Accuracy of digital and conventional implant-level impression techniques for maxillary full-arch screw-retained prosthesis: A crossover randomized trial.

OBJECTIVES: This study aimed to compare the accuracy of implant-level conventional and digital impressions for atrophied maxillary ridges. MATERIALS AND METHODS: Twelve participants with atrophied edentulous maxillary ridges received six implants. Six months later and after soft tissue maturation around healing abutments, a control cast was constructed using the final passive restoration for each patient. Two types of implant-level impression techniques were carried out for each patient: (1) conventional (splinted open-tray) impression technique and (2) digital impression technique. For both techniques, scan bodies were labeled from the most distal implant on the left side (A, B, C, D, E, and F) and scanning was made. Accuracy of both techniques was measured using in vitro (two-dimensional and three-dimensional) and in vivo (clinical) methods. Two-dimensional methods include measurement of the difference in linear distances AB, AC AD, AE, and AF. Geomagic software was used to assess the three-dimensional deviation between the two impression techniques using the superimposition of standard tessellation language files. The incidence and percentage of nonpassive frameworks and framework misfits of final restorations for both types of impression techniques were assessed using the single screw test. RESULTS: For all distances, digital impressions recorded significantly higher deviation from control measurements than conventional impressions. The highest two-dimensional linear deviation was noted for AF distance and the lowest difference was noted for AB distance. For all scan bodies, digital impressions recorded significantly higher three-dimensional deviation than conventional impressions. The highest three-dimensional deviation was noted with scan bodies C and D. Digital impressions recorded a significantly higher incidence of nonpassive frameworks and framework misfits than digital impressions. CONCLUSION: Within the limitations of this study, it could be concluded that the conventional implant-level impression technique showed greater in vitro and in vivo accuracy than the digital impression technique when used for full-arch maxillary fixed restorations on inclined implants.

Closed sinus lift and fixed prostheses versus implant-assisted overdentures in management of atrophied distal extension maxillary ridges: A one-year randomized clinical trial.

STATEMENT OF PROBLEM: Rehabilitation of elderly or medically compromised patients with an atrophied unilateral posterior maxillary ridge by an implant-supported prosthesis may be complicated by maxillary sinus pneumatization with insufficient bone for implant placement. PURPOSE: This short-term clinical trial assessed clinical results of closed sinus lift and fixed prosthesis versus implant-assisted overdentures in the management of participants with atrophied distal extension maxillary ridges. MATERIAL AND METHODS: Forty participants with unilateral atrophying distal extension maxillary ridges were randomly assigned into 2 groups. The CSL group (n=20) participants received fixed prostheses supported by 3 implants following a closed sinus lift. The IOD group (n=20) participants received removable partial overdentures assisted by a single implant that was positioned mesially to the maxillary sinus. The modified plaque index (MPI), modified gingival index (MGI), pocket depth (PD), implant stability (IS), and vertical bone loss (VBL) were measured at prosthesis delivery (T0), and 6 (T6) and 12 months (T12) after delivery. The oral health impact profile (OHIP-14) questionnaire was used to assess oral health-related quality of life (OHRQoL) at T12. Significant differences between observation times were performed using Friedman and Wilcoxon signed-rank tests for MPI and MGI and using repeated measures ANOVA with Bonferroni correction of P values for PD, IS, VBL, and OHIP. Between-group comparison of MPI and MGI the Mann-Whitney test was used, while for PD, IS, VBL, and OHIP comparison was made using independent samples t test (α=.05 for all tests). RESULTS: The implant survival rates were 100% for both groups. MPI and PD significantly increased with time for both groups. MGI significantly increased with time for the CSL group only (P=.049). The IS significantly decreased with time for the IOD group. VBL increased significantly from T6 to T12 for the CSL (P=.042) and the IOD (P=.002) groups. The CSL group recorded higher MPI, MGI, PD, and IS values than the IOD group (P<.05). The IOD group recorded higher VBL than the CSL group (P<.001). The CSL group scored significantly lower OHIP-14 values (better OHRQoL) than the IOD group for all values (P<.05). CONCLUSIONS: In comparison with implant-assisted partial overdentures, closed sinus lift with fixed prostheses had higher implant stability, reduced bone loss, and higher participant OHRQoL. However, peri-implant soft tissue health was found to be better with implant overdentures.

