Significance of primary factors influencing students' performance at the College of Dentistry, King Saud University, Saudi Arabia.

OBJECTIVE: To determine the effect of different enabling factors such as curriculum, role of faculty, academic advising and availability of learning resources and supportive services on the performance of students pursuing their Bachelor's degree in dentistry. METHODS: Data was collected from the male and female students of the College of Dentistry, King Saud University, during the academic year 2008-2009. All undergraduate students (576) constituted the total sample size of the study. The respondents were requested to fill a questionnaire form, which was specially designed in accordance with requirements of the Association for Dental Education in Europe (ADEE). The questionnaire comprised 45 questions addressing all aspects of the relevant factors. The five-point Likert scale was used to evaluate the feedback. All the responses (239) were thoroughly examined and only the completely filled forms (169) were subjected to regression analyses, taking student's CGPA as a dependent factor and a depiction of their performance. The t-tests were also worked out to evaluate variations in the responses of male and female students to each sub-factor. RESULTS: The study showed a significant impact of faculty and learning resources and support services on a student's achievement (alpha = 0.05). Surprisingly, academic advising and the dental curriculum had non-significant effect at 95% level of confidence. However, the critical analyses acknowledged that the non-significant impact was due to poor performance of the two factors. CONCLUSION: The role of faculty and learning resources as well as of support services had significant effect on students' performance. However, there is an immense need to improve the level of academic advising and revise the curriculum to have a significant impact of these factors on the student's achievements.

Color management of the cervical region using different framework materials.

BACKGROUND: Color-matching of the cervical area between natural teeth and different crown prostheses is a common clinical problem. PURPOSE: The purpose of this study was to compare the color of the cervical region of five commercially available crown systems to an extracted natural tooth and to each other. MATERIALS AND METHODS: The color of the cervical region of an extracted maxillary incisor was measured by means of a colorimeter (ShadeVision, X-Rite). Fifty master dies were fabricated, divided into five groups (N=10) according to the framework material; group 1: high-noble gold alloy, group 2: same as group 1 but treated with gold paste material, group 3: precious reinforced alloy, group 4: white zirconium oxide substructure (Lava 3M ESPE), and group 5: shaded zirconium oxide (Lava). A direct comparison of L*, a*, and b* parameters was accomplished between the control natural tooth and the five crown systems, and the mean color differences (ΔE) was calculated. The data were statistically analyzed with one-way analysis of variance and post hoc multiple comparison (α=0.05). RESULTS: Compared to the natural tooth, the mean color differences (ΔE) values were clinically unacceptable for all groups (ΔE > 3.7). The detected color differences, among different porcelain systems, were not visually perceptible (ΔE < 3.7). CONCLUSIONS: Within the limitations of this study, the cervical color of an extracted natural tooth could not be duplicated using different crowns systems. CLINICAL SIGNIFICANCE: Color-matching of the cervical region of different crown systems with natural tooth remains a difficult task.

Effect of different onlay systems on fracture resistance and failure pattern of endodontically treated mandibular molars restored with and without glass fiber posts.

PURPOSE: To investigate the relationship between post and core build-up materials on the fracture resistance of endodontically treated teeth restored with different onlay restorations. METHODS: 60 mandibular molars were endodontically treated and divided into three experimental groups that received one of the following onlay restorations: gold onlays, glass ceramic onlays (Empress I), or resin composite onlays (Gradia). Half of the specimens in each group received a fiber post (n=10). Two controls groups (n=10) were included: one group composed of sound mandibular molars, and the second group was composed of endodontically treated unrestored molars. Fracture tests were carried out by applying axial load using a universal loading machine until fracture. All fractured specimens were fractographically examined using a scanning electron microscope (SEM). Data were analyzed using two-way ANOVA and Tukey multiple comparison tests (alpha=0.05). RESULTS: Statistical analysis showed that restoration of endodontically treated teeth with gold onlays improved fracture resistance when compared to glass ceramic or resin composite onlays. The presence of a fiber post significantly improved (P<0.045) fracture resistance of gold onlays from 2271 to 2874N while it did not influence the performance of the other two groups. Fractographic analyses revealed that the presence of fiber post resulted in more restorable fractures due to better stress distribution of the applied load. All onlay systems resulted in significant improvement of the fracture resistance compared to unrestored teeth (711N) but neither of them resulted in restoring the fracture resistance to match that of sound teeth (3212 N).

