Fracture strength of anterior cantilever resin-bonded fixed partial dentures fabricated from high translucency zirconia with different intaglio surface treatments.

PURPOSE: To compare the fracture resistance and failure modes of anterior cantilever resin-bonded fixed partial dentures (RBFPDs) fabricated from high translucency zirconia with different intaglio surface treatments. MATERIALS AND METHODS: Sound-extracted canines (N = 50) were randomly divided into five groups (n = 10) to be restored with high translucency zirconia RBFBDs of different intaglio surface treatments. The RBFPD was designed using exocad software and fabricated using a CAM milling machine. The RBFPDs were treated differently: abrasion with 50 µm alumina particles (Group 1); abrasion with 30 µm silica-coated alumina particles (Group 2); abrasion with silica-coated alumina particles (30 µm) and silane application (Group 3); abrasion with silica-coated alumina particles (30 µm) and 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) primer application (Group 4); abrasion with silica-coated alumina particles (30 µm) and silane, and 10-MDP primer application. All RBFPDs were cemented using dual-cured resin cement. The RBFPDs underwent 6000 thermal cycles with distilled water at 5/55°C for 2 min per cycle and then mechanical cyclic loading with 1200,000 cycles of 50 N at a 1.7 Hz frequency at an angle of 135° to the abutment's long axis. Then, RBFPDs were loaded to fracture using a universal testing machine at 1 mm/min. Maximum fracture forces and failure modes were recorded. Fractured specimens and uncemented specimens were examined using a scanning electron microscope. Data was analyzed using ANOVA and Games-Howell post hoc tests at p < 0.05. RESULTS: Mean fracture load results showed a statistically significant difference between the research groups (p < 0.0001) and it ranged from 69.78 to 584 N. Group 4 exhibited the highest fracture load mean (p < 0.0001) which was significantly different from all other groups. Group 2 recorded a significantly higher fracture load mean than Group 3 (p = 0.029). Three modes of failure were observed: prosthesis debonding, prosthesis fracture, and abutment fracture. CONCLUSIONS: Abrasion of zirconia surface with 30 µm silica-coated alumina particles and application of 10-MDP primer yielded the highest mean fracture loads of monolithic high translucency zirconia RBFPD. The mode of fracture of the RBFPDs was influenced by the type of surface treatments.

Mechanical properties and bonding of maxillofacial silicone elastomer mixed with nano-sized anti-microbials.

OBJECTIVES: The antibacterial efficacy of silicone is improved by impregnating it with antimicrobials such as chlorohexidine and zinc oxide. The purpose of this study was to examine mechanical properties and bonding of maxillofacial silicone elastomer mixed with Zinc Oxide nanoparticles (ZnO-NP), and Chlorohexidine Diacetate Salt (CHX) at three different concentrations (1 %, 3 %, and 5 %). METHODS: Specimens of a silicone elastomer (M511) were prepared and divided into 7 groups. Group 1 was control of no additive. Groups 2-4 included silicone elastomer mixed with ZnO-NP (surface area = 67 m2/g) at 3 different concentrations (by weight %); 1 %, 3 % and 5 %. Groups 5-7 included silicone elastomer mixed with CHX at the same concentrations. Tear and tensile strengths, elongation percentage, modulus of elasticity, and shear bond strength to primed acrylic resin surfaces were evaluated. Data was analyzed with 1-way ANOVA, Bonferroni, and Dunnett's T3 post-hoc tests (P < 0.05). RESULTS: There was significant effect of the additives on the tensile strength, elongation percentage, tear strength, and shear bond strength (P < 0.05). Shear bond strengths ranged from 0.55 to 0.96 MPa. Silicone elastomer mixed with CHX (5 %) resulted in the highest shear bond strength (P < 0.05). Non-linear regressions between tensile strength and ZnO and CHX additives were 0.95 and 0.96 respectively. SIGNIFICANCE: All additives reduced the tensile strength of the silicone. However, CHX at 5 % optimized shear bond strength and thus is proposed in order to fabricate maxillofacial prostheses of sufficient mechanical properties, bonding and antimicrobial activity.

Blended learning in undergraduate dental education: a global pilot study.

