PURPOSE: The purpose of this prospective randomized controlled clinical study was to evaluate crest bone-level changes and patient satisfaction with mandibular overdentures retained by 1 or 2 titanium-zirconium (Ti-Zr) implants with immediate loading protocols after 1 year.

MATERIAL AND METHODS: Thirty-six Ti-Zr implants were placed in 24 participants (single central implant in 12 participants and 2 interforaminal implants in 11 participants) by a single operator. LOCATOR attachments were used to retain the mandibular overdentures with an immediate loading protocol, and observations were made at 1 month and 1 year. Changes to the crestal bone level were evaluated with digital periapical radiographs. A 100-mm visual analog scale (VAS) was used to evaluate patient satisfaction. The Mann-Whitney U test was used to analyze the data.

RESULTS: At 1 month, the mean crestal bone loss was 0.23 mm in the 2-implant group (n=22) and 0.39 mm (P=.181) in the single-implant group (n=11). At 1 year, the bone loss was 0.67 mm in the 2-implant group and 0.88 mm (P=.248) in the single-implant group. The mean VAS score for patient satisfaction level increased from 38.3% to 49.7% for single-implant participants and from 40.5% to 54.8% for 2-implant participants 1 month after implant placement (P=.250) and from 38.3% to 54.5% for single-implant participants and from 40.5% to 58.9% for 2-implant participants after 1 year (P=.341).

Settings and Design: Randomized Controlled Trial.

Materials and Methods: Fifty-two edentulous participants treated with mandibular overdentures using either single implant (n = 26) or two implants (n = 26) with immediate loading protocol by a single operator. The low-profile stud-attachments (LOCATOR; Zest Anchors) were attached to the implants and female attachments were picked up within 0-7 days of implant placement. The OHRQoL was recorded using Oral Health Impact Profile-14 (OHIP-14) questionnaire either in English or in the Malay language before treatment and 1 month and 1 year after treatment.

Statistical Analysis Used: Kruskal Wallis test was used to find out significant difference amongst 3 timepoints and 7 OHIP-14 domains and Mann-Whitney-U test to compare 1IMO or 2IMO groups.

Results: Compared to baseline OHIP-14 scores, participants had a statistically significant decrease in total OHIP-14 at 1 month and 1 year after-treatment time points in both 1IMO and 2IMO groups (P < 0.05). The difference between 1 month and 1 year after-treatment total and subscale scores were also found to be statistically significant (P < 0.05). The overall QoL improvement was comparatively higher in 2IMO group than 1IMO group. The OHIP-14 scores were statistically different within seven domains (P < 0.05). Overall total scores between 1IMO and 2IMO groups were also found to be statistically significant (P < 0.05) at baseline and insignificant (P > 0.05) at 1 month and 1 year.

PURPOSE: The purpose of this prospective clinical study was to evaluate correlations between different implant positions and crestal bone loss and between interimplant distance and the crestal bone loss in patients with 2IMOs with immediate loading protocols at 1-year follow-up.

MATERIAL AND METHODS: A total of 24 participants (13 men, 11 women, mean ±standard deviation age 63.25 ±10.76 years) were treated with 2IMOs (48 Ti-Zr implants) by a single operator between August 2015 and October 2020. The implant diameters (3.3 mm or 4.1 mm) and lengths (10 mm or 12 mm) were selected based on the crestal bone width, and the implants were placed, if possible, in the canine regions. Implant positions and interimplant distance (mm) were measured intraorally with dividers. Prefabricated mandibular dentures were immediately loaded with the LOCATOR-attachments by using a direct intraoral pickup procedure. Crestal bone-level changes were measured with a software program on the mesial and distal sides of each implant from periapical radiographs made with a paralleling technique (at baseline and 1-year follow-up). The measurement values were normalized. The Spearman rho correlation test and paired samples t tests were used for data analysis (α=.05).