Fracture resistance and failure patterns of endodontically treated mandibular molars with and without glass fiber post in combination with a zirconia-ceramic crown.

OBJECTIVE: The aim of this study was to investigate the influence of a fiber post on the fracture mechanics of zirconia crowns inserted over endodontically treated teeth with different extent of coronal damage. METHODS: Endodontically treated human molars with three types of coronal damage received fiber posts before cementation of zirconia-veneered crowns. Controls received composite resin cores without fiber posts. The specimens were loaded to failure and fractographically examined using a scanning electron microscope (SEM). RESULTS: Statistical analysis revealed that specimens with fiber posts demonstrated significantly higher failure loads and favorable fracture pattern compared to the controls. At fractographic analysis, specimens with fiber posts demonstrated delamination of the veneer ceramic from intact zirconia under structure. Meanwhile, the specimens that were restored without a fiber post demonstrated micro-cracking of the composite core build-up resulting in loss of the support under the zirconia crowns which was responsible for the initiation of radial crack and catastrophic damage. CONCLUSIONS: Within the limitation of this study, the insertion of fiber post improved the support under zirconia crowns which resulted in higher fracture loads and favorable failure type compared to composite core build-up.

Arthroscopy versus arthrocentesis. A retrospective study of disc displacement management without reduction.

OBJECTIVE: To compare the outcome of arthroscopic surgery and arthrocentesis of internal derangement (disc displacement without reduction) of the temporomandibular joint (TMJ). METHODS: The charts of 48 patients with TMJ derangement and treated with arthroscopy or arthrocentesis were included in this study carried out in a specialized private clinic in Beirut, Lebanon, between January 2001 and July 2005. Inclusion criteria included patients with a history of clicking followed by a sudden onset of limited mouth opening without clicking, a complaint of TMJ pain with mouth opening or chewing difficulty, or both, or a positive magnetic resonance imaging diagnosis of TMJ disc displacement without reduction. Patients with limited mouth opening caused by only muscle spasm, prior TMJ surgery, bilateral joint involvement, or serious systemic diseases were excluded from the study. Twenty-eight patients underwent arthroscopy (group one) and 20 patients were treated with arthrocentesis (group 2). RESULTS: Both methods showed a significant reduction in pain and an increase in maximal mouth opening on follow up (p<0.01). There was no statistical difference between the methods. CONCLUSION: Further research should be conducted before one can definitely determine if real benefits are achieved through surgery in TMJ articular disorders. Within the limits of this study, less invasive procedures are highly recommended.

Removable partial denture design: a study of a selected population in Saudi Arabia.

Determination of the incidence of various classes of removable partial dentures (RPDs) including their designs and their comparison with previous studies provide clinically useful information for dental training and continuing education. The purpose of this study is to determine the pattern of partial edentulism, the major connector, clasping, and design of 740 cobalt chromium RPD frameworks constructed for a selected population in Saudi Arabia. RPD framework design information and patient personal data were obtained from the work authorization form and the dental records respectively. The relationship among age, sex, nationality, and various Kennedy classes of the RPDs was determined by chi-square statistical analysis. Results indicate that Kennedy Class III removable partial dentures were the most frequently constructed. Although gender had no significant relationship, age and nationality had statistically significant relationship with the distribution of various Kennedy classes of removable partial dentures. Lingual bars and anterior posterior palatal straps were the most commonly used mandibular and maxillary major connectors. Lingual and palatal plates, however, were more frequently used than any major connectors for distal extension RPDs. Comparison with previous findings confirms the established variation in designing RPDs. The distribution of partially edentulousness revealed the influence of the general pattern of tooth loss, which could be modified by patient's demands and socio-economic status. Practitioners need to avail themselves fully of basic RPD design principles concerning the most commonly encountered classes of RPDs.