AIMS: To explore the global trends in blended learning in undergraduate dental education during the COVID pandemic and during the recovery phase by engaging with the students and faculty and evaluate the implications for dental education in the post-COVID era. METHODS: It was a pilot cross-sectional study which employed a convenience sampling technique to recruit representatives of dental faculty and undergraduate students in 80 dental institutions globally. A previously validated questionnaire consisting of a combination of closed and open-ended items was used for data collection. Responses to these online questionnaires were processed and analysed using the R statistical computing environment. RESULTS: A total of 320 dental students and 169 faculty members from 47 different dental institutions participated in the study. Video and Live Online Tutorials were considered to be the most effective method of online learning followed by online question banks by both groups. Significant differences were noted between faculty and students regarding time spent and effectiveness of online teaching and learning, respectively, both before and after the start of COVID. The results highlight the faculty need to engage more closely with the students to address their learning needs. Finally, the participants provided several recommendations regarding the future development of teaching and learning strategies as well as assessments in the post-pandemic era. CONCLUSIONS: This is the first study which explores blended learning in dental education with participants from multiple institutions in different regions of the globe. Compared to the faculty, students considered online learning to be less interactive and preferred learning activities and all assessments to be delivered face-to-face. The results underscore the need to adapt teaching practices to suit the learning needs of the students.

Effect of piezocision-assisted lower second molar protraction on periodontal tissues, alveolar bone height, and lower second molar root resorption.

OBJECTIVES: To assess the effect of piezocision on periodontal tissues and alveolar bone height and to detect lower second molar root resorption in piezocision-assisted mandibular second molar protraction compared to no-piezocision molar protraction. MATERIALS AND METHODS: Twenty-one subjects (four males, 17 females, aged 22.43 ± 2.83 years) who presented with bilateral extraction of lower first molars were included. The patients were divided into two groups; Group 1: Piezocision-assisted molar protraction (right or left side of subjects) in which piezocision was performed immediately before lower second molar protraction and, Group 2: No-piezocision molar protraction in which lower second molar protraction was not surgically assisted. Plaque index (PI), gingival index (GI), periodontal pocket depth (PPD), width of keratinized gingiva (WKG), gingival recession (GR), lower second molar mesial root resorption, alveolar bone height, and mandibular bone height were recorded at T1 (immediately before molar protraction) and at T2 (after second molar space closure). RESULTS: In the piezocision-assisted molar protraction group, significant changes were detected in the WKG (P < .001), GR (P < .05), and the mandibular bone height (P < .001). Compared to the no-piezocision group, piezocision-assisted molar protraction resulted in an increased WKG (P < .001) and less second molar mesial root resorption (P < .01). CONCLUSIONS: Piezocision does not have any detrimental effect on the periodontium and produces less root resorption.

Surface Roughness of Monolithic and Layered Zirconia Restorations at Different Stages of Finishing and Polishing: An In Vitro Study.

PURPOSE: To evaluate surface roughness and topography of different zirconia-based restorations at various steps of finishing and polishing. MATERIALS AND METHODS: Seventy-five zirconia discs were fabricated and divided into 3 layered and 2 monolithic groups: layered conventional (VM9; Vita), layered pressed (PM9; Vita), layered digital (TriLuxe Forte; Vita), opaque monolithic (Ceramill Zi; Amann Girrbach), and translucent monolithic (Zolid FX; Amann Girrbach). Surface roughness testing (Ra, Rz) and scanning electron microscopy were performed at the glazed, unglazed, finished, polished, super-polished, and super-polished with diamond paste steps. One-way ANOVA and Tukey tests were used for statistical analysis. RESULTS: There were significant differences in all groups among the different steps (p < 0.001, F = 77.67 for layered conventional; p < 0.001, F = 133.90 for layered pressed; p < 0.001, F = 47.94 for layered digital; p < 0.001, F = 48.05 for zirconia opaque; p < 0.001, F = 43.91 for zirconia translucent). For the layered groups, glazed stage was significantly different from all other steps (p < 0.001). For the layered conventional and digital groups, polishing using diamond paste was not significantly different from the polished and super-polished steps (p = 0.448, p = 0.153), while for the layered pressed group, polishing using diamond paste was not significantly different from the super polished step (p = 0.815). For monolithic groups, there were no significant differences between the polished and super-polished steps (p = 0.957 for zirconia opaque, p = 1.00 for zirconia translucent). Both the diamond paste and super-polished steps showed no significant differences (p = 0.620, p = 0.550) from the glazed surface in the opaque zirconia group. CONCLUSIONS: Surface roughness of monolithic and layered zirconia was improved by polishing; however, only opaque zirconia reached the level of surface roughness of the glazed stage. Type of buildup affected the surface roughness of adjusted ceramics, with monolithic zirconia showing lower surface roughness than layered zirconia. Polishing with diamond paste provided no significant improvement in the surface roughness of monolithic or layered zirconia.

