The effect of one-time abutment placement on clinical and radiographic outcomes: A 5-year randomized clinical trial.

OBJECTIVE: The aim of this study was to evaluate the long-term (5 years) clinical efficacy of the one-abutment one-time protocol (test) versus the standard of care by placing the definitive abutment on the day of the prosthetic delivery (control). MATERIALS AND METHODS: In this study, 39 subjects with 60 implants were randomly allocated to either the test or the control group. Changes in the radiographic interproximal bone levels (DIB), modified sulcus bleeding index, probing depth, modified plaque index, papilla fill (Jemt score), incidence of peri-implantitis and peri-implant mucositis as well as patient-reported outcomes measures (PROMs) were collected and compared at 1, 3 and 5 years. RESULTS: At 5 years, the control group showed a greater, although not statistically significant, change in mean DIB values (0.97 mm vs. 0.53 mm). Regarding the other clinical parameters evaluated, no statistically significant differences were observed between groups at any time point. At 5 years, 51% of the implants presented peri-implant mucositis (25.5% in the control and 23.5% in the test), and only one implant in the test group developed peri-implantitis. CONCLUSIONS: The connection and disconnection of healing abutments during the healing period was not associated with higher long-term bone loss. Clinical outcomes and PROMs were similar between groups.

Efficacy of platelet-rich fibrin in maxillary sinus augmentation and simultaneous implant placement in deficient maxillary ridges: A pilot comparative study.

Background: Rehabilitation with dental implants has become the most widely accepted treatment protocol for rehabilitation of lost natural teeth. Direct sinus lift is one of the most predictable procedures for augmenting the deficient posterior maxillary ridges. Methods: The study was designed in patients with insufficient bone for implants in the maxillary posterior ridges. The test group received platelet-rich fibrin alone as filler, and the control group received a bone allograft. The residual bone height (RBH), implant mobility, and soft tissue characteristics between and within the groups were compared and analyzed. Results: Both the groups had considerable gain in RBH, and the intragroup analysis revealed clinical gain in bone height in both the groups, with the test group exhibiting statistically significant gain which kept on improving from 6 months with z= -3.477 and a p value of 0.001 to 9 months with z=-3.531 and a p value of 0.027. Conclusion: The results suggest that the use of platelet-rich fibrin alone improves the bone regeneration, thereby achieving predictable and stable augmentation of the sinus floor required for the success of implant therapy.

In Silico Mechanical Effort Analysis of the All-On-4 Design Performed With Platform-Switching Distal Short Dental Implants.

Short dental implants with platform matching connection have been used for the rehabilitation of atrophic jaws whenever standard-length dental implants cannot be placed without prior bone augmentation. Yet, there remains a lack of data regarding the risk of technical failures when the all-on-4 configuration is performed in atrophic jaws with platform-switching distal short dental implants. Thus, the current study used the finite element method to evaluate the mechanical behavior at the level of the prosthetic components of the all-on-4 concept performed in atrophic mandible using short-length distal implants with platform switching (PSW) connection. Three models of the all-on-4 configuration were generated in human atrophic mandibles. The geometric models consisted of PSW connection tilted standard (AO4T; θ = 30 deg; 11 mm-length), straight standard (AO4S; θ = 0 deg; 11 mm-length) and straight short (AO4Sh; θ = 0 deg; 8 mm-length) distal implants. A resultant force of 300 N was performed obliquely in the left side and posterior region of the prosthetic bar. The von Mises equivalent stress (σvm) and maximum and minimum principal stresses (σmax and σmin) were performed at level of the prosthetic components/implants and peri-implant bone crest, respectively. The general displacement of the models was also evaluated. The stress analysis was performed on the side of load application. The AO4S configuration showed the lowest values of σvm in the mesial left (ML) and distal left (DL) abutments (37.53 MPa and 232.77 MPa, respectively) and dental implants (91.53 MPa and 231.21 MPa, respectively). The AO4Sh configuration showed the highest values of σvm in the bar screw (102.36 MPa), abutment (117.56 MPa), and dental implant (293.73 MPa) of the ML area. Among the models, the highest values of σmax and σmin were noticed in the peri-implant bone crest of the AO4T design (131.48 MPa and 195.31 MPa, respectively). All models showed similar values of general displacements, which were concentrated in the mandible symphysis. The all-on-4 configurations designed with PSW connection and tilted standard (AO4T; θ = 30 deg; 11 mm-length), straight standard (AO4S; θ = 0 deg; 11 mm-length) or straight short (AO4Sh; θ = 0 deg; 8 mm-length) distal implants were not associated with higher odds of technical failures. The AO4Sh design may be a promising option for the prosthetic rehabilitation of atrophic jaws.

