Web-Based Behavioral Intervention Utilizing Narrative Persuasion for HIV Prevention Among Chinese Men Who Have Sex With Men (HeHe Talks Project): Intervention Development.

BACKGROUND: In the era of potent antiretroviral therapy, a high level of condomless anal intercourse continues to drive increases in HIV incidence in recent years among men who have sex with men. Effective behavior change strategies for promoting HIV-preventive behaviors are warranted. Narrative persuasion is a novel health communication approach that has demonstrated its persuasive advantages in overcoming resistance to counterattitudinal messages. The efficacy of narrative persuasion in promoting health behavior changes has been well documented, but critical research gaps exist for its application to HIV prevention. OBJECTIVE: In this study, we aimed to (1) capitalize on narrative persuasion to design a web-based multisession intervention for reducing condomless anal intercourse among men who have sex with men in Hong Kong (the HeHe Talks Project) by following a systematic development process; and (2) describe the main components of the narrative intervention that potentially determine its persuasiveness. METHODS: Persuasive themes and subtopics related to reducing condomless anal intercourse were initially proposed based on epidemiological evidence. The biographic narrative interview method was used to elicit firsthand experiential stories from a maximum variation sample of local men who have sex with men with diverse backgrounds and experiences related to HIV prevention; different types of role models were established accordingly. Framework analysis was used to aggregate the original quotations from narrators into collective narratives under 6 intervention themes. A dedicated website was finally developed for intervention delivery. RESULTS: A series of video-based intervention messages in biographic narrative format (firsthand experiential stories shared by men who have sex with men) combined with topic-equivalent argumentative messages were produced and programmed into 6 intervention sessions. The 6-week intervention program can be automatically delivered and monitored online. CONCLUSIONS: We systematically created a web-based HIV prevention intervention derived from peer-generated stories. Strategies used to enhance the efficacy of the narrative intervention have been discussed within basic communication components. This paper describes the methods and experiences of the rigorous development of a narrative communication intervention for HIV prevention, which enables replication of the intervention in the future.

A Comparative Evaluation of Factors that Affect the Retentive Efficacy of a Partially Customized Abutment Specifically Designed for Single Implant Application in the Esthetic Zone.

PURPOSE: The purpose of this study is to compare the factors of taper, length, angle and number of vertical axial walls that affect the retentive strength of a cemented crown on a partially customizedhybrid abutment in the esthetic zone. MATERIALS AND METHOD: A total of 35 metal copings were used in this study divided into one group with 30 copings cemented to their corresponding 8° tapered abutment with lengths from 3 to 8 mm with 1 mm increments. The remaining five consisted of a standardized metal coping matching a hexagonal abutment with 3 mm vertical axial walls and the sequential removal of 1, 2, and 3 contiguous vertical axial walls. Dislodgment tests were performed for all copings in both groups. Maximum retentive forces were measured in kgF with a conversion factor of 9.807 N to 1 kgF. RESULTS: At each tapered abutment length, the retentive strength increased proportionally and was significantly different from 31.67 ± SD 4.10 kgF to 67.68 ± SD 11.22 kgF, respectively [F (5,24) =20.46, p < 0.001]. An unmodified hexagonal abutment demonstrated the highest retentive strength of 70.15 ± SD 12.97 kgF. Sequential removal of 1, 2, and 3 contiguous vertical axial walls of the hexagonal abutment was 59.89 ± SD 10.06 kgF, 57.01 ± SD 9.62 kgF, and 55.99 ± SD 9.35 kgF, respectively with no significant difference (p > 0.05) in retentive strength. CONCLUSION: A partially customized abutment with vertical axial walls on one side and a profile reduction on the opposite side can provide comparable retention of cemented copings at 1/3 the length and 1/6 the surface area of an 8 mm high abutment with an 8° taper.

The Effect of Cement and Screw on the Resistance of an Implant Crown Telescopically Engaged to a Hexagonal Shaped Abutment Under Compressive Dynamic Cyclic Fatigue Loading.

PURPOSE: To investigate the resistance of an implant crown telescopically engaged to a geometrically defined hexagonal abutment with and without cement under compressive dynamic cyclic fatigue loading. MATERIALS AND METHODS: 40 crowns, 9 mm in height, were cast from prefabricated plastic copings each telescopically engaged to a 3 mm high machined hexagonal abutment. 20 crowns were retained with zinc phosphate cement and 20 crowns were retained with a screw. A vertical load of 15 kg was applied to all samples under oscillation. A Periotest was used to measure the mobility of the implant crown in Periotest values (PTV). Test endpoints were defined by; fatigue cycles ≥ 20 million; crown PTV > 10; or if samples became visibly loose or component fracture. RESULTS: Cement-retained crowns failed on average at 2.60 x 106 cycles ± 2.27, while screw-retained crown samples failed at 2.17 x 106 cycles ± 1.27 with no significant difference (p > 0.05). Implant and abutment screw fractures were the most prevalent mode of failure in the cement-retained group, while in the screw-retained group failures were caused by the loosening of one or both screw joints. The rate of increase in PTV was higher in the screw-retained group than in the cement-retained group. CONCLUSIONS: Under the experimental conditions, an implant crown telescopically engaged vertically to a 3 mm tall hexagonal abutment, under compressive dynamic cyclic fatigue loading with or without cement demonstrated no differences in resistance or failure outcomes. A cement-retained implant crown with telescopic engagement to the abutment is more rigid, resulting in more implant and abutment screw fractures than loosening.