An In Vitro Investigation of Veneered Zirconia-Based Restorations Shade Reproducibility.

PURPOSE: To examine the effects of the veneering technique on the shade reproducibility of zirconia-based crowns. MATERIALS AND METHODS: An artificial tooth was prepared with a 1.2 mm heavy chamfer finish line and 8° taper. The prepared tooth was scanned using CAD/CAM technology to fabricate 45 cobalt chromium (CoCr) testing dies. One CoCr die was scanned, and 45 zirconia copings were milled and devided according to the veneering technique into 3 groups of 15 specimens each: layering veneering (LV) using Vita Vm9, overpressing veneering (OV) using Vita Pm9, and digital veneering (DV) using Vita Triluxe forte. All veneering layers had the same shade (A2). The specimens were cemented onto the testing dies using glass inomer cement. A spectrophotometer was used to measure the shade coordinates (L, C, h, a, b) for a Vita A2 shade tab and for each specimen. Both the CIE Lab (ΔEab ) and the CIE DE2000 (ΔE00 ) color difference formulas were applied to compare the shade tab and the study groups. One-way ANOVA and multiple comparison Bonferroni tests were applied for statistical analysis of the results. RESULTS: Means and standard deviations (SDs) of ΔEab were 2.3 ± 1.3 for LV, 3.5 ± 0.8 for OV, and 4.0 ± 0.7 for DV. Means and SDs of ΔE00 were 1.4 ± 0.8 for LV, 2.1 ± 0.5 for OV, and 3.1 ± 0.4 for DV. ΔEab of LV group was significantly lower (p < 0.05) than both OV and DV groups, whereas the difference in ΔEab between OV and DV groups was not significant (p = 0.39). The differences in ΔE00 between all groups were significant (p < 0.05). CONCLUSIONS: LV group was superior to other groups in terms of shade reproducibility. The ΔEab and the ΔE00 values of LV and OV groups were within clinically acceptable ranges; however, the ΔEab and the ΔE00 values of group DV were beyond the clinically acceptable ranges. The ΔE00 formula demonstrated a statistically significant difference between OV and the DV groups, while the ΔEab formula did not. The zirconia veneering technique had a significant influence on the shade reproducibility of zirconia-based crowns.

Veneered Zirconia-Based Restorations Fracture Resistance Analysis.

PURPOSE: To examine the effects of the veneering technique on the fracture resistance of zirconia-based crowns. MATERIALS AND METHODS: An artificial tooth was prepared with a 1.2 mm heavy chamfer finish line and 8° taper. The prepared tooth was scanned using CAD/CAM technology to fabricate 45 cobalt chromium (CoCr) testing dies. One CoCr die was scanned, and 45 zirconia copings were milled and divided according to the veneering technique into three groups of 15 specimens each: layering veneering (LV) using Vita Vm9, overpressing veneering (OV) using Vita Pm9, and digital veneering (DV) using Vita Triluxe forte. The crowns were cemented onto the testing dies using glass ionomer cement. The specimens were thermocycled (3000 cycles, 5° to 55°) then statically loaded (3.7 mm ball, 0.5 mm/min crosshead speed) until failure. Failed crowns were inspected using a magnifier, and failure patterns were identified. One-way ANOVA and multiple comparison Bonferroni tests were applied for statistical analysis of the results. RESULTS: Means and standard deviations of failure loads were 1200 ± 306 N for the LV group, 857 ± 188 N for the OV group, and 638 ± 194 N for the DV group. The differences in failure loads were statistically significant between all groups (p < 0.05). Failure mode was predominantly cohesive for LV and OV groups, whereas it was predominantly adhesive for the DV group. CONCLUSIONS: The LV group was superior to other groups in terms of fracture resistance, while the DV group was inferior to the other groups in the same aspect.

