Skip to main content
NCBI home page
Clinical and Experimental Dental Research logoLink to Clinical and Experimental Dental Research
. 2021 Aug 21;7(6):1025–1036. doi: 10.1002/cre2.471

The effect of implant‐abutment connections on peri‐implant bone levels around single implants in the aesthetic zone: A systematic review and a meta‐analysis

Caroliene M Meijndert 1,✉, Gerry M Raghoebar 1, Arjan Vissink 1, Konstantina Delli 1, Henny J A Meijer 1,2
PMCID: PMC8638280  PMID: 34418324

Abstract

Objective

To systematically review literature about the effect of different implant‐abutment interface designs on peri‐implant bone level changes, implant loss and mid‐buccal mucosa changes around single implants in the anterior maxilla. Reviewing three connection configurations: Platform switched conical (PS‐conical); Platform switched parallel (PS‐parallel); Platform matched parallel (PM‐parallel).

Methods

A detailed search was carried out in Pubmed, EMBASE, Cochrane, Scopus, Open Gray and African journals Online (until December 1, 2020) and was restricted to clinical prospective studies of at least 1 year and with at least 10 human participants. A meta regression analysis was carried out primarily on the pooled peri‐implant bone level changes followed by implant loss and mid‐buccal mucosa level change. Risk of bias was assessed with RoB 2.0 and ROBINS‐I. The manuscript complied with the PRISMA guidelines and was registered in the PROSPERO database (ID: 225092).

Results

A total of 5513 hits gave 44 eligible articles for the analyses. Bone level change did not differ significantly between the two platform switched connections; their bone loss scores were significantly lower than PM‐connection. The PS‐conical connections have significantly lower implant losses than the PM connection. Mid‐buccal mucosa level change was comparable between the three connection configurations. Moderate to high risk of bias was detected in the included studies.

Conclusions

The performance of PS‐conical and PS‐parallel connection configurations both favored bone loss scores compared to the PM‐parallel connection configuration. All three demonstrated mid‐buccal mucosa changes that were small and did not differ significantly amongst the groups.

Keywords: aesthetic region, bone level, implant‐abutment connection, systematic review

1. INTRODUCTION

The range of implants used in restorative dentistry has become increasingly sophisticated and, simultaneously, more complex (Buser et al., 2017). The variation has become so large, that it is difficult for clinicians to choose between the various available components (Shafie & White, 2014). One of these components is the implant‐abutment connection configuration. A clear distinction can be made between external and internal implant‐abutment connections. External connections are hardly used anymore because of the susceptibility to complications (Gracis et al., 2012; Koo et al., 2012; Steinebrunner et al., 2005). Internal connections have a number of geometric variations (Koutouzis, 2019). For example, the internal implant geometry is parallel‐walled or conical/tapered. The parallel‐walled connection types are often equipped with various indexing/anti‐rotational features like an octagon or a hexagon, and exist with a platform switch or a platform match. A conical/tapered connection type implicates a cone‐in‐cone or has a conical portion in the inner cervical part, with or without indexing features in the apical part (Shafie & White, 2014).

All the previous mentioned variations were developed in an effort to reduce mechanical failure (Ceruso et al., 2017) and to minimize crestal bone resorption (Koutouzis, 2019). It is presumed that the long‐term survival and success of implant treatment can be affected by peri‐implant crestal bone resorption (Schwartz‐Arad et al., 2005). This bone resorption can affect the stability of the mucosa, and may therefore affect the aesthetic outcome, which is particularly interesting in the aesthetic zone (Belser et al., 2009; Fürhauser et al., 2005; Jemt, 1997). Eliminating, or at least reducing the amount of bacterial leakage, could have a positive influence on peri‐implant tissue stability, and thus on the aesthetics. It has been suggested that an internal implant‐abutment connection with a conical configuration is the most stable connection, with less bacterial leakage, than the other configurations (Zipprich et al., 2018).

In 2018, Caricasulo et al. (2018) performed a systematic review, with a meta‐analysis, of the difference between conical, internal and external connection configurations. They concluded that significantly less bone loss occurs with conical and internal connections compared to external connections. Although they did not distinguish between platform switching and platform matching, they concluded after performing an additional analysis that a platform switch might be of more importance in preserving peri‐implant bone levels than the connection configuration itself. The finding that platform switching might have a positive effect on preserving peri‐implant bone levels was also mentioned by Hsu et al. (2017). However, Caricasulo et al. (2018) and Hsu et al. (2017) did not focus specifically on the aesthetic region or on a possible effect on the aesthetic outcome.

Vetromilla et al. (2019) did perform a systematic review on implant abutment connections in the aesthetic region. They concluded from an aesthetic scoring index by professionals, being the Pink Esthetic Score and White Esthetic Score (PES/WES; Belser et al., 2009) that the internal hexagon performs better aesthetically, but were not able to quantify their observations. Additionally, they did not distinguish between platform‐switched and platform‐matched connections, but this might be a noteworthy nuance when considering the Caricasulo et al. (2018) outcome.

Since the aesthetic outcome of a restoration in the aesthetic region is so important, it would be interesting to know if the implant abutment connection can contribute to achieving the best possible results. So far, to the best of our knowledge, a systematic review with a meta‐analysis of the effect of solely internal connections in the aesthetic region, distinguishing between platform switching and matching, is not available. Therefore, the aim of our systematic review was to determine whether the type of implant connection configuration, that is, platform switched conical connections (PS‐conical), platform switched parallel connections (PS‐parallel) or platform matched parallel connections (PM‐parallel), has a significant impact on peri‐implant bone changes, whether an implant‐abutment connection influences implant survival, and whether the stability of the mid‐buccal mucosa level, as a factor determining the aesthetic outcome, is influenced by the connection configuration.

2. METHODS

2.1. Research protocol

This systematic review was conducted following the Cochrane Handbook for systematic reviews and was reported according to the PRISMA Statement guidelines 2009 (Moher et al., 2009). The protocol of this systematic review was entered under the PROSPERO registration number: ID: 225092. The research question was formulated by means of a PICO:

P—solitary implants in the maxillary aesthetic region with titanium implants.

I—conical implant‐abutment connections.

C—parallel walled implant‐abutment connections with and without a platform switch.

O—peri‐implant bone level change.

The primary outcome is peri‐implant bone level change and the secondary outcome are implant loss and mid‐buccal mucosa level change.

2.2. Information sources

We conducted a literature research of the following databases: PubMed, Cochrane Library EMBASE Scopus, Open Grey and African journals Online. According to the syntax rules of each database, key words and their combinations were used to identify studies published until December 2020. No time restrictions were applied (Table 1).

TABLE 1.