[Three-dimensional finite element analysis of cement flow in abutment margin-crown platform switching].

OBJECTIVE: To analyze the cement flow in the abutment margin-crown platform switching structure by using the three-dimensional finite element analysis, in order to prove that whether the abutment margin-crown platform switching structure can reduce the inflow depth of cement in the implantation adhesive retention. METHODS: By using ANSYS 19.0 software, two models were created, including the one with regular margin and crown (Model one, the traditional group), and the other one with abutment margin-crown platform switching structure (Model two, the platform switching group). Both abutments of the two models were wrapped by gingiva, and the depth of the abutment margins was 1.5 mm submucosal. Two-way fluid structure coupling calculations were produced in two models by using ANSYS 19.0 software. In the two models, the same amount of cement were put between the inner side of the crowns and the abutments. The process of cementing the crown to the abutment was simulated when the crown was 0.6 mm above the abutment. The crown was falling at a constant speed in the whole process spending 0.1 s. Then we observed the cement flow outside the crowns at the time of 0.025 s, 0.05 s, 0.075 s, 0.1 s, and measured the depth of cement over the margins at the time of 0.1 s. RESULTS: At the time of 0 s, 0.025 s, 0.05 s, the cements in the two models were all above the abutment margins. At the time of 0.075 s, in Model one, the gingiva was squeezed by the cement and became deformed, and then a gap was formed between the gingiva and the abutment into which the cement started to flow. In Model two, because of the narrow neck of the crown, the cement flowed out from the gingival as it was pressed by the upward counterforce from the gingival and the abutment margin. At the time of 0.1 s, in Model one, the cement continued to flow deep inside with the gravity force and pressure, and the depth of the cement over the margin was 1 mm. In Model two, the cement continued to flow out from the gingival at the time of 0.075 s, and the depth of the cement over the margin was 0 mm. CONCLUSION: When the abutment was wrapped by the gingiva, the inflow depth of cement in the implantation adhesive retention can be reduced in the abutment margin-crown platform switching structure.

Influence of the loading protocol and platform switching in two-implant bar-retained overdentures: 3-year results from a randomized controlled equivalence clinical trial.

OBJECTIVES: To test the null hypothesis that vertical peri-implant bone level alterations (ΔIBL) are equivalent in immediately (IL) and 3-month post-placement (DL) loaded implants in mandibular implant overdentures (IODs) on two implants. MATERIALS AND METHODS: Thirty-two patients receiving two interforaminal implants, one with a platform-switched and one with a platform-matching abutment were randomly assigned to the IL or DL group (allocation ratio 1:1). All implants were primarily splinted with chairside-customized bars, converting the existing removable complete dentures to IODs. Standardized radiographs were recorded. The influence of the loading protocol (IL vs. DL), implant platform (platform switched vs. platform matching), implant site (43 vs. 33), participant age (≤65 vs. >65 years), and definition of baseline (implant placement vs. implant loading) were analyzed, applying linear regression analyses (α = 0.05). The equivalence range was [-0.4; 0.4]. RESULTS: Three participants of the IL group were lost during follow-up. The overall mean ΔIBL was -0.96 ± 0.89 mm. The ΔIBL was equivalent in terms of the implant platform and implant site but not in terms of participant age (in favor of more elderly participants) and the loading protocol. A significantly smaller ΔIBL was observed in the IL when the baseline was considered to be implant placement (p = .017), but not when it was considered to be implant loading (p = .084). CONCLUSION: Immediate loading of primary-splinted implants in two-implant bar-retained overdentures, seems beneficial relative to loading 3 months post-placement, with respect to ΔIBL. The ΔIBL were equivalent in terms of platform switching.

Microgap and microleakage of a hybrid connection platform-switched implant system in the absence or presence of a silicone-based sealing agent.