Dentists' Most Common Practices when Selecting an Implant System.

PURPOSE: To report a comprehensive description of dental implant system selection practices among dentists practicing implantology worldwide. MATERIALS AND METHODS: An online questionnaire was designed and sent to members of 15 dental implant organizations. The survey questions addressed: dental implant system selection criteria, implant design variables, dentists' perspective to implant quality stamps, and dentists' satisfaction with their implant system(s). Responses were compiled and analyzed to determine correlation of responses using the chi-squared test (level of significance α ≤ 0.05). RESULTS: Out of 4264 invitations sent, a total of 2001 (response rate = 46.9%) dentists participated in the survey. Approximately half of survey respondents (48.7%) were general dentists. More than two-thirds of the survey respondents (72.5%) were performing both the surgical and prosthetic implant phases. Implant-abutment connections were the most important dental implant system selection criterion (84.7%), followed by scientific evidence available on the implant system (82.8%), and simplicity of prosthetic steps (81.4%). Patient preferences (19.8%) were rated as the least important aspect. Sandblasted large gritted acid etched implant surfaces (SLA) were the most commonly used implant surfaces (75.8%); fluoride coated surfaces were the least commonly used (15.4%). CONCLUSION: According to the results of this survey, most survey respondents practiced both surgical and prosthetic phases of dental implantology. The majority of survey respondents agreed on the importance of implant-abutment connections, scientific evidence available on implant systems, and simplicity of prosthetic steps when selecting implant systems.

Spectrophotometric Analysis of the Influence of Metal Alloy Choice, Opaque Thickness, and Repeated Firing on the Shade of Metal Ceramic Restorations.

PURPOSE: To determine the effect of type of base metal alloy, opaque thickness, and repeated firing on color of metal ceramic restorations. MATERIALS AND METHODS: Four nickel chromium and four cobalt chromium were selected with one noble alloy as a control. Ten discs (16 mm 0.5 mm) were prepared for each group. Color of specimens were measured using a spectrophotometer and were calculated using CIEDE2000 formula (ΔL', ΔC', ΔH', ΔE') between experimental groups and control at six stages of porcelain constructions: opaque 0.1 and 0.3 mm, dentine, enamel, glaze, and three times repeated firing. Shade A3 was used. One-way analysis of variance and Bonferroni multiple test were performed (α = 0.05). RESULTS: Alloy type and stage showed statistical significance on total color and color parameter differences from the control and there was significant interaction between them (p < .05). Nidour alloy was the closest to control. Increase in ΔC' and a decrease in ΔH' and in a* and b* was the commonest in comparison with the control. However, ΔE' was below acceptability threshold for all alloys at all stages. CONCLUSION: Despite the statistical significance, base metal alloys performed as good as noble metal control. Neither opaque thickness, nor repeated firing affected color variations from the control group. There was no obvious trend in the behavior of metal alloys at all stages. However, increase in chroma and a decrease in hue, with green blue shift, was the most common. CLINICAL SIGNIFICANCE: Records of the effects of eight commonly used base metal alloys on the color of final shade of the metal-ceramic restorations, at various stages of ceramic buildup, have considerable value. (J Esthet Restor Dent 28:S56-S67, 2016).

Improved Construction of Auricular Prosthesis by Digital Technologies.

