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.

Clinical and Radiographic Outcomes of a New Fully Tapered Implant with the One-Abutment One-Time Approach: In-Line Clinical Case Series with a 1-Year Follow-up

PURPOSE

To evaluate the bone level changes in a new implant design (fully tapered with platform switching) with the one-abutment one-time protocol after 1 year of loading.

MATERIALS AND METHODS

Thirty patients received 1 or 2 implants (6-, 8-, or 10-mm length and 3.5-, 3.75-, or 4.5-mm diameter, bone-level design) to replace one or multiple edentulous sites. Only the mesial implant was assessed. Radiographic, clinical, and esthetic results and the survival and success rates were evaluated 1 year after final loading.

RESULTS

At 1 year, no peri-implant bone loss was seen in any of the cases. Mean marginal crestal bone loss between surgery and crown placement was 0.19 ± 0.17 mm (P < .0001). Between surgery and the 1-year follow-up, the mean marginal crestal bone loss was 0.25 ± 0.24 mm (P < .0001). The difference in the modified Plaque Index between 1 year of follow-up and crown placement was significant for in the mesial (0.33 ± 0.54 mm; P = .003) and distal surfaces (0.5 ± 0.73 mm; P = .001). The probing pocket depth was statistically significantly deeper at 1 year than at crown placement at the mesial and distal aspects (average depth = 0.75 mm; P < .0005). No statistically significant differences were found for any other clinical or esthetic parameters. The overall survival and success rates after 1 year were 100%.

CONCLUSIONS

The fully tapered, deep-thread, platform-switched implant design placed with the one-abutment one-time protocol demonstrated minimal marginal crestal bone loss and crestal bone stability at 1 year of follow-up.

Clinical and radiographic results of crestal vs. subcrestal placement of implants in posterior areas: A split-mouth randomized controlled clinical trial

OBJECTIVE

The objective of this study was to evaluate the peri-implant soft tissue and marginal bone loss (MBL) around implants with platform-switching and internal conical connection placed at crestal and subcrestal levels in posterior areas.

MATERIALS AND METHODS

Nineteen partially edentulous patients with at least two adjacent missing teeth in posterior areas unilaterally or bilaterally were included. Forty-two implants were placed randomly at the crestal or subcrestal (1 mm) level in a split-mouth design. Implant-supported fixed dental prostheses with screw retention were delivered after 4 months of healing. Clinical and radiological measurements were performed at implant placement (T0), restoration delivery (T1), and 1-year follow-up after loading (T2). MBL was calculated as the change in distance from the implant-abutment interface to the first radiographically visible bone-implant contact. A repeated-measures mixed ANOVA followed by a paired Student's t-test with the Bonferroni correction was used for statistical analysis. p < 0.05 was considered statistically significant.

RESULTS

Eighteen patients with thirty-eight implants completed the study at T2. The MBL was lower in the subcrestal group than in the crestal group (0.04 ± 0.08 vs. 0.17 ± 0.17 mm, p = 0.004). The peri-implant probing depth (PD) was 2.31 ± 0.48 mm in the subcrestal group and 1.92 ± 0.43 mm in the crestal group; this difference was statistically significant (p = 0.002). Intragroup comparison showed no significant differences in MBL, or PD around the crestal group and subcrestal group from T1 to T2.

CONCLUSION

After 1 year of functional loading, subcrestal placement of implants with platform-switching and internal conical connection showed lower MBL and was associated with greater PD and peri-implant soft tissue height than implants placed at the crestal level.

One-Year Outcomes of Subcrestal Platform-Switched Implants With and Without Sterile Prosthetic Abutments: A Randomized Controlled Trial

Surface contaminants on customized implant abutments could trigger inflammatory response in the peri-implant tissues. The aim of this randomized controlled study was to assess the radiographic bone changes around implants restored with customized, platform-switched abutments, with and without autoclave treatment, 12 months after definitive restoration. Dental implants were placed 1 mm subcrestally in 64 systemically healthy patients (mean age 63.3 ± 10.0 years, 31 with history of periodontitis) to replace single or multiple missing teeth. According to a randomization list, abutments were subjected to steam and autoclave sterilization (43 implants, test group) or steam cleaning alone (44 implants, control group). Periapical standardized radiographs were taken at the time of implant insertion, prosthetic abutment connection and 12 months after definitive cement-retained restoration. All implants were clinically stable without any sign of infection at the 12-month follow-up. An average marginal bone loss of 0.25 ± 0.19 mm was found in the test group compared to 0.35 ± 0.23 mm in the control group without statistically significant difference, while the percentage of bleeding sites was significantly higher in the control group (8.7 ± 13.1% versus 19.1 ± 19.8%, P = .035). Autoclave treatment of customized abutments would seem to reduce the inflammatory response around subcrestally placed implants.

Impact of Platform Switched Implants on Marginal Bone Level in Mandibular Overdentures: A Six-Year Follow-Up Longitudinal Study

PURPOSE

To evaluate the impact of the platform-switched implant on marginal bone loss (MBL) and the probing pocket depth (PPD) in patients wearing mandibular overdenture.

PATIENTS AND METHODS

This longitudinal study included 40 completely edentulous patients aged 51-64 years. All patients received complete dentures and were distributed into two groups randomly; 20 patients each. The first group GI received two platform switched implants; however, the 2nd group GII received two platform matched implants (3.6 × 11.5 mm) in the canine region of the mandible. The radiographic evaluations were carried out every year for six years, whereas probing pocket depth was evaluated every six months for 72 months for both groups. The data were analyzed by repeated ANOVA, Friedman's, and Student's t-test.