The present study aims to characterize, for the first time, the microgap and bacterial microleakage of a platform-switched implant system with hybrid connection, screwed at distinct torque values (manufacturer recommended torque-25 N cm-and a reduced torque-5 N cm-mimicking the long-term functional use), in the absence or presence of a silicon-based sealing agent. Microgap was determined through scanning electron microscopy and bacterial microleakage was evaluated in vitro, upon Enterococcus faecalis colonization of the system. The sealing efficacy was evaluated in the absence or presence of a commercially available silicon-based sealer. The cytotoxicity of the sealer was further addressed in vitro, with a fibroblastic cell line, in accordance with reference standards. A low microgap of the implant system was verified, regardless of the applied torque load-maximal values ranged around 0.25 and 1.25 µm, for 25 and 5 N cm torques, respectively. No bacterial microleakage was reported at 25 N cm, while at 5 N cm, leakage was verified on 38% of the samples. The application of a silicon-based sealer-with an adequate cytocompatible profile-was effective on preventing the bacterial microleakage on the assayed experimental setting. The assayed platform-switched implant system with hybrid connection presented a low interfacial misfit and an effective sealing capability at manufacturer recommended torque. Despite the increased microleakage at low torque conditions, the application of a cytocompatible silicon-based sealing agent restored the sealing effectiveness of the system. The use of a silicon-based sealing agent can assist on the maintenance of the sealing effectiveness even at low torque conditions.

Effect of the prosthetic index on stress distribution in Morse taper connection implant system and peri-implant bone: a 3D finite element analysis.

BACKGROUND: The combination of a prosthetic index with Morse taper connection was developed, with the purpose of making prosthetic procedures more precise. However, the presence of the index may compromise the mechanical performance of the abutment. The aim of this study is to evaluate the effect of prosthetic index on stress distribution in implant-abutment-screw system and peri-implant bone by using the 3D finite element methodology. METHODS: Two commercial dental implant systems with different implant-abutment connections were used: the Morse taper connection with platform switching (MT-PS) implant system and the internal hex connection with platform matching (IH-PM) implant system. Meanwhile, there are two different designs of Morse taper connection abutment, namely, abutments with or without index. Consequently, three different models were developed and evaluated: (1) MT-PS indexed, (2) MT-PS non-indexed, and (3) IH-PM. These models were inserted into a bone block. Vertical and oblique forces of 100 N were applied to each abutment to simulate occlusal loadings. RESULTS: For the MT-PS implant system, the maximum stress was always concentrated in the abutment neck under both vertical and oblique loading. Moreover, the maximum von Mises stress in the neck of the MT-PS abutment with index even exceed the yield strength of titanium alloy under the oblique loading. For the IH-PM implant system, however, the maximum stress was always located at the implant. Additionally, the MT-PS implant system has a significantly higher stress level in the abutment neck and a lower stress level around the peri-implant bone compared to the IH-PM implant system. The combined average maximum stress from vertical and oblique loads is 2.04 times higher in the MT-PS indexed model, and 1.82 times for the MT-PS non-indexed model than that of the IH-PM model. CONCLUSIONS: MT-PS with index will cause higher stress concentration on the abutment neck than that of without index, which is more prone to mechanical complications. Nevertheless, MT-PS decreases stress within cancellous bone and may contribute to limiting crestal bone resorption.

Bone-level changes around implants with 1- or 3-mm-high abutments and their relation to crestal mucosal thickness: A 1-year randomized clinical trial.

AIM: To evaluate 1-year bone-level changes around subcrestal platform-switching implants with 1 or 3 mm definitive abutments. The influence of mucosal thickness on bone-level alterations was further analysed. MATERIALS AND METHODS: Implants were placed in the posterior sextants and positioned 1.5 mm subcrestally with an abutment of 1 or 3 mm height. Final restorations were delivered after 16 weeks. Radiographic measurements of inter-proximal bone level were the primary outcome and were adjusted by vertical mucosal thickness. Peri-implant clinical conditions and resonance frequency analysis were also compared. RESULTS: A total of 65 subjects with 99 implants were analysed. The overall 1-year implant survival rate between the 1- and 3-mm groups was 96.4% and 94.4%, respectively. Statistically significant lower inter-proximal marginal bone-level changes were observed in the 3-mm group (1 mm: -0.17 ± 0.02 mm at mesial and -0.21 ± 0.02 mm distal; 3 mm: -0.03 ± 0.02 mm at mesial and -0.03 ± 0.02 mm and distal; mesial: p = .001; distal: p < .001). Initial vertical mucosal thickness was not correlated with inter-proximal marginal bone loss. CONCLUSIONS: Subcrestal implants with 3-mm abutment were associated with minimal inter-proximal bone loss. Independent of the abutment height, crestal mucosal thickness was not correlated with bone loss.

