Dentin bond strength of bioactive cement in comparison to conventional resin cement when photosensitized with Er,Cr:YSGG Laser.

OBJECTIVE: The purpose of the present study was to assess dentin shear bond strength (SBS) and mode of bond failure of bioactive cement (BA) in comparison to conventional resin cement when photosensitized by Er,Cr: YSGG Laser (ECL). METHODS: The present in-vitro study was carried out from March 2019 to May 2019. Sixty permanent non-carious, intact, non-fractured molars were isolated and mounted vertically in acrylic resin. Buccal surface of each molar tooth was ground, polished and surface treated with ECL. Ketac conditioner was applied on the surface washed and air dried surface. Tetric -N-Bond adhesive was applied on forty-five samples and light cured. The specimens were allocated into four groups (n=15) according to the type of cement used i.e., Calibra (C), BA, Variolink II (V) and Maxcem-Elite (ME). For SBS testing was performed using the universal testing machine. Eight samples from each group were assessed for modes of failure. Means and standard deviations were compared using analysis of variance (ANOVA) and Tukey's post hoc test at a significance level of p < 0.05. RESULTS: The highest mean SBS was observed in group ECL-C (21.55±3.08). The lowest mean SBS was displayed in group ECL-ME (14.25±3.55). Mean SBS values for group ECL-C (21.55±3.08) and group ECL-V (20.74±4.15) were comparable (p <0.05). Similarly, SBS values of group ECL-BA (15.48±3.62) and group ECL-ME (14.25±3.55) were comparable (p <0.05). CONCLUSION: Dentin surface conditioned with Er,Cr: YSGG and bonded to C and V cements exhibit favourable bond strength values.

Survival Rates of Short Dental Implants (≤ 6.5 mm) Placed in Posterior Edentulous Ridges and Factors Affecting their Survival after a 12-Month Follow-up Period: A Systematic Review.

PURPOSE: Dental implant placement in atrophic ridges is challenged by availability of bone and proximity to vital structures. Although short dental implants have been considered favorable, there is no consensus regarding their long-term survival and factors affecting it. This systematic review addressed the focused question, "What is the survival rate of short dental implants (SDI; length ≤ 6.5 mm) placed in posterior edentulous ridges without any ridge augmentation procedures and followed up for 12 months post-prosthetic loading, and what are the factors affecting their survival?" MATERIALS AND METHODS: Based on a search of the indexed literature, 51 studies fulfilling the inclusion criteria were quantitatively reviewed. Overall SDI survival and factors influencing survival, such as anatomic location, surgical protocol, time of loading, type of prosthesis retention, nature of prosthesis, implant stability, crown-to-implant ratio (C/I ratio), and marginal bone loss at follow-up were evaluated. SDI survival based on clinical factors was compared to overall survival using odds ratio (OR), and continuously distributed data were evaluated using Pearson's correlation (P < .05). RESULTS AND CONCLUSION: Based on this review, SDI placed in edentulous posterior regions of the maxilla and mandible have survival rates (96.45%) similar to those of conventional-length implants after a follow-up period of 12 months post-prosthetic loading. Except for smaller implant diameter (OR = 1.59, 95% confidence interval [CI] = 1.03-2.43, P < .05), screw-retained restorations (OR = 2.11, 95% CI = 1.25-3.57, P < .01), and C/I ratio ≥ 2 (Pearson's R = -0.694, P < .01), other variables relating to implant surgery, prosthetic loading, nature and type of prosthesis, and follow-up did not significantly affect SDI survival.

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 Tukey's 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-µm 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 (α=.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 (µm) 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.

Comparison of clinical and radiographic parameters around short (6 to 8 mm in length) and long (11 mm in length) dental implants placed in patients with and without type 2 diabetes mellitus: 3-year follow-up results.

OBJECTIVE: To compare the clinical and radiographic parameters around short (6 to 8 mm in length) and long (11 mm in length) dental implants placed in patients with and without type 2 diabetes mellitus (T2DM). MATERIAL AND METHODS: Forty-five male patients with T2DM (Group-1) and 42 male non-diabetic controls (Group-2) who had undergone implant therapy in the posterior mandible were included. Depending upon the length of the implant, patients were divided into two subgroups: (a) patients with short implants (6-8 mm long) and (b) patients with long implants (11 mm long). Peri-implant plaque index (PI), bleeding on probing (BOP), probing depth (PD) and crestal bone loss (CBL) were measured at 18 and 36 months of follow-up in both groups. Hemoglobin A1c (HbA1c) levels were measured at baseline and after 18 and 36 months of follow-up in both groups. P-values less than 0.05 were considered statistically significant. RESULTS: The mean age of patients in groups 1 and 2 was 42.5 and 40.6 years, respectively. The mean HbA1c levels at baseline among patients in groups 1 and 2 were 7.7% and 4.5%, respectively. At 18 and 36 months of follow-up, the mean HbA1c levels among patients in groups 1 and 2 were 6.6% and 4.5% and 6.5% and 4.4%, respectively. The mean duration of T2DM among patients that received short and long implants was 4.3 years and 4.1 years, respectively. There was no significant difference in PI, BOP, PD and CBL around implants placed in both groups at 18 and 36 months of follow-up. Success rate of short and long dental implants was 100% in both groups. CONCLUSION: Short implants can demonstrate clinical and radiographic stability in a manner similar to conventional long implants in patients with and without T2DM. The role of oral hygiene and glycemic maintenance in this scenario cannot be disregarded.