RESULTS

This study included 36 patients; 56 ± 3.6 years was the mean age; 17 females (47%) and 19 males (53%) completed the study. Statistically significant differences were observed in MBL and PPD in each of GI and GII after 6 years, p ≤ 0.05. Between GI and GII after 6 years, a statistically insignificant difference was detected in MBL or PPD, p ≥ 0.05, except in PPD at loading, 2 and 6 years, p ≤ 0.05.

CONCLUSION

Time positively affected MBL and PPD in platform switched and matched implants retained mandibular overdentures. Platform switching influences probing pocket depth in implants retained mandibular overdentures.

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.

The influence of new immediate tissue level abutment on crestal bone stability of subcrestally placed implants: A 1-year randomized controlled clinical trial

BACKGROUND

The relation between implant abutment disconnection (AD) and increased crestal bone loss is still debated.

PURPOSE

To compare bone changes below implant-abutment junction of subcrestally placed implants between: (1) implant level restorations, that underwent four ADs and (2) implants with immediate tissue level abutment with no AD, 1 month (T2) and 1-year (T3) after final restoration delivery.

MATERIALS AND METHODS

Sixty-four patients received 64 bone level implants with platform-switching and conical connection in edentulous sites of posterior mandible and maxilla. All implants were placed 1.5 mm subcrestally and distributed among: (1) control group, that received a regular healing abutment and (2) test group with immediate tissue level (ITL) abutment, which was torqued to implants during surgery, transforming bone level implant to tissue level type. After 2-3 months of healing and a 1-month temporization, final zirconia-based screw-retained crowns were delivered to both groups. Crestal bone levels were calculated after final crown delivery (T2); after 1-year follow-up (T3) and compared using Mann-Whitney U test (p ≤ .05).

RESULTS

Early bone loss of the test and control groups was 0.14 ± 0.27 mm and 0.64 ± 0.64 mm, respectively; the 0.5 mm difference was statistically significant (p = .0001). Late bone loss was 0.06 ± 0.16 mm and 0.21 ± 0.56 mm for the test and control group, respectively; the 0.15 mm difference between the groups was no more statistically significant (p = .22). Both groups displayed bone gain, 0.08 and 0.43 mm, respectively, and the overall crestal bone loss was reduced.

CONCLUSIONS

Immediate tissue level abutments can significantly reduce early bone loss when measured 1 month after final prosthesis delivery, however, after 1-year follow-up, difference between the groups was no more statistically significant.

Effect of soft tissue thickness on crestal bone loss of early loaded implants with platform switching: 1- and 5-year data

Objectives: The aim of this retrospective study was to evaluate the effect of vertical soft tissue thickness (STT) on crestal bone loss (CBL) of early loaded implants after 1 and 5 years. Method and materials: Forty-four tapered implants with platform switching and conical connection were placed in the posterior mandible and maxilla to rehabilitate edentulous sites. STT at implant sites was divided into two groups: thin (n = 21, mean STT = 2.0 ± 0.3 mm) and thick (n = 23, mean STT = 3.0 ± 0.8 mm). The implants were loaded after 6 to 8 weeks. Survival and success rates and CBL were measured after 1 and 5 years. Results: The survival and success rates at 1 and 5 years were 100% and 97.8%, respectively. At the 1-year follow-up, the CBL of the thin and thick gingival groups was 0.96 ± 0.49 and 0.55 ± 0.41 mm, respectively; the difference was statistically significant (P = .004). At 5 years, the CBL of the thin and thick gingiva groups increased to 1.12 ± 0.84 and 0.65 ± 0.69 mm, respectively; the difference was not statistically significant (P = .052). Conclusion: At 1 year, the CBL was more pronounced at sites with a thin gingiva; at 5 years the difference between the groups was not statisically significantly different. Within the limitations of this study, early loading of implants with platform switched and conical connection was safe.

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.

Influence of abutment height and vertical mucosal thickness on early marginal bone loss around implants: A randomised clinical trial with an 18-month post-loading clinical and radiographic evaluation

PURPOSE

To investigate the influence of vertical mucosal thickness on marginal bone loss around implants with short and long prosthetic abutments and the marginal bone loss progression rate up to 18 months after prosthetic loading.

MATERIALS AND METHODS

Internal hex platform-switched implants were placed equicrestally using a two-stage protocol in the posterior mandible of two groups of patients with different vertical mucosal thickness, thin (≤ 2.0 mm) and thick (> 2.0 mm). Elevated prosthetic abutments of different heights (1 mm or 3 mm) were randomly assigned for single screw-retained crowns in both groups. Mesial and distal marginal bone loss were measured at implant placement (T0) and crown delivery (after 4 months [T1]), and after 6 (T2), 12 (T3) and 18 months (T4) of functional loading.

RESULTS

Eighty implants were placed in eighty patients. Three patients dropped out at T2. At T4, 74 out of 77 implants were functioning, resulting in a 96% survival rate. Marginal bone loss (mean ± SE) at T2 was significantly greater in the 1-mm abutment groups (0.61 ± 0.09 mm with thin mucosa; 0.64 ± 0.07 mm with thick mucosa) than in the 3-mm abutment groups (0.32 ± 0.07 mm with thin mucosa; 0.26 ± 0.04 mm with thick mucosa). The marginal bone loss pattern over 18 months of loading showed that the greatest amount of marginal bone loss occurred during the first 6 months of function.

