Sulieman S. Al-Johany

Effects of calcium phosphate composition in sputter coatings on in vitro and in vivo performance.

Calcium phosphate (CaP) ceramic coatings have been used to enhance the biocompatibility and osteoconductive properties of metallic implants. The chemical composition of these ceramic coatings is an important parameter, which can influence the final bone performance of the implant. In this study, the effect of phase composition of CaP-sputtered coatings was investigated on in vitro dissolution behavior and in vivo bone response. Coatings were prepared by a radio frequency (RF) magnetron sputtering technique; three types of CaP target materials were used to obtain coatings with different stoichiometry and calcium to phosphate ratios (hydroxyapatite (HA), α-tricalciumphosphate (α-TCP), and tetracalciumphosphate (TTCP)) were compared with non-coated titanium controls. The applied ceramic coatings were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy. The in vitro dissolution/precipitation of the CaP coatings was evaluated using immersion tests in simulated body fluid (SBF). To mimic the in vivo situation, identical CaP coatings were also evaluated in a femoral condyle rabbit model. TCPH and TTCPH showed morphological changes during 4-week immersion in SBF. The results of bone implant contact (BIC) and peri-implant bone volume (BV) showed a similar response for all experimental coatings. An apparent increase in tartrate resistant acid phosphatase (TRAP) positive staining was observed in the peri-implant region with decreasing coating stability. In conclusion, the experimental groups showed different coating properties when tested in vitro and an apparent increase in bone remodeling with increasing coating dissolution in vivo.

ICK classification system for partially edentulous arches.

Several methods of classification of partially edentulous arches have been proposed and are in use. The most familiar classifications are those originally proposed by Kennedy, Cummer, and Bailyn. None of these classification systems include implants, simply because most of them were proposed before implants became widely accepted. At this time, there is no classification system for partially edentulous arches incorporating implants placed or to be placed in the edentulous spaces for a removable partial denture (RPD). This article proposes a simple classification system for partially edentulous arches with implants based on the Kennedy classification system, with modification, to be used for RPDs. It incorporates the number and positions of implants placed or to be placed in the edentulous areas. A different name, Implant-Corrected Kennedy (ICK) Classification System, is given to the new classification system to be differentiated from other partially edentulous arch classification systems.

Comparison of clinical and radiographic status around immediately loaded versus conventional loaded implants placed in patients with type 2 diabetes: 12‐ and 24‐month follow‐up results

There are no studies that have compared the clinical and radiographic status around immediately loaded (IL) and conventional loaded (CL) implants placed in patients with type 2 diabetes mellitus (T2DM). The aim was to compare the clinical and radiographic status around IL and CL implants placed in T2DM patients. One hundred and eight diabetic patients [55 with IL implants (Group 1) and 53 with CL implants (Group 2)] were included in this cross-sectional study. All implants were placed in healed sites in the maxillary and mandibular premolar and molar regions and supported single restorations. All patients underwent full mouth mechanical debridement biannually. Haemoglobin A1c (HbA1c) levels, clinical [bleeding on probing (BOP) and probing depth (PD) ≥ 4 mm] and radiographic [crestal bone loss (CBL)] peri-implant parameters were measured for both groups at 12- and 24-month follow-up. Group comparisons were performed using the Mann-Whitney U-test (P < 0·05). The mean age and duration of T2DM in groups 1 and 2 were 50·6 ± 2·2 and 51·8 ± 1·7 years, and 9·2 ± 2·4 and 8·5 ± 0·4 years, respectively. At 12- and 24-month follow-up, the mean HbA1c levels in groups 1 and 2 were 5·4% (4·8-5·5%) and 5·1% (4·7-5·4%) and 5·1% (4·7-5·2%) and 4·9% (4·5-5·2%), respectively. At 12- and 24-month follow-up, there was no statistically significant difference in peri-implant BOP, PD and CBL in both groups. It was concluded that clinical and radiographic status is comparable around IL and CL implants placed in patients with T2DM. The contribution of careful case selection, oral hygiene maintenance and glycaemic control is emphasised.

