The effect of implant-abutment junction position on crestal bone loss: A systematic review and meta-analysis

Preloading peri-implant crestal bone loss: A retrospective study of incidence and related factors

BACKGROUND

The aim of this study was to evaluate the incidence of preloading crestal bone loss (PLCBL) and to identify the patient-related and implant-related factors associated with PLCBL.

METHODS

This retrospective cohort examined the dental records of patients who received at least one dental implant. PLCBL was defined as a reduction ⩾0.5 mm and severe PLCBL (primary variable) as a reduction ⩾1.5 mm in mesial and/or distal bone level, measured from the day of implant placement to uncovering or abutment installation/crown delivery. The incidence of PLCBL and patient and implant variables were recorded. Bivariate analysis and binary logistic regression identified factors associated with PLCBL ⩾0.5 mm and ⩾1.5 mm.

RESULTS

A total of 746 dental implants placed in 361 patients from January 2011 to July 2021 was included in the analyses. Of the implants assessed, 24.4% (n = 182) exhibited PLCBL ⩾ 0.5 mm and 10.5% (n = 78) presented severe PLCBL (i.e., ⩾1.5 mm). Males (odds ratio [OR] = 1.85, 95% confidence interval [CI] = 1.11-3.07), patients with diabetes (OR = 3.33, 95% CI = 1.73-6.42), and those allergic to penicillin (OR = 3.13, 95% CI = 1.57-6.22) were more likely to experience severe PLCBL (p < 0.05). Implants placed in the anterior area (OR = 2.08, 95% CI = 1.16-3.73), with bone-level platform-abutment connection (OR = 4.73, 95% CI = 1.94-11.49) and inserted supracrestally (OR = 3.77, 95% CI = 1.84-7.72), presented a greater risk of developing severe PLCBL (p < 0.05). Implants placed in a previously grafted area presented a lower likelihood of developing severe PLCBL (OR = 0.489, 95% CI = 0.28-0.84).

CONCLUSION

The incidence of PLCBL ⩾ 0.5 mm and ⩾1.5 mm was 24.4% and 10.5%, respectively. Male sex, diabetes, allergy to penicillin, anterior location, bone-level platform-abutment connection, and supracrestal implant placement are potential risk factors for severe PLCBL. A previously grafted area is a potential protective factor.

Comparative osseointegration of hydrophobic tissue-level tapered implants-A preclinical in vivo study

PURPOSE

To histometrically compare the osseointegration and crestal bone healing of a novel tapered, self-cutting tissue-level test implant with a standard tissue-level control implant in a submerged healing regimen.

MATERIALS AND METHODS

In a mandibular minipig model, implants were inserted and evaluated histometrically after a healing period of 3, 6, and 12 weeks. The primary outcome was the evaluation of bone-to-implant contact (BIC) and secondary outcomes were primary stability as per insertion torque and first BIC (fBIC). Outcomes for the test and control implants were compared using Wilcoxon signed-rank tests and mixed linear regression models.

RESULTS

Insertion torque values were significantly higher for the test (50.0 ± 26.4 Ncm) compared to the control implants (35.2 ± 19.7 Ncm, p = .0071). BIC values of test implants were non-inferior to those of control implants over the investigated study period. After 12 weeks, the corresponding values measured were 81.62 ± 11.12% and 90.41 ± 4.81% (p = .1763) for test and control implants, respectively. Similarly, no statistical difference was found for fBIC values, except for the 12 weeks outcome that showed statistically lower values for the test (-675.58 ± 590.88 μm) compared to control implants (-182.75 ± 197.40 μm, p = .0068).

CONCLUSIONS

Novel self-cutting tissue-level implants demonstrated noninferior osseointegration and crestal bone height maintenance to the tissue-level implants. Histometric outcomes between both implants demonstrated test implants were statistically noninferior to control implants, despite substantial differences in the bone engagement mechanism and resulting differences in insertion torque and qualitative bone healing patterns.

Effect of one-time placement of the definitive abutment versus multiple healing abutment disconnections and reconnections during the prosthetic phase on radiographic and clinical outcomes: A 12-month randomized clinical trial

OBJECTIVE

The aim of this investigation was to evaluate the effect on clinical and radiological outcomes of the one-abutment, one-time protocol (test) versus placing the definitive abutment on the day of functional loading after having disconnected and connected three times the healing abutment during the prosthetic phase (control).