CONCLUSIONS

Internal hex platform-switched implants placed equicrestally and restored with 1-mm abutments presented greater marginal bone loss than identical implants with 3-mm abutments, with vertical mucosal thickness having no significant influence.

Platform switching versus regular platform single implants: 5-year post-loading results from a randomised controlled trial

PURPOSE

To compare the clinical and radiographic outcomes of platform switching (PS) and regular platform (RP) implants.

MATERIALS AND METHODS

This study was designed as a randomised controlled split-mouth trial. Eighteen patients, with bilaterally missing single premolars or molars to be restored with implant-supported single crowns, were consecutively enrolled. Implant sites were randomly assigned to be treated according to the PS concept (PS group), or with matching implant-abutment diameters (RP group). A total of 36 implants were placed in healed bone, with an insertion torque between 35 and 45 Ncm, according to a one-stage protocol. All the implants were loaded with a screw-retained provisional crown 3 months after implant insertion. Definitive screw-retained single crowns were delivered 2 months later. Outcome measures were implant and prosthetic survival rates, biological and prosthetic complications, marginal bone level (MBL) changes, pocket probing depth (PPD) and bleeding on probing (BOP). Clinical data were collected at implant placement (baseline), implant loading (3 months later) and at 9, 36 and 60 months after loading.

RESULTS

One patient dropped out after 4 years of follow-up. No implant failed and no prosthetic complications were recorded during the study period. One patient experienced mucosal inflammation with positive BOP (RP group) after 3 months and three patients had bilateral peri-implant mucosal inflammation with positive BOP at 6, 24 and 36 months, respectively. No other biological complications were recorded up to 60 months of follow-up. There were no statistically significant differences between groups for complications (3/18 versus 4/18; P = 1.0). Nine months after loading the mean MBL was 0.93 ± 0.26 mm (95% CI 0.81 to 1.05) for RP implants and 0.84 ± 0.23 mm (95% CI 0.73 to 0.95) for PS implants. No statistically significant difference was observed between the groups (P = 0.18). Thirty-six months after loading, the mean MBL was 1.09 ± 0.31 mm (95% CI 0.95 to 1.24) in the RP group and 1.06 ± 0.24 mm (95% CI 0.94 to 1.17) in the PS group, with no statistically significant difference between groups (P = 0.70). Sixty months after loading the mean MBL was 1.24 ± 0.39 mm (95% CI 1.05 to 1.43) in the RP group and 1.20 ± 0.21 mm (95% CI 1.01 to 1.39) in the PS group, with no statistically significant difference between the groups (P = 0.85). The mean PPD was 2.58 ± 0.58 mm (95% CI 2.32 to 2.84) in the RP group and 2.40 ± 0.72 mm (95% CI 2.21 to 2.59) in the PS group at 60 months follow-up, with no statistically significant difference between the groups (P = 0.49). The mean BOP was 0.90 ± 0.88 (95% CI 0.58 to 1.22) in the RP group and 0.93 ± 0.97 (95% CI 0.51 to 1.35) in the PS group at 60 months of follow-up, with no statistically significant difference between the groups (P = 0.85).

CONCLUSIONS

Implants restored according to the PS concept and matching implant-abutment diameters showed comparable clinical and radiographic results up to 5 years after loading.

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.

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.

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.

Evaluation of the Peri-Implant Bone Level around Platform-Switched Dental Implants: A Retrospective 3-Year Radiographic Study

OBJECTIVE

To describe remodeling of the mesial and distal marginal bone level around platform-switched (PS) and platform-matched (PM) dental implants that were sandblasted with large grit and etched with acid over a three-year period.

MATERIALS AND METHODS

Digital periapical radiographs were obtained at the following time-points: during Stage I of the surgical placement of dental implants, before loading, immediately after loading (baseline), and one, three, six, 12, and 36 months after loading for measuring the horizontal and vertical marginal bone levels.

RESULTS

Sixty implants were successfully osseointegrated during the overall observation period. Vertical marginal bone levels for the PS and PM dental implants were 0.78 ± 0.77 and 0.98 ± 0.81 mm, respectively, whereas the horizontal marginal bone levels for the PS and PM implants were 0.84 ± 0.45 and 0.98 ± 0.68 mm, respectively. During the time leading up to the procedure until 36 months after the procedure, the average vertical marginal bone level resulted in less bone loss for the PS and PM groups-0.96 ± 1.28 and 0.30 ± 1.15 mm, respectively (p < 0.05). The mean levels of the horizontal marginal bone also showed increases of 0.48 ± 1.01 mm in the PS and 0.37 ± 0.77 mm in the PM groups from the time before loading until 36 months after the procedure. However, these increases were not statistically significant (p > 0.05).

CONCLUSION

PS dental implants appeared to be more effective than PM implants for minimizing the mean marginal vertical and horizontal marginal bone loss during the three-year period. Regardless of which abutment connection was used, the dental implant in the present retrospective investigation exhibited minimal marginal bone remodeling, thus indicating long-term stability.

Ratio between Height and Thickness of the Buccal Tissues: A Pilot Study on 32 Single Implants

BACKGROUND

Previous studies have suggested that mucosal height is related to the bone level and soft tissue thickness. The purpose of this pilot study was to investigate the ratio between the height and width of the tissues around single implants with a conical connection and platform switching.