Effect of the Unfilled Space Size of the Abutment Screw Access Hole on the Extruded Excess Cement and Retention of Single Implant Zirconia Crowns

PURPOSE To evaluate in vitro the effect of the size of the unfilled space of the abutment screw access hole on the amount of extruded excess cement and the retention of zirconia copings. MATERIALS AND METHODS Twelve dental implant replicas were attached to the corresponding abutments and embedded in acrylic resin blocks. A total of 36 CAD/CAM zirconia copings were fabricated by one technician using the standard technique. Abutments were divided into group I: the entire screw access channel was completely filled (nonspaced); group II: 1-mm-spaced; and group III: 2-mm-spaced. The copings were air-abraded and temporarily cemented under constant load of 60 N for 10 minutes. The excess cement was calculated as the difference between the post-cementation and post-excess-removal weights using a digital scale. Retention test was performed by a universal testing machine at a 0.5 mm/min crosshead speed. The ultimate force and tensile strength required for separation were recorded. One-way ANOVA and Tukeys test were used for statistical analysis at p ˂ 0.05. RESULTS The average amount of extruded cement in groups 1, 2, and 3 was 33.48 ± 1.55, 23.05 ± 5.48, and 15.58 ± 5.98 mg, respectively. Multiple comparisons showed significant differences in the amount of extruded excess cement between the three groups (p ˂ 0.001). The maximum load at decementation in groups 1, 2, and 3 was 98.8, 87.5, and 88.6 N, respectively. Groups 1, 2, and 3 separated at 6.90 ± 1.2, 6.12 ± 0.7, and 6.21 ± 0.9 MPa, respectively, with no significant differences between them. CONCLUSIONS The amount of extruded excess cement was reduced by more than half when a 2-mm space of the screw access hole was left unfilled in comparison to the nonspaced counterpart. The retention of zirconia copings was not affected by the reported technique.

Influence of space size of abutment screw access channel on the amount of extruded excess cement and marginal accuracy of cement-retained single implant restorations

Statement of problem. The detrimental effect of extruded excess cement on peri‐implant tissue has been well documented. Although several techniques have been proposed to reduce this effect by decreasing the amount of extruded cement, how the space size of the abutment screw access channel (SAC) affects the amount of extruded cement and marginal accuracy is unclear. Purpose. The purpose of this in vitro study was to evaluate the effect of the size of the unfilled space of the abutment SAC on the amount of extruded excess cement and the marginal accuracy of zirconia copings. Material and methods. Twelve implant replicas and corresponding standard abutments were attached and embedded in acrylic resin blocks. Computer‐aided design and computer‐aided manufacturing (CAD‐CAM) zirconia copings with a uniform 30‐&mgr;m cement space were fabricated by 1 dental technician using the standard method. The copings were temporarily cemented 3 times at different sizes of the left space of the SAC as follows: the nonspaced group (NS), in which the entire SAC was completely filled, the 1‐mm‐spaced group (1MMS), and the 2‐mm‐spaced group (2MMS). Abutments and crowns were ultrasonically cleaned, steam cleaned, and air‐dried. The excess cement was collected and weighed. To measure the marginal accuracy, 20 measurements were made every 18 degrees along the coping margin at ×300 magnification and compared with the pre‐cementation readings. One‐way ANOVA was calculated to determine whether the amount of extruded excess cement differed among the 3 groups, and the Tukey test was applied for multiple comparisons (&agr;=.05). Results. The mean weights (mg) of extruded excess cement were NS (33.53 ±1.5), 1MMS (22.97 ±5.4), and 2MMS (15.17 ±5.9). Multiple comparisons showed significant differences in the amount of extruded excess cement among the 3 test groups (P<.001). The mean marginal discrepancy (&mgr;m) of the pre‐cemented group (29.5 ±8.2) was significantly different (P<.01) from that of the NS (72.3 ±13.7), the 1MMS (70.1 ±19), and the 2MMS group (70.1 ±18.8). No significant differences were found in marginal accuracy among the 3 test groups (P=.942). Conclusions. Within the limitations of this in vitro study, leaving a 2‐mm space in the SAC reduced the amount of extruded excess cement by 55% in comparison with the nonspaced abutments. However, no effect was found on the marginal accuracy of zirconia copings.