Search strings

Pubmed (1673 hits)
(“Dental Implants, Single‐Tooth” [Mesh] OR (implant*[tiab] AND (single[tiab] OR solitary[tiab]))) AND (“Maxilla” [Mesh] OR “Esthetics, Dental” [Mesh:NoExp] OR esthetic*[tiab] OR aesthetic*[tiab] OR anterior[tiab] OR maxilla*[tiab] OR incisor*[tiab] OR front*[tiab]) AND (“Alveolar Bone Loss” [Mesh] OR bone[tiab]) AND (“Clinical Trial” [Publication Type] OR “Cohort Studies” [Mesh] OR “Case Reports” [Publication Type] OR “Observational Study” [Publication Type] OR “Treatment Outcome” [Mesh:NoExp] OR “Comparative Study” [Publication Type] OR random*[tiab] OR trial[ti] OR outcome*[tiab] OR cohort[tiab] OR follow‐up[tiab] OR followup[tiab] OR prospectiv*[tiab] OR longitudinal*[tiab] OR case ser*[tiab])
Embase (1539 hits)
(“single tooth implant”/exp OR (implant* AND (single OR solitary)):ab,ti) AND (“maxilla”/exp OR “esthetics”/exp OR (esthetic* OR aesthetic* OR anterior OR maxilla* OR incisor* OR front*):ab,ti) AND (“alveolar bone loss”/exp OR bone:ab,ti) AND (“clinical study”/exp OR “observational study”/exp OR “cohort analysis”/exp OR “comparative study”/exp OR “treatment outcome”/de OR trial:ti OR (random* OR outcome* OR cohort OR “follow‐up” OR followup OR prospectiv* OR longitudinal* OR “case ser*”):ab,ti)
Cochrane (527 hits)
(implant* AND (single OR solitary)) AND (esthetic* OR aesthetic* OR anterior OR maxilla* OR incisor* OR front*) AND (bone)
Scopus (1626 hits)
(TITLE‐ABS‐KEY (implant* AND ( single OR solitary))) AND (TITLE‐ABS‐KEY (dental OR tooth OR teeth OR crown*)) AND (TITLE‐ABS‐KEY (esthetic* OR aesthetic* OR anterior OR maxilla* OR incisor* OR front*)) AND (TITLE‐ABS‐KEY (bone)) AND (TITLE‐ABS‐KEY (“clinical trial*” OR prospectiv* OR cohort* OR “case report*” OR “case stud*” OR observational* OR “follow‐up” OR followup OR random* OR outcome* OR longitudinal* OR “case ser*” OR “clinical stud*” OR “controlled stud*”))
Open Grey (24 hits)
Single implant
African Journal Online (145 hits)
Dental AND implant AND single AND maxilla AND bone
Open in a new tab

The following study criteria were handled:

Inclusion criteria:

  • Human subjects included in the studies should be ≥18 years of age.

  • Titanium, bone level implants.

  • Implants supporting single crowns placed in the anterior region of the maxilla (second premolar to second premolar).

  • Only healed sites (at least 3 months healing time after extraction) and either or not a bone augmentation procedure has been performed in an earlier session.

  • Follow‐up of at least 1 year after implant placement.

  • Detailed information on bone level changes measured on peri‐apical radiographs.

  • Randomized clinical trials or prospective clinical studies with a minimum sample of 10 participants per study group.

Exclusion criteria:

  • External implant‐abutment connections.

  • No details of the implant type.

  • Did not report bone level changes.

  • Bone level measurements obtained with cone beam computer tomography (CBCT) or orthopantomograms.

  • Animal studies, in vitro studies, retrospective studies, reviews.

The impact of implant‐abutment connection already starts at the time of connection and a possible reaction of surrounding hard and soft tissues to the amount of bacterial leakage can be found within the first year of functioning. Therefore, a minimum follow‐up time of 1‐year is considered as meaningful.

Mean marginal bone change was defined as the mean value of the change in marginal bone level at the mesial and distal side of the implant, measured along the implant axis and calculated as the difference in bone level between start of the functional period and the follow‐up evaluation.

Studies with immediate implant placement were not included. With immediate implant placement the first bone‐implant contact at start of the evaluation period is not in the area of the neck of the implant. It takes a certain period of time to heal for the remaining socket around the implant. This healing period could possibly interfere with possible bone level changes due to the implant‐abutment connection.

Both screw‐retained and cement‐retained single crowns were included. There is no evidence in the literature that one type is performing better with respect to marginal bone level changes.

2.3. Study selection

Two reviewers (C.M.M., H.J.A.M.) independently screened the results from the electronic searches, according to the inclusion and exclusion criteria, in two rounds. Articles were first screened by title and abstract. In case of disagreement or doubt, the study was moved to the next round (full text assessment). The Cohen's κ and percentage of agreement were calculated to determine the measure of agreement between the two reviewers. Any disagreement regarding the inclusion was resolved by a consensus discussion. In case of persistent disagreement, an external independent reviewer (G.M.R.) with experience in implant dentistry could be consulted.

2.4. Quality assessment

Methodological quality and risk of bias were assessed using the Cochrane risk of bias tool (RoB 2.0; Sterne et al., 2019) for randomized controlled trials and the ROBINS‐1 tool (Sterne et al., 2016) for prospective clinical non‐randomized trials by the same two reviewers (C.M.M., H.J.A.M.), independently. Any disagreement was resolved by consensus between the reviewers.

2.5. Data extraction

Following a pre‐specified form, the following data were extracted cooperatively by C.M.M. and H.J.A.M.: authors, year of publication, study design, follow‐up time, type of implant, type of implant‐abutment connection, number of implants, number of implant failures, bone level changes and, if available, additional data on the mid‐buccal mucosa level changes. It was decided to group the studies according to the properties of the internal configuration. When an implant connection was fully or partially conical/tapered along the inner wall of the implant body and the corresponding portion of the abutment, the implant was classified as conical and placed in the “platform switched conical” group (PS‐conical). Any connection where the inner portion of the implant and abutment was parallel‐walled were classified based on the presence or absence of a platform switch and were placed accordingly into either the “platform switch parallel” (PS‐parallel) or “platform matched parallel” group (PM‐parallel).

2.6. Statistical analysis

Inter‐observer agreement was calculated with IBM SPSS Statistics 20 (SPSS, Chicago, IL). Publication bias was assessed by plotting the log odds ratio against its standard error. Pooling of implant survival, bone loss and mid buccal mucosa changes was performed by using the software Comprehensive Meta‐Analysis, Version 3.3.070 (CMA, Biostat, Englewood, NJ). A random effects model was used on the pooled outcomes. To analyze sources of heterogeneity between studies, a meta‐regression analysis (random effects model) was performed on the connection types, that is, PS‐conical, PS‐parallel and PM‐parallel.

3. RESULTS

3.1. Study identification and selection

The study selection procedure is summarized in Figure 1. A total of 5513 publications was identified after the electronic and hand search, up to the July 1, 2020. After discarding the duplicates from the output, a total of 2395 publications underwent title abstract selection whereupon 2071 did not meet the inclusion criteria. A total of 324 articles remained for full‐text analysis and, of these, 281 did not meet the in‐ and exclusion criteria, or they were a follow‐up of an earlier study. A last update was done on the December 1, 2020 and, of the 111 new results, 1 was suitable for analysis. A total of 44 publications was finally included for data extraction. There was substantial agreement between the two reviewers' judgments, κ = 0.76, (93.9% agreement) at title/abstract selection. At full text selection, this agreement was also substantial, κ = 0.75, (91.4% agreement). There was no need to consult the third reviewer in any of the study selection phases.

FIGURE 1.