METHODS

All patients receiving single implants (Anyridge^®, MegaGen, Gyeongbuk, South Korea) and restored with single crowns, in a three-month period, were included in this study. After a provisionalization of 12 months, precision impressions were taken and stone casts were poured for measurements. For each implant, two values were collected at the buccal site: the mucosal height (MH), calculated from the vestibular shoulder of the implant to the upper gingival margin of the supra-implant tissue; and the mucosal thickness (MT), calculated from the vestibular shoulder of the analogue to the external mucosa point perpendicular to the implant major axis. Mean, standard deviation (SD), and confidence intervals (CI 95%) for MH and MT, as well as their ratios, were calculated. Correlation between MH and MT was assessed by Pearson's correlation coefficient, with significance level set at 0.05.

RESULTS

32 single Anyridge^® implants were eligible for this evaluation. The mean MH was 3.44 mm (±1.28), the mean MT was 3.29 (±1.46). The average of the ratio between MH and MT of the supra-implant mucosa was therefore 1:1.19 (±0.55). The relation between MH and MT was statistically significant at p ≤ 0.01 (Pearson two-tailed 95% CI).

CONCLUSIONS

Our study found a constant relationship between width and height of the peri-implant mucosa. However, our results are different from those of Nozawa et al., who found a ratio of 1:1.5 between height and thickness of the peri-implant tissues. This may be determined by the different sample and follow-up period, as well as by the implants used in our study.

Platform switching technique and crestal bone loss around the dental implants: A systematic review

Background:

The overall success of dental implants depends on the crestal bone support around the implants. During the initial years of dental implant placement, the bone loss around the implants determines the success rate of treatment. Platform switching (PLS) concept preserves the crestal bone loss, and this approach should be applied clinically for the overall success of dental implants.

Purpose:

The purpose of this study is to discuss the literature dealing with the concept of PLS concept and preservation of marginal bone, the mechanism by which it contributes to maintenance of marginal bone, its clinical applications, advantages, and disadvantages, to assess its survival rates.

Materials and Methods:

PubMed and Google Scholar search was done to find out the studies involving PLS concept from 2005 to 2017. Data were analyzed using SPSS statistical software.

Results:

Literature search revealed studies involving concepts of PLS, comparison of platform-switched and nonplatform-switched implants, case reports on PLS, and studies with histological and finite element analyses regarding PLS.

Conclusion:

PLS helps preserve crestal bone around the implants, and this concept should be followed when clinical situations in implant placement permit.

Bone Level Measurements Around Platform Switched and Platform Matched Implants: A Comparative Study

BACKGROUND

The overall success of dental implants depends on the crestal bone support around the implants. During the initial years, the bone loss around the implants determines the success rate of treatment. Platform switching (PLS) preserves the crestal bone loss, and this approach must be applied clinically.

AIM

The purpose of this study was to determine the changes in vertical and horizontal marginal bone levels in platform-switched and platform-matched dental implants.

MATERIALS AND METHODS

One fifty patients received one fifty dental implants in the present study over a 1-year period. Measurement was performed between the implant shoulder and the most apical and horizontal marginal defect by periapical radiographs to examine the changes of peri-implant alveolar bone before and 12 months after prosthodontic restoration delivery.

RESULTS

These marginal bone measurements showed a bone gain of 1.56 ± 2.4 mm in the vertical gap and 1.49 ± 2.24 mm in the horizontal gap of the platform matching, while in the PLS, a bone gain of 2.67 ± 2.0 mm in the vertical gap (P < 0.05) and 2.89 ± 1.67 mm in the horizontal gap was found. Only a statistically significant difference was found comparing bone gains in the vertical gap between the two groups (P < 0.05).

CONCLUSION

PLS helps preserve crestal bone around the implants, and this concept should be followed when clinical situations in implant placement permit.

Peri-implant tissue healing at implants with different designs and placement protocols: An experimental study in dogs

OBJECTIVES

To compare the peri-implant tissue response to subcrestal or crestal placement of implants with or without "platform-switched" implant/abutment connections.

MATERIAL AND METHODS

On each side of the mandible in six Labrador dogs, two "platform-switched" (PS) implants and two implants with matching implant/abutment diameters (PM) were placed in a crestal or a 1.5 mm subcrestal position. Sulcus formers/abutments were connected, baseline radiographs obtained and the distance between the abutment-fixture junction (A/F) and the marginal bone level (B) was determined. Five months later, radiographic and clinical examinations were repeated and biopsies were obtained and processed for histological analysis.

RESULTS

The radiographic analysis showed that marginal bone level changes occurred during the first observation period (13 weeks). PS-implants showed minor marginal bone level alterations during the full observation period (20 weeks), regardless of placement depth. For PM-implants, placement had a significant impact on bone level changes; crestal placement resulted in a mean bone loss of 0.4 mm and subcrestal placement in a 1.5 mm bone loss. The histometric measurements resulted in a distance A/F-B of 0.6 and 0.0 mm for PS implants, placed in a crestal or subcrestal position, respectively. The corresponding distance at PM-implants was 1.5 mm irrespective of placement protocol. The peri-implant mucosa was thicker at subcrestally placed implants as compared to a crestal placement.

CONCLUSIONS

Bone remodeling occurred within the early healing phase. During the full 20 weeks of observation, PS-implants demonstrated significantly less crestal bone loss compared to PM-implants.

Impact of platform switching on inter-proximal bone levels around 8.5 mm implants in the posterior region; 5-year results from a randomized clinical trial

AIM

To assess the medium-term results of 8.5 mm implants supplied with a conventional platform-matched implant-abutment connection or a platform-switched design.

