The aim of this study was to determine the static load-bearing capacity of composite resin onlay restorations made of particulate filler composite (PFC) with two different types of fiber-reinforced composite (FRC) substructures. In addition, flexural properties of the material combination and the effect of polymerization devices were tested.

Specimens were prepared to simulate an onlay restoration, which consisted of 2 to 3 mm of FRC layer as a substructure (short random and continuous bidirectional fiber orientation) and a 1 mm surface layer of PFC. Control specimens were prepared from plain PFC. In Group A the specimens were incrementally polymerized only with a hand-light curing unit for 40 s, while in Group B the specimens were post-cured in a light-curing oven for 15 min before they were statically loaded with a steel ball.

Bar-shaped test specimens were prepared to measure the flexural properties of material combination using a three-point bending test (ISO 10477).

Analysis of variance (ANOVA) revealed all specimens with a FRC substructure have higher values of static load-bearing capacity and flexural properties than those obtained with plain PFC (p<0.001).

The load-bearing capacity of all the specimens decreased after post-curing and water storage.

Restorations made from a material combination of FRC and PFC showed better mechanical properties than those obtained with plain PFC.

Garoushi SK, Lassila LVJ, Tezvergil A, Vallittu PK. Fiber-reinforced Composite Substructure: Loadbearing Capacity of an Onlay Restoration and Flexural Properties of the Material. J Contemp Dent Pract 2006 September;(7)4:001-008.

Despite the improvements to compomer materials, the bond strength of these materials remains inferior to .composite/resin bonding. systems and limits their clinical use. The purpose of this study was to evaluate the effect of acidic conditioning with phosphoric acid and Prompt L-Pop (PLP) on the shear bond strength of two compomers Dyract AP (DAP) and Composan Glass (CG) to dentin.

Sixty extracted bovine teeth were used to test the shear bond strength of two compomers to flat dentin labial surfaces. The dentin specimens were randomly assigned to six groups of ten specimens each: Group 1: DAP and Prime & Bond NT (PBNT); Group 2: DAP/PBNT with a 15 second dentin etch prior to bonding; Group 3: DAP placed with PLP adhesive; Group 4: CG and Compobond NE (CBNE); Group 5: CG/CBNE with a 15 second dentin etch; and Group 6: CG placed with PLP adhesive. The specimens were stored at 37°C with 100% humidity for 24 hours then mounted and sheared using an Instron Universal Testing Machine at a cross head speed of 0.5 mm/min. The results were recorded in Mega Pascals (MPa). The sheared specimens were examined under a light microscope, and the type of failure (adhesive, cohesive, or mixed) was recorded.

The mean dentin shear bond strength value (MPa) for the groups was: Group 1 (11.6±3.9); Group 2 (13.2±3.3); Group 3 (12.4±2.0); Group 4 (13.0±4.3); Group 5 (19.3±3.7); and Group 6 (13.1±3.0). One way analysis of variance (ANOVA) and Tukey HSD post-hoc tests detected a significantly higher bond strength (P ≤ 0.003) for group 5. For groups 1, 3, 4, and 6, the mode of failure was mostly adhesive. When acid etching of dentin was performed (groups 2 and 5), cohesive fracture within dentin was the predominant mode of failure. Acid etching and the use of PLP significantly reduced the number of adhesive fractures and reduced variability in the shear bond strength results.

Acid etching significantly increased the shear bond strength of CG to dentin but did not affect DAP. The application of PLP resulted in a shear bond strength not statistically different from PBNT or CPNE. CG bond to dentin is improved with acid etching using phosphoric acid. However, PLP provided no significant improvement in the shear bond strength of DAP and CG.

Al-Nahedh H, Ateyah N. Effect of Different Bonding Conditions on the Shear Bond Strength of Two Compomers to Bovine Dentin. J Contemp Dent Pract 2006 September;(7)4:009-016.

Gypsum products are used for the preparation of stone casts of oral and maxillofacial structures and as important adjuncts to dental laboratory operations involved in the production of dental prostheses. The aim of this study was to determine the effect on the dimensional accuracy of a working cast of adding a stone base using different stone products.

A total of forty impressions of a mandibular dentoform were made. The impressions were dried with compressed air and stored at room temperature for 24 hours before pouring stone casts. The forty impressions were randomly divided into four groups of ten each. All forty impressions were poured once using one pre-weighed 140 Gm package of Silky Rock (SR) Type IV improved stone (Whip Mix Corporation, Louisville, KY, USA) per impression. All working casts and the die setups were prepared according to the manufacturer's recommendations for pin placement (M.R. Dual pin and sleeve). Four different types of dental stone (II, III, and IV) and Flow Stone (FS) were used as bases for the working models. They were mixed according to the manufacturer's recommendations.