RESULTS: The mean ±standard deviation position of the implants from the midline was 8.78 ±2.25 mm (9.00 ±2.22 mm right side, 8.56 ±2.31 mm left side), and the mean interimplant distance was 16.94 ±4.03 mm. At 1-year follow-up, the mean ±standard deviation crestal bone loss was 0.50 ±0.47 mm (n=48) (0.57 ±0.65 mm mesial, 0.43 ±0.53 mm distal). The mean ±standard deviation crestal bone loss was 0.46 ±0.4 mm with Ø3.3-mm implants (n=42) and 0.9 ±0.8 mm with Ø4.1-mm implants (n=6) (P=.005). Implant positions were negatively correlated (rs=-0.37) with the crestal bone loss, and the correlation was significant (P=.009). Interimplant distances were also negatively correlated with crestal bone loss (rs=-0.60; P=.002). Bone loss on the mesial side was positively correlated with that on the distal side rs=0.20; however, the correlation was not significant (P=.16).

METHOD: A questionnaire containing 19 single-answer, multiple-choice type questions was mailed to 503 GDPs practising in the Greater Manchester area in January 2002. An explanatory covering letter and a stamped addressed return envelope were enclosed. The data obtained were processed using SPSS statistical software.

RESULTS: Three hundred and fifty-one (70%) of the practitioners responded to the questionnaire. The restoration of root-filled teeth was normally undertaken within 1-2 weeks of completing root canal therapy by 63% of the practitioners. Only 35% of the GDPs used posts routinely in the restoration of root-filled anterior teeth; the corresponding figure for posterior teeth was 15%. While a cast, precious metal post was the preferred choice in the restoration of anterior teeth, the use of prefabricated posts and related techniques predominated in the restoration of posterior teeth. Composite resin was the most popular choice of material for core build-up procedures in anterior teeth. Amalgam tended to be favoured for core build-ups in posterior teeth. The majority of the practitioners (56%) routinely restored root-filled anterior teeth by means of porcelain-fused-to-metal crowns. Seventy-three per cent of the GDPs preferred to restore root-filled posterior teeth by means of a full veneer crown.

PURPOSE: The purpose of this finite element analysis study was to evaluate the biomechanical behavior (stress distribution pattern) in the mandibular overdenture, mucosa, bone, and implants when retained with 2 standard implants or 2 mini implants under unilateral or bilateral loading conditions.

MATERIAL AND METHODS: A patient with edentulous mandible and his denture was scanned with cone beam computed tomography (CBCT), and a 3D mandibular model was created in the Mimics software program by using the CBCT digital imaging and communications in medicine (DICOM) images. The model was transferred to the 3Matics software program to form a 2-mm-thick mucosal layer and to assemble the denture DICOM file. A 12-mm-long standard implant (Ø3.5 mm) and a mini dental implant (Ø2.5 mm) along with the LOCATOR male attachments (height 4 mm) were designed by using the SOLIDWORKS software program. Two standard or 2 mini implants in the canine region were embedded separately in the 3D assembled model. The base of the mandible was fixed, and vertical compressive loads of 100 N were applied unilaterally and bilaterally in the first molar region. The material properties for acrylic resin (denture), titanium (implants), mucosa (tissue), and bone (mandible) were allocated. Maximum von Mises stress and strain values were obtained and analyzed.

RESULTS: Maximum stresses of 9.78 MPa (bilaterally) and 11.98 MPa (unilaterally) were observed in 2 mini implants as compared with 3.12 MPa (bilaterally) and 3.81 MPa (unilaterally) in 2 standard implants. The stress values in the mandible were observed to be almost double the mini implants as compared with the standard implants. The stresses in the denture were in the range of 3.21 MPa and 3.83 MPa and in the mucosa of 0.68 MPa and 0.7 MPa for 2 implants under unilateral and bilateral loading conditions. The strain values shown similar trends with both implant types under bilateral and unilateral loading.