MATERIALS AND METHODS

Eighty patients with one or more missing teeth in the maxillary or mandibular posterior zone were randomly assigned for treatment with implants with a conventional (control group) or platform-switched (test group) implant-abutment connection. Follow-up visits were conducted 1 month, 1 year and 5 years after functional loading. Inter-proximal bone loss, assessed with standardized peri-apical radiographs, clinical parameters, survival of implants and satisfaction of patients were the outcome parameters studied.

RESULTS

After 5 years of loading, five of the 80 patients were lost to follow-up. The inter-proximal bone loss in the test group (0.38 ± 0.61 mm) was comparable to the bone loss in the control group (0.41 ± 0.47 mm; p = 0.201). Remarkably, bone loss has not progressed compared to the 1-year results. Implant survival, clinical parameters and satisfaction of the patients were favourable and comparable for the test and control group.

CONCLUSION

The 5-years results showed that inter-proximal bone resorption was minor and comparable around platform-matched and platform-switched implants, and implant survival, peri-implant health and patients' satisfaction were favourable.

Effect of platform switching on crestal bone levels around implants in the posterior mandible: 3 years results from a multicentre randomized clinical trial

Objective

Evaluation of differences in the clinical performance and crestal bone levels between implants restored with single crowns with platform‐matched or platform‐switched abutments after 3 years.

Material and Methods

The study enrolled adult patients missing two or more adjacent teeth in the posterior mandible with natural teeth mesial to the implant site. Randomization followed open‐flap implant insertion and the corresponding matching or switching healing abutments placed at surgery. Conventional loading was made with cemented crowns. Clinical follow‐up took place annually after loading up to 3 years. Bone level changes were measured in standardized radiographs as the variation in crestal bone from one evaluation to the next.

Results

Sixty‐three patients with a total of 135 implants (66 platform matching, 69 platform switching) were analysed. From surgery to 36 months, mean bone loss was 0.28 ± 0.56 mm for the platform‐switching group and 0.68 ± 0.64 mm for the platform‐matching group. A statistically significant difference was found between groups (p = 0.002) with an estimate of 0.39 mm (0.15–0.64, 95% CI) in favour of platform switching.

Conclusions

After 3 years, platform‐switching restorations showed a significant effect in the preservation of marginal bone levels compared to platform‐matching restorations.

The effect of one-time abutment placement on interproximal bone levels and peri-implant soft tissues: a prospective randomized clinical trial

OBJECTIVE

To compare the effect of placing the definitive abutment at the time of implant placement versus at a later stage, on the soft and hard tissue changes around dental implants.

MATERIAL AND METHODS

Platform-switched implants were placed in the posterior maxilla or mandible of partial edentulous patients and they were randomized to receive the definitive abutment at the moment of implant placement, or 6-12 weeks later. Final prostheses were delivered 2-4 weeks later. Radiographic assessment of vertical bone level changes (primary outcome), clinical status of peri-implant tissues, changes in soft tissues margin, papilla filling, patient-related outcomes and adverse events were assessed 6 and 12 months after loading.

RESULTS

60 implants were placed in 40 patients, replacing single or multiple absent teeth. One implant was lost 1 week after insertion (overall survival rate: 98.3%). A statistically significant greater bone resorption from surgery to 6 months post-loading was observed for those implants subjected to abutment change (control group: -1.24 ± 0.79 mm; test group: -0.61 ± 0.40 mm; P = 0.028). Periodontal clinical parameters and patient-related outcomes, however, did not demonstrate significant differences between groups at any time point. A significant increase in papilla height was observed from loading to 12 months in all implants (control group: 1.17 ± 1.47 mm; test group: 0.98 ± 0.89 mm) and a slight but not significant coronal migration of the gingival margin.

CONCLUSIONS

The connection and disconnection of healing abutments is associated with significantly increased bone loss during the healing period between implant placement and 6 months post-loading, when compared to one-time abutment placement.

Morse taper dental implants and platform switching: The new paradigm in oral implantology

The aim of this study was to conduct a literature review on the potential benefits with the use of Morse taper dental implant connections associated with small diameter platform switching abutments. A Medline bibliographical search (from 1961 to 2014) was carried out. The following search items were explored: “Bone loss and platform switching,” “bone loss and implant-abutment joint,” “bone resorption and platform switching,” “bone resorption and implant-abutment joint,” “Morse taper and platform switching.” “Morse taper and implant-abutment joint,” Morse taper and bone resorption,” “crestal bone remodeling and implant-abutment joint,” “crestal bone remodeling and platform switching.” The selection criteria used for the article were: meta-analysis; randomized controlled trials; prospective cohort studies; as well as reviews written in English, Portuguese, or Spanish languages. Within the 287 studies identified, 81 relevant and recent studies were selected. Results indicated a reduced occurrence of peri-implantitis and bone loss at the abutment/implant level associated with Morse taper implants and a reduced-diameter platform switching abutment. Extrapolation of data from previous studies indicates that Morse taper connections associated with platform switching have shown less inflammation and possible bone loss with the peri-implant soft tissues. However, more long-term studies are needed to confirm these trends.

Comparison of clinical and radiographic status of platform-switched implants placed in patients with and without type 2 diabetes mellitus: a 24-month follow-up longitudinal study

OBJECTIVE

The purpose of the present 24-month follow-up longitudinal study was to compare the clinical and radiographic status of platform-switched implants placed in patients with and without type 2 diabetes mellitus (T2DM).