Vertical versus angled immediately loaded implants for assisting maxillary overdentures with locator attachments: A preliminary results of one-year randomized clinical trial.

OBJECTIVES: This study aimed to evaluate the clinical outcomes and patient satisfaction of 4-implant-assisted maxillary overdentures using two different designs. MATERIALS AND METHODS: Thirty edentulous participants received four implants in the maxillary ridge. The patients were randomly divided into two equal groups: (1) the control (CG, Vertical) group (n = 15); participants received four vertical implants with straight locator attachments to retain maxillary overdentures, and (2) the study (SG, Angled) group (n = 15); participants received four angled implants with angled locator attachments to retain maxillary overdentures. Peri-implant tissue health [Plaque (PL) and gingival (GI) indices, pocket depth (PD), implant stability (ISQ) and crestal bone loss (CBL)] were evaluated after denture insertion (T0), 6 (T6), and 12 (T12) months after insertion. Patient satisfaction was evaluated using a visual analog scale (VAS) after 12 months. RESULTS: The survival rates were 96.7% and 95% for the control and study groups respectively. PL, GI, and PD increased significantly in both groups with the passage of time. No significant difference in PL, GI, PD, and ISQ was noted between groups at all observation times. CG showed higher CBL than SG at T12. For the VAS results, there was no significant difference between groups. SG recorded significantly higher satisfaction regarding comfort with maxillary and mandibular dentures, retention of mandibular dentures, oral hygiene, the ability to chew hard food, and occlusion than CG. CONCLUSION: Within the limitations of this study, angled implants with angled locator attachments may be recommended to retain maxillary overdentures opposing intact dentition or fixed restoration as it was associated with improvements of several parameters of peri-implant tissue health and patient satisfaction compared to vertical implants with straight locator attachments.

Rehabilitation of distal extension maxillary ridges with fixed and removable implant-supported prostheses: Preliminary 12-month randomized clinical trial.

PURPOSE: This trial evaluated clinical outcomes of fixed and removable implant-supported prostheses for rehabilitation of atrophied distal extension maxillary ridges. MATERIALS AND METHODS: A total of 54 participants with atrophied distal extension maxillary ridges were randomly assigned into three groups (n = 18/group). Group I (SLF); participants treated with fixed restoration supported by three long implants after sinus augmentation, Group II (SF); participants treated with fixed restoration supported by one long and two short implants, and Group III (OD): participants treated with removable partial denture assisted by one long implant that was placed mesial to maxillary sinus (IARPD). Modified plaque index (MPI), modified gingival index (MGI), pocket depth (PD), implant stability (IS), and crestal bone loss (CBL) were measured after prosthesis insertion (T0), 6 (T6), and 12 months (T12) after insertion. Patient satisfaction was measured at T12 using a visual analog scale (VAS). RESULTS: The implant survival rates were 96.8%, 92.4%, and 84.6% for SLF, SF, and OD groups respectively. The SLF recorded the highest MPI, MGI, PD, and IS values, followed by the SF, and the OD showed the lowest values. The OD recorded the highest CBL followed by the SF and the SLF showed the lowest CBL. With exception of satisfaction with surgery and cleaning, SLF and SF groups recorded significantly higher patient satisfaction than the OD for all VAS questions. CONCLUSION: Fixed restorations supported with either long or short implants were associated with improved implant stability, reduced bone loss, and increased patient satisfaction compared to implant-assisted RPDs. However, implant-assisted RPDs were associated with more favorable peri-implant soft tissue health and increased satisfaction with surgery, healing, and cleaning.