The Effects of a Vertical Compressive Cyclic Load on Abutment Screws and the Stability of the Prosthesis in Nonengaging and Partially Engaging Abutments in a Screw-Retained Splinted Fixed Dental Prosthesis.

PURPOSE: To evaluate the effects of vertical compressive cyclic load on abutment screws and the stability of screw-retained splinted fixed dental prostheses supported by bone-level nonengaging and partially engaging abutments. MATERIALS AND METHODS: Ten standardized two-unit prostheses integrated with nonengaging and partially engaging abutments were 3D-printed and cast in nonprecious metal and attached to two implant analogs with conical connections angled 15 degrees toward the vertical axis in a resin bock. The common path of insertion for the prosthesis with partially engaging abutments to angled implant analogs was created by selectively reducing the abutment surface that obstructed the implant housing. A 500-N average load was applied to each sample while oscillating 30 degrees from the vertical axis at 60 Hz to failure. Prosthesis stability was measured by deflection from the initial position using a linear displacement measuring device. Sample groups were assessed using the independent-samples t test and one-way repeated-measures analysis of variance (ANOVA) with post hoc tests. RESULTS: The mean cycles to failure for nonengaging and partially engaging abutment groups were 27,180 ± 29,420 and 457,890 ± 265,734, respectively. Failed nonengaging samples had 9 out of 10 abutment screws fracture inside the implant housing but with minimal wear to the top of the implant analog. For partially engaging samples, 8 out of 10 implant housings and 7 out of 10 abutment screws fractured at test endpoints. There was no difference in initial deflections between groups. Prostheses supported by nonengaging abutments failed before deflection measurements could be taken after loading. Prosthesis displacement of partially engaged abutments decreased significantly from the initial position after 300,000 load cycles. CONCLUSION: Under the experimental conditions, screw-retained splinted fixed dental prostheses supported by partially engaging abutments are 17 times more stable than prostheses supported by nonengaging abutments. Abutment screw fractures are the most prevalent mode of failure for nonengaging abutments at significantly lower cycles with minimal wear on implant analogs. Partially engaging abutment groups failed from implant housing and abutment screw fractures at higher cycles. Loading appears to concentrate preferentially on the medial side on all angled implant components. Selective removal of the abutment obstruction allows a common path of insertion for multiple implants and partial engagement to implant housings.

Clinical Application of PEEK as a Provisional Fixed Dental Prosthesis Retained by Reciprocated Guide Surfaces of Healing Abutments During Dental Implant Treatment.

PURPOSE: The aim of this study was to evaluate the clinical use of a high-performance polymer, polyether ether ketone (PEEK), as a material for use in provisional fixed dental prostheses (FDPs) that can be retained by reciprocated guide surfaces of hexagonal-shaped healing abutments during dental implant treatment. MATERIALS AND METHODS: Patients requiring teeth replacement with dental implants for partially and fully edentulous cases in the maxilla and mandible were included. The provisional FDP was fabricated with hex castable copings and PEEK granules using the lost wax technique. The common path of insertion was established by reducing the coping that is in obstruction to the healing abutment. Retention was provided by the reciprocated guide surfaces of multiple hexagonal-shaped healing abutments. RESULTS: Twenty-three custom provisional PEEK FDPs supported by 166 implants in 20 partially and fully edentulous patients were provided during the treatment period. The mean functional periods of the provisional PEEK FDPs for maxillary and mandibular cases were 6.95 ± 0.84 months and 1.90 ± 0.62 months, respectively. All provisional PEEK FDPs functioned as intended for the entire treatment period. There were a total of 10 complications: 4 cases had resin and denture veneers debond from the PEEK framework; 3 partially edentulous cases required supplementary screw retention; and 3 implants in separate cases did not osseointegrate, requiring extended use of the provisional prosthesis. Two provisional mandibular PEEK FDPs with prolonged usage (over 2 years) were excluded from calculations. No fracture of the PEEK framework was observed. CONCLUSION: The results from this study suggest that PEEK can be a suitable material for use in provisional FDPs during dental implant treatment. Prosthetic complications were frequent but were resolved intraorally. The reciprocated guide surfaces of multiple hexagonal-shaped healing abutments can provide adequate retention and resistance for edentulous cases during the implant treatment period. However, in partially edentulous cases, a prosthesis without cross-arch stabilization supplementary screw retention was required.

Resistance to crown displacement on a hexagonal implant abutment.

The purpose of this study was to evaluate the resistance and retention of a hexagonal abutment to crown displacement with varying crown heights (10, 12, and 14 mm) and axis of load. Implants were embedded in resin blocks at a 30 degree angle to the vertical. Crowns were made at heights of 10, 12, and 14 mm. Groups of 5 crowns for each of the 3 crown heights were loaded (200 N) both under the long axis and off axis. The marginal gaps were measured using standardized periapical radiographs before and after loading. The gaps were statistically compared using a 3-way analysis of variance with factors of load, crown height, and point of load. Crowns were loaded to 10 cycles or point of failure. The 10-mm crowns did not show any displacement. The 12-mm and 14-mm groups only showed displacement of the off axis-loaded crowns. The average marginal displacement was 193.56 micro (standard deviation [SD] +/- 138.62 micro) at point of failure (320,717 cycles) and 400.18 micro (SD +/- 644.31) at point of failure (134,278 cycles), respectively. A 1-piece implant with a standardized abutment design can provide sufficient resistance and retention form for crowns of varying dimension if loads are centered over the long axis of the crown.