Implant-retained auricular prostheses are a successful prosthetic treatment option for patients who are missing their ear(s) due to trauma, oncology, or birth defects. The prosthetic ear is aesthetically pleasing, composed of natural looking anatomical contours, shape, and texture along with good color that blends with surrounding existing skin. These outcomes can be optimized by the integration of digital technologies in the construction process. This report describes a sequential process of reconstructing a missing left ear by digital technologies. Two implants were planned for placement in the left mastoid region utilizing specialist biomedical software (Materialise, Belgium). The implant positions were determined underneath the thickest portion (of anti-helix area) left ear that is virtually simulated by means of mirror imaging of the right ear. A surgical stent recording the implant positions was constructed and used in implant fixtures placement. Implants were left for eight weeks, after which they were loaded with abutments and an irreversible silicone impression was taken to record their positions. The right existing ear was virtually segmented using the patient CT scan and then mirror imaged to produce a left ear, which was then printed using 3D printer (Z Corp, USA). The left ear was then duplicated in wax which was fitted over the defect side. Then, it was conventionally flasked. Skin color was digitalized using spectromatch skin color system (London, UK). The resultant silicone color was mixed as prescribed and then packed into the mold. The silicone was cured conventionally. Ear was trimmed and fitted and there was no need for any extrinsic coloring. The prosthetic ear was an exact match to the existing right ear in shape, skin color, and orientation due to the great advantages of technologies employed. Additionally, these technologies saved time and provided a base for reproducible results regardless of operator.

Fracture resistance of fixed partial dentures supported by different abutment combinations: an ex vivo study.

This study sought to compare the fracture resistance of and categorize failure modes exhibited by fixed partial dentures (FPDs) supported by natural teeth, implants, or mixed tooth-implant abutments. Three groups utilized three different abutment combinations: all natural teeth, all implants, and a mixture of teeth and implants. The teeth were prepared and zero-angled titanium abutments were installed over the implants. Standardized conventional three-unit porcelain-fused-to-metal FPDs were fabricated, following the conventional ceramic build-up technique. The inner surfaces of the bridges were air-abraded (50 µm Aluminum Oxide at 80 psi), cleaned in an ultrasonic bath for 10 minutes, and cemented over abutments using glass ionomer cement. The FPDs were fixed in a universal testing machine and compressed to fracture using a three-unit metal block at a 5 mm/minute crosshead speed. Fracture loads ranged from 460 to 5,700 N. Bridges supported by either implant abutments only or mixed implant-tooth abutments showed higher fracture loads (2,940 and 3,390 N, respectively) than those supported entirely by natural teeth (1,386 N) (p < 0.05). However, fracture of the veneering porcelain was common among all types of abutments.

Efficacy and persistence of tooth bleaching using a diode laser with three different treatment regimens.

STATEMENT OF PROBLEM: Studies have measured the effectiveness of tooth bleaching, however there are very few studies that have measured the persistence in color change after a 6-month follow-up. PURPOSE: This study assessed the efficacy of the laser bleaching process using different regimens, and the persistence of color change over a 6-month period. METHOD AND MATERIALS: Sixty patients divided into three equal groups were subjected to bleaching using a diode laser with 34% hydrogen peroxide. Group 1: patients subjected to one session of laser bleaching. Group 2: patients subjected to two sessions of laser bleaching with a 1-week interval. Group 3: the same as Group 2 but followed by home bleaching once a month for 3 months. The color was assessed four times: before bleaching, directly after bleaching, 3 months after bleaching, and 6 months after bleaching. RESULTS: All teeth had a significant color change at 6 months, but all teeth had regressed from the maximum value. There was significantly less regression in color for Group 3, followed by Groups 2 and 1, respectively. CONCLUSION: The combined technique of in-office laser bleaching for two sessions with a 1-week interval, followed by home bleaching once a month for 3 months gave more persistence in color change. CLINICAL SIGNIFICANCE: In-office power bleaching using a laser assisted hydrogen peroxide system repeated after a week, combined with home bleaching once a month for 3 months, is an effective bleaching regimen with less color regression after 6 months compared to a regimen of in-office bleaching alone.

Parallelism of abutment teeth on fixed partial dentures.

A total of 100 working dies for fixed partial denture (FPD) abutments were prepared to fit 50 three-unit fixed-fixed conventional FPDs. For each FPD, the axial convergence angles between the mesial and distal axial walls of the abutment teeth were measured. For all FPDs, there were no statistically significant differences between the mesial and distal convergence angles of abutment teeth measured, regardless of their location within the oral cavity. The distal convergence angle of posterior FPD abutments was the highest angle, while the lowest was recorded for the mesial convergence angle of the anterior FPD abutments.

A comparison between conventional visual and spectrophotometric methods for shade selection.