Surgical treatment of melanin-pigmented gingiva; an esthetic approach.

The aim of this clinical article is to review the methods of depigmentation of melanin pigmentation of gingiva and explain scalpel surgical technique for depigmentation of gingiva.

Allocation of color space for different age groups using three-dimensional shade guide systems.

PURPOSE: To determine the color space and the coverage error of two manual shade guide systems in four age groups of a selected population. MATERIAL AND METHODS: A total of 174 patients were divided into four age groups and the shade of their natural teeth was measured (2067 teeth) with a spectrophotometer (Vita Easyshade). Color parameters in terms of L*, a*, b* values, chroma, and hue were recorded for each tooth. Color difference (ΔE*min) between each natural tooth and the closest match using two manual shade guide systems were calculated (3D Master shade guide standard and 3D Master shade guide with intermediate values). A Wilcoxon test was used to assess statistical differences between mean ΔE*min values for each system (α = 0.05). RESULTS: The recoded ΔE of the two tested manual systems was 6.19 for 3D Master shade guide (standard) and 6.02 for 3D Master shade guide (intermediate values). A statistically significant difference (P < 0.001) was found between the mean ΔE*min of the two systems. 47% of natural teeth presented a best match with intermediate value and chroma shade tabs. The mean ΔE*min was influenced by the age group of the patients (5.15, 5.23, 6.58, and 6.69, respectively). CONCLUSION: Using intermediate value and chroma did not improve shade match, nor the coverage error of the tested population. Nevertheless, better coverage error was observed in younger age groups compared to older anterior teeth.

Effect of different ferrule designs on the fracture resistance and failure pattern of endodontically treated teeth restored with fiber posts and all-ceramic crowns.

OBJECTIVE: This study investigated the effect of different ferrule heights on endodontically treated premolars. MATERIAL AND METHODS: Fifty sound mandibular first premolars were endodontically treated and then restored with 7-mm fiber post (FRC Postec Plus #1 Ivoclar-Vivadent) luted with self-polymerized resin cement (Multilink, Ivoclar Vivadent) while the coronal section was restored with hybrid composite core build-up material (Tetric Ceram, Ivoclar-Vivadent), which received all-ceramic crown. Different ferrule heights were investigated: 1-mm circumferential ferrule without post and core (group 1 used as control), a circumferential 1-mm ferrule (group 2), non-uniform ferrule 2-mm buccally and 1-mm lingually (group 3), non-uniform ferrule 3-mm buccally and 2-mm lingually (group 4), and finally no ferrule preparation (group 5). The fracture load and failure pattern of the tested groups were investigated by applying axial load to the ceramic crowns (n=10). Data were analyzed statistically by one-way ANOVA and Tukey's post-hoc test was used for pair-wise comparisons (α=0.05). RESULTS: There were no significant differences among the failure load of all tested groups (P<0.780). The control group had the lowest fracture resistance (891.43 ± 202.22 N) and the highest catastrophic failure rate (P<0.05). Compared to the control group, the use of fiber post reduced the percentage of catastrophic failure while increasing the ferrule height did not influence the fracture resistance of the restored specimens. CONCLUSIONS: Within the limitations of this study, increasing the ferrule length did not influence the fracture resistance of endodontically treated teeth restored with glass ceramic crowns. Insertion of a fiber post could reduce the percentage of catastrophic failure of these restorations under function.

A comparative in vitro study on the retention and stability of implant-supported overdentures.