MATERIALS AND METHODS

Forty patients with 80 implants were randomly allocated to either the test or the control group. Changes in the radiographic marginal bone levels (MBLs), clinical outcomes, prosthetic-related outcomes, and patient-reported outcomes measures (PROMs) were assessed and compared 6 and 12 months after functional loading.

RESULTS

Thirty-seven patients with 74 implants were followed at 12 months. A statistically significant bone remodeling was observed in both groups following implant placement. MBLs were significantly greater in the control group at the 6- (-0.13 mm vs. -0.61 mm) and 12-month visits (-0.01 mm vs. -0.53 mm). Bone loss was significantly greater in the control group from surgery to 6 and 12 months and from loading to 6 and 12 months. The abutment height was significantly greater in the test group, however, there were no significant differences in the restorative angle. Similarly, there were no statistically significant differences between groups for the measured clinical variables (probing depth, plaque, and bleeding index) and PROMs.

CONCLUSIONS

Disconnecting and reconnecting the healing abutment was associated with significantly higher bone loss after 12 months, as compared to the placement of the definitive abutment at implant installation.

Impact of bone levels on stress distribution around all-on-four concept: A 3-D finite element analysis

This study aimed to investigate the impact of implant placement levels within the bone on stress distribution in the context of the All-on-Four concept. In this Finite Element Analysis(FEA), two 4.1 mm x 10 mm implants were axially placed in the anterior region of the jawbone, while two 4.1 mm x 14 mm implants were tilted at 30 ° in the posterior region following the all-on-four concept. In the EC scenario, all implants were inserted at the equicrestal level. In other scenarios, implants were positioned at 1 mm and 2 mm subcrestal levels (SC1, SC2). In all groups, the prosthesis was designed to replicate a group-function occlusion. A total load of 450 N was applied to the prosthesis. Upon deeper implant placement below the crest level, a trend of decreasing Von Mises stresses was observed in both implants and implant fragments. The highest Pmax value in the bone was recorded in SC-2, characterized by the absence of cortical bone support, with values of 3.16 N/mm2 in the anterior region and 1.55 N/mm2 in the posterior region. Conversely, the lowest Pmax values were noted in SC-1 for the anterior implant (2.67 N/mm2) and the EC for the posterior implant (0.87 N/mm2). Implant placements devoid of cortical bone support result in stress transmission from the implant and its components to the peri-implant bone. Optimal stress minimization is achieved by placing anterior axial angle implants deeper than the crest level while retaining cortical bone support and positioning posterior tilted implants at the crest level.

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 outcomes of implant- versus abutment-level connection in screw-retained fixed dental prostheses: A 5-year randomized controlled trial

AIM

The aim of the study was to evaluate the 5 years clinical outcomes associated with implant-level connection (IL) versus abutment-level connection (AL) for implants with an internal conical connection (ICC) supporting a screw-retained fixed partial denture.

MATERIALS AND METHODS

Fifty patients with 119 implants were randomly allocated to either the AL or IL group. Radiographic (Marginal bone loss) and clinical outcomes (Bleeding on Probing, probing pocket depth, plaque accumulation, incidence of peri-implantitis and peri-implant mucositis as well as prosthetic complications) were collected and compared at 1, 2, 3, and 5 years. A linear mixed model was used to evaluate the differences between groups.

RESULTS

Five years after treatment, the MBL change was not significantly different between the groups at any point. The MBL was 0.23 ± 0.64 mm (AL) and 0.23 ± 0.29 mm (IL). The bleeding on Probing was 44% (AL) and 45% (IL) (p = .89). The mean probing depth was 2.91 ± 1.01 mm (AL) and 3.51 ± 0.67 mm (IL). This difference between the groups was statistically significant but clinical insignificant. Presence of plaque was slightly higher (p = .06) in the IL group (34.4%) compared with the AL group (26.3%). The overall technical, biological, and prosthetic complication rates were similar between groups. None of the implants developed peri-implantitis during the entire follow-up period.

CONCLUSION

The results of this clinical trial indicated that all clinical and radiographical parameters were clinically comparable between the study groups.