OBJECTIVE: Inconsistencies among dentists in matching natural tooth shades have been documented. This study examined the reliability of a spectrophotometer in shade selection compared to visual method. METHOD AND MATERIALS: Nine observers with normal color vision were asked to visually and digitally match shades of nine maxillary models with incisors being replaced by Vita Classical shade guide tabs. The same test was carried out in vivo on nine subjects' maxillary central incisors. Observers included prosthodontists, dental technicians, and postgraduate students. RESULTS: No significant difference was found among observers in shade selection regardless of the selection method. However, there was a significant difference between digital and visual methods in shade selection. Digital method was five times more likely to match the original shade color compared to visual method. CONCLUSION: The system does not solve all problems involved in the determination of a tooth shade. Vita Easyshade spectrophotometer was more likely to match the shade compared to visual method. Nevertheless, this system needs further refinement, as well as software upgrades. Shade-matching devices could help clinicians and technicians achieve a better shade choice. The combination of visual shade analysis and digital shade measurement together lies in the precise predictability of the miscibility of shades.

Fracture resistance of aluminium oxide and lithium disilicate-based crowns using different luting cements: an in vitro study.

AIM: The aim of this study was to investigate the fracture resistance of two types of ceramic crowns cemented with two different cements. METHODS AND MATERIALS: Forty premolar crowns were fabricated using lithium-disilicate (IPS Empress-2) and glass-infiltrated aluminium-oxide (In-Ceram) ceramic systems. The crowns were divided into four groups (n=10) with Group 1 (IPS Empress-2) and Group 2 (In-Ceram) cemented with glass ionomer cement. Group 3 (IPS Empress-2) and Group 4 (In-Ceram) were cemented with resin cement. Crowns were tested in a universal testing machine at a compressive-load speed of 10 mm/min. Fracture modes were grouped into five categories. One way analysis of variance (ANOVA) and Bonferroni post-hoc tests were used to detect statistical significances (p<0.05). RESULTS: The mean (SD) fracture resistance (Newtons) for Groups 1 to 4 were: 245.35 (82.69), 390.48 (67.03), 269.69 (10.33), and 418.36 (26.24). The cement type had no statistical significant effect (p>0.05) on fracture resistance within each ceramic system tested. In-Ceram crowns cemented with either glass ionomer or resin cements exhibited a statistically significantly higher fracture-resistance than IPS Empress-2 crowns (p<0.05). Minimal fracture in the test crowns was the common mode exhibited. CONCLUSION: Fracture resistance of IPS Empress-2 and In-Ceram crowns was not affected by the type of cement used for luting. CLINICAL SIGNIFICANCE: Both In-Ceram and IPS Empress-2 crowns can be successfully luted with the cements tested with In-Ceram exhibiting higher fracture resistance than IPS Empress-2.

Fracture resistance of teeth restored with different post systems: in vitro study.

OBJECTIVES: The objective of this study was to investigate fracture resistance and mode of failure of teeth restored with different prefabricated post systems. STUDY DESIGN: Thirty teeth were collected, sectioned 15 mm from the apex, root canal prepared, and randomly allocated into 3 groups as follows: glass fiber posts (group 1), carbon fiber posts (group 2), and Radix-Anchor titanium posts (group 3). Teeth were then restored with a composite core and tested using a universal testing machine at 10 mm/min cross-head speed. Mode of failure was identified as either reparable or irreparable (catastrophic). RESULTS: Mean values of fracture forces (N) for teeth restored with Radix posts (571.6) were statistically significantly higher than teeth restored with either carbon fiber (420.6) or glass fiber posts (393.9). There were 86.67% of fractures that were catastrophic in nature. CONCLUSIONS: Teeth restored with Radix-titanium posts were more resistant to fracture than those restored with either carbon or glass fiber posts. Most of the fracture modes were catastrophic in nature.

Clinical performance of IPS-Empress 2 ceramic crowns inserted by general dental practitioners.