Fiber-Reinforced Hybrid Prosthesis Veneered With Composite Resin for 4 Implant-Supported Fixed Provisional and Definitive Restorations.

This technical note describes the fabrication and benefits of fiberglass-reinforced hybrid prosthesis veneered with composite resin for 4 implant-supported fixed professional and final restorations. The described prosthesis reduces rehabilitation time, minimizes impression problems, and ensures a passive fit of professional restoration. The prosthesis provides immediate rehabilitation of 4 implants with ease of adjustments and repair during the entire provisional phase. Moreover, it can be easily converted to final restoration with minimal modifications, excellent esthetic results, and reduced costs.

Axial and Nonaxial Retention Forces of Different Designs of Milled Bar Attachments for Maxillary Implant Overdentures: An In Vitro Study.

PURPOSE: To compare the axial and nonaxial retention forces of different milled bar attachment designs for maxillary implant overdentures. MATERIALS AND METHODS: Four implants were placed in the canine and second premolar areas of an edentulous maxillary ridge model and connected to a cobalt-chromium milled bar either with or without Locator attachments. According to the type of bar and overlying housing, the following groups (n = 10 each) were investigated: group 1 (MWM) = milled bar without attachments and metal housing; group 2 (MWP) = milled bar without attachments and PEEK housing; group 3 (MAM) = milled bar with Locator attachments and metal housing; and group 4 (MAP) = milled bar with Locator attachments and PEEK housing. Axial and nonaxial (anterior, posterior, and lateral) retention forces were measured both at baseline and after wear simulation, then compared between groups and dislodging directions. RESULTS: MAM showed the highest axial (53.20 ± 2.28 N) and nonaxial (anterior [33.80 ± 1.48 N], posterior [37.60 ± 2.07 N], and lateral [34.40 ± 1.67 N]) retention forces at baseline, followed by MAP, then MWM, and MWP (P < .001). MAP showed the highest axial (42.80 ± 2.28 N) and nonaxial (anterior [24.00 ± 1.58 N], posterior [29.40 ± 2.07 N], and lateral [27.80 ± 1.64 N]) retention forces after wear simulation, followed by MAM, then MWP, and finally MWM (P < .001). MAM showed the highest axial (25.25 ± 2.45 N) and nonaxial (anterior [28.29 ± 4.03 N], posterior [24.40 ± 3.25 N], and lateral [25.55 ± 1.65 N]) retention loss, followed by MWM, then MAP, and finally MWP (P < .001). For all groups, the highest retention forces were noted with axial dislodging, followed by posterior dislodging, then lateral dislodging, and finally vertical dislodging (P < .001). CONCLUSION: Milled bars with PEEK housings and Locator attachments for maxillary implant overdentures were associated with the highest axial and nonaxial retention forces after wear simulation, while milled bars with metal housing and no attachments showed the lowest forces. Milled bars with metal housing and attachments showed the highest retention loss, while milled bars with PEEK housing with no attachments showed retention gain.

A technique for measuring the clinical retentive forces of mandibular implant-supported overdentures.

A novel device for measuring the clinical retentive forces of mandibular implant overdentures is described. The device addresses several drawbacks of the conventionally used methods regarding the application of pure vertical dislodging forces perpendicular to the occlusal plane and the elimination of nonaxial dislodging forces and tipping or rotation of overdentures during the measurements. Moreover, the technique allows for the standardization of the occlusal plane and points of load application.

Resilient Stud Versus Bar Attachments for Inclined Implants Supporting Mandibular Overdentures. An In Vitro Study of Loading and Dislodging Strains.