Influence of implant length and insertion depth on primary stability of short dental implants: An in vitro study of a novel mandibular artificial bone model

Background/purpose

Dental implants are a mainstream solution for missing teeth. For the improvement of dental implant surface treatment and design, short dental implants have become an alternative to various complex bone augmentation procedures, especially those performed at the posterior region of both the maxilla and mandible. The objective of this study was to evaluate the effect of various insertion methods on the primary stability of short dental implants.

Materials and methods

Commercial dental implants were inserted into artificial mandibular bone specimens using various insertion methods (equicrestal position, subcrestal position 1.5 mm, and lateral cortical anchorage) in accordance with an implant surgical guide. Insertion torque value (ITV) curves were recorded while implant procedures were performed. Both maximum ITVs (MITVs) and final ITVs (FITVs) were evaluated. Subsequently, Periotest values (PTVs) and implant stability quotients (ISQs) were measured for all specimens. A Kruskal-Wallis test was conducted to analyze the results for four primary stability parameters, and the Dunn test was used for a post hoc pairwise comparison when a difference was identified.

Results

For all groups, their mean MITVs ranged from 33.6 to 59.4 N cm, whereas their mean FITVs ranged from 17.5 to 43.5 N cm. Insertion torque value, ISQ, and PTV decreased significantly when implants were inserted into subcrestal positions. When implants were inserted in the lateral bicortical position, the four aforementioned parameters yielded greater values.

Conclusion

When 6-mm short implants were inserted in a lateral cortical anchorage position, high primary stability was yielded.

Crestal and Subcrestal Placement of Morse Cone Implant-Abutment Connection Implants: An In Vitro Finite Element Analysis (FEA) Study

The issue of dental implant placement relative to the alveolar crest, whether in supracrestal, equicrestal, or subcrestal positions, remains highly controversial, leading to conflicting data in various studies. Three-dimensional (3D) Finite Element Analysis (FEA) can offer insights into the biomechanical aspects of dental implants and the surrounding bone. A 3D model of the jaw was generated using computed tomography (CT) scans, considering a cortical thickness of 1.5 mm. Subsequently, Morse cone implant-abutment connection implants were virtually positioned at the model's center, at equicrestal (0 mm) and subcrestal levels (-1 mm and -2 mm). The findings indicated the highest stress within the cortical bone around the equicrestally placed implant, the lowest stress in the -2 mm subcrestally placed implant, and intermediate stresses in the -1 mm subcrestally placed implant. In terms of clinical relevance, this study suggested that subcrestal placement of a Morse cone implant-abutment connection (ranging between -1 and -2 mm) could be recommended to reduce peri-implant bone resorption and achieve longer-term implant success.

Implant prosthodontic design as a predisposing or precipitating factor for peri-implant disease: A review

Over the past decade, emerging evidence indicates a strong relationship between prosthetic design and peri-implant tissue health. The objective of this narrative review was to evaluate the evidence for the corresponding implant prosthodontic design factors on the risk to peri-implant tissue health. One of the most important factors to achieve an acceptable implant restorative design is the ideal implant position. Malpositioned implants often result in a restorative emergence profile at the implant-abutment junction that can restrict the access for patients to perform adequate oral hygiene. Inadequate cleansability and poor oral hygiene has been reported as a precipitating factors to induce the peri-implant mucositis and peri-implantitis and are influenced by restorative contours. The implant-abutment connection, restorative material selection and restoration design are also reported in the literature as having the potential to influence peri-implant sort tissue health.

Influence of apico-coronal positioning of tissue-level implants on marginal bone stability during supracrestal tissue height establishment: A multi-center prospective study

INTRODUCTION

Supracrestal tissue height establishment is a crucial factor influencing peri-implant marginal bone modifications prior to prosthesis delivery. If mucosal thickness is insufficient, peri-implant marginal bone resorption occurs to allow appropriate supracrestal tissue height formation. This study evaluates if marginal bone resorption occurring around tissue-level implants before prosthetic loading could be compensated by adapting apico-coronal positioning to mucosal thickness.

METHODS

Patients requiring placement of one single implant in the posterior mandible were treated with tissue-level implants with a 3-mm high transmucosal machined component and moderately rough implant body. Based upon vertical mucosal thickness measured after buccal flap reflection, implants were placed with the treated part: (group 1) 2 mm below crestal level in presence of thin mucosa (<2.5 mm); (group 2) 1 mm below the crestal level in presence of medium mucosa (2.5-3.5 mm); (group 3) at equicrestal level in presence of thick mucosa (>3.5 mm).