FIGURE 1

Open in a new tab

Study identification and selection process. A total of 43 studies were included following the main screening process (up to July 1, 2020). The updated search resulted on December 1, 2020 resulted in one additional study

3.2. Description of the selected studies

The search results yielded 24 non‐randomized clinical trials (nRCTs) and 20 randomized clinical trials (RCTs). The studies' median follow‐up was 1 [1;5] year (ranging from 1 to 10 years). Detailed data from the included studies is listed in Table 2. If an article reported data on two groups, but the same connection type was used, the groups were pooled. When an article reported data from two groups with different connection types, the groups were viewed separately. Consequently, a total of 31 groups (1105 implants) had PS‐conical connections, 5 groups (124 implants) had a PS‐parallel connection, and 12 groups (356 implants) had a PM‐parallel connection.

TABLE 2.

Characteristics and outcomes of the included studies

Reference Publication year Follow‐up time (years) Study type Implant type No of implants Annual implant loss (%) Annual bone level change in mm (mean ± SD) Annual mid‐buccal level change in mm. (mean ± SD)
PS‐conical Kemppainen et al. (1997) 1997 1 RCT Astra Tech ST 35 2 −0.14 ± 0.10 nr
Palmer et al. (2000) 2000 5 Prosp. study Astra Tech ST 14 0 0.02 ± 0.10 nr
Cooper et al. (2001) 2001 1 Prosp. study Astra Tech ST 53 4 −0.40 ± 0.51 0.34 ± 0.94
Norton (2004) 2004 1 Prosp. study Astra Tech ST 11 4 −0.55 ± 0.49 nr
Cooper et al. (2007) 2007 3 Prosp. study Astra Tech ST 43 2 −0.14 ± 0.32 0.17 ± 0.47
Gotfredsen (2012) 2012 10 Prosp. study Astra Tech ST 10 0 −0.09 ± 0.04 nr
Vanlioglu et al. (2012) 2012 5 Prosp. study Astra Tech OsseoSpeed 10 0 −0.05 ± 0.01 nr
Bashutski et al. (2013) 2013 1 RCT Astra Tech OsseoSpeed 24 8 −0.53 ± 0.51 nr
Grandi et al. (2013) 2013 1 Prosp. study JD Evolution 24 4 −0.60 ± 0.51 nr
Berberi et al. (2014) 2014 5 Prosp. study Astra Tech OsseoSpeed 20 0 −0.04 ± 0.03 nr
Cooper et al. (2014) 2014 5 Prosp. study Astra Tech OsseoSpeed 49 0 0.02 ± 0.26 0.08 ± 0.21
Vanlioglu et al. (2014) 2014 1 Prosp. study Straumann Bone Level implant 55 0 −0.10 ± 0.08 nr
Cosyn et al. (2015) 2015 1 Prosp. study Nobel Active 50 0 −0.48 ± 0.46 0.06 ± 0.60
Esposito et al. (2015) 2015 1 RCT Mega Gen, EZ Plus 46 0 −0.27 ± 0.14 nr
Raes et al. (2015) 2015 2 Prosp. study Astra Tech OsseoSpeed 85 2 0.02 ± 0.45 0.10 ± 0.45
Hsu et al. (2016) 2016 1 RCT SuperLine Dentium 13 0 −0.21 ± 0.56 −0.38 ± 0.49
Slagter et al. (2016) 2016 1 RCT Nobel Active 20 0 −0.65 ± 0.46 nr
Yildiz et al. (2016) 2016 1 Prosp. study Straumann Bone Level implant 29 7 0.08 ± 0.82 nr
Allen et al. (2017) 2017 2 Prosp. study Straumann Bone Level implant 20 0 −0.41 ± 0.26 nr
De Bruyckere et al. (2018) 2018 1 RCT Nobel Active 42 0 −0.60 ± 0.69 −0.18 ± 0.33
Eghbali et al. (2018) 2018 5 Prosp. study Nobel Active 32 0 −0.09 ± 0.08 −0.02 ± 0.07
Jonker et al. (2018) 2018 1 RCT Straumann Bone Level implant 43 2 −0.42 ± 0.55 nr
Raes et al. (2018) 2018 8 Prosp. study Astra Tech OsseoSpeed 18 0 −0.06 ± 0.24 nr
Zuiderveld et al. (2018) 2018 1 RCT Nobel Replace CC 40 0 −0.02 ± 0.11 −0.11 ± 1.19
Cooper et al. (2019) 2019 3 RCT Astra Tech OsseoSpeed 45 0 −0.04 ± 0.17 0.07 ± 0.23
Friberg and Ahmadzai (2019) 2019 1 Prosp. study Nobel Parallel CC 22 2 −0.41 ± 0.36 nr
Heydecke et al. (2019) 2019 3 Prosp. study Nobel Replace CC 90 0 −0.29 ± 0.17 nr
Hosseini et al. (2020) 2019 5 Prosp. study Astra Tech EV 33 0 −0.02 ± 0.07 0.07 ± 0.11
Meijndert et al. (2020) 2019 5 Prosp. study Straumann Bone Level implant 50 0 −0.03 ± 0.13 nr
Zuiderveld et al. (2019) 2019 1 Prosp. study Nobel Replace CC 40 0 0.05 ± 0.44 −0.04 ± 0.28
Wittneben et al. (2020) 2020 3 RCT Straumann Bone Level implant 39 0 −0.10 ± 0.17 nr
PS‐parallel Canullo et al. (2013) 2013 2 RCT Sweden&Martina Premium SP 20 0 −0.17 ± 0.20 nr
Canullo et al. (2016) 2016 5 RCT Sweden&Martina Premium SP 30 0 −0.09 ± 0.07 0.08 ± 0.11
Canullo et al. (2018) 2018 5 Prosp. study Sweden&Martina Premium SP 22 0 −0.06 ± 0.06 nr
Cooper et al. (2019) 2019 3 RCT Biomet 3i, NanoTite Certain Prevail 32 5 −0.35 ± 0.17 0.10 ± 0.23
Lowy et al. (2019) 2019 1 RCT BioHorizons Tapered Plus 20 0 −0.05 ± 0.21 0.10 ± 0.70
PM‐parallel Raghoebar et al. (2009) 2009 1 RCT Nobel Replace Groovy 45 0 −0.54 ± 0.13 ‐0.63 ± 1.63
Fu et al. (2014) 2014 1 RCT Tapered Screw‐Vent 26 0 −1.28 ± 0.91 nr
Felice et al. (2015) 2015 1 RCT Dentsply Friadent, XiVE S plus 23 0 −0.19 ± 0.10 nr
Meloni et al. (2015) 2015 1 RCT Nobel Replace Tapered 30 0 −0.87 ± 0.19 nr
Den Hartog et al. (2016) 2016 5 RCT Nobel Replace Tapered Groovy 27 1 −0.03 ± 0.10 nr
Guarnieri et al. (2016) 2016 3 Prosp. study BioHorizons Tapered Internal 13 0 −0.14 ± 0.07 −0.01 ± 0.04
Hsu et al. (2016) 2016 1 RCT Zimmer dental, Tapered Screw‐Vent 13 0 −0.74 ± 0.47 nr
Den Hartog et al. (2017) 2017 5 RCT Nobel Tapered Groovy 54 0 −0.25 ± 0.20 nr
Gjelvold et al. (2017) 2017 1 RCT BioHorizons Tapered Internal 50 2 −0.63 ± 0.54 0.21 ± 0.46
Cooper et al. (2019) 2019 3 RCT Nobel Speedy Replace 34 5 −0.34 ± 0.17 nr
Lowy et al. (2019) 2019 1 RCT BioHorizons Internal 20 0 −0.65 ± 0.59 0.50 ± 0.90
Gjelvold et al. (2020) 2020 1 Prosp. study BioHorizons Tapered Internal 21 2 −0.4 ± 0.41 −0.02 ± 0.36
Open in a new tab

3.3. Risk of bias

ROBINS‐1 was used on the prospective non‐randomized trials and the domain with a high risk of bias was “bias due to confounding.” Low risk of bias was detected in “bias due to deviations from intended interventions” and in “bias in selection of the reported result.” Five studies had a high risk of bias on at least one domain (20.8%), 15 studies had a moderate risk of bias on at least one domain (62.5%), and 4 studies had a low risk of bias (16.7%) (see Figure S1).