PURPOSE: To evaluate strain around resilient stud and bar attachments for inclined implants supporting mandibular overdentures during loading and dislodging. MATERIALS AND METHODS: A mandibular edentulous model was printed using the laser sintering technique. Two vertical implants and two 30-degree distally inclined implants were placed in canine and premolar areas, respectively. Overdentures were attached to the implants with either a resilient stud (Locator, group 1) or a bar/clip (group 2) attachment. Three strain gauges were mounted at the buccal, lingual, and proximal surfaces of each implant. Microstrains were registered during vertical loading and dislodging force applications and compared between attachments (resilient stud and bar) and implant positions (vertical and inclined). RESULTS: For canine implants, bar overdentures recorded significantly higher microstrains than Locator overdentures during vertical loading. For premolar (inclined) implants, Locator overdentures recorded significantly higher microstrains than bar overdentures during vertical dislodging. For both groups (during loading) and the bar overdenture group (during dislodging), canine (vertical) implants showed significantly higher microstrains than premolar (inclined) implants. CONCLUSION: Within the limitations of this in vitro study, canine (vertical) implants may be at risk of increased stresses during loading if bar attachments are used for vertical and inclined implants supporting mandibular overdentures, and premolar (inclined) implants may be at risk of increased stresses during dislodging if Locator attachments are used. For both attachments, canine implants showed significantly higher microstrains than premolar implants during loading and dislodging.

Patient Satisfaction and Prosthetic Complications of Maxillary Implant Overdentures Opposing Mandibular Implant Overdentures with Bar, Telescopic, and Stud Attachments: A 1-Year Prospective Trial.

PURPOSE: To evaluate patient satisfaction and prosthetic complications of maxillary conventional dentures and implant overdentures opposing mandibular implant overdentures with different attachments. MATERIALS AND METHODS: A total of 60 patients with maxillary conventional dentures (maxillary CD) and mandibular two-implant overdentures received four implants in the maxilla. The implants were connected to the maxillary overdentures with a stud attachment (maxillary OD). The participants were classified into three groups according to the type of mandibular overdenture attachment: bar overdentures (BOD, n = 20), resilient telescopic overdentures (TOD, n = 20), and resilient stud/Locator overdentures (LOD, n = 20). Patient satisfaction (using a visual analog scale [VAS] and oral health-related quality of life (OHRQoL)] and prosthetic/soft tissue complications were evaluated for maxillary CD and maxillary OD after 1 year of insertion. RESULTS: LOD showed higher VAS and oral health impact profile (OHIP-14) scores with maxillary CD and maxillary OD than BOD and TOD except for ease of chewing (VAS) and satisfactory diet (OHIP-7). For maxillary CD, TOD showed a significantly higher frequency of prosthetic and soft tissue complications than BOD and LOD. For all groups, maxillary OD showed significantly higher patient satisfaction regarding VAS and OHIP-14 scores, and lower prosthetic and soft tissue complications than the maxillary CD. CONCLUSION: Locator-retained maxillary overdentures opposing mandibular implant overdentures improved patient satisfaction and reduced prosthetic complications compared to conventional maxillary dentures. Such overdentures are best opposed by Locator-retained mandibular overdentures, as they increase patient satisfaction and reduce prosthetic and soft tissue complications compared to the bar and telescopic attachments.

Peri-implant tissue health and patient satisfaction of vertical versus inclined posterior implants used to support overdentures with bar attachments. A one-year randomized trial.

INTRODUCTION: This study aimed to evaluate peri-implant tissue health and patient satisfaction of vertical and inclined posterior implants for mandibular bar overdentures. MATERIALS AND METHODS: Thirty edentulous participants received four implants in the interforaminal area of the mandible. The patients were randomly assigned into two equal groups; (1) vertical group (control): all implants were inserted vertically parallel to each other. Inclined group (study): the anterior implants were placed vertically, and the posterior implants were tilted 30° distally. Hader bar attachment with two 7 mm-distal cantilevers (vertical group) and without cantilevers (inclined group) was used to connect the implants to mandibular overdentures. Peri-implant tissue health (Plaque [PL] and gingival [GI] indices, pocket depth [PD], and crestal bone loss [CBL]) were evaluated after denture insertion (T0), 6 (T6), and 12 (T12) months after insertion. Patient satisfaction was evaluated using a visual analog scale after 12 months. RESULTS: At T12, the vertical group showed significantly higher PL, PD, and CBL than the inclined group for anterior (p < 0.037) and posterior (p < 0.017) implants. The vertical group showed significantly higher GI than the inclined group for anterior implants (p = 0.003), and the inclined group showed significantly higher GI than the vertical group for posterior implants (p = 0.016). The inclined group showed significantly higher scores for general satisfaction (p = 0.049), prosthesis as a part of you (p = 0.013), appearance (p < 0.001), stability (p = 0.002), ease of cleaning (p < 0.001), and comfort (p = 0.001) than the vertical group. CONCLUSION: Inclined posterior implants used to support mandibular bar overdentures are recommended than vertical implants, as it was associated with improved patient satisfaction and peri-implant tissue health.