MATERIAL AND METHODS

In total, 45 male non-smokers were included. In Group-1, there were 23 patients with T2DM, and patients in Group-2 comprised of 22 self-reported non-diabetic controls. Under local anesthesia, platform-switched implants were placed in the mandible. Peri-implant bleeding on probing (BOP), probing depth (PD), marginal bone loss (MBL) and hemoglobin A1c (HbA1c) levels were measured at 12 and 24 months of follow-up. Participants were also enrolled in a biannual oral hygiene maintenance program.

RESULTS

The mean age of participants in groups 1 and 2 were 42.4 years (40-46 years) and 41.8 years (39-44 years), respectively. In Group-1, the mean duration of T2DM was 14.5 ± 0.7 months. At 12 and 24 months of follow-up, there was no significant difference in the mean HbA1c levels among patients in groups 1 and 2. At 12 and 24 months of follow-up, there was no significant difference in peri-implant BOP, PD and MBL in both groups.

CONCLUSIONS

Platform-switched implants can remain clinically and radiographically stable in patients with T2DM in a manner similar to non-diabetic individuals. However, it is emphasized that bone loss around implants is influenced by several factors (such as oral hygiene status, glycemic control and tobacco smoking) and not merely platform switching.

Impact of Platelet-Rich Plasma on Bone Height Changes around Platform Switched Implants Supporting Mandibular Overdentures in Controlled Diabetic Patients

BACKGROUND:

The platform switching concept was recently introduced to implant dentistry involving the reduction of restoration abutment diameter with respect to the diameter of dental implant. Long-term follow-up around these implants showed higher levels of bone preservation and proper stress distribution and improved esthetics.

AIM:

The aim of the present study was to evaluate the changes in bone height by means of radiographic examination around platform switched implant supporting mandibular overdentures in controlled diabetic patients.

SUBJECTS AND METHODS:

Fourteen male complete edentulous patients were selected and enrolled in a follow-up study plan. Split mouth technique was applied; one side implant chosen randomly with Platelet-rich-plasma (PRP) and the other without PRP, bone height changes was assessed by Cone Beam Computed Tomography (CBCT) radiographic examination after 3 months, 6 months, 9 months and 1 year later.

RESULTS:

There was increase in bone height loss in both sides but with no statistical significance difference between the two sides after 3 months, 6 months, 9 months and 1 year respectively.

CONCLUSION:

The result of this article satisfied the patients both esthetically and functionally with recorded increase in bone height loss.

Soft and Hard Tissue Changes around Tissue-Oriented Tulip-Design Implant Abutments: A 1-Year Randomized Prospective Clinical Trial

BACKGROUND

The advantages of platform switching using narrower abutments remain controversial. Many researchers suggest that platform switching can yield enhanced clinical results, while others remain skeptical. We hypothesize that the effectiveness of platform switching might be associated with the degree of reduction in size of the abutment.

PURPOSE

To radiographically and clinically examine a new abutment design created to move the implant-abutment interface farther medially.

MATERIALS AND METHODS

This was a prospective, randomized controlled clinical trial that included 27 patients (41 MIS Lance Plus® implants; MIS Implant Technologies, Karmiel, Israel). The patients' age ranged from 39 to 75 years. At the second stage of the surgery, the implants were randomly assigned to either the new platform switch Tulip abutment (TA) design or to the standard platform abutment (SA). Implant probing depth (IPD) and bleeding on probing (BOP) were recorded at baseline and after 12 months. Standardized periapical radiographs were taken (at baseline and at 12 months) and the marginal bone height measured.

RESULTS

All implants were successfully integrated. The mean IPD at 1 year post-op was 2.91 mm for the SA group and 2.69 mm for the TA group (p > .05). Similarly, the BOP at 1 year was almost identical in both groups. The mean values of bone resorption at baseline were 0.98 ± 0.37 mm and 0.69 ± 0.20 for the TA and SA groups, respectively (p > .05). Bone loss (baseline to 12 months) was significantly greater in the SA group compared with the TA group.

CONCLUSIONS

Use of the new TA, with its significantly downsized diameter, resulted in reduced bone loss at 1 year. Further research will be required to assess the long-term effect of this abutment on peri-implant health.

Impact of platform switching on marginal peri-implant bone-level changes. A systematic review and meta-analysis

OBJECTIVE

To address the focused question, is there an impact of platform switching (PS) on marginal bone level (MBL) changes around endosseous implants compared to implants with platform matching (PM) implant-abutment configurations?

MATERIAL AND METHODS

A systematic literature search was conducted using electronic databases PubMed, Web of Science, Journals@Ovid Full Text and Embase, manual search for human randomized clinical trials (RCTs) and prospective clinical controlled cohort studies (PCCS) reporting on MBL changes at implants with PS-, compared with PM-implant-abutment connections, published between 2005 and June 2013.

RESULTS

Twenty-two publications were eligible for the systematic review. The qualitative analysis of 15 RCTs and seven PCCS revealed more studies (13 RCTs and three PCCS) showing a significantly less mean marginal bone loss around implants with PS- compared to PM-implant-abutment connections, indicating a clear tendency favoring the PS technique. A meta-analysis including 13 RCTs revealed a significantly less mean MBL change (0.49 mm [CI95% 0.38; 0.60]) at PS implants, compared with PM implants (1.01 mm [CI95% 0.62; 1.40] (P < 0.0001).

CONCLUSIONS

The meta-analysis revealed a significantly less mean MBL change at implants with a PS compared to PM-implant-abutment configuration. Studies included herein showed an unclear as well as high risk of bias mostly, and relatively short follow-up periods. The qualitative analysis revealed a tendency favoring the PS technique to prevent or minimize peri-implant marginal bone loss compared with PM technique. Due to heterogeneity of the included studies, their results require cautious interpretation.