BACKGROUND: Literature lacks information on various unsplinted attachment systems and their effect on peri-implant tissue health. A focus question (as per PICOS) was set as follows: Does one particular unsplinted attachment system (I) compared with another (C) results in better peri-implant outcomes (O) in two implant-retained mandibular overdentures (P) using randomized controlled trials (RCTs) (S)? The literature search was conducted in the PubMed, MEDLINE and Cochrane Central Register of Controlled Trials (CENTRAL) databases between January 2011 and December 2021. The keywords used were "denture, overlay," "denture," "overlay" AND "dental prosthesis, implant supported," "dental implants," "dental implant abutment design" AND "jaw, edentulous," "mouth, edentulous" AND "mandible." Only RCTs on two implant-retained mandibular overdentures using unsplinted attachment systems measuring peri-implant tissue outcomes with minimum 1-year follow-up were selected. In total, 224 studies were identified in initial search, and 25 were shortlisted for full-text evaluation. Four studies were included for systematic review upon considering inclusion and exclusion criteria. The risk of bias was evaluated using Cochrane Risk of Bias Tool 2.0 (RoB 2.0).

REVIEW RESULTS: A total of 41 patients received ball attachments (in 3 studies), 36 patients received low-profile attachments (in 3 studies), 16 patients received magnet attachments (in 1 study), and 13 patients received telescopic attachments (in 1 study). All four studies used standard sized implants, however, differed in implant manufacturers. Two studies which compared ball attachments low-profile attachments revealed-similar peri-implant tissue health parameters but differed in crestal bone-level changes. One study compared ball with telescopic attachments and revealed similar results in crestal bone-level changes and all four peri-implant tissue health parameters. Single study compared magnets with low-profile attachments and shown lesser bone loss with magnet attachments. Single study was judged to have low risk of bias, single with some concerns, and remaining two to have high risk of bias.

CONCLUSION: Gingival index and bleeding index of the patients were not influenced by any of the unsplinted overdenture attachment (stud, magnet, telescopic) system. Inconclusive results found among the studies evaluated comparing crestal bone loss and plaque index.

MATERIALS AND METHODS: Dental academics in Malaysian dental schools were invited to complete a questionnaire by email and post. The survey comprised questions on research activities in the past 12 months, socio-demographic and professional characteristics, and the R&D Culture Index. Principal components factor analysis was carried out to confirm the factor structure of the R&D Culture Index. Chi-square test was used to identify association of research activities with R&D culture, and socio-demographic and professional characteristics. Binary logistic regression was carried to identify predicators of research activities.

RESULTS: Of 256 potential participants contacted, 128 (50%) useable responses were returned. Three R&D Culture factors accounting for 57.4% of variance were extracted. More positive perception of R&D Support was associated with Malaysians (0.025) and those employed in Government schools (0.017). R&D Skills and Aptitude were associated with older respondents (0.050), PhD qualification (0.014) and more years in academia (0.014). R&D Intention was associated with any of the socio-demographic characteristics. Thirty (23.4%) respondents reported a peer-review research publication in the past 12 months, which was associated with having a PhD (OR 12.79, CI 1.28-127.96), after adjustment in regression analyses.

PURPOSE: The purpose of this finite element analysis study was to evaluate stress and strain distribution patterns in 2-implant mandibular overdentures with different positions and angulations of implants under unilateral and bilateral loading.

MATERIAL AND METHODS: A cone beam computed tomography (CBCT)-based, 3-dimensional (3D) model of the mandible and an intraoral scanning-based 3D model of the denture were developed in the Mimics software program. A 3D model of a standard-sized implant with a low-profile overdenture attachment (LOCATOR) was developed in the Solidworks software program. Two implants were inserted in the 3D model of the mandible, with implants placed at different positions, 5, 10, 15, and 20 mm from the midline, and different distal angulations, 0-5, 0-10, 0-15, 5-5, 10-10, and 15-15 degrees (at 10-mm distance), in the 3Matics software program. Unilateral and bilateral vertical loads of 100 N were applied on the first molars in the ANSYS software program to record maximum von Mises stresses and strain values.