Within-patient evaluation of chewing efficiency and maximum bite force of conventional dentures, fixed prostheses, and milled bar overdentures used for All-on-4 implant rehabilitation of atrophied mandibular ridges: A short-term randomized trial.

PURPOSE: This crossover study aimed to evaluate chewing efficiency and maximum bite force (BF) of conventional dentures, fixed prostheses, and milled bar overdentures (MO) used for All-on-4 implant rehabilitation of atrophied mandibular ridges. METHODS: Sixteen edentulous participants with resorbed mandibular ridges received new conventional dentures (CD, control). Four implants were inserted after 3 months in the mandible using the All-on-4 protocol and loaded immediately with acrylic prosthesis. In a crossover manner, each patient had either fixed restoration (FR, 12 occlusal units) or MO (14 occlusal units) randomly in a crossover study design. Chewing efficiency was evaluated using the mixing ability test. The hue deviation (HD) of two-colored gum was calculated after being chewed for 5, 10, 20, 30, and 50 masticatory cycles. Maximum BF was evaluated using a BF device. HD and BF were measured after using CD, FR, and MO prostheses. RESULTS: For all groups, the highest HD (i.e., the lowest chewing efficiency) was noted with 5 strokes, followed by 10, 20, 30 strokes, and the lowest HD (i.e., the highest chewing efficiency) was noted with 50 strokes. For all number of chewing strokes, CD showed the highest HD, then FR, and MO recorded the lowest HD. The highest BF was observed with MO, then FR, and the lowest BF was noted with CD. CONCLUSION: Within the limitations of this short-term investigation, both FR and MO used for All-on-4 implant rehabilitation of patients with resorbed mandibular ridges improve masticatory efficiency and maximum BFs compared to CD. However, MO was associated with significantly higher chewing efficiency and maximum BFs than fixed prosthesis.

Angled ball and locator attachments for immediate loaded inclined implants used to retain maxillary overdentures: A cross over study of patient satisfaction and oral health related quality of life.

OBJECTIVES: The aim of this was to compare the influence of two different angulated abutment designs on patient satisfaction, oral health-related quality of life, and prosthetic aspects of implant-supported maxillary overdentures. MATERIALS AND METHODS: For this cross-over study, 18 patients with completely edentulous maxillary ridges opposing implant-retained mandibular overdentures received 4 implants between the maxillary sinuses using computer-guided surgery. The anterior implants were installed at canine/lateral incisor areas and inclined 15° labially. The posterior implants were inserted just anterior to the maxillary sinuses and inclined 15o distally. Eight patients received maxillary overdentures retained by angled ball attachment (ball overdenture [BOD]) and angled locator attachment in random order. After 6 months, patients indicated satisfaction with their prosthesis using a visual analog scale (VAS), and oral health impact profile (OHIP-14). Moreover, postinsertion prosthodontic maintenance and complications were recorded for both attachments. Comparisons of patient satisfaction and prosthetic complications between groups were performed using the Wilcoxon matched-pairs test and the McNemar test, respectively. RESULTS: Locator overdenture (LOD) recorded significantly higher scores than the BOD group regarding all the VAS questions except for ease of cleaning (p < 0.007). LOD recorded significantly higher patient satisfaction regarding the pronunciation of sounds (p = 0.009), painful aching (p = 0.018), feeling tense (p = 0.011), unsatisfactory diet (p = 0.013), irritability with people (p = 0.005), and life in general (p = 0.004). The most common complications were matrix activation/renewal (n = 34). BOD showed a significantly higher incidence of attachment loosening (p = 0.002), and teeth fracture (p = 0.049) than LOD. LOD showed a significantly higher incidence of attachment wear and replacement than BOD (p <0.001). There was no difference between groups regarding soft tissue complications. CONCLUSION: Within the limitations of this study, and in terms of improved patient-centered outcomes, angled locator attachments are recommended to retain maxillary implant overdentures opposed by implant retained mandibular overdentures at it was associated with increased patient satisfaction and oral health-related quality of life than angled ball attachments. However, locator attachment was associated with more postinsertion prosthodontic maintenance than ball attachment.