The lower posterior teeth were flattened on the dentoform prior to taking the impressions. All were indexed using a mounted abrasive disc. Four teeth were selected as follows: 21, 28, 30, and 18. These represented A, B, C, and D landmarks, respectively. All measurements (five times for each specimen) were made with a Universal measuring microscope (Unitron Instruments, Inc., Bohemia, NY, USA). After the pre-sectioned measurements were recorded, the stone base was poured. A manual hand saw was used to section and fabricate removable dies for the mandibular landmarks A, B, C, and D. The dies were later seated and removed ten times to simulate the average amount of handling during laboratory procedures. Each die was carefully seated and measurements were made using the same technique as for the master model and unsectioned casts. Multivariate repeated measures analysis of variance (MANOVA) was used to test the difference in three different landmark distances (AB, AC, and AD) among the master model before and after sectioning of the working dies and among the four different base materials. Univariate analysis of variance (ANOVA) was conducted for each measurement, AB, AC, and AD to test the difference in landmark distances on the master model at pre sectioning and then at post sectioning using four different base materials. When there was a significant main effect (p < .05), the Student-Newman-Keul's (SNK) were used to test for pair wise comparison of means (P<0.05).

The results of the MANOVA indicated there was a significant difference in three landmark measurements on the master model before and after sectioning of the working dies for the four different base materials (F=6.60, p=0.0001). In addition there was a significant difference in three landmark measurements on the master model at: (1) pre sectioning (p=0.0001), (2) between the master model and SR material (p=0.0002), (3) between the master model and Laboratory Plaster (LP) material (p=0.0001), (4) between the master model and Quick Stone (QS) material (p=0.0001), and (5) between the master model and FS material (p=0.0001).

Al-Abidi K, Ellakwa A. The Effect of Adding a Stone Base on the Accuracy of Working Casts Using Different Types of Dental Stone. J Contemp Dent Pract 2006 September;(7)4:017-028.

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).

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.

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%).

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.

Al-Hamad KQ, Al-Omari M, Al-Wahadni A, Darwazeh A. Radiographic Assessment of Post-retained Crowns in an Adult Jordanian Population. J Contemp Dent Pract 2006 September;(7)4:029-036.

The viability of the periodontal ligament (PDL) cells is critical for successful healing of replanted avulsed teeth. Viability is primarily dependent on the duration of the extra-alveolar time and storage medium used to preserve teeth. Several storage media have been suggested but milk ranks highest. It would be desirable to evaluate other media as a suitable alternative for milk. The purpose of this study was to determine the viability of human PDL fibroblasts and their morphology after storage in different types of contact lens solutions.

PDL fibroblasts were cultured from a healthy extracted impacted human tooth and exposed to Bausch and Lomb (Renu), Ciba Vision (Titmus), and Alcon (Opti-free) contact lens solutions. Eagle's minimal essential medium served as control. The experiment was performed in plastic tissue culture clusters containing 24 wells. The PDL fibroblasts were grown in each well for three days. On the day of the experiment the culture medium was decanted, the cells were washed with phosphate buffered saline solution (PBS), and 1 ml of the tested solution was placed in each culture well. All tissue culture clusters were incubated at 37°C in 5% CO₂ and 95% air for one, four, and 24 hrs. At the end of the incubation period, the cells were fixed and prepared for scanning electron microscope (SEM) examination.

The results indicated Renu and Opti-free solutions were superior to Titmus solution in terms of their capacity to maintain the viability and normal morphology of PDL fibroblasts.

Contact lens solution is a good storage medium to maintain the viability of PDL fibroblasts for a short-term period.

Al-Nazhan S, Al-Nasser A. Viability of Human Periodontal Ligament Fibroblasts in Tissue Culture After Exposure to Different Contact Lens Solutions. J Contemp Dent Pract 2006 September;(7)4:037-044.

The aim of this study was to assess the apical sealing ability of Resilon™ obturation material.

Forty-two single rooted extracted human teeth were selected and randomly divided into three groups. They were obturated using lateral condensation with gutta-percha and AH 26/AH plus and Resilon™; also, 12 root canals were used as control groups. The apical leakage was measured using the dye penetration methodology.

The teeth filled with gutta-percha and AH 26 displayed the most apical leakage. The least apical leakage was shown with Resilon™

The differences in leakage among the groups, gutta-percha with AH 26 (2.4 mm, SD:1.87), gutta-percha with AH plus (2.1 mm, SD: 1.69), and Resilon™ (1.7 mm, SD:1.32), were statistically significant (p< 0.001).