RoB‐2.0 was applied to the RCTs and a high risk of bias was seen in the domain “bias due to deviations from intended interventions.” Low risk of bias was detected in the domain “bias due to missing outcome data.” Eighteen studies had a high risk of bias on at least 1 domain (90%), and the remaining two studies had low risk of bias (10%; see Figure S2).

3.4. Publication bias

The funnel plot showed no studies on the lower right part of the plot, indicating a possibility of publication bias (see Figure S3).

3.5. Quantitative synthesis

3.5.1. Bone level change

All the study groups reported bone level changes (n = 48). The pooled bone level change per year for all the groups was −0.24 mm (95% CI: −0.27 to −0.20). In the PS‐conical group, it was −0.16 mm (95% CI: −0.19 to −0.13), while in the PS‐parallel group it was −0.14 mm (95% CI: −0.3 to −0.06) and in the PM‐parallel group it was −0.48 mm (95% CI: −0.63 to −0.32).

A meta‐regression analysis revealed that the differences in bone change per year were statistically significant between the two platform switched and the platform matched group; PS‐conical versus PM‐parallel (p = 0.00), PS‐parallel versus PM‐parallel (p = 0.00). The difference between the conical and parallel platform switched groups (p = 0.52) was not significant. The Forest plots of the random effects meta‐analysis are depicted in Figures 2, 3, 4.

FIGURE 2.

FIGURE 2

Open in a new tab

Forest plots for random effects meta‐analysis of studies evaluating bone level change in the PS‐conical group

FIGURE 3.

FIGURE 3

Open in a new tab

Forest plots for random effects meta‐analysis of studies evaluating of bone level change in the PS‐parallel group

FIGURE 4.

FIGURE 4

Open in a new tab

Forest plots for random effects meta‐analysis of studies evaluating of bone level change in the PM‐parallel group

3.5.2. Implant loss

Forty‐seven study groups reported on implant survival. The percentage of pooled implant loss per year for all the groups was 0.19 (95% CI: 0.16–0.21) with 0.13 (95% CI: 0.10–0.16) in the PS‐conical group, 0.22 (95% CI: 0.12–0.33) in the PS‐parallel group, and 0.73 (95% CI: 0.55–0.91) in the PM‐parallel group.

A meta‐regression analysis revealed a significant statistical difference in implant loss between the PS‐conical and the PM‐parallel group. There was no statistical difference found when PS‐conical versus PS‐parallel (p = 0.79) and PS‐parallel versus PM‐parallel (p = 0.10) were analyzed. Forest plots of the random effects meta‐analysis are depicted in Figure S4.

3.5.3. Mid‐buccal mucosa level changes

Twenty study groups reported changes in mid‐buccal mucosa level, namely, 12 in the PS‐conical group, 3 in the PS‐parallel group, and 5 in the PM‐parallel connection group. The groups' pooled mid‐buccal mucosa level change per year was 0.05 mm (95% CI: 0.01 to 0.08), composed of 0.04 mm (95% CI: −0.02 to 0.09) in the PS‐conical group, 0.08 mm (95% CI: 0.05 to 0.12) in the PS‐parallel group, and 0.04 mm (95% CI: −0.08 to 0.16) in the PM‐parallel group. A meta‐regression analysis revealed no statistically significant difference between the three groups. Forest plots of the random effects meta‐analysis are depicted in Figure S5.

4. DISCUSSION

There is a relationship between the type of implant‐abutment connection configuration and peri‐implant bone loss around implants placed in the anterior region of the maxilla. The PS‐conical and PS‐parallel connection configurations are comparable with less peri‐implant bone loss than PM‐parallel connections. The results of this systematic review reveal that the presence of a platform switch seems to be of more influence on peri‐implant bone loss than the internal connection configuration itself.

In the present review, PS‐conical and PS‐parallel connection configurations result in significantly less peri‐implant bone loss than the PM‐parallel connections. However, it must be noted that this is based on three PS‐parallel groups and five PM‐parallel groups, compared to 12 PS‐conical groups. This uneven distribution might affect the statistical power of the meta‐analysis. Although the Caricasulo et al. (2018), Vetromilla et al. (2019) and Yu et al. (2020) studies confirmed that the least amount of bone loss occurs with conical connections, only Caricasulo et al. (2018) researched the effect of platform switching. They found 0.30 mm more bone loss on applying PM connections than the PS‐conical connection (significant), and that the PS‐parallel only resulted in 0.05 mm more bone loss than the conical connection (not significant). This is in agreement with our study's outcome where there is no significant difference between the PS connection, but the difference with the PM is significant. Both Vetromilla et al. (2019) and Yu et al. (2020) did not look into the effect of platform switching which might explain why Yu et al. (2020) found a significant difference between the conical and the non‐conical group and why Vetromilla et al. (2019) found fairly high amounts of bone loss in the internal‐connection group (0.7 mm). This is closer to the 0.52 mm bone loss in our PM groups than to the 0.14 mm bone loss in our PS groups. Hsu et al. (2017) did compare platform‐switching with platform‐matching. They concluded that platform switched connections are accompanied with less peri‐implant bone loss than the platform matched connections. Comparing the results of previous authors (Caricasulo et al., 2018; Hsu et al., 2017; Vetromilla et al., 2019; Yu et al., 2020) with the present review reveals that platform‐switching plays an important protective role in preserving the level of peri‐implant bone. Perhaps, supported by the Caricasulo et al. (2018) results, it can even be cautiously stated that the presence of a platform switch has more influence on bone level change than the presence or absence of a conical component in the connection.

The meta‐regression analysis of the present review revealed a significant statistical difference in implant loss between the PS‐conical and the PM‐parallel group. There was no statistical difference found when PS‐conical versus PS‐parallel (p = 0.79) and PS‐parallel versus PM‐parallel (p = 0.10) were analyzed. Hsu et al. (2017) did compare platform‐switching with platform‐matching, but they did not find a significant difference in implant survival rate. Vetromilla et al. (2019) concluded that a conical connection resulted in a higher implant survival rate than a platform‐matched configuration, which is in line with the meta‐analysis in our study.