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.

Effect of Attachment Type, Maximum Occlusal Force, and Denture Deformation on Marginal Bone Loss of Two-Implant Overdentures: A Short-Term Clinical Trial.

PURPOSE: This study aimed to investigate the effect of attachment type, maximum occlusal force, denture deformation, and other confounding factors on marginal bone loss of two-implant overdentures after 1 year. MATERIALS AND METHODS: Ninety edentulous patients received two implants in canine areas of the mandible using the computer-guided flapless surgical technique. Three months later, overdentures were connected to the implants with bar, resilient telescopic, and resilient stud attachments. Marginal bone loss was evaluated using standardized digitized periapical radiographs. Maximum occlusal forces were evaluated using a digital bite-force meter. Denture base deformation (denture strains, µm) was evaluated using strain gauges bonded to the polished surface of the denture at the level of the attachments. Regression analysis was adopted to find the relation between marginal bone loss and the following confounders (age, sex, mandibular bone height, period of edentulism, number of previous dentures, attachment type, maximum occlusal force, and denture strains). RESULTS AND CONCLUSION: Telescopic overdentures showed the highest marginal bone loss and maximum occlusal force, followed by bar overdentures, and stud overdentures demonstrated the lowest values. The highest denture strains were noted with bar overdentures, followed by telescopic overdentures, and stud overdentures showed the lowest strains. Age (P = .022), mandibular bone height (P = .023), number of previous dentures (P = .004), maximum occlusal force (P ≤ .001), and denture strains (P = .048) were significantly correlated with marginal bone loss. For every 1-year increase in age, there was a decrease in bone loss by 0.3%. For every 1-mm increase in bone height, there was an increase in bone loss by 1%. For every one increase in the number of worn dentures, there was a decrease in bone loss by 4.2%. For every 10-N increase in maximum occlusal force, there was an increase in bone loss by 6.4%. For every 10-µm increase in denture strains, there was an increase in bone loss by 0.21%. Sex, time of edentulism, and attachment type did not demonstrate a significant correlation with marginal bone loss.

Metal-Ceramic and Polyether Ether Ketone-Composite Maxillary Fixed Prosthesis Supported by Four Implants and Opposed by Removable Distal Extension Partial Dentures: A Comparative Study of Clinical and Prosthetic Outcomes.