Bacterial Composition at the Implant-Abutment Connection under Loading in vivo

PURPOSE

Platform-switched implants have been demonstrated to prevent bone loss after loading. The present study evaluated bacterial composition of sites from implant-abutment connections of immediately loaded implants, which were placed in the anterior mandible. Ten patients participated in this study.

MATERIALS AND METHODS

A and B implant systems with two different prosthetic connections (Morse tapered vs internal polygonal butt-joint connections, respectively) were placed and loaded for 2 years. The abutments were removed (AB sample) after careful decontamination. Bacterial sampling of the abutments, inner part of the implants (before/visit 1 and after rinsing with chlorhexidine [CHX]/visit 2), and after new abutment connection and loading for 1 additional month, a new sampling (visit 3) was taken to compare the bacteria composition in association with the two connections. Bacterial profiles of samples were determined by using the human oral microbe identification microarray.

RESULTS

A total of 240 samples were analyzed taken at different time intervals. Nonparametric statistical analysis (Wilcoxon Rank sum) with uncorrected alpha (p < .05) and after corrections (Benjamini-Hochberg) found no statistical significance between the two connections. No significant changes in the overall microbial profiles were detected at the different time intervals. However, there were trends toward presence of periodontitis-associated species at the B implants in all samples (AB, visit 1, even after CHX irrigation) and after decontamination, abutment replacement, and 1-month loading period.

CONCLUSIONS

CHX irrigation does not seem to have any effect on decontamination of connections. As shown previously, there is significantly more bone loss around B implants compared with A implants. Although there was no statistical difference in the microbial profiles, there was indeed a trend for the presence of typical periodontal pathogens associated with the internal polygonal butt-joint connection. A possible scenario is that this connection tends to harbor the pathogens that may be involved in subsequent bone loss.

Clinical and Radiographic Evaluation of Marginal Bone Changes around Platform-Switching Implants Placed in Crestal or Subcrestal Positions: A Randomized Controlled Clinical Trial

BACKGROUND

It has been reported in many articles that marginal bone resorptions are prevented by platform-switching design. However, what occurs when these implants are placed in the apical position is not completely known.

PURPOSE

This report describes a randomized controlled clinical trial study that aims to test the hypothesis that less resorption will occur when platform-switching implants are placed 1 mm below bone level.

MATERIALS AND METHODS

A total of 56 randomly selected implants were inserted bilaterally, either 1 mm below bone level (test group, 28 implants) or at bone level (control group, 28 implants) of the patients' posterior regions. Marginal bone resorptions were examined through periapical radiographies taken with the parallel technique at the time of crown cementation and the third, sixth, 12th, and 36th months after prosthetic loading. The modified plaque index, gingival index, bleeding on probing, and probing depths were used for follow-up periodontal care of the implants.

RESULTS

After 3 years, the mean radiographic vertical bone loss in the control group was significantly lower than in the test group (0.56 ± 0.35 mm and 1.21 ± 1.05 mm, respectively) (p < .01). In terms of periodontal indexes, there were no statistically significant differences between the two groups (p > .05). No peri-implantitis or peri-implant mucositis was observed around the test or control implants.

CONCLUSIONS

More marginal bone resorptions occurred after the third year of loading in implants placed 1 mm below bone level. However, the resorptions did not reach the implants thread. In the control group, the first bone implant contact was placed under the level of the first threads. Therefore, the present randomized clinical trial confirmed the hypothesis that placing platform-switching implants 1 mm below bone level reduced marginal bone loss. It can be noted that to reduce resorption, platform-switching implants should be placed below bone level.

A three-dimensional finite element study on the stress distribution pattern of two prosthetic abutments for external hexagon implants

Objective:

The purpose of this study was to evaluate the mechanical behavior of two different straight prosthetic abutments (one- and two-piece) for external hex butt-joint connection implants using three-dimensional finite element analysis (3D-FEA).

Materials and Methods:

Two 3D-FEA models were designed, one for the two-piece prosthetic abutment (2 mm in height, two-piece mini-conical abutment, Neodent) and another one for the one-piece abutment (2 mm in height, Slim Fit one-piece mini-conical abutment, Neodent), with their corresponding screws and implants (Titamax Ti, 3.75 diameter by 13 mm in length, Neodent). The model simulated the single restoration of a lower premolar using data from a computerized tomography of a mandible. The preload (20 N) after torque application for installation of the abutment and an occlusal loading were simulated. The occlusal load was simulated using average physiological bite force and direction (114.6 N in the axial direction, 17.1 N in the lingual direction and 23.4 N toward the mesial at an angle of 75° to the occlusal plan).

Results:

The regions with the highest von Mises stress results were at the bottom of the initial two threads of both prosthetic abutments that were tested. The one-piece prosthetic abutment presented a more homogeneous behavior of stress distribution when compared with the two-piece abutment.

Conclusions:

Under the simulated chewing loads, the von Mises stresses for both tested prosthetic-abutments were within the tensile strength values of the materials analyzed which thus supports the clinical use of both prosthetic abutments.

Clinical and radiographic evaluation of osseotite-expanded platform implants related to crestal bone loss: a 10-year study

OBJECTIVE

The aim of this prospective clinical study was to evaluate the survival rates at 10 years of expanded platform implants placed in the anterior zone of the maxilla and immediately restored with single crowns.