According to our study, in contrast to bone level change platform switching seems to have little influence on the mid‐buccal mucosa level. When searching for studies that compared implant abutment connections in the aesthetic region, only one RCT (Cooper et al., 2019) was set up in the anterior maxilla and reported no statistically significant differences between the three connection types concerning mid‐buccal mucosa changes. The overall mid‐buccal retractions in both the PS‐conical, PS‐parallel and PM‐parallel groups were small and the differences were negligible.

Although there are statistically significant differences between the abutment connection configurations, all three types' clinical and radiographic results are good. All the reported bone loss, implant loss and mid‐buccal mucosa level change results are within the range of what is deemed acceptable. However, long term stability is important, especially the durability of an aesthetically good result, hence the authors favored the internal connections with a platform switch over the connections with a platform match. Yet, the included studies only had a relatively short follow‐up (mostly 1 year) and since the tissues around implants change continuously, albeit only a little, it would be useful to re‐evaluate the previous statement when more long‐term studies are available.

5. STRENGTH AND LIMITATIONS

The strength of this meta‐analysis is the broad and detailed literature search in multiple databases. A limitation to this study is that the quality of the reporting in the included studies was weak and the median follow‐up time was short (1 [1;5] year). Also, the meta‐analysis was done for variables that can be measured in many ways (in particular bone level change and mucosa level change) and are subject to confounding factors (such as surgical and restauration protocol and implant geometry) and was thus subject to heterogeneity, which means that the outcome must be viewed with caution. Another limitation is the decision to calculate annual bone loss, annual implant loss and annual mucosa change rates which, although good for comparability purposes, resembles a linear relation that assumes that the same quantity of bone, implants or mucosa is lost every year. Yet, in real life, most remodeling takes place in the first year, and only a few changes in the years thereafter. We accepted this limitation in order to perform a meta‐analysis and this approach is commonly accepted in the dental implant literature, but one should still interpret the results with caution.

6. RECOMMENDATIONS FOR FUTURE RESEARCH

Due to a lack of well‐designed RCTs and high quality studies, additional well designed studies are needed to be able to truly rate the effect of different implant‐abutment connections in the aesthetic zone. We therefore encourage efforts to come to a consensus on how to measure and report clinical and radiographic variables, as well as aesthetic ratings, accurately and homogenously.

7. CONCLUSION

The performance of conical and parallel connection configurations with a platform switch is comparable regarding peri‐implant bone loss and implant loss when applied to solitary implant restorations in the aesthetic zone. Parallel walled platform matched connections showed the most bone level change and implant loss. None of the connection configurations was significantly better at preserving the mid‐buccal mucosa levels.

CONFLICT OF INTEREST

The authors declare to have no conflict of interest with the contents of this article.

AUTHOR CONTRIBUTIONS

Caroliene M. Meijndert: concept/design, execution of search and data analysis/interpretations, drafting of article, final approval, accountable for all aspects of the work. Gerry M. Raghoebar: critical revision of article, final approval. Arjan Vissink: critical revision of article, final approval. Konstantina Delli: concept/design, data analysis/interpretation, drafting of article, critical revision of article, final approval, accountable for all aspects of the work. Henny J. A. Meijer: data collection, concept/design, statistics, data analysis/interpretation, drafting of article, final approval, accountable for all aspects of the work.

Supporting information

Figure S1 Visualization risk‐of‐bias assessments ROBINS‐1 for prospective non‐randomized trials

Figure S2: Visualization risk‐of‐bias assessment RoB‐2 for randomized controlled trials

Figure S3: Funnel plot of standard error by log odds ratio.

Figure S4: Forest plots for random effects meta‐analysis of studies evaluating implant loss in the PS‐Conical group

‐ Forest plots for random effects meta‐analysis of studies evaluating implant loss in the PS‐parallel group

‐ Forest plots for random effects meta‐analysis of studies evaluating implant loss in the PM‐parallel group

Figure S5: Forest plots for random effects meta‐analysis of studies evaluating mid‐buccal mucosa level change in the PS‐Conical group.

‐ Forest plots for random effects meta‐analysis of studies evaluating mid‐buccal mucosa level change in the PS‐parallel group

‐ Forest plots for random effects meta‐analysis of studies evaluating mid‐buccal mucosa level change in the PM‐parallel group

Click here for additional data file. (3.4MB, zip)

Meijndert, C. M. , Raghoebar, G. M. , Vissink, A. , Delli, K. , & Meijer, H. J. A. (2021). The effect of implant‐abutment connections on peri‐implant bone levels around single implants in the aesthetic zone: A systematic review and a meta‐analysis. Clinical and Experimental Dental Research, 7(6), 1025–1036. 10.1002/cre2.471