AIM: The aim of this study was to evaluate the clinical performance of IPS-Empress 2(R) all-ceramic crowns placed by general dental practitioners. METHODS AND MATERIALS: Eighty-two IPS-Empress 2 crowns placed in 64 patients (27 females and 37 males) were evaluated. These crowns had been in place for 15.2 to 57.2 months (mean 25.3 months, SD=9.3). Survival analysis was conducted using the Kaplan-Meier method. RESULTS: Of the 82 crowns 93.9% were rated satisfactory. In terms of the integrity of the restorations, fracture was observed in three crowns and two showed a crack upon transillumination. Five crowns were rated unsatisfactory for color match; one for marginal adaptation; and none for discoloration, secondary caries, or sensitivity. CONCLUSIONS: IPS-Empress 2(R) is a suitable material to fabricate all-ceramic crowns; when these all-ceramic crowns were inserted by general dental practitioners, they functioned satisfactorily with low failure rates during an observation period ranging between 15.2 to 57.2 months.

Shear bond strength of orthodontic brackets bonded to different ceramic surfaces.

This study was undertaken to measure the shear bond strength (SBS) of stainless steel brackets bonded to different ceramic surfaces, to compare the SBS of the different ceramics with each other and with conventional ceramo-metal porcelains, and to determine the mode of failure for each group following debonding. A total of 60 ceramic crowns were constructed on extracted teeth and divided into three equal groups as follows: In-Ceram ceramic crowns, IPS-Impress ceramic crowns, and conventional ceramo-metal porcelain. Standard edgewise metal premolar brackets were bonded to the prepared porcelain surfaces. After bonding, all samples were tested in shear mode on an Instron universal testing machine. Statistical analysis was undertaken using analysis of variance, LSD, and chi-squared tests. The results showed that the SBS for the ceramo-metal and the In-Ceram groups were comparable, with mean values of 80.54 +/- 13.44 N and 78.87 +/- 13.47 N, respectively. The IPS-Impress group showed the weakest SBS which averaged 67.40 +/- 8.99 N. This was significantly lower than that of the conventional ceramo-metal porcelain (P < 0.001) and the In-Ceram surface (P < 0.01). The mode of failure in the ceramo-metal group was between the porcelain surface and adhesive and in the other two ceramic groups, between the brackets and adhesive (P < 0.001). The SBS of orthodontic brackets to the three tested ceramic surfaces were adequate for orthodontic use.

Foreign body ingestion and aspiration in dentistry: a review of the literature and reports of three cases.

This article reviews several cases of foreign body ingestion or inhalation reported in the literature. Prevention, complication and management of this event are discussed and three case reports presented. Two of the cases were bridge ingestion and one was ingestion of an orthodontic band. The three cases were managed by watchful waiting and the ingested foreign bodies came out in the stools without complications.

Radiographic assessment of post-retained crowns in an adult Jordanian population.

AIM: The objective of this study was to radiographically assess and compare the quality of post-retained crowns fabricated at the Dental Health Centre of the Jordan University of Science & Technology (JUST). METHODS AND MATERIALS: Study data were collected in 2002 from existing dental records for all patients receiving treatment with post-retained crowns between October, 1997 and June, 1999. The posts were assessed radiographically to evaluate various aspects of the quality of post-retained crowns. All 129 posts were fabricated in the dental school. RESULTS: The most-frequently restored teeth were the maxillary incisors (38.8%). Sixty-two percent of the posts were tapered, while 38% were parallel-sided. The mean length of the posts was 0.95 mm (SD 0.41) with a range between 0.22-2.85 mm. Caries was diagnosed radiographically in 10.8% of cases with lesions located on root surfaces in 64.3% of them, while 35.7% of lesions were within the root canal. Three posts (2.3%) were deviated from the line of the root canal in the mesio-distal plane. No evidence of root filling was found in 2.3% of the cases. In the remainder of teeth 15.5% had gutta percha extended to the radiographic apex of the tooth, while 59.7% fell 0.5-1 mm short of the radiographic apex. Gutta-percha was extruded beyond the apex in 22.5% of the teeth. Space between the end of the post and the root filling was found in 22.2%. The percentage of canals with apparently completely healthy periapical tissue was 51.2%. In the rest of the cases 34.8% had areas of radiolucency at or near the root apices and 14% demonstrated widening of the periodontal space around the root apex. Root resection had been completed in 2.3% cases. Signs of external resorption were apparent in one case (0.78%). CONCLUSION: The standards of the treatment of the endodontically treated teeth made at the dental hospital were satisfactory but could be improved by a controlled academic supervisory environment and a strict scientific approach to fixed prosthodontics within the dental school.