MATERIALS AND METHODS

Implants incorporating the platform-switching concept were placed in fresh extraction sockets in the maxillary arch, with each patient receiving a provisional restoration immediately after implant placement. After 15 days, final screwed restorations were inserted. Mesial and distal bone heights were evaluated using digital radiography on the day following implant placement and at 1, 5, 7, and 10 years. Primary stability was measured with resonance frequency analysis (RFA) using the Osstell Mentor device. Eighty-six implants were placed in 32 men and 32 women ranging in age between 29 and 60 (mean, 39.64 ± 5.16 years).

RESULTS

Marginal bone loss from implant collar to bone crest between baseline and 10 years follow-up was 1.01 mm ± 0.22. Mesial site crestal bone loss ranged from 3.57 mm ± 1.1 at baseline to 3.77 mm ± 0.7 at 10-year. Distal site crestal bone loss ranged from 3.49 mm ± 0.8 at baseline to 3.73 mm ± 0.7 at 10 year.

CONCLUSION

The platform-switched implants remained stable over the course of 10 years and had an overall survival rate of 97.1%.

Marginal bone response of implants with platform switching and non-platform switching abutments in posterior healed sites: a 1-year prospective study

OBJECTIVES

This 1-year prospective study evaluated the implant success rate and marginal bone response of non-submerged implants with platform and non-platform switching abutments in posterior healed sites.

MATERIAL AND METHODS

Nineteen patients (9 male, 10 female) with posterior partially edentulous spaces, between the ages of 23 and 76 (mean = 55.4 years), were included in this study. A total of 30 implants (15 implants restored with platform switching [PS] abutments [control] and 15 implants restored with non-platform switching [NPS] abutments [test]) were assigned between two groups using a randomization procedure. The definitive abutments with conical connections were placed at the time of surgery, and the definitive restorations were placed at 3 months. All patients were evaluated clinically and radiographically using standardized radiographs at time of implant placement (0), 3, 6 and 12 months after implant placement. Data were analyzed using Friedman test with post hoc pairwise comparisons, Mann-Whitney U-test, and Pearson's chi-square test at the significance level of α = 0.05.

RESULTS

At 12 months, all 30 implants remained osseointegrated corresponding to a 100% success rate. The overall mean marginal bone level change at 12 months was -0.04 ± 0.08 mm for PS group and -0.19 ± 0.16 mm for NPS group. Statistically significant difference in the marginal bone level change was observed between groups at 0 to 12 months and 3 to 12 months (P < 0.05).

CONCLUSIONS

This 1-year randomized control study suggests that when a conical implant-abutment connection is present, similar peri-implant tissue responses can be achieved with platform switching and non-platform switching abutments.

Platform switching: A panacea for bone loss??

The goal of modern implant therapy entails more than just the successful osseointegration of the implant. A successful result must also include an esthetic and functional restoration surrounded by stable peri-implant tissue levels that are in harmony with the existing dentition. In an attempt to improve long-term bone maintenance around implants, a new implant-to abutment connection referred to as “platform switching” has been proposed. It refers to the use of an abutment of smaller diameter connected to an implant neck of larger diameter. Platform switching is a simple and effective way to control circumferential bone loss around dental implants. This short communication aims to present an overview of concept of platform switching in dental implantology.

Implants in reconstructed bone: a comparative study on the outcome of Straumann® tissue level and bone level implants placed in vertically deficient alveolar ridges treated by means of autogenous onlay bone grafts

PURPOSE

To evaluate: (1) the survival rate of Straumann® Tissue Level and Bone Level implants placed in atrophic edentulous jaws previously reconstructed by means of autogenous onlay bone grafts; (2) to compare peri-implant bone resorption values over time.

MATERIALS AND METHODS

From 2005 to 2010, 50 patients presenting with vertical or tridimensional defects of the edentulous ridges were treated with autogenous bone grafts. Three to 7 months afterward, 192 implants were placed (Group A: 97 Tissue Level implants; Group B: 95 Bone Level implants) in the reconstructed areas. After a further waiting period of 2 to 3 months, patients were rehabilitated with implant-supported fixed prostheses. The follow-up ranged from 12 to 68 months after the start of prosthetic loading (mean: 33 months).

RESULTS

No implants were removed (survival rate: 100%), but in Group B 13 implants (8 placed in iliac grafts, 2 placed in ramus grafts, and 3 placed in calvarial grafts) presented peri-implant bone resorption values higher than those proposed by Albrektsson and colleagues. for successful implants: the overall implant success rate was then 100% for Group A and 86.8% for Group B. No prosthetic failures were recorded, thus leading to a 100% prostheses success rate.

CONCLUSION

No significant differences were found between the two types of implants as far as implant survival rate is concerned, but results from this study seem to demonstrate that Tissue Level implants may present better long-term results in terms of peri-implant bone maintenance, as compared with Bone Level implants, when placed in reconstructed areas.

Current results and trends in platform switching

The platform switching (PLS) concept was introduced in the literature in 2005. The biological benefits and clinical effectiveness of the PLS technique have been established by several studies. In this article different aspects of PLS concept are discussed. Crestal bone loss, biologic width, and stress distribution in this concept are comprehensively reviewed. In this article the relative published articles from 1990 to 2011 have been evaluated by electronic search. Because of controversial results especially in immediate loading and animal studies, further modified research is needed to establish the mechanism and effect of the PLS technique. Essential changes in studies including using the control group for accurate interpretation of results and long-term observation, particularly through, randomized, prospective, multicenter trials with large numbers of participants, and implants are necessary.