RESULTS

Forty-nine implants, placed in 49 patients were included in final analysis (group 1: 18 implants; group 2: 16 implants; group 3: 15 implants). Mean marginal bone resorption after 5 months of healing was 0.66 ± 0.49 mm, 0.32 ± 0.41 mm, and 0.22 ± 0.52 mm in groups 1, 2, and 3, respectively. Inter-group analysis highlighted significant differences between the three groups after ANOVA test (p = 0.025). However, adaptation of apico-coronal implant positioning in relation to mucosal thickness, allowed to avoid early exposure of the treated surface in 100%, 93.7%, and 53.3% of the implants in groups 1, 2, and 3, respectively.

CONCLUSION

During supracrestal tissue height formation, tissue-level implants inserted adapting apico-coronal positioning in relation to mucosal thickness exhibited greater marginal bone resorption at sites with thin mucosa than at sites with medium or thick mucosa. However, anticipating supracrestal tissue height establishment by adapting apico-coronal implant positioning in relation to mucosal thickness may effectively prevent unwanted exposure of treated implant surface.

Is the degree of physiological bone remodeling a predictive factor for peri-implantitis?

BACKGROUND

The amount of initial physiological bone remodeling (IPBR) after implant placement varies and the ways it may play a role in peri-implantitis development remains unknown. The aim of this retrospective study was to investigate the association between the amount of IPBR during the first year of implant placement and incidence of peri-implantitis as well as the pattern of progressive bone loss.

METHODS

Clinical and radiographic documentation of implants at the time of implant placement (T0), 1 year ± 6 months after crown placement (T1), and at a ≥2-year follow-up from implant placement (T2) were retrospectively collected. IPBR was defined as the bone loss occurring from implant placement to the end of the bone remodeling (T1). Cases were grouped into those diagnosed with (test) or without peri-implantitis (PIm) (control). Linear regression model under generalized estimation equation approach was estimated to assess correlation between marginal bone loss (MBL) rates in both periods (T1-T0) and (T2-T1). Receiver operating characteristics curve was estimated to explore an optimal cut-off point of T1-T0 MBL to discriminate between PIm and no-PIm implants.

RESULTS

A total of 45 patients receiving 57 implants without PIm and 40 with PIm were included. There were no associations between PIm and IPBR (p &gt; 0.05), nor between BML of (T2-T1) and (T1-T0). However, arch and total follow-up showed significant influence on the probability of PIm. Splinted implants showed an MBL rate of 0.60-mm/year higher than non-splinted implants (p &lt; 0.001) from T1 to T2.

CONCLUSION

No statistically significant association was found between IPBR and incidence of peri-implantitis.

Effect of implant placement depth on bone remodeling on implant-supported single zirconia abutment crown: A 3D finite element study

PURPOSE

This study aimed to evaluate the influence of subcrestal implant placement depth on bone remodeling using time-dependent finite element analysis (FEA) with a bone-remodeling algorithm over 12 months.

METHODS

Seven models of different subcrestal implant placement depths (0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mm) were analyzed using FEA to evaluate the biomechanical responses in the bone and implant, including von Mises equivalent stress, strain energy density (SED), and overloading elements. SED was used as a mechanical stimulus to simulate cortical and cancellous bone remodeling over the first 12 months after final prosthesis delivery.

RESULTS

The highest increase in cortical bone density was observed at Depth 1.5, whereas the lowest increase was observed at Depth 3.0. In contrast, the highest increase in bone density was observed at Depth 3.0 in the cancellous bone, whereas the lowest increase was observed at Depth 0. The highest peak von Mises stress in the cortical bone occurred at Depth 2.5 (107.24 MPa), while that in the cancellous bone was at Depth 2.5 (34.55 MPa). Notably, the maximum von Mises stress values in the cancellous bone exceeded the natural limit of the bony material, as indicated by the overloading elements observed at the depths of 2.0, 2.5, and 3.0 mm.

CONCLUSION

Greater bone density apposition is observed with deeper implant placement. An implant depth of more than 1.5 mm exhibited a higher maximum von Mises stress and greater overloading elements.