Prevalence and risk/protective indicators of peri-implant diseases: A university-representative cross-sectional study.

AIM: To evaluate the prevalence of peri-implant diseases and to identify risk/protective indicators of peri-implantitis. MATERIALS AND METHODS: Two hundred and forty randomly selected patients from a university clinic database were invited to participate. Those who accepted, once data from their medical and dental history were collected, were examined clinically and radiographically to assess the prevalence of peri-implant health and diseases. Peri-implantitis was defined as the presence of BoP/SoP together with radiographic bone levels (BL) ≧2 mm. An intermediate peri-implant health category between peri-implant mucositis and peri-implantitis was also identified, defined by the presence of BoP/SoP together with 1 mm ≦BL < 2 mm. A multilevel multivariate logistic regression analysis was carried out to identify those factors associated either positively (risk) or negatively (protective) with peri-implantitis. RESULTS: Ninety-nine patients with a total of 458 dental implants were analyzed. The prevalences of pre-periimplantitis and of peri-implantitis were, respectively, 31.3% and 56.6% at patient-level, while 31.7% and 27.9% at implant level. The following factors were identified as risk indicators for peri-implantitis: smoking (OR = 3.59; 95% CI: 1.52-8.45), moderate/severe periodontitis (OR = 2.77; 95% CI: 1.20-6.36), <16 remaining teeth (OR = 2.23; 95% CI: 1.05-4.73), plaque (OR = 3.49; 95% CI: 1.13-10.75), implant malposition (too vestibular: OR = 2.85; 95% CI: 1.17-6.93), implant brand (Nobel vs. Straumann: OR = 4.41;95% CI: 1.76-11.09), restoration type (bridge vs. single crown: OR = 2.47; 95% CI: 1.19-5.12), and trauma as reason of tooth loss (vs. caries: OR = 6.51; 95% CI: 1.45-29.26). Conversely, the following factors were identified as protective indicators: interproximal flossing/brushing (OR = 0.27; 95% CI: 0.11-0.68), proton pump inhibitors (OR = 0.08; 95% CI: 0.01-0.90), and anticoagulants (OR = 0.08; 95% CI: 0.01-0.56). CONCLUSIONS: Peri-implant diseases are highly prevalent among patients with dental implants in this university-based population. Several factors were identified as risk- and protective- indicators of peri-implantitis.

Differences in the progression of experimental peri-implantitis depending on the implant to abutment connection.

OBJECTIVES: The aim was to evaluate the rate of bone loss progression during experimentally induced peri-implantitis using two different implant-abutment connections in implants with identical surface topography. MATERIAL AND METHODS: Forty-eight Regular Neck tissue-level SLA implants with a matching implant to abutment connection (TL) and 36 bone-level SLA implants with a switching platform implant to abutment connection (BL) were subjected to experimental peri-implantitis in two independent in vivo pre-clinical investigations. Experimental peri-implantitis was induced by means of silk ligatures during 3 months (induction phase), and followed for one extra month without ligatures (progression phase). Radiographic and clinical outcomes were evaluated longitudinally along both studies and subsequently compared between experiments. RESULTS: During the induction phase, radiographic bone loss was significantly higher in implants with matched abutments compared with those with platform switching connections (2.65 ± 0.66 mm vs 0.84 ± 0.16 mm, respectively, p = 0.001). During the progression phase, both types of implant-abutment connection exhibited similar rates of radiographic bone loss. Similar outcomes were observed clinically. CONCLUSIONS: A platform switching connection resulted in a more benign development of peri-implantitis during the experimental induction phase of the disease. These differences, however, disappeared once the ligatures were removed (progression phase). CLINICAL RELEVANCE: Influence of the implant-abutment connection in peri-implantitis progression may be relevant when considering implant selection in the moment of placement. In this sense, platform switching abutment demonstrated less peri-implantitis development when compared to implant matching connection.