Funding information University Medical Center Groningen

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

REFERENCES

  1. Allen, P. F. , Lee, S. , & Brady, P. (2017). Clinical and subjective evaluation of implants in patients with hypodontia: A two‐year observation study. Clinical Oral Implants Research, 28(10), 1258–1262. [DOI] [PubMed] [Google Scholar]
  2. Bashutski, J. D. , Wang, H. L. , Rudek, I. , Moreno, I. , Koticha, T. , & Oh, T. J. (2013). Effect of flapless surgery on single‐tooth implants in the esthetic zone: A randomized clinical trial. Journal of Periodontology, 84(12), 1747–1754. [DOI] [PubMed] [Google Scholar]
  3. Belser, U. C. , Grütter, L. , Vailati, F. , Bornstein, M. M. , Weber, H. P. , & Buser, D. (2009). Outcome evaluation of early placed maxillary anterior single‐tooth implants using objective esthetic criteria: A cross‐sectional, retrospective study in 45 patients with a 2‐ to 4‐year follow‐up using pink and white esthetic scores. Journal of Periodontology, 80(1), 140–151. [DOI] [PubMed] [Google Scholar]
  4. Berberi, A. N. , Sabbagh, J. M. , Aboushelib, M. N. , Noujeim, Z. F. , & Salameh, Z. A. (2014). A 5‐year comparison of marginal bone level following immediate loading of single‐tooth implants placed in healed alveolar ridges and extraction sockets in the maxilla. Frontiers in Physiology, 5, 29. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Buser, D. , Sennerby, L. , & De Bruyn, H. (2017). Modern implant dentistry based on osseointegration: 50 years of progress, current trends and open questions. Periodontology 2000, 73(1), 7–21. 10.1111/prd.12185 [DOI] [PubMed] [Google Scholar]
  6. Canullo, L. , Omori, Y. , Amari, Y. , Iannello, G. , & Pesce, P. (2018). Five‐year cohort prospective study on single implants in the esthetic area restored using one‐abutment/one‐time prosthetic approach. Clinical Implant Dentistry and Related Research, 20(5), 668–673. [DOI] [PubMed] [Google Scholar]
  7. Canullo, L. , Penarrocha, D. , Micarelli, C. , Massidda, O. , & Bazzoli, M. (2013). Hard tissue response to argon plasma cleaning/sterilisation of customised titanium abutments versus 5‐second steam cleaning: Results of a 2‐year post‐loading follow‐up from an explanatory randomised controlled trial in periodontally healthy patients. European Journal of Oral Implantology, 6(3), 251–260. [PubMed] [Google Scholar]
  8. Canullo, L. , Tallarico, M. , Peñarrocha‐Oltra, D. , Monje, A. , Wang, H. L. , & Peñarrocha‐Diago, M. (2016). Implant abutment cleaning by plasma of argon: 5‐year follow‐up of a randomized controlled trial. Journal of Periodontology, 87(4), 434–442. [DOI] [PubMed] [Google Scholar]
  9. Caricasulo, R. , Malchiodi, L. , Ghensi, P. , Fantozzi, G. , & Cucchi, A. (2018). The influence of implant‐abutment connection to peri‐implant bone loss: A systematic review and meta‐analysis. Clinical Implant Dentistry and Related Research, 20(4), 653–664. [DOI] [PubMed] [Google Scholar]
  10. Ceruso, F. M. , Barnaba, P. , Mazzoleni, S. , Ottria, L. , Gargari, M. , Zuccon, A. , Bruno, G. , & DI Fiore, A. (2017). Implant‐abutment connections on single crowns: A systematic review. Journal of Oral Implantology (Rome), 10(4), 349–353. 10.11138/orl/2017.10.4.349 [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Cooper, L. , Felton, D. A. , Kugelberg, C. F. , Ellner, S. , Chaffee, N. , Molina, A. L. , Moriarty, J. D. , Paquette, D. , & Palmqvist, U. (2001). A multicenter 12‐month evaluation of single‐tooth implants restored 3 weeks after 1‐stage surgery. The International Journal of Oral & Maxillofacial Implants, 16(2), 182–192. [PubMed] [Google Scholar]
  12. Cooper, L. F. , Ellner, S. , Moriarty, J. , Felton, D. A. , Paquette, D. , Molina, A. , Chaffee, N. , Asplund, P. , Smith, R. , & Hostner, C. (2007). Three‐year evaluation of single‐tooth implants restored 3weeks after 1‐stage surgery. The International Journal of Oral & Maxillofacial Implants, 22(5), 791–800. [PubMed] [Google Scholar]
  13. Cooper, L. F. , Reside, G. , Stanford, C. , Barwacz, C. , Feine, J. , Nader, S. A. , Scheyer, T. , & McGuire, M. (2019). Three‐year prospective randomized comparative assessment of anterior maxillary single implants with different abutment interfaces. The International Journal of Oral & Maxillofacial Implants, 34(1), 150–158. [DOI] [PubMed] [Google Scholar]
  14. Cooper, L. F. , Reside, G. J. , Raes, F. , Garringa, J. S. , Tarrida, L. G. , Wiltfang, J. , Kern, M. , & De Bruyn, H. (2014). Immediate provisionalization of dental implants placed in healed alveolar ridges and extraction sockets: A 5‐year prospective evaluation. The International Journal of Oral & Maxillofacial Implants, 29(3), 709–717. [DOI] [PubMed] [Google Scholar]
  15. Cosyn, J. , Pollaris, L. , Van der Linden, F. , & De Bruyn, H. (2015). Minimally invasive single implant treatment (M.I.S.I.T.) based on ridge preservation and contour augmentation in patients with a high aesthetic risk profile: One‐year results. Journal of Clinical Periodontology, 42(4), 398–405. [DOI] [PubMed] [Google Scholar]
  16. De Bruyckere, T. , Eeckhout, C. , Eghbali, A. , Younes, F. , Vandekerckhove, P. , Cleymaet, R. , & Cosyn, J. (2018). A randomized controlled study comparing guided bone regeneration with connective tissue graft to re‐establish convexity at the buccal aspect of single implants: A one‐year CBCT analysis. Journal of Clinical Periodontology, 45(11), 1375–1387. [DOI] [PubMed] [Google Scholar]
  17. den Hartog, L. , Meijer, H. J. A. , Vissink, A. , & Raghoebar, G. M. (2017). Anterior single implants with different neck designs: 5 year results of a randomized clinical trial. Clinical Implant Dentistry and Related Research, 19(4), 717–724. [DOI] [PubMed] [Google Scholar]
  18. den Hartog, L. , Raghoebar, G. M. , Stellingsma, K. , Vissink, A. , & Meijer, H. J. (2016). Immediate loading of anterior single‐tooth implants placed in healed sites: Five‐year results of a randomized clinical trial. The International Journal of Prosthodontics, 29(6), 584–591. [DOI] [PubMed] [Google Scholar]
  19. Eghbali, A. , Seyssens, L. , De Bruyckere, T. , Younes, F. , Cleymaet, R. , & Cosyn, J. (2018). A 5‐year prospective study on the clinical and aesthetic outcomes of alveolar ridge preservation and connective tissue graft at the buccal aspect of single implants. Journal of Clinical Periodontology, 45(12), 1475–1484. [DOI] [PubMed] [Google Scholar]
  20. Esposito, M. , Barausse, C. , Pistilli, R. , Jacotti, M. , Grandi, G. , Tuco, L. , & Felice, P. (2015). Immediate loading of post‐extractive versus delayed placed single implants in the anterior maxilla: Outcome of a pragmatic multicenter randomised controlled trial 1‐year after loading. European Journal of Oral Implantology, 8(4), 347–358. [PubMed] [Google Scholar]
  21. Felice, P. , Pistilli, R. , Barausse, C. , Trullenque‐Eriksson, A. , & Esposito, M. (2015). Immediate non‐occlusal loading of immediate post‐extractive versus delayed placement of single implants in preserved sockets of the anterior maxilla: 1‐year post‐loading outcome of a randomised controlled trial. European Journal of Oral Implantology, 8(4), 361–372. [PubMed] [Google Scholar]