Based on the data of this study, all groups produced a satisfactory seal. However, Resilon™ and Epiphany™ sealer showed the least apical leakage.

Bodrumlu E, Tunga U. Apical Leakage of Resilon™ Obturation Material. J Contemp Dent Pract 2006 September;(7)4:045-052.

The aims of the study are to investigate the bactericidal effect of three antiseptics (chlorhexidine solution, povidone-iodine solution, and Walkhoff solution) and to determine the minimum inhibitory concentration and their effect on different microbial species.

The study was performed on microflora derived from root canals with simple and complicated pulp gangrene and on pure strains of Enterococcus and Candida albicans.

Chlorhexidine and povidone-iodine proved to have antibacterial and antifungal effects if used in the treatment of pulp gangrene and in cases not responding to conventional therapy.

According to the obtained results, the spectrum of antibacterial agents used in infected canal irrigation can be enlarged to include the agents tested.

Shurrab MY. Antimicrobial Efficiency of Some Antiseptic Products on Endodontic Microflora Isolated from Gangrenous Pulp Tissue. J Contemp Dent Pract 2006 September;(7)4:053-062.

The aim of this study was to evaluate the dental development of patients with â-thalassemia major and to compare it with unaffected children.

Panoramic radiographs of 44 thalassemic patients taken before the age of 16 years were examined. The subjects consisted of 29 males and 15 females ranging in age from 4.9 to 15.7 (mean = 10.8±2.9) years and 44 controls matched for age and sex. The seven left mandibular permanent teeth, second molar to central incisor, were rated on an eight stage scale using the methods described by Demirjian et al.10 The stage of each tooth was converted to the corresponding numeric value and then all values were added to obtain a dental maturity score which corresponded to a dental age. Dental and chronologic ages were compared using a paired t-test. The relationship between the chronologic age and the amount of delay was also determined.

Thirty-nine patients had a delay in the development of their dentition. The mean developmental dental delay was found to be 1.01 years (p<0.05). The range in delay was from 0.1 to 2.9 years. There was no significant difference between the mean chronologic and dental age of the control group (p> 0.05). The amount of delay in dental development increases as the patient.s age increased (p<0.05). Males were found to have a greater delay (mean 1.16 years) than females (mean delay 0.73 years), but this difference was not statistically significant.

The delay in dental development in β-thalassemia major varied according to the patient.s age. This positive correlation parallels the general growth of thalassemic children.

Hazza.a AM, Al-Jamal G. Dental Development in Subjects with Thalassemia Major. J Contemp Dent Pract 2006 September;(7)4:063-070.

The aim of this study was to compare self reported joint related temporomandibular disorder (TMD) symptoms in Lebanese and Italian dental and non-dental students and to detect any correlation between different symptoms.

A questionnaire was distributed in Sardinia (Italy) to dental and psychology students and in Lebanon to dental, physical therapy, and biology students to investigate the prevalence, intensity, and correlation of four temporomandibular joint (TMJ) symptoms.

Prevalence of earache varied among the groups from 10.1% to 29.2%, ear stuffiness from 22.5% to 30.8%, TMJ pain from 13.2% to 21.2%, and TMJ sounds from 18.4% to 46.2%.

Different prevalence and intensity of earache and TMJ sounds were found in the examined subpopulations diverse in cultural background and education. However, prevalence and intensity of ear stuffiness and TMJ pain were similar. Association between TMJ sounds and TMJ pain was detected in selected subpopulations, and correlation between one symptom on one side of the head with the same symptom on the contralateral side were noted suggesting most of these symptoms are bilateral.

The results of the study might be useful to anticipate the possible occurrence of associated symptoms or the same symptom on both sides of the head. Correlations with cultural background and education are difficult to establish.

Abou-Atme YS, Zawawi KH, Melis M. Prevalence, Intensity, and Correlation of Different TMJ Symptoms in Lebanese and Italian Subpopulations. J Contemp Dent Pract 2006 September;(7)4:071-078.

Giachetti L, Scaminaci Russo D, Bambi C, Grandini R. A Review of Polymerization Shrinkage Stress: Current Techniques for Posterior Direct Resin Restorations. J Contemp Dent Pract 2006 September;(7)4:079-088.

de Oliveira Ribas M, Martins WD, de Sousa MH, Braga AM. Traumatic Pseudolipoma of the Oral Cavity: Report of a Case. J Contemp Dent Pract 2006 September;(7)4:089-097.

Bayram M, Özer M, SŞener I. Bilaterally Impacted Maxillary Central Incisors: Surgical Exposure and Orthodontic Treatment: A Case Report. J Contemp Dent Pract 2006 September;(7)4:098-105.