Early crestal bone loss around implants placed at previously failed sites compared with initially integrated implants: A retrospective cohort study

BACKGROUND

There is minimal information on early crestal bone loss (CBL) associated with implants placed at failed sites.

PURPOSE

This retrospective cohort study aimed to evaluate CBL of surviving and restored implants placed at previously failed sites (replaced implants [RIs]) compared to that of implants initially integrated and restored (pristine implants [PIs]), within the same subjects from implant placement to 17 months post-delivery of restoration.

METHODS

Subjects who had both PI(s) and RI(s) were recruited. The following data were retrieved: patient demographics, implant locations, types of implant failure, use of bone graft procedure(s), and intraoral radiographs at implant placement (T0), restoration delivery (T1), and the post-restoration follow-up (T2). A blinded evaluator measured crestal bone levels at T0, T1, and T2.

RESULTS

Forty-four implants (22 in the RI and 22 in the PI group) from the 22 subjects were reviewed. The 22 implants in the RI group were placed either at early failure (17) or late failure (5) sites. There was a 4.6 times higher likelihood of bone graft procedures performed in association with RIs compared to PIs when using a generalized linear mixed model. Differences in crestal bone levels were compared between the two groups at each time point. There were no significant differences in the mesial and mean crestal bone levels between the PI and RI groups. The RI group exhibited lower crestal bone levels on the distal side compared to the PI group at all time points. However, this difference was due to crestal bone level at T0 (p = 0.039) not due to implant replacement (p = 0.413) or bone graft procedure (p = 0.302) when using mixed regression modeling.

CONCLUSION

The effect of replacements of implants at failed sites on CBL was not significant. RIs, once integrated, exhibited the same pattern of CBL as pristine implants.

Prosthodontics Using Removable Platform Switching Technologies (Multiunit, On1) as Exemplified by Conical Connection Implant Systems for Early and Immediate Loading

The removable platform switching technology (multiunit, Оn1) was tested intraoperatively using the passive placement technique as exemplified by a conical connection implant system, which makes it possible to visually control the placement of these platforms with respect to the alveolar bone in the correct orthopedic position. The technology is characterized by a rapid epithelialization of tissues around the base platform until the final integration of the implant, minimal trauma in the emergence profile zone, and an improved minimally invasive orthopedic protocol for working on a removable platform switching base.

Periimplant bone changes in different abutment heights and insertion timing in posterior mandibular areas: Three-year results from a randomized prospective clinical trial

AIM

To compare the influence of the abutment height and its insertion timing on the marginal bone change (MBC) variation of implants placed at posterior mandibular partial edentulous areas in a medium follow-up period.

MATERIAL AND METHODS

This randomized clinical trial (RCT) comprised a sample of patients with posterior mandibular edentulous areas, treated with at least two implants and distributed into three groups: implants connected to a 2 mm height abutment during the surgical stage (Group A); implants connected to a 1 mm height abutment during the surgical stage (Group B); and implants connected to a 2 mm height abutment after 2 months (Group C). Clinical and radiographic measurements were performed during a 36-month period (T4). The MBC was set as the main variable in study. Statistical significance was set at 0.05.

RESULTS

A total of 29 subjects and 59 implants were enrolled in this study. A mean MBC of 0.35 ± 0.46 mm, 0.60 ± 0.81 mm, and 0.71 ± 0.90 mm was computed for groups A, B and C, respectively, at T4. Significant differences were found between groups A and C in terms of MBC variation after 3 years of treatment (p = .048). Multiple linear regression analysis showed a significant influence of the first-year MBC and the abutment insertion timing has independent predictor variables for the MBC assessed at T4.

CONCLUSION

The installation of 2-mm prosthetic abutments, at the time of implant placement, in areas with limited keratinized mucosa presents as a favorable treatment option in terms of periimplant marginal bone maintenance.

Peri-implant tissue conditions at implants treated with Sub-periosteal Peri-implant Augmented Layer technique: A retrospective case series

OBJECTIVES

To assess peri-implant tissue conditions on the short term in patients receiving the Sub-periosteal Peri-implant Augmented Layer (SPAL) technique and in patients with adequate thickness (≥2 mm) of the peri-implant buccal bone plate (PBBP) at placement.