  22. Friberg, B. , & Ahmadzai, M. (2019). A prospective study on single tooth reconstructions using parallel walled implants with internal connection (NobelParallel CC) and abutments with angulated screw channels (ASC). Clinical Implant Dentistry and Related Research, 21(2), 226–231. [DOI] [PubMed] [Google Scholar]
  23. Fu, J. H. , Oh, T. J. , Benavides, E. , Rudek, I. , & Wang, H. L. (2014). A randomized clinical trial evaluating the efficacy of the sandwich bone augmentation technique in increasing buccal bone thickness during implant placement surgery: I. clinical and radiographic parameters. Clinical Oral Implants Research, 25(4), 458–467. 10.1111/clr.12171 [DOI] [PubMed] [Google Scholar]
  24. Fürhauser, R. , Florescu, D. , Benesch, T. , Haas, R. , Mailath, G. , & Watzek, G. (2005). Evaluation of soft tissue around single‐tooth implant crowns: The pink esthetic score. Clinical Oral Implants Research, 16(6), 639–644. [DOI] [PubMed] [Google Scholar]
  25. Gjelvold, B. , Kisch, J. , Chrcanovic, B. R. , Albrektsson, T. , & Wennerberg, A. (2017). Clinical and radiographic outcome following immediate loading and delayed loading of single‐tooth implants: Randomized clinical trial. Clinical Implant Dentistry and Related Research, 19(3), 549–558. [DOI] [PubMed] [Google Scholar]
  26. Gjelvold, B. , Kisch, J. , Mohammed, D. J. H. , Chrcanovic, B. R. , Albrektsson, T. , & Wennerberg, A. (2020). Immediate loading of single implants, guided surgery, and intraoral scanning: A nonrandomized study. The International Journal of Prosthodontics, 33(5), 513–522. [DOI] [PubMed] [Google Scholar]
  27. Gotfredsen, K. (2012). A 10‐year prospective study of single tooth implants placed in the anterior maxilla. Clinical Implant Dentistry and Related Research, 14(1), 80–87. [DOI] [PubMed] [Google Scholar]
  28. Gracis, S. , Michalakis, K. , Vigolo, P. , Vult Von Steyern, P. , Zwahlen, M. , & Sailer, I. (2012). Internal vs. external connections for abutments/reconstructions: A systematic review. Clinical Oral Implants Research, 23(6), 202–216. 10.1111/j.1600−0501.2012.02556.x [DOI] [PubMed] [Google Scholar]
  29. Grandi, T. , Guazzi, P. , Samarani, R. , & Grandi, G. (2013). Immediate provisionalisation of single post‐extractive implants versus implants placed in healed sites in the anterior maxilla: 1‐year results from a multicentre controlled cohort study. European Journal of Oral Implantology, 6(3), 285–295. [PubMed] [Google Scholar]
  30. Guarnieri, R. , Belleggia, F. , & Grande, M. (2016). Immediate versus delayed treatment in the anterior maxilla using single implants with a laser‐microtextured collar: 3‐year results of a case series on hard‐ and soft‐tissue response and esthetics. Journal of Prosthodontics, 25(2), 135–145. [DOI] [PubMed] [Google Scholar]
  31. Heydecke, G. , Mirzakhanian, C. , Behneke, A. , Behneke, N. , Fügl, A. , Zechner, W. , Baer, R. A. , Nölken, R. , Gottesman, E. , Colic, S. , Ottria, L. , & Pozzi, A. (2019). A prospective multicenter evaluation of immediately functionalized tapered conical connection implants for single restorations in maxillary anterior and premolar sites: 3‐year results. Clinical Oral Investigations, 23(4), 1877–1885. [DOI] [PubMed] [Google Scholar]
  32. Hosseini, M. , Worsaae, N. , & Gotfredsen, K. (2020). Tissue changes at implant sites in the anterior maxilla with and without connective tissue grafting: A five‐year prospective study. Clinical Oral Implants Research, 31(1), 18–28. [DOI] [PubMed] [Google Scholar]
  33. Hsu, Y. T. , Chan, H. L. , Rudek, I. , Bashutski, J. , Oh, W. S. , Wang, H. L. , & Oh, T. J. (2016). Comparison of clinical and radiographic outcomes of platform‐switched implants with a rough collar and platform‐matched implants with a smooth collar: A 1‐year randomized clinical trial. The International Journal of Oral & Maxillofacial Implants, 31(2), 382–390. [DOI] [PubMed] [Google Scholar]
  34. Hsu, Y. T. , Lin, G. H. , & Wang, H. L. (2017). Effects of platform‐switching on peri‐implant soft and hard tissue outcomes: A systematic review and meta‐analysis. The International Journal of Oral & Maxillofacial Implants, 32(1), e9–e24. [DOI] [PubMed] [Google Scholar]
  35. Jemt, T. (1997). Regeneration of gingival papillae after single‐implant treatment. The International Journal of Periodontics & Restorative Dentistry, 17(4), 326–333. [PubMed] [Google Scholar]
  36. Jonker, B. P. , Wolvius, E. B. , van der Tas, J. T. , & Pijpe, J. (2018). The effect of resorbable membranes on one‐stage ridge augmentation in anterior single‐tooth replacement: A randomized, controlled clinical trial. Clinical Oral Implants Research, 29(2), 235–247. [DOI] [PubMed] [Google Scholar]
  37. Kemppainen, P. , Eskola, S. , & Ylipaavalniemi, P. (1997). A comparative prospective clinical study of two single‐tooth implants: A preliminary report of 102 implants. The Journal of Prosthetic Dentistry, 77(4), 382–387. [DOI] [PubMed] [Google Scholar]
  38. Koo, K. T. , Lee, E. J. , Kim, J. Y. , Seol, Y. J. , Han, J. S. , Kim, T. I. , Lee, Y. M. , Ku, Y. , Wikesjö, U. M. , & Rhyu, I. C. (2012). The effect of internal versus external abutment connection modes on crestal bone changes around dental implants: A radiographic analysis. Journal of Periodontology, 83(9), 1104–1109. 10.1902/jop.2011.110456 [DOI] [PubMed] [Google Scholar]
  39. Koutouzis, T. (2019). Implant‐abutment connection as contributing factor to peri‐implant diseases. Periodontology 2000, 81(1), 152–166. 10.1111/prd.12289 [DOI] [PubMed] [Google Scholar]
  40. Lowy, J. , Kwon, H. S. , Patel, A. , Greenwell, H. , Hill, M. , Katwal, D. , Rademacher, A. C. , & Mendoza, J. (2019). The effect of platform‐switching plus laser grooving on peri‐implant hard and soft tissue level: A randomized, controlled, blinded clinical trial. The International Journal of Periodontics & Restorative Dentistry, 39(5), 669–674. [DOI] [PubMed] [Google Scholar]
  41. Meijndert, C. M. , Raghoebar, G. M. , Santing, H. J. , Vissink, A. , & Meijer, H. J. A. (2020). Performance of bone‐level implants with conical connections in the anterior maxilla: A 5‐year prospective cohort study. Clinical Oral Implants Research, 31(2), 173–180. [DOI] [PubMed] [Google Scholar]
  42. Meloni, S. M. , Tallarico, M. , Lolli, F. M. , Deledda, A. , Pisano, M. , & Jovanovic, S. A. (2015). Postextraction socket preservation using epithelial connective tissue graft vs porcine collagen matrix. 1‐year results of a randomised controlled trial. European Journal of Oral Implantology, 8(1), 39–48. [PubMed] [Google Scholar]
  43. Moher, D. , Liberati, A. , Tetzlaff, J. , Altman, D. G. , & PRISMA Group . (2009). Preferred reporting items for systematic reviews and meta‐analyses: The PRISMA statement. PLoS Med, 6(7), e1000097. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Norton, M. R. (2004). A short‐term clinical evaluation of immediately restored maxillary TiOblast single‐tooth implants. The International Journal of Oral & Maxillofacial Implants, 19(2), 274–281. [PubMed] [Google Scholar]