OBJECTIVES: Implant-supported overdentures have become the treatment of choice in restoring complete edentulism, but the number of implants required and type of connectors to assure retention and stability are still controversial. The aim of this study was to evaluate the effect of connector type and implant number and location on the retention and stability of implant-supported overdentures by measuring retentive forces during vertical and 2 types of rotational dislodgment. METHOD AND MATERIALS: Two model designs were selected based on the number and location of the inserted implants: In a first setup, 2 implants were placed in the canine regions; in a second setup, 2 implants were placed in the canine regions and 2 in the premolar regions. Three types of connector were used in each model: magnets, balls, and locators; 10 resin bases were fabricated and 3 hooks fixed at tripodal locations for chain testing. Vertical dislodging forces and 2 aspects (oblique and posterior rotational dislodging forces) of stability were tested. RESULTS: Two-way analysis of variance showed significant differences in retention among the 3 connectors in the 2 models, with the lowest values obtained with the magnet group (mean [SD]: 2.15 N [0.09]) and highest values with the locator group (31.30 N [0.12]). Posterior rotational dislodging forces showed higher values than vertical or lateral forces in both models; 4-implant models required higher dislodging forces than did 2-implant models. CONCLUSION: Locator connectors provide significantly higher retention and stability of implant-supported overdentures, followed by ball connectors and then magnets. The 2-implant design offers less retention and stability than the 4-implant model. Number of implants and type of connector significantly affected retention and stability of implant-supported overdentures.

The effect of location and number of endosseous implants on retention and stability of magnetically retained mandibular overdentures: an in vitro study.

The aim of this study was to compare the effect of location and number of implants on the retention and stability of magnetically retained mandibular overdentures. Four groups of such prostheses were classified according to number and position of the implants in the canine, premolar, or molar regions. Significant differences in retention were observed when 6 magnets were used (4.66 +/- 0.45 N), whereas the lowest retention was obtained with 2 magnets (2.1 +/- 0.43 N). Only oblique stability was improved significantly when the number of implants was increased.

The effect of different full-coverage crown systems on fracture resistance and failure pattern of endodontically treated maxillary incisors restored with and without glass fiber posts.

The aim of this study was to compare the fracture resistance and failure pattern of endodontically treated maxillary incisors restored using composite resin with or without fiber-reinforced composite (FRC) posts under different types of full-coverage crowns. The null hypothesis tested was that fracture resistance and the failure pattern of these teeth were not affected by the use of FRC posts or by the type of full-coverage crown. One hundred twenty maxillary incisors were endodontically treated and divided into 4 groups of 30 each. Each group was divided into two subgroups: restoration with or without fiber post. PFM crowns were placed in group 1, Empress II crowns in group 2, SR Adoro crowns in group 3, and Cercon crowns in group 4. Fracture tests were performed by loading specimens to fracture. Data were analyzed with two-way analysis of variance (alpha = 0.05). The type of crown was not a significant factor affecting fracture resistance (p = 0.4), whereas the presence of a post was (p = 0.001). Both the presence of post and the type of crown had a significant influence on the proportion of restorable versus unrestorable fractures. Although prosthodontics textbooks do not generally advocate the placement of fiber posts in endodontically treated incisors, the results of this study indicate that the use of fiber posts in such teeth increases their resistance to fracture and improves the prognosis in case of fracture.

Effects of surface conditioning on the retentiveness of titanium crowns over short implant abutments.