METHODS

Patients where either a dehiscence defect or thin PBBP at implant placement was corrected by SPAL technique (SPAL_dehiscence and SPAL_thin groups, respectively) and patients presenting a residual PBBP thickness ≥2 mm at implant placement (control group) were retrospectively selected. The number of peri-implant sites positive to bleeding on probing (BoP) at 6 months following prosthetic loading was the primary outcome. Also, height of keratinized mucosa, marginal soft tissue level, Plaque Index, peri-implant probing depth, suppuration on probing, and interproximal radiographic bone level (RBL) were evaluated.

RESULTS

Thirty-four patients (11 in the SPAL_dehiscence group, 11 in the SPAL_thin group, and 12 in the control group) were included. In each SPAL group, 10 patients (90.9%) showed peri-implant tissue thickness ≥2 mm at the most coronal portion of the implant at uncovering. The prevalence (number) of BoP-positive sites was 2, 1, and 0 in the SPAL_dehiscence , SPAL_thin , and control groups, respectively. RBL amounted to 0.3 mm in the SPAL_dehiscence group, 0.2 mm in the SPAL_thin group, and 0 mm in the control group.

CONCLUSION

After 6 months of prosthetic loading, patients treated with SPAL technique show limited peri-implant mucosal inflammation in association with shallow PD and adequate KM. At implants receiving SPAL technique, however, interproximal RBL was found apical to its ideal position.

Static computer-aided, partially guided, and free-handed implant placement: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To analyze the outcomes of static computer-aided implant placement (sCAIP) compared to partially guided (PGIP) and free-handed (FHIP) implant placement.

MATERIAL AND METHODS

This study was registered in PROSPERO (CRD42019131397). A comprehensive literature search was performed by two independent examiners. Only randomized controlled trials (RCTs) were selected. Treatment modalities included sCAIP, PGIP, and FHIP. Data pertaining to the outcomes of interest were extracted. Random-effects meta-analyses were feasible for a subset of outcomes.

RESULTS

From an initial list of 2,870 records, fourteen articles for a total of ten RCTs were selected. Data from 7 of these studies allowed for the conduction of three meta-analyses comparing accuracy of implant placement across modalities. Survival rate up to 12 months post-loading was high (>98%) and comparable between treatments (low-quality evidence). No tangible differences in terms of patient perception of intra- or postoperative discomfort were observed (low-quality evidence). Quantitative analyses revealed significantly lower angular (MD = 4.41°, 95% CI 3.99-4.83, p < .00001), coronal (MD = 0.65 mm, 95% CI 0.50-0.79, p < .00001), and apical (MD = 1.13 mm, 95% CI 0.92-1.34, p < .00001) deviation values for sCAIP as compared to FHIP (8 studies, 383 patients, 878 implants, high-quality evidence). A similar discrepancy, in favor of sCAIP, was observed for angular deviation only as compared to PGIP (MD = 2.11°, 95% CI 1.06-3.16, p < .00001).

CONCLUSIONS

sCAIP is associated with superior accuracy compared to PGIP and FHIP.

Does Probiotic Lactobacillus Have an Adjunctive Effect in the Nonsurgical Treatment of Peri-Implant Diseases? A Systematic Review and Meta-analysis

OBJECTIVE

To evaluate the additional effect of probiotic Lactobacillus in the nonsurgical management of peri-implant diseases (peri-implant mucositis and peri-implantitis).

METHODS

Six databases were searched up to May 2019 without time and language restrictions. Study selection and data extraction were conducted independently by 2 reviewers. The inclusion criteria for this systematic review were defined based on the participants, intervention, comparison, outcomes, and study design (PICOS) format. Randomized controlled trials comparing nonsurgical treatment combined with probiotic Lactobacillus or placebo agent in patients with peri-implant diseases were included. The methodological quality of retrieved studies was assessed according to the Cochrane Collaboration's Risk of Bias tool, and the quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool. Odds ratio and 95% confidence interval (CI) were used to describe dichotomous data, while mean difference and standardized mean difference with 95% CI were used to describe continuous variables.