  45. Palmer, R. M. , Palmer, P. J. , & Smith, B. J. (2000). A 5‐year prospective study of Astra single tooth implants. Clinical Oral Implants Research, 11(2), 179–182. [DOI] [PubMed] [Google Scholar]
  46. Raes, S. , Cosyn, J. , Noyelle, A. , Raes, F. , & De Bruyn, H. (2018). Clinical outcome after 8 to 10 years of immediately restored single implants placed in extraction sockets and healed ridges. The International Journal of Periodontics & Restorative Dentistry, 38(3), 337–345. [DOI] [PubMed] [Google Scholar]
  47. Raes, S. , Rocci, A. , Raes, F. , Cooper, L. , De Bruyn, H. , & Cosyn, J. (2015). A prospective cohort study on the impact of smoking on soft tissue alterations around single implants. Clinical Oral Implants Research, 26(9), 1086–1090. [DOI] [PubMed] [Google Scholar]
  48. Raghoebar, G. M. , Slater, J. J. , Hartog, L. D. , Meijer, H. J. , & Vissink, A. (2009). Comparison of procedures for immediate reconstruction of large osseous defects resulting from removal of a single tooth to prepare for insertion of an endosseous implant after healing. International Journal of Oral and Maxillofacial Surgery, 38(7), 736–743. [DOI] [PubMed] [Google Scholar]
  49. Schwartz‐Arad, D. , Herzberg, R. , & Levin, L. (2005). Evaluation of long‐term implant success. Journal of Periodontology, 76(10), 1623–1628. 10.1902/jop.2005.76.10.1623 [DOI] [PubMed] [Google Scholar]
  50. Shafie, H. R. , & White, B. A. (2014). Different implant—Abutment connections. In Shafie H. R. (Ed.), Clinical and laboratory manual of dental implant abutments (p. 33). John Wiley & Sons. [Google Scholar]
  51. Slagter, K. W. , Meijer, H. J. , Bakker, N. A. , Vissink, A. , & Raghoebar, G. M. (2016). Immediate single‐tooth implant placement in bony defects in the esthetic zone: A 1‐year randomized controlled trial. Journal of Periodontology, 87(6), 619–629. [DOI] [PubMed] [Google Scholar]
  52. Steinebrunner, L. , Wolfart, S. , Bössmann, K. , & Kern, M. (2005). In vitro evaluation of bacterial leakage along the implant‐abutment interface of different implant systems. The International Journal of Oral & Maxillofacial Implants, 20(6), 875–881. [PubMed] [Google Scholar]
  53. Sterne, J. A. , Hernán, M. A. , Reeves, B. C. , Savovic, J. , Berkman, N. D. , Viswanathan, M. , Henry, D. , Altman, D. G. , Ansari, M. T. , Boutron, I. , Carpenter, J. R. , Chan, A. W. , Churchill, R. , Deeks, J. J. , Hróbjartsson, A. , Kirkham, J. , Jüni, P. , Loke, Y. K. , Pigott, T. D. , Ramsay, C. R. , … Higgins, J. P. (2016). ROBINS‐I: A tool for assessing risk of bias in non‐randomised studies of interventions. BMJ, 355, i4919. [DOI] [PMC free article] [PubMed] [Google Scholar]
  54. Sterne, J. A. C. , Savović, J. , Page, M. J. , Elbers, R. G. , Blencowe, N. S. , Boutron, I. , Cates, C. J. , Cheng, H. Y. , Corbett, M. S. , Eldridge, S. M. , Emberson, J. R. , Hernán, M. A. , Hopewell, S. , Hróbjartsson, A. , Junqueira, D. R. , Jüni, P. , Kirkham, J. J. , Lasserson, T. , Li, T. , McAleenan, A. , … Higgins, J. (2019). RoB 2: A revised tool for assessing risk of bias in randomised trials. BMJ, 366, l4898. [DOI] [PubMed] [Google Scholar]
  55. Vanlioglu, B. A. , Kahramanoğlu, E. , Ozkan, Y. , & Kulak‐Özkan, Y. (2014). Clinical and radiographic evaluation of early loaded maxillary anterior single‐tooth bone‐level implants. The International Journal of Oral & Maxillofacial Implants, 29(6), 1369–1373. [DOI] [PubMed] [Google Scholar]
  56. Vanlıoglu, B. A. , Özkan, Y. , Evren, B. , & Özkan, Y. K. (2012). Experimental custom‐made zirconia abutments for narrow implants in esthetically demanding regions: A 5‐year follow‐up. The International Journal of Oral & Maxillofacial Implants, 27(5), 1239–1242. [PubMed] [Google Scholar]
  57. Vetromilla, B. M. , Brondani, L. P. , Pereira‐Cenci, T. , & Bergoli, C. D. (2019). Influence of different implant‐abutment connection designs on the mechanical and biological behavior of single‐tooth implants in the maxillary esthetic zone: A systematic review. The Journal of Prosthetic Dentistry, 121(3), 398–403. [DOI] [PubMed] [Google Scholar]
  58. Wittneben, J. G. , Gavric, J. , Sailer, I. , Buser, D. , & Wismeijer, D. (2020). Clinical and esthetic outcomes of two different prosthetic workflows for implant‐supported all‐ceramic single crowns‐3 year results of a randomized multicenter clinical trail. Clinical Oral Implants Research, 31(5), 495–505. [DOI] [PubMed] [Google Scholar]
  59. Yildiz, P. , Zortuk, M. , Kiliç, E. , Dinçel, M. , & Albayrak, H. (2016). Clinical outcomes after immediate and late implant loading for a single missing tooth in the anterior maxilla. Implant Dentistry, 25(4), 504–509. [DOI] [PubMed] [Google Scholar]
  60. Yu, X. , Han, Y. , & Wang, J. (2020). Is an internal tapered connection more efficient than an internal nontapered connection? A systematic review and meta‐analysis. The Journal of Prosthetic Dentistry, 124(4), 431–438. [DOI] [PubMed] [Google Scholar]
  61. Zipprich, H. , Weigl, P. , Ratka, C. , Lange, B. , & Lauer, H. C. (2018). The micromechanical behavior of implant‐abutment connections under a dynamic load protocol. Clinical Implant Dentistry and Related Research, 20(5), 814–823. [DOI] [PubMed] [Google Scholar]
  62. Zuiderveld, E. G. , Meijer, H. J. , Vissink, A. , & Raghoebar, G. M. (2019). Outcome of treatment with single implants in preserved versus nonpreserved alveolar ridges: A 1‐year cohort study. The International Journal of Oral & Maxillofacial Implants, 34(6), 1457–1465. [DOI] [PubMed] [Google Scholar]
  63. Zuiderveld, E. G. , Meijer, H. J. A. , Vissink, A. , & Raghoebar, G. M. (2018). The influence of different soft‐tissue grafting procedures at single implant placement on esthetics: A randomized controlled trial. Journal of Periodontology, 89(8), 903–914. [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Figure S1 Visualization risk‐of‐bias assessments ROBINS‐1 for prospective non‐randomized trials

Figure S2: Visualization risk‐of‐bias assessment RoB‐2 for randomized controlled trials

Figure S3: Funnel plot of standard error by log odds ratio.

Figure S4: Forest plots for random effects meta‐analysis of studies evaluating implant loss in the PS‐Conical group

‐ Forest plots for random effects meta‐analysis of studies evaluating implant loss in the PS‐parallel group

‐ Forest plots for random effects meta‐analysis of studies evaluating implant loss in the PM‐parallel group

Figure S5: Forest plots for random effects meta‐analysis of studies evaluating mid‐buccal mucosa level change in the PS‐Conical group.

‐ Forest plots for random effects meta‐analysis of studies evaluating mid‐buccal mucosa level change in the PS‐parallel group

‐ Forest plots for random effects meta‐analysis of studies evaluating mid‐buccal mucosa level change in the PM‐parallel group

Click here for additional data file. (3.4MB, zip)

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Articles from Clinical and Experimental Dental Research are provided here courtesy of Wiley

RESOURCES