Implant-prosthetic Rehabilitation with and without Platform Switching: A Retrospective Clinical Cohort Study.

AIM: The study aimed to retrospectively compare peri-implant bone loss, prosthetic complications, and patient-reported outcome measures (PROMs) after implant-prosthetic treatment on abutments with platform switch or platform match. MATERIALS AND METHODS: Records of patients, who received implant-prosthetic treatment on abutments with/without platform switch in a single dental clinic between November 2015 and November 2018, were retrospectively analyzed. Analysis was restricted to the following patient selection criteria: no need for any bone grafting procedures before/during implant placement, and no serious systemic disease. Implants were conventionally loaded with screwed prosthetic restorations after a healing period of 3 months. Crestal bone loss was measured by digital radiography at implant placement and after at least 2 years under functional implant loading conditions. Patient satisfaction was recorded with the visual analogue scale (VAS) at the time of the follow-up examination. RESULTS: Clinical records of 59 patients were available for analysis. Patients of the study cohort received in total 128 implants with different lengths and diameters according to the manufacturer's specifications. Prosthetic restorations were fixed either on abutments with platform switch (BEGO PS-UNI: n = 74; 57.8%) or platform match (BEGO SUB-TEC Universal: n = 54; 42.2%). No implant was lost and no failure of prosthetic restoration was recorded during follow-up, except for prosthetic screw loosening in 32 implants (25.0%). Abutment type and location (maxilla vs mandible) had a significant impact on peri-implant bone loss (OR = 3.4; 2.8). A significant reduced rate of bone loss was observed at implant sites, provided with abutments according to the platform switch concept (35.1 vs 64.8%). No significant correlation was recorded between less bone loss and a higher patient satisfaction, while loosening of the prosthetic screw was significantly associated with lower satisfaction scores. CONCLUSION: BEGO PS-UNI abutments with a platform switch design revealed significant less crestal bone loss after a mean observation period of 20.8 months. CLINICAL SIGNIFICANCE: Abutments with a platform switch design may lead to less peri-implant bone loss. In order to maintain a higher patient satisfaction, clinicians should focus on the quality of the implant-prosthetic connection in screwed restorations.

Platform switching in two-implant bar-retained mandibular overdentures: 1-year results from a split-mouth randomized controlled clinical trial.

OBJECTIVES: The concept of platform switching is widely applied in current implant dentistry; however, the influence on peri-implant bone-level alterations (ΔIBL), especially in the field of implant overdentures (IODs), remains inconclusive. Therefore, the present study aimed to test the alternative hypothesis that there is an equivalent ΔIBLs at platform-switching and platform-matching implant abutments in 2-implant bar-retained IODs. MATERIALS AND METHODS: Two interforaminal implants were placed in 32 subjects, who were randomly assigned to either an immediate- or a 3-month post-placement loading group. Furthermore, one implant in each subject was randomly assigned to receive a platform-switched abutment (test), and one a platform-matching abutment (control). The implants were splinted with prefabricated, chairside customized bars. ΔIBL was recorded by using customized radiograph holders at implant placement, implant loading, 3 months, 6 months, and 12 months after loading. RESULTS: After 1 year, equivalent ΔIBL could be identified (test: -0.51 mm ± 0.49 versus control: -0.56 mm ± 0.52; p < .001). ΔIBL increased over time and was more pronounced in the delayed-loaded implants (-0.87 mm ± 0.61) relative to the immediately loaded implants (-0.35 mm ± 0.43; p = .022). CONCLUSIONS: The prosthetic concept of platform switching does not necessarily lead to reduced bone loss. Immediate-loading of implants, primarily splinted with a bar, might be beneficial regarding peri-implant bone-level alterations over a short-term period.

Effect of different implant placement depths on crestal bone levels and soft tissue behavior: A 5-year randomized clinical trial.