Tooth Numbering System in Saudi Arabia: Survey.

Objective There were four aims of the current study: (1) to find the most commonly used Tooth Numbering System (TNS) in Saudi Arabia in both academic and non-academic institutions, (2) to identify the most commonly taught TNS in dental colleges, (3) to understand the reasons why dental practitioners prefer to use a specific TNS, and (4) the consequences of using more than one TNS. Materials and method Between May 2014 and May 2015, a self-administered questionnaire containing 21 questions was randomly distributed to 121 individuals (20 deans of dental colleges and 101 heads of governmental dental centers). Results The most commonly used TNS is the Fédération Dentaire Internationale (FDI) TNS for both primary and permanent dentitions in both academic and non-academic institutions, followed by the Palmer TNS and then the Universal TNS. Conclusion The FDI TNS proved to be the most taught TNS in dental colleges in Saudi Arabia. It is advised that the FDI TNS be implemented as a unified system in Saudi Arabia due to the advantages of this particular TNS and the benefits of using one single TNS.

Effect of the Unfilled Space Size of the Abutment Screw Access Hole on the Extruded Excess Cement and Retention of Single Implant Zirconia Crowns: Partial Filling of Abutment Screw Access Hole

PURPOSE To evaluate in vitro the effect of the size of the unfilled space of the abutment screw access hole on the amount of extruded excess cement and the retention of zirconia copings. MATERIALS AND METHODS Twelve dental implant replicas were attached to the corresponding abutments and embedded in acrylic resin blocks. A total of 36 CAD/CAM zirconia copings were fabricated by one technician using the standard technique. Abutments were divided into group I: the entire screw access channel was completely filled (nonspaced); group II: 1-mm-spaced; and group III: 2-mm-spaced. The copings were air-abraded and temporarily cemented under constant load of 60 N for 10 minutes. The excess cement was calculated as the difference between the post-cementation and post-excess-removal weights using a digital scale. Retention test was performed by a universal testing machine at a 0.5 mm/min crosshead speed. The ultimate force and tensile strength required for separation were recorded. One-way ANOVA and Tukeys test were used for statistical analysis at p ˂ 0.05. RESULTS The average amount of extruded cement in groups 1, 2, and 3 was 33.48 ± 1.55, 23.05 ± 5.48, and 15.58 ± 5.98 mg, respectively. Multiple comparisons showed significant differences in the amount of extruded excess cement between the three groups (p ˂ 0.001). The maximum load at decementation in groups 1, 2, and 3 was 98.8, 87.5, and 88.6 N, respectively. Groups 1, 2, and 3 separated at 6.90 ± 1.2, 6.12 ± 0.7, and 6.21 ± 0.9 MPa, respectively, with no significant differences between them. CONCLUSIONS The amount of extruded excess cement was reduced by more than half when a 2-mm space of the screw access hole was left unfilled in comparison to the nonspaced counterpart. The retention of zirconia copings was not affected by the reported technique.

A modified spruing technique for multiple-unit fixed partial denture frameworks

aAssistant Professor, Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University; former Resident, Graduate Prosthodontics Program, Indiana University, Indianapolis, Ind. (J Prosthet Dent 2008;99:324-325) The accuracy of casting a framework for a fixed partial denture (FPD) becomes critical when multiple units are involved, such as for a long-span FPD. Casting an FPD as a single piece or separate units followed by soldering have been described to achieve an acceptably fitting multiple-unit FPD framework.1,2 Different techniques for spruing have been described.3-6 The method and care used in spruing the pattern prior to investing can affect the quality of the cast restoration. One of the spruing techniques is the gate technique,6 in which a series of short 8-gauge wax sprue formers are attached to a continuous 6or 8-gauge “runner bar” of wax or prefabricated plastic pattern. This runner bar in turn is attached to the crucible former by 2 or more large sprue formers. During the spruing of a framework with multiple units, one or more of the wax patterns may move away from their respective abutments on the cast. A modified spruing technique is described in which the wax pattern of each prepared abutment is attached to the cast with wax before beginning the spruing procedure. This method has the advantage of securing these wax patterns over their respective abutments and eliminating movement of the patterns away from their abutments during the spruing procedure.