Dental Implant Length and Diameter: A Proposed Classification Scheme.

PURPOSE: To propose a length-and-diameter-based classification scheme for dental implants to standardize terminology in the dental literature and communication between interested parties. MATERIALS AND METHODS: This study was mainly based on searching two major resources: published scientific research papers and 14 of the most popular dental implant manufacturers. Indexed databases were searched from January 2004 up to and including February 2016 using the keywords "dental implant length" and "dental implant diameter." Retrieved titles and abstracts were screened, and related full-text articles were reviewed. Full-text articles that clearly stated the terms and measurements of implants used were included and considered for proposing this classification scheme. RESULTS: The initial search for implant diameter and length yielded 1007 and 936 articles, respectively. A total of 85 studies (41 about diameter, 44 about length) were selected and reviewed. The remaining studies (966 about diameter, 892 about length) that did not abide by the eligibility criteria were excluded. The terms "long," "short," "standard," "wide," and "narrow" were the most commonly used terms in the literature. A classification scheme for implants by diameter and length was proposed. CONCLUSIONS: Indexed publications contain a variety of terms used by authors to describe diameter and length of dental implants without conformity and standardization. The classification scheme proposed in this article could serve as a reference for interested parties.

Soft tissue changes and crestal bone loss around platform-switched implants placed at crestal and subcrestal levels: 36-month results from a prospective split-mouth clinical trial.

OBJECTIVE: The aim of the present 36-month prospective split-mouth clinical trial was to investigate the peri-implant soft tissue changes and crestal bone loss (CBL) around delayed loaded platform-switched implants placed at crestal and subcrestal levels. MATERIAL AND METHODS: Twenty-three individuals with bilaterally missing either mandibular first or second molars were included. The test and control sites were defined as follows: (i) test sites: implants placed 2 mm below the alveolar crest (subcrestal); (ii) control sites: implants placed at bone level (crestal). Forty-six implants (23 implants in test sites and 23 in control sites) were placed in the center of the healed alveolar ridge in the posterior mandible. Peri-implant bleeding on probing (BOP), probing depth (PD ≥ 4 mm), and CBL was compared at 6, 18, and 36 months of follow-up. P < 0.05 was considered statistically significant. RESULTS: Sixteen males and seven females with a mean age of 43.5 years (29-50) were included. In the control group (n = 23), the highest mean percentage of sites that showed BOP and PD ≥ 4 mm were at 6 months (7.4% and 1.4%, respectively). In the test group (n = 23), the highest mean percentage of sites that showed BOP and PD ≥ 4 mm were at 6 months (2.4% and 1.2%, respectively). The total amount of CBL around crestal and subcrestal implants after 36 months of loading was 0.45 ± 0.2 and 0.3 ± 0.2 mm, respectively. At all follow-up intervals, all intragroup and intergroup comparisons showed no significant differences in BOP, PD ≥ 4 mm, and CBL around implants placed at crestal and subcrestal levels. CONCLUSION: Up to 36 months of follow-up, soft tissue parameters and crestal bone levels can remain equally stable around dental implants placed at crestal and subcrestal levels. The need for long-term follow-up clinical trials is also emphasized.

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.

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.

A survey of left-handed dental students and interns in Saudi Arabia.

The purpose of this study was to survey left-handed (LH) dental students and interns concerning whether they face any problems in their dental education or in their practice of dentistry. The questionnaires were distributed in four dental colleges in different regions in Saudi Arabia. The questionnaire was comprised of sixteen questions to assess the following issues: demographic information, difficulties in dental school or dental practice due to left-handedness, preferred hand in performing different dental procedures, and musculoskeletal complications. The study found that the percentage of LH dental students was around 7 percent (110 out of 1,660). More than half of these participants (n=56) reported that being LH is not a problem in general, while when performing the required dental work, around 51 percent (n=56) agreed to having a problem. The majority (68 percent; n=75) reported that they had a problem with having RH instructors, and 84.5 percent (n=93) responded that their institution is not properly equipped to accommodate LH students. Only 34 percent (n=37) agreed that using facilities of an RH dentist may cause musculoskeletal complications to an LH dentist. The results of this study suggest that dental schools should provide LH students with appropriate equipment and a proper learning environment.

Evaluation of different esthetic smile criteria.

PURPOSE: The aim of this study was to evaluate the existence of different esthetic smile criteria as determined on the smiles of celebrities, which were considered by lay people to be beautiful. MATERIALS AND METHODS: An Internet search for "best smile" and "female celebrities" in the years 2007 and 2008 identified 50 celebrities who were voted to have beautiful smiles. Another search was made for images of these celebrities that showed the entire face with an open smile. The images were analyzed using Digimizer image analysis software for different esthetic smile criteria. RESULTS: Eighty percent of the sample was classified as having an average upper lip position, 62% showed upward upper lip curvature, and 78% had a parallel smile line. Forty-two percent of the images showed the maxillary anterior teeth not touching the lower lip, while 34% were touching, and 24% slightly covered it. Sixty percent displayed up to the second premolar, and 32% displayed up to the first molar when smiling. Midline deviation was detected in 36% of the sample. Diastema and golden proportion were not seen in any of the subjects. CONCLUSION: Female celebrities voted to have the best smile by lay people showed most of the esthetic smile criteria with slight variations, except for the golden proportion. The opinions and perceptions of lay people about beauty should be studied and evaluated.

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.