OBJECTIVES: This randomized clinical trial analyzed the long-term (5-year) crestal bone changes and soft tissue dimensions surrounding implants with an internal tapered connection placed in the anterior mandibular region at different depths (equi- and subcrestal). MATERIALS AND METHODS: Eleven edentulous patients were randomly divided in a split-mouth design: 28 equicrestal implants (G1) and 27 subcrestal (1-3 mm) implants (G2). Five implants were placed per patient. All implants were immediately loaded. Standardized intraoral radiographs were used to evaluate crestal bone (CB) changes. Patients were assessed immediately, 4, 8, and 60 months after implant placement. The correlation between vertical mucosal thickness (VMT) and soft tissue recession was analyzed. Sub-group analysis was also performed to evaluate the correlation between VMT and CB loss. Rank-based ANOVA was used for comparison between groups (α = .05). RESULTS: Fifty-five implants (G1 = 28 and G2 = 27) were assessed. Implant and prosthetic survival rate were 100%. Subcrestal positioning resulted in less CB loss (-0.80 mm) when compared to equicrestal position (-0.99 mm), although the difference was not statistically significant (p > .05). Significant CB loss was found within the G1 and G2 groups at two different measurement times (T4 and T60) (p < .05). Implant placement depths and VMT had no effect on soft tissue recession (p > .05). CONCLUSIONS: There was no statistically significant difference in CB changes between subcrestal and equicrestal implant positioning; however, subcrestal position resulted in higher bone levels. Neither mucosal recession nor vertical mucosa thickness was influenced by different implant placement depths.

Influence of the implant-abutment connection on the ratio between height and thickness of tissues at the buccal zenith: a randomized controlled trial on 188 implants placed in 104 patients.

BACKGROUND: To compare tissue response to two implant systems, featuring internal hexed connections with different designs. METHODS: Patients enrolled in this randomized controlled trial were assigned to two groups. In Group 1, patients were treated with implants with a 5° conical internal hexed connection (Anyridge®, MegaGen, South Korea). In Group 2, patients were treated with implants with an internal hexed connection (Core®, Kristal, Italy). After implant placement and a provisionalisation period of 12 months, impressions were taken, stone casts were poured and digitised with a desktop scanner (D700®, 3Shape, Copenhagen, Denmark). In a digital environment, for each fixture, two values were collected at the buccal zenith: the height of the peri-implant mucosa (mucosal height; MH), calculated from the vestibular shoulder of the implant analogue to the upper gingival margin of the supra-implant tissue; and the width of the peri-implant mucosa (mucosal thickness; MT), calculated from the vestibular shoulder of the analogue to the external mucosa point perpendicular to the implant major axis. The mean and standard deviation for MH and MT, as well as their ratios, were calculated for each group; the sectors in which the implants were placed were also considered. Finally, correlation between MH, MT, connection type and sector was assessed by Pearson's correlation coefficient, with significance level set at 0.05, and a confidence interval (CI) set at 95%. RESULTS: Data deriving from 188 implants placed in 104 patients were evaluated. The mean MH values were 3.32 (± 0.12) and 2.70 (± 0.16) mm for Groups 1 and 2, respectively. The mean MT values were 4.37 (± 0.16) and 3.93 (± 0.18) mm for Groups 1 and 2, respectively. Group 1 showed higher MH and MT values and a better ratio (1.50 ± 0.88) than Group 2 (1.81 ± 1.20). The MH, MT and MH/MT ratio were significantly influenced both by sector (p = 0.015) and group (p = 0.047). CONCLUSIONS: Within the limits of this study, the 5° connection implants supported a more extended tissue height and thickness at the buccal zenith, and a better ratio between them. TRIAL REGISTRATION: This study was retrospectively registered in Clinicaltrials.gov, with number NCT04160689, dated 13/11/2019.

Comparative Evaluation of Stress Distribution around Various Threaded Implants with and without Platform Switch: A 3-D Finite Element Analysis.