RESULTS

Seven randomized controlled trials with 296 implants were included in this meta-analysis. The mean difference of probing pocket depth (PPD) was -0.05 (95% CI: -0.28 to 0.18; P = .67) immediately after treatment termination and -0.17 (95% CI: -1.01 to 0.67, P = .69) at least 2 months after treatment termination. There was a slight reduction of PPD after treatment termination. Compared with placebo, Lactobacillus provided limited benefits in peri-implant mucositis. There were no significant differences in the secondary outcomes of bleeding on probing or plaque index (P > .05). In a narrative synthesis of peri-implantitis, the effect of Lactobacillus on PPD and bleeding on probing remained controversial.

CONCLUSIONS

This systematic review and meta-analysis showed that probiotic Lactobacillus provide limited benefits to the nonsurgical treatment of peri-implant mucositis or peri-implantitis.

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.

Longevity and marginal bone loss of narrow-diameter implants supporting single crowns: A systematic review

PURPOSE

To compare the longevity and marginal bone loss of narrow-diameter (≤3.3-mm) versus standard-diameter implants supporting single crowns.

MATERIAL AND METHODS

The MEDLINE (via PubMed), Scopus, and SciELO databases were searched for relevant publications. In addition, the scientific references provided by each of the implant companies that appeared in the search were reviewed. Intervention studies comparing longevity and bone loss between narrow-diameter and standard-diameter implants were included.

RESULTS

The search was limited to in vivo studies in humans. The query returned 1931 results, of which 4 met the inclusion criteria. The implant success rate ranged from 93.8% to 100% over a maximum follow-up of 3 years, with no difference between narrow- and standard-diameter implants. Meta-analysis of all included studies showed greater bone loss in narrow-diameter implants as compared with standard ones; however, when analysis was restricted to randomized trials, no such difference was present.

CONCLUSION

The meta-analysis showed no difference in longevity between narrow implants and standard implants when supporting single crowns. However, narrow-diameter implants may be associated with greater marginal bone loss. These findings should be regarded cautiously due to the short follow-up duration and methodological heterogeneity of the primary studies.

A randomized controlled trial to compare aesthetic outcomes of immediately placed implants with and without immediate provisionalization

INTRODUCTION

There are mixed results regarding the aesthetic advantage of immediate provisionalization of dental implants. Therefore, this study aimed to compare facial mucosal level of single immediately placed implants with and without immediate provisionalization.

METHODS

Single implants were immediately placed to replace a hopeless maxillary anterior or premolar tooth in 40 subjects. Each implant was randomly assigned to receive a non-occluding temporary crown or a healing abutment after implant placement. At 4 months, these implants were permanently restored and followed up for 12 months. Clinical and radiographic parameters were measured and compared.

RESULTS

The implant survival rate at 12 months in the test and control group was 90% and 100%, respectively. Mid-facial mucosal marginal level and papilla height changes were minimal within groups, and no significant differences were found between the two groups. The amount of marginal bone remodelling was modest, with no significant difference between the two groups. Radiographic bone changes were not statistically different between the groups, except for the vertical crestal bone resorption.

CONCLUSION

Immediate implant placement with or without provisionalization can achieve stable vertical soft tissue level for 12 months as compared to pre-extraction level. However, immediate provisionalization was not able to improve the aesthetic outcome further.

Systematic review versus structured critical analysis

Objective: This analysis discusses common problems with systematic reviews (SRs) and presents a novel solution, the structured critical analysis (SCA) that can be incorporated into a SR or used as an alternative literature review design.Methods: A cross-sectional survey of current SRs related to interdisciplinary restorative dentistry was obtained by evaluating 100 current SRs for their self-reported methodological quality and its effect on scientific validity.Results: The preferred reporting items for systematic reviews and meta-analyses protocol (PRISMA) was used in 99/100 SRs, but only 8/100 reported a low risk of bias. High statistical heterogeneity precluding meta-analysis was found in 44/100 SRs. Only 94 paragraphs/100 SRs provided critical analysis.Discussion: Significant problems were found with current SRs that can compromise their reliability as the premier level of evidence for clinical science research. The reader must be aware of these deficiencies to correctly interpret the SR and cannot rely on the format alone.

Single-Implant Treatment

The replacement of one tooth using one implant involves a set of unique criteria for long-term success. Successful therapy should be based on long-term function and health of the adjacent tissues. Sections of this article examine these critical criteria that when working together can result in successful long-term tooth replacement.