RESULTS: The stresses in the implants were maximum when placed at a 20-mm distance (4.18 MPa under unilateral and 4.2 MPa under bilateral loading), while for the implants placed at 5 mm, 10 mm, and 15 mm, the indicated stresses were less than 2.46 MPa following an increasing trend with an increase in the distance. The stresses in the implants were maximum when placed at 15-15-degree angulations (0.93 under unilateral and 0.92 MPa under bilateral loading). For lower angulations, the stresses on the implants ranged from 0.05 to 0.87 MPa. No specific trend was observed in stresses and strains with 0-5-, 0-10-, and 0-15-degree angulations, but an increasing trend was observed with 5-5-, 10-10-, and 15-15-degree angulations under unilateral loading. Under bilateral loading, the stresses and strains on the implants and the mandible showed negligible variations across all 6 angulations.

PURPOSE: The purpose of this in vitro study was to evaluate the crestal strain around 2 implants to support mandibular overdentures when placed at different positions.

MATERIAL AND METHODS: Edentulous mandibles were 3-dimensionally (3D) designed separately with 2 holes for implant placement at similar distances of 5, 10, 15, and 20 mm from the midline, resulting in 4 study conditions. The complete denture models were 3D designed and printed from digital imaging and communications in medicine (DICOM) images after scanning the patient's denture. Two 4.3×12-mm dummy implants were placed in the preplanned holes. Two linear strain gauges were attached on the crest of the mesial and distal side of each implant (CH1, CH2, CH3, and CH4) and connected to a computer to record the electrical signals. Male LOCATOR attachments were attached, the mucosal layer simulated, and the denture picked up with pink female nylon caps. A unilateral and bilateral force of 100 N was maintained for 10 seconds for each model in a universal testing machine while recording the maximum strains in the DCS-100A KYOWA computer software program. Data were analyzed by using 1-way analysis of variance, the Tukey post hoc test, and the paired t test (α=.05).

PURPOSE: The purpose of this 3D finite element analysis study was to evaluate the biomechanical behavior of 2-implant mandibular overdentures (2IMO) and their individual components by using implants of different diameters.

MATERIAL AND METHODS: A 3D mandibular model was obtained from the cone beam computed tomography (CBCT) images of a 59-year-old edentulous man, and a 3D denture model was developed from intraoral scanning files in the Mimics software program. A 3D model of different diameters of implants (2.5 mm, 3.0 mm, 3.5 mm, and 4.0 mm) with a LOCATOR attachment was developed in the Solidworks software program. Two same-sized implants were inserted in the mandibular model at 10 mm from the midline in the 3Matics software program. A vertical load of 100 N was applied on the first molar region on the right side or both sides in the ANSYS software program. The maximum von Mises stresses and strains were recorded and analyzed.

RESULTS: Stresses within the implants decreased with an increase in diameter (from 2.5 mm to 3 mm, 3.5 mm, and 4.0 mm) of the implants. The highest stresses were observed with 2.5-mm-diameter implants (0.949 MPa under unilateral and 0.915 MPa under bilateral loading) and the lowest with Ø4-mm implants (0.710 MPa under unilateral and 0.703 MPa under bilateral loading). The strains on the implants ranged between 0.0000056 and 0.0000097, and those on the mandible ranged between 0.0000513 and 0.0000566 across all diameters of the implants without following a specific trend.

METHODS: The study from March 2016 to April 2017 was conducted to validate the 'Work Readiness Scale' (WRS; Deakin University) using Principal Component Analysis and Cronbach - α for internal consistency. It was modified to a four-item even-point scale and distributed as an online survey to 335 final year students of the three programs.

RESULTS: A reduction from 64 to 53 items provided good internal consistency in all factors: WC 0.85, OA 0.88, SI 0.88 and PC 0.71. The PC domain had the greatest item reduction from 22 to 6, whilst the SI domain increased in items from 8 to 19. These changes may be associated with difference in understanding or interpretation of the items in the SI domain.