PURPOSE: The integrity and retention of cemented restorations over implant abutments is difficult to achieve when the axial wall height of the abutment is short. PURPOSE: : To compare the effect of different surface conditions on the retentiveness of titanium crowns cemented over short (3 mm) ITI solid abutments using 2 types of cement. Surface pretreatment included sandblasting, silicoating, and application of alloy primer. METHODS AND MATERIALS: Forty-eight ITI implants and solid abutments 5.5 mm in height were divided into six groups. The axial height of abutments in group I was unaltered to serve as a control. The remaining abutments in (groups II-VI) were reduced to a 3-mm height. Groups I and II were luted with ZnPO4 cement without any surface pretreatment. In groups III and IV, the fit surface of the castings and solid abutments were sandblasted, before luting, with ZnPO4 or Panavia 21, respectively. In group V castings and abutments were sandblasted, pretreated with Siloc Bond, and luted with Panavia 21. In group VI castings and abutments were sandblasted, pretreated with alloy primer, and luted with Panavia 21. Crown retention was measured using a universal testing machine after 1 week of storage in water at 37 degrees C. RESULTS: Analysis of variance revealed a highly significant difference among the groups. Sandblasted castings and abutments pretreated with alloy primer or Siloc Bond before luting with Paravia 21 resin cement exhibited the greatest retentive strength (P < 0.05). Castings luted with zinc phosphate over short ITI solid abutment exhibited the lowest retention (P < 0.05). CONCLUSION: The retention of titanium castings luted over ITI solid abutments was influenced by axial height, surface texture, surface pretreatment, and type of cement. Phosphoric alloy primer is more effective and less technique sensitive than the Siloc Bond with regard to retention enhancement of titanium castings over short ITI solid abutment.

Effect of different ferrule designs on the fracture resistance and failure pattern of endodontically treated teeth restored with fiber posts and all-ceramic crowns

OBJECTIVE: This study investigated the effect of different ferrule heights on endodontically treated premolars. MATERIAL AND METHODS: Fifty sound mandibular first premolars were endodontically treated and then restored with 7-mm fiber post (FRC Postec Plus #1 Ivoclar-Vivadent) luted with self-polymerized resin cement (Multilink, Ivoclar Vivadent) while the coronal section was restored with hybrid composite core build-up material (Tetric Ceram, Ivoclar-Vivadent), which received all-ceramic crown. Different ferrule heights were investigated: 1-mm circumferential ferrule without post and core (group 1 used as control), a circumferential 1-mm ferrule (group 2), non-uniform ferrule 2-mm buccally and 1-mm lingually (group 3), non-uniform ferrule 3-mm buccally and 2-mm lingually (group 4), and finally no ferrule preparation (group 5). The fracture load and failure pattern of the tested groups were investigated by applying axial load to the ceramic crowns (n=10). Data were analyzed statistically by one-way ANOVA and Tukey's post-hoc test was used for pair-wise comparisons (α=0.05). RESULTS: There were no significant differences among the failure load of all tested groups (P<0.780). The control group had the lowest fracture resistance (891.43±202.22 N) and the highest catastrophic failure rate (P<0.05). Compared to the control group, the use of fiber post reduced the percentage of catastrophic failure while increasing the ferrule height did not influence the fracture resistance of the restored specimens. CONCLUSIONS: Within the limitations of this study, increasing the ferrule length did not influence the fracture resistance of endodontically treated teeth restored with glass ceramic crowns. Insertion of a fiber post could reduce the percentage of catastrophic failure of these restorations under function.

Special technique for attachment incorporation with an implant overdenture.

The Hader bar system is a popular bar and clip concept because of its 20-degree clip rotation, simplicity, and versatility. Two procedures may be used to incorporate the Hader nylon clip into a denture base. The direct technique consists of attaching the clip to the denture base as a clinical procedure. With the indirect technique, the clip is attached during laboratory processing. An alternative method of attaching the clip with a metal superstructure is presented. This procedure combines the advantages of the direct and indirect techniques for incorporation of the nylon clip of the Hader bar into the denture base.

Risk factors and management of dehiscent wounds in implant dentistry.

Successful implant dentistry is based on adequate training, proper selection of patients, careful surgery, preplanned restorations, and postoperative and supportive care. Although implant therapy is highly successful and predictable, it is not without possible early and/or late complications. The aim of this article is to highlight the importance of a relatively neglected subject of dehiscent wounds in the dental implant literature. This article covers the definitions of wound healing and wound dehiscence and some of the common risk factors related to suture line opening as an immediate postoperative complication. These factors appear to be largely iatrogenic in nature and partly related to patient neglect. Hence, it deserves documentation to confirm a strategy for their avoidance and management. A management protocol is presented on how to deal with different types of dehiscence and causal factors.