Clinical assessment of maxillary screw-retained implant prosthesis fabricated from digital versus conventional full- arch implant impression. A randomized controlled clinical trial.

OBJECTIVES: To evaluate the peri-implant marginal bone loss (MBL) and prosthodontic complications of maxillary screw-retained implant prosthesis fabricated from digital versus conventional full- arch implant impression. MATERIAL AND METHODS: 28 participants with edentulous maxillary arches were randomly selected and enrolled in two equal groups; Group I conventional impression group (CIG) and Group II Digital impression group (DIG). All patients were rehabilitated with maxillary screwretained implant prosthesis retained by 6 implants. Peri-implant MBL and prosthodontic complications and were registered at 6, 12, and 24 months (m). Data was collected and statistically analyzed. RESULTS: Regarding the effect of time, there was a statistically significant increase in MBL at 6, 12 and 24 m follow-up periods (P<.001). As for the effect of groups, there was no statistically significant difference in MBL between CIG and DIG at 6, 12 and 24 m where P value was 0.083, 0.087 and 0.133 respectively. Prosthetic complications were recorded 19 times in the conventional group and 12 times in the digital group with no significant difference between both groups (P=.303). CONCLUSION: Digital full -arch implant impression is a reliable impression technique and may represent an alternative to conventional impression technique in the fabrication of maxillary screw-retained implant prosthesis.

Prosthetic complications and maintenance of different attachments used to stabilize mandibular 2-implant overdentures in patients with atrophied ridges. A 5-year randomized controlled clinical trial.

PURPOSE: This randomized clinical trial aimed to evaluate prosthetic complications and maintenance of different attachments used to stabilize mandibular 2-implant overdentures in patients with atrophied ridges. METHODS: Ninety edentulous patients with a maladaptive capacity of wearing conventional dentures due to mandibular ridge atrophy received 2-implants in the canine regions using computer-guided surgery. The patients were randomly assigned into three groups; (1) Bar group: overdentures were connected to the implants with bar/clip attachments, (2) Telescopic group: overdentures were connected to the implants using a resilient telescopic attachment, and (3) Stud group: overdentures were connected to the implants with resilient stud (Locator) attachments. Prosthetic complications of attachments, mandibular overdentures, and maxillary dentures, and soft tissue complications of mandibular overdentures and maxillary dentures were evaluated 1 year (T1), 3 years (T3), and 5 years (T5) after denture insertion. RESULTS: The majority of prosthetic and soft tissue complications for all groups occurred in the first year. The most frequent prosthetic complication was wear/distortion of retentive components of locator and telescopic attachments and activation of clips of bar attachment. The bar group showed the highest incidence of overdenture relines, fractures, hyperplasia, maxillary denture mucositis, and soreness. The telescopic group showed the highest incidence of screw loosening, teeth wear/fracture, maxillary denture relines, fractures, teeth wear, teeth separation, and flappy ridges. The stud group recorded the highest incidence of wear and replacement of retentive components. CONCLUSION: For 2-implant overdentures in patients with atrophied mandibles, bar attachments showed the highest incidence of complications related to mandibular overdentures, telescopic attachments showed the highest incidence of complications related to maxillary dentures, and stud attachments showed the highest incidence of complications related to the attachment components.

Retention and Stability Characteristics of Soft-Liner and Clip Attachments Used for Bar/Implant-Assisted Mandibular Overdentures: An In Vitro Study.

PURPOSE: To investigate retention and stability characteristics of soft-liner and clip attachments used for bar/implant-assisted mandibular overdentures. MATERIALS AND METHODS: Two implants were placed in an edentulous mandibular model. According to the type of bar, presence of cantilevers, and type of attachments, eight groups were tested: (1) Dolder bar with cantilevers and three titanium clips (DCC), (2) Dolder bar with cantilevers and resilient liner attachments (DLC), (3) Dolder bar without cantilevers and one titanium clip (DCWC), (4) Dolder bar without cantilevers and resilient liner attachments (DLWC), (5) Hader bar with cantilevers and three plastic clips (HCC), (6) Hader bar with cantilevers and resilient liner attachments (HLC), (7) Hader bar without cantilevers and one plastic clip (HCWC), and (8) Hader bar without cantilever and resilient liner (HLWC). Axial (retention) and nonaxial (stability during anterior, posterior, and lateral dislodging) forces were evaluated initially and after 540 times of prosthesis insertion and withdrawal. RESULTS: The highest retention and stability forces were observed with HCC, and the lowest forces were recorded with DLWC. The lowest retention and stability after wear was noted with DCWC and HCWC. For the majority of groups, the highest forces were noted with posterior dislodgment, and the lowest forces were observed with lateral dislodgment. The largest retention loss was recorded with DCC and HCC, and the lowest retention loss was noted with HLWC. DLC and HLC showed retention gain. CONCLUSION: Hader bar with clips and cantilever extensions achieved the highest retention and stability forces after wear simulation, while bars without cantilevers and clips showed the lowest forces. For cantilevered Dolder and Hader bars, clip attachments showed increased retention loss, while soft-liner attachments showed retention gain.