AIM: The purpose of this study was to compare the stress distribution around various thread design implants with or without platform switching in the maxillary posterior region. MATERIALS AND METHODS: Stress-based performances of four different thread design implants (single, double, triple, and asymmetric thread design each with or without platform switching) were analyzed by the three-dimensional finite element method under a static load of 100 N at 15° oblique direction buccolingually at the central portion of the abutment. A geometric model of the posterior maxillary segment (first molar region) with an implant and abutment was modeled using the CATIA V5R19 software. Type IV bone quality was approximated and complete osseous integration was assumed. RESULTS: The von Mises stresses recorded around the neck of the fourthread design implants without platform switching were greater than the platform switching variety. The single-threaded implant with platform switching showed the lowest amount of von Mises stress. Additionally, total displacement or micromovement of single, triple, and asymmetric thread implants with platform switching was found to be greater than the without platform switching variety. Further, the total displacement of the single-threaded implant without platform switching was lowest. CONCLUSION: Implant surface design, platform switching, and site of placement affect load transmission mechanisms. Due to low crestal resorption, single thread design with platform switching is preferred. The success of an implant in the maxillary molar region is more challenging in terms of the density of bone and the worst load transfer mechanism. With the right kind of implant surface design selection, this can be reduced to a great extent by the preservation of crest of the ridge. CLINICAL SIGNIFICANCE: Crestal bone resorption following implant placement is an important issue. An optimum implant design with a single thread having a platform switch could compensate for this issue to a great extent.

Peri-implant marginal bone loss reduction with platform-switching components: 5-Year post-loading results of an equivalence randomized clinical trial.

AIM: To compare the clinical performance and marginal bone levels of implants restored with platform-switching (PS) or platform-matching (PM) abutments. MATERIALS AND METHODS: Adult patients missing two or more adjacent teeth in the posterior mandible received 2-4 CAMLOG SCREW-LINE implants and were randomly allocated to the PM or PS group, receiving the corresponding prosthetic components from surgery onwards. Implants were conventionally loaded with single cemented crowns. Patients were followed annually for 5 years. Outcome measures were marginal bone level changes, implant survival, performance of the prosthetic components and clinical parameters plaque index, sulcus bleeding index and pocket probing depth. RESULTS: Thirty-three patients received 72 implants in the PM group, and thirty-five patients received 74 implants in the PS group. Sixty patients attended the final appointment, 31 had received PS components and 29 had received PM components with 65 and 63 implants, respectively. Global survival rate was 96.6% with no differences between groups (p = 0.647). After 5 years of functional loading, PS restored implants presented 0.23mm (95% CI: [0.03, 0.43], p = 0.025) lower marginal bone level changes. The two groups were declared non-equivalent. CONCLUSION: Patients requiring implant supported restorations in healed bounded or free end edentulous gaps of the mandible benefit from the use of PS components in terms of peri-implant marginal bone level maintenance, though it may not be clinically noticeable.

Discomfort/pain due to periodontal and peri-implant probing with/without platform switching.

OBJECTIVE: To compare discomfort/pain following periodontal probing around teeth and peri-implant probing around implants with or without platform switching. METHODS: Two dentists recruited and examined 65 patients, each of them exhibiting a dental implant with a contralateral tooth. Only two types of implants were included: one with and one without platform switching. Periodontal and peri-implant probing depths (PPD) and probing attachment level (PAL) were assessed. Whether implant or tooth was measured first was randomly assigned. Immediately after probing, patients scored discomfort/pain using a visual analogue scale (VAS). The emergence profiles of implant crowns were assessed as angles between interproximal surfaces on radiographs. RESULTS: Sixty-five patients (age 69; 63/76 years [median; lower/upper quartile]; 38 females, 11 smokers) were examined. With the exception of mean PPD and PAL (p < .05) clinical parameters (PPD, PAL, bleeding on probing, suppuration) were well balanced between implants and teeth. Peri-implant probing (VAS: 10; 0.75/16.25) caused significantly (p < .001) more discomfort/pain than periodontal probing (4; 0/10). Logistic regression analysis identified a larger difference between discomfort/pain for peri-implant and periodontal probing in the maxilla than the mandible (p = .003). Comparing discomfort/pain between implants maxilla (p = .006) and emergence profile (p = .015) were associated with discomfort/pain. Type of implant (with/without platform switching) had no significant effect on discomfort/pain. CONCLUSIONS: Peri-implant probing caused significantly more discomfort/pain than periodontal probing. Implant design with/without platform switching failed to have a significant effect on discomfort/pain.

Biological width establishment around dental implants is influenced by abutment height irrespective of vertical mucosal thickness: A cluster randomized controlled trial.