PURPOSE: This study aimed to evaluate clinical and prosthetic outcomes of metal-ceramic and polyether ether ketone (PEEK) fixed prostheses supported by four maxillary implants and opposed by distal extension removable partial dentures. MATERIALS AND METHODS: Thirty participants with edentulous maxillary and distal extension mandibular ridges received four implants according to the All-on-4 treatment concept. The implants were immediately loaded by fixed acrylic prostheses. After 6 months, patients received either metal frameworks covered with porcelain teeth (metal group) or PEEK framework veneered with composite teeth (PEEK group). Plaque Index (PI), Gingival Index (GI), pocket depth (PD), implant stability quotient (ISQ), peri-implant marginal bone loss (MBL, using digital periapical radiographs), and implant survival were measured at baseline, 1 year, and 3 years. Prosthetic complications were measured on the patient and implant levels after 3 years. RESULTS: No implant failures occurred after insertion of the definitive prosthesis, and the implant survival rate was 100% in both groups. PI, GI, PD, ISQ, and MBL increased significantly with time. The most frequent complications were veneer fracture for the PEEK group and prosthetic screw loosening for the metal group. The metal group showed significantly higher PI, PD, and MBL than the PEEK group after 3 years. PEEK was associated with significantly higher veneer fracture than metal, while metal was associated with significantly higher prosthetic screw loosening than PEEK. CONCLUSION: Within the limitations of this study, the PEEK framework veneered with composite may be a suitable alternative to a metal porcelain prosthesis for All-on-4 implant rehabilitation in patients with maxillary edentulous arches opposed by distal extension mandibular ridges, as it was associated with favorable clinical and prosthetic outcomes after 3 years. However, it was associated with an increased rate of veneer or artificial gingiva fracture.

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.

Resilient Stud Versus Bar Attachments for Immediately Loaded Implants Supporting Mandibular Overdentures: 1-year Randomized Controlled Clinical Trial.

PURPOSE: This study aimed to examine clinical and patient-centered outcomes of resilient stud and stress-free bar attachments used for immediately loaded implants supporting mandibular overdentures. MATERIALS AND METHODS: Thirty edentulous patients with sufficient bone mesial and distal to the mental foramen received new dentures. The patients were randomly assigned into two groups. After 3 months of adaptation, four implants were placed in the canine and second premolar areas of the mandible using computer-guided surgery and the flapless surgical approach. Overdentures were connected immediately to the implants using either resilient stud (Locator) or stress-free implant bar (SFI-Bar) attachments. Marginal resorption of bone, plaque and gingival indices, pocket depth, and implant stability were evaluated for both groups at baseline (prosthesis delivery) and 6 and 12 months thereafter. Implant survival and patient satisfaction were calculated after 12 months. RESULTS: For both groups, marginal bone loss (P < .043), plaque scores (P < .001), and probing depth (P < .002) increased significantly with time. SFI-Bar recorded lower marginal bone loss (P = .048) and higher plaque scores (P = .021) and probing depth (P = .001) than Locator after 12 months of denture insertion. The implant survival was 96.6% and 98.3% for Locator and SFI-Bar, respectively. No significant difference was found in the survival rate between groups (P = .56). Locator showed significantly higher general satisfaction, satisfaction with retention, comfort, and cleaning of overdentures compared with SFI-Bar (P < .001). CONCLUSION: Within the limits of this investigation, both resilient stud and stress-free bar attachments can be used successfully with mandibular four-implant overdentures subjected to an immediate loading protocol. However, studs may be preferred regarding peri-implant soft tissue health, patient satisfaction with retention, cleaning, and comfort, and stress-free bar attachments could be more effective in terms of marginal bone preservation.

Masseter muscle activity of conventional denture, fixed prosthesis, and milled bar overdenture used for All-on-4 implant rehabilitation: A within-subject study.

PURPOSE: to examine the electromyographic (EMG) activity of the masseter muscles in patients with conventional dentures and compare it to EMG activity of fixed prosthesis, and milled bar overdentures used to rehabilitate mandibular atrophied ridges according to the All-on-4 concept. METHODS: Eighteen edentulous subjects with atrophied mandibles received complete dentures (CD, control). After 3 months, four implants were installed between the mental foramina according to the "All-on-4" protocol and loaded immediately. After osseointegration, fixed prostheses (FPD) or milled bar overdentures (MBO) were given to the patients in random order. Primary (amplitude), and secondary (chewing rate, time of the masticatory cycle, time of masticatory burst, and masticatory time) outcomes were evaluated 3 months after using CD, FPD, and MBO. The evaluations were made during mastication of carrot (hard) and cake (soft) foods. RESULTS: FPD and MBO were associated with a significantly higher (amplitude, time of masticatory cycle, and time of masticatory burst), and significantly lower (chewing rate and masticatory time) compared with conventional dentures. Primary and secondary outcomes did not differ between FPD and MBO. Carrot had significantly higher amplitude, chewing rate, time of masticatory burst, and masticatory time than cake, while cake had a significantly higher time of masticatory cycle than carrot. CONCLUSIONS: Within limitations of this study, milled bar overdentures for All-on-4 implant rehabilitation of atrophied mandible is not less efficient than fixed prostheses in terms of electromyographic activity of the masseter muscle. Both prostheses significantly improve muscle activity, chewing rate, time of masticatory cycle, time of masticatory burst, and masticatory time compared with conventional dentures.

