were equally distributed into 2 groups (16 each) according to the water flow rate used during the preparation phase. Group 1 had a water flow rate of 24 mL/min, and group 2 had a water flow rate of 40 mL/min. Each abutment was prepared in the axial plane for 1 minute and in the occlusal plane for 1 minute with a coarse tapered diamond bur using a high-speed dental handpiece. Thermocouples embedded at the cervix of the implant surface were used to record the temperature of heat transmission from the abutment preparation. Heat generation was measured at 3 distinct times (immediately and 30 seconds and 60 seconds after the end of preparation). Statistical analyses were carried out using 2-way analysis of variance and the Student t test. Water flow rates (24 mL vs 40 mL) and time interval had no statistically significant effect on the implant's temperature change during the abutment preparation stage (P = .431 and P = .064, respectively). Increasing the water flow rate from 24 to 40 mL/min had no influence on the temperature of the implant fixture recorded during preparation of the abutment.

Tooth shade measurements under standard and nonstandard illumination and their agreement with skin color.

PURPOSE: The purpose of this study was to examine the relationship between skin color (shade) and tooth shade under standard and nonstandard illumination sources. MATERIALS AND METHODS: Four hundred Jordanian participants (200 males, 200 females, 20 to 50 years of age) were studied. Skin colors were assessed and categorized using the L'Oreal and Revlon foundation shade guides (light, medium, dark). The Vita Pan Classical Shade Guide (VPCSG; Vident) and digital Vita EasyShade Intraoral Dental Spectrophotometer (VESIDS; Vident) were used to select shades in the middle thirds of maxillary central incisors; tooth shades were classified into four categories (highest, high, medium, low). RESULTS: Significant gender differences were observed for skin colors (P = .000) and tooth shade guide systems (P = .001 and .050 for VPCSG and VESIDS, respectively). The observed agreement was 100% and 93% for skin and tooth shade guides, respectively. The corresponding kappa statistic values were 1.00 and 0.79, respectively (substantial agreement, P < .001). The observed agreement between skin color and tooth shades (VPCSG and VESIDS) was approximately 50%. CONCLUSIONS: The digital tooth shade guide system can be a satisfactory substitute for classical tooth shade guides and clinical shade matching. There was only moderate agreement between skin color and tooth shade.

Awareness, attitude, and expectations toward dental implants among removable prostheses wearers.

PURPOSE: To assess removable denture patient awareness, expectations, and source of information about dental implants (DIs). MATERIALS AND METHODS: Three hundred patients [150 removable partial denture (RPD) wearers and 150 complete denture wearers (CDWs)] attended the removable prosthodontic clinic at Faculty of Dentistry, Jordan University of Science and Technology. Patients were evaluated using a pilot-tested, 21-question questionnaire. RESULTS: Ninety-six percent of participants were aware of DIs, with no difference between CDWs and RPD wearers (p > 0.05). The participants' friends and relatives were the main source of information (63.4%), followed by dentists (32.4%). Improvement in function was the predominant reason (55.7%) for patients to consider DIs. Fear of unknown side effects was the major factor in preventing patients from choosing DIs (11.7%), followed by high cost (9.7%) and surgical risk (8.7%). Approximately 89% had no information or were poorly informed about DIs. Over two-thirds of patients did not know about the care (78.3%) of DIs, causes of DI failure (69.7%), or DI duration of service (80.7%). Only 24.7% knew that DIs would be anchored to the jawbone; however, 27.3% and 56.7% of CDWs and RPD wearers, respectively, preferred (p < 0.05) to have their teeth replaced with DIs. High costs were considered the major disadvantage of DIs in 45% of participants, followed by fear of surgery (27.3%), and long treatment times (24.7%). CONCLUSIONS: There was a high awareness about DIs among removable denture patients; however, this awareness was associated with a low level of accurate information.

Xerostomia in complete denture wearers: prevalence, clinical findings and impact on oral functions.

OBJECTIVES: To investigate the prevalence of dry mouth in a select sample of edentulous Jordanian older population wearing complete dentures and to evaluate its impact on oral functions. BACKGROUND: The prevalence and impact of Xerostomia as a cofactor in causing denture problems in Jordanians have not been previously investigated. MATERIALS AND METHODS: This study included 455 participants (253 men and 202 women). Perception of dry mouth was measured by a pilot-tested questionnaire. Xerostomic status was confirmed clinically. Complete denture function was also assessed. RESULTS: One hundred and thirty six subjects (29.9%) had reported a subjective feeling of dry mouth with a prevalence of 24.9% in men (n = 63) and 36.1% in women (n = 73) (p < 0.01). 136 of the 145 subjects with satisfactory dentures showed one or more signs suggestive of Xerostomia. The majority of xerostomic participants with different sets of complete dentures were dissatisfied with oral functions (p < 0.05). There was a significant association between dry mouth and increasing age, female gender and smoking status (p < 0.05). CONCLUSION: Among complete denture wearers, Xerostomia is significantly more prevalent in women and associated with increased age and smoking. Xerostomia adversely affects oral functions and overall satisfaction with dentures.

Effect of luting agents on the tensile bond strength of glass fiber posts: An in vitro study.

STATEMENT OF PROBLEM: Fiber posts can fail because of loss of retention; and it is unknown which luting agent provides the highest bond strength. PURPOSE: The purpose of this study was to investigate the tensile bond strength of glass fiber posts luted to premolar teeth with 6 resin composite luting agents. MATERIAL AND METHODS: Ninety-six single-rooted extracted human mandibular premolars were sectioned 2 mm coronal to the most incisal point of the cementoenamel junction. Root canals were instrumented and obturated with laterally condensed gutta percha and root canal sealer (AH26). Gutta percha was removed from the canals to a depth of 8 mm and diameter post spaces with a 1.5 mm were prepared. The specimens were divided into the following 6 groups according to the luting agent used (n=16): Group V, Variolink II; Group A, RelyX ARC; Group N, Multilink N; Group U, RelyX Unicem; Group P, ParaCore; Group F, MultiCore Flow. Each specimen was secured in a universal testing machine and a separating load was applied at a rate of 0.5 mm/min. The forces required to dislodge the posts were recorded. A 1-way analysis of variance (ANOVA) was applied to the mean retentive strengths of various cement materials (α=.05). RESULTS: Significant differences were recorded among the 6 cement types (P<.001). Three materials provided statistically equivalent mean bond strengths (RelyX Unicem, Paracore, and MultiCore Flow) that were significantly greater than for the other 3 materials. CONCLUSIONS: Fiber posts luted with RelyX Unicem, Paracore, and MultiCore Flow demonstrated significantly higher bond strengths.