OBJECTIVE: Prosthetic abutment height and peri-implant mucosal thickness are considered factors that influence marginal bone remodeling during biological width establishment around dental implants. However, no clinical studies have evaluated their simultaneous effect on marginal bone loss (MBL). This study analyzes the influence of abutment height on MBL around implants surrounded by both thin and thick mucosa up to 12 months after prosthetic loading. MATERIAL AND METHODS: Seventy platform-switched implants with internal hex were placed equicrestally in two groups of patients with different vertical mucosal thickness: thin (≤2.0 mm) and thick mucosa (>2.0 mm). After three months of submerged healing, prosthetic abutments with a height of 1 mm (short) or 3 mm (long) were randomly assigned for single crown screwed restoration in both groups. MBL was evaluated on radiographs taken at implant placement (T0 ), restoration delivery (T1 ), and after 6 months (T2 ) and 12 months (T3 ) of loading. RESULTS: After 12 months of loading, 66 implants were functioning (two dropouts, two failures), resulting in a 97% survival rate. Compared with T0 , mean MBL at T3 ranged between 0.59 and 0.80 mm in short abutment groups and between 0.28 and 0.37 mm in long abutment groups. Differences resulted statistically significant, irrespective of vertical peri-implant mucosal thickness. The MBL pattern over time showed the greatest amount of bone resorption in the first 6 months after loading, particularly around implants with short abutments. CONCLUSIONS: Platform-switched implants restored with short abutments present greater marginal bone loss than identical implants with long abutments, without significant peri-implant mucosal thickness effects.

Influence of abutment height and implant depth position on interproximal peri-implant bone in sites with thin mucosa: A 1-year randomized clinical trial.

OBJECTIVES: The aim of this RCT was to assess radiographically the effect of abutment height and depth of placement of platform-switched implants on interproximal peri-implant bone loss (IPBL) in patients with thin peri-implant mucosa. MATERIAL AND METHODS: Thirty-three patients received one prosthesis supported by two implants replacing at least two adjacent missing teeth (66 implants). Patients were randomly allocated and implant insertion depth adapted to abutment height groups (3 mm height group the implants were placed 2 mm subcrestally; 1 mm height group, equicrestally). Clinical and radiological measurements were performed at 3, 6 and 12 months after surgery. Interproximal bone-level changes were compared between treatment groups using repeated measures mixed ANOVA. The association between IPBL and categorical variables was also analyzed. RESULTS: The mean IPBL in 1 mm abutment group was 0.76 ± 0.79 mm at 3 months, 0.92 ± 0.88 mm at 6 months, and 0.95 ± 0.88 mm at 12 months, while in the 3 mm abutment group was 0.06 ± 0.21, 0.07 ± 0.22 mm, and 0.12 ± 0.33 mm, respectively. Significant differences between both groups were observed at every time point. When the influence of patient characteristics and clinical variables was analyzed, no statistically significant differences were also observed. CONCLUSIONS: The use of long abutments, in combination with subcrestal implant position in sites with thin mucosa, led to lower IPBL in comparison with the use of short abutments.

Evaluation of peri-implant marginal tissues around tissue-level and bone-level implants in patients with a history of chronic periodontitis.

OBJECTIVE: To evaluate clinical and radiographic characteristics in peri-implant marginal tissues in patients with a history of chronic periodontitis, rehabilitated using tissue-level or bone-level implants. MATERIAL AND METHODS: Using a split-mouth design, 20 patients with a history of chronic periodontitis were selected and received two different implants, tissue-level group (n = 20) and the bone-level group (n = 20). Peri-implant probing depth, relative peri-implant mucosal margin position, relative peri-implant clinical attachment level, peri-implant plaque index and peri-implant bleeding on probing were evaluated at prosthesis installation, 1, 3, 6, 12 and 24 months after implant loading. Radiographic marginal bone level was evaluated at implant insertion, prosthesis installation, 6 and 24 months after implant loading. RESULTS: The mean difference of peri-implant marginal bone resorption from implant installation to 24 months in function was 0.75 ± 1.12 mm for the tissue-level group and 0.70 ± 0.72 mm for the bone-level group. No statistically significant difference was found between groups at all assessment periods for clinical and radiographic peri-implant evaluation. CONCLUSION: Under a rigid supportive therapy, both approaches performed likewise regarding clinical and radiographic parameters for rehabilitation of patients with a history of chronic periodontitis.