Milled Bar with PEEK and Metal Housings for Inclined Implants Supporting Mandibular Overdentures: 1-Year Clinical, Prosthetic, and Patient-Based Outcomes.

PURPOSE: This investigation aimed to evaluate clinical, prosthetic, and patient-based outcomes of a milled bar with polyether ether ketone (PEEK) and metal housings for inclined implants supporting mandibular overdentures. MATERIALS AND METHODS: Eighteen edentulous participants received four implants in the interforaminal area of the mandible (two vertically and two distally inclined), and implants were connected with milled bars. Overdentures were attached to the bars with PEEK female housing (test group). The control group consisted of participants who received milled bar overdentures with conventional metal housings but were case matched to the test group and served as a historical cohort. Clinical parameters (Plaque Index, Gingival Index, pocket depth, and bone loss) were measured at baseline, 6 months, and 12 months. Patient satisfaction (using visual analog scale) and prosthetic complications were recorded after 12 months. RESULTS: The control group showed a significantly higher plaque score and marginal bone resorption compared with the test group. The test group showed higher satisfaction with retention, stability, speech, and esthetics compared with the control group (P < .048). The test group showed a significantly lower incidence of female housing wear (P = .017), plastic clip wear (P < .001), and plastic clip fracture/renewal (P = .049) than the control group. No difference between groups was noted for other clinical, prosthetic, and patient-based outcomes. CONCLUSION: PEEK housing of a milled bar may be a successful alternative to conventional metal housing for inclined implants supporting mandibular overdentures, as it is associated with favorable clinical, prosthetic, and patient-based outcomes after 1 year.

Maxillary Bone Resorption with Conventional Dentures and Four-Implant-Supported Fixed Prosthesis Opposed by Distal-Extension Partial Dentures: A Preliminary 5-year Retrospective Study.

PURPOSE: The aim of this preliminary study was to evaluate maxillary bone resorption with conventional dentures and implant-supported prostheses opposed by distal-extension removable partial dentures (RPDs). MATERIALS AND METHODS: Fifteen patients (seven women and eight men) with totally edentulous maxillary ridges and partially edentulous mandibular ridges (Class I Kennedy classification) received maxillary fixed prostheses on four implants and mandibular distal-extension RPDs (study group). The control group consisted of 15 patients who received conventional maxillary dentures and distal-extension mandibular RPDs without any implant treatment but were matched to the study group and acted as a historical group. Evaluation of vertical maxillary bone resorption for both groups was made at the time of prosthesis insertion (T0) and 5 years later (T2) using the proportional area measurements made on digital panoramic radiographs for anterior and posterior areas. RESULTS: The control group showed significantly higher vertical bone loss than the test group (P < .001). The control group had 0.270 higher maxillary bone loss than the test group. For both groups, anterior maxillary areas showed significantly higher bone loss than posterior areas (P < .003). Anterior maxillary areas had 0.122 higher bone loss compared with posterior areas. Women had 0.035 higher maxillary bone loss compared with men. CONCLUSION: Within the limitations of this study, implant-supported fixed prostheses for the edentulous maxilla opposed by remaining mandibular anterior teeth reduce maxillary anterior and posterior alveolar bone loss compared with conventional dentures. However, they do not prevent maxillary bone loss.