Int. J. Oral Maxillofac. Surg. 2015; 44: 493–506 http://dx.doi.org/10.1016/j.ijom.2014.11.011, available online at http://www.sciencedirect.com
Meta-analysis Dental implants
Immediately loaded non-submerged versus delayed loaded submerged dental implants: A meta-analysis
B. R. Chrcanovica,, T. Albrektssona,b, A. Wennerberga a
Department of Prosthodontics, Faculty of Odontology, Malmo¨ University, Malmo¨, Sweden; bDepartment of Biomaterials, Go¨teborg University, Go¨teborg, Sweden
B.R. Chrcanovic, T. Albrektsson, A. Wennerberg: Immediately loaded non-submerged versus delayed loaded submerged dental implants: A meta-analysis. Int. J. Oral Maxillofac. Surg. 2015; 44: 493–506. # 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. The purpose of the present meta-analysis was to test the null hypothesis of no difference in the implant failure rate, postoperative infection, and marginal bone loss for patients being rehabilitated with immediately loaded non-submerged dental implants or delayed loaded submerged implants, against the alternative hypothesis of a difference. An electronic search without time or language restrictions was undertaken in March 2014. Eligibility criteria included clinical human studies, either randomized or not. The search strategy resulted in 28 publications. The inverse variance method was used for a random- or fixed-effects model, depending on the heterogeneity. The estimates of an intervention were expressed as the risk ratio (RR) and mean difference (MD) in millimetres. Twenty-three studies were judged to be at high risk of bias, one at moderate risk of bias, and four studies were considered at low risk of bias. The difference between procedures (submerged vs. non-submerged implants) significantly affected the implant failure rate (P = 0.02), with a RR of 1.78 (95% confidence interval (CI) 1.12–2.83). There was no apparent significant effect of non-submerged dental implants on the occurrence of postoperative infection (P = 0.29; RR 2.13, CI 0.52–8.65) or on marginal bone loss (P = 0.77; MD 0.03, 95% CI 0.23 to 0.17).
Introduction
Historically, the original Bra˚nemark protocol for placing dental implants prescribed a two-stage surgery with a submerged healing period of at least 3 months in the mandible and 6 months in the maxilla,1 allowing the implant to osseointegrate without being exposed to external forces. After bone healing, a second surgery is performed to connect a 0901-5027/040493 + 014
healing abutment. One of the main reasons for implant insertion in the two-stage procedure was to minimize the risk of infection, since the peri-implant tissue is allowed to heal separate from the oral microbial environment.2 Extended treatment times, the requirement for two surgical interventions, and the need for interim prostheses during healing are disadvantages of conventional implant treatment.3
Keywords: Dental implants; Submerged; Nonsubmerged; One-stage implant; Two-stage implant; Implant failure rate; Postoperative infection; Marginal bone loss; Meta-analysis. Accepted for publication 19 November 2014 Available online 23 December 2014
Over time, the concepts of implant placement in fresh extraction sockets,4,5 immediate loading, and non-submerged implants were introduced, focusing on shorter and less invasive procedures. To reduce the treatment time and offer the patient early function and aesthetics, it is necessary to use a one-stage surgical procedure and to load the implants as soon as possible. In the one-stage surgical approach (non-submerged implant), the coronal part
# 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
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Chrcanovic et al.
of the implant is positioned above the gingiva level in the case of single-part implants, or transmucosal healing abutments are placed in the case of two-part implants. In the one-stage surgical approach, the implant can be loaded immediately or not. The encouraging early experiences of immediate loading in the mandible and the development of new implant designs and surfaces have inspired researchers to further explore applications of immediate loading.6 Inserting implants in one stage has several advantages. Only one surgical intervention is required, which is convenient for the patient, especially for the medically compromised patient. In addition, there is a considerable cost-benefit advantage. The prosthetic phase can start earlier because there is no wound-healing period related to a second surgical procedure. Furthermore, the implants are accessible for clinical monitoring during the osseointegration period.7 It allows for a healed peri-implant mucosa at the time of prosthetic rehabilitation. Although immediate loading of implants shortens the treatment duration and also provides patients with an acceptable aesthetic appearance, there is concern that immediate loading may increase the risk of implant failure. The aim of this meta-analysis was to compare the survival rate, postoperative complications, and marginal bone loss of non-submerged immediately loaded dental implants with those of submerged delayed loaded implants. The present study presents a more detailed and in-depth analysis of the influence of the submerged and non-submerged approaches on implant failure rates previously assessed in a published systematic review.8 Materials and methods
This study followed the PRISMA Statement guidelines.9 A review protocol does not exist. The purpose of the present meta-analysis was to test the null hypothesis of no difference in implant failure rate, postoperative infection, and marginal bone loss for patients rehabilitated with immediately loaded non-submerged dental implants or delayed loaded submerged implants, against the alternative hypothesis of a difference.
‘dental journals’ in the filter ‘journal categories’: {Subject AND Adjective} {Subject: (dental implant [title]) AND Adjective: (submerged OR nonsubmerged OR non-submerged OR one-stage OR single-stage OR two-stage [title])}. The following terms were used in the search strategy on Web of Science, refined by selecting the term ‘dentistry oral surgery medicine’ in the filter ‘research area’: {Subject AND Adjective} {Subject: (dental implant [title]) AND Adjective: (submerged OR nonsubmerged OR non-submerged OR one-stage OR single-stage OR two-stage [title])}. The following terms were used in the search strategy for the Cochrane Oral Health Group Trials Register: (dental implant OR dental implant failure OR dental implant survival OR dental implant success AND (submerged OR nonsubmerged OR non-submerged OR one-stage OR single-stage OR two-stage)). A manual search of journals covering dental implant research was also done, including British Journal of Oral and Maxillofacial Surgery, Clinical Implant Dentistry and Related Research, Clinical Oral Implants Research, European Journal of Oral Implantology, Implant Dentistry, International Journal of Oral and Maxillofacial Implants, International Journal of Oral and Maxillofacial Surgery, International Journal of Periodontics and Restorative Dentistry, International Journal of Prosthodontics, Journal of Clinical Periodontology, Journal of Dental Research, Journal of Oral Implantology, Journal of Craniofacial Surgery, Journal of Cranio-Maxillofacial Surgery, Journal of Dentistry, Journal of Maxillofacial and Oral Surgery, Journal of Oral and Maxillofacial Surgery, Journal of Oral Rehabilitation, Journal of Periodontology, and Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology. The reference lists of the studies identified and relevant reviews on the subject were also scanned for possible additional studies. Moreover, online databases providing information on clinical trials in progress were checked (http://clinicaltrials.gov; http://www.centerwatch.com/ clinical-trials; http://www.clinicalconnection.com).
Search strategies
An electronic search without time or language restrictions was undertaken in March 2014 in the following databases: PubMed, Web of Science, and the Cochrane Oral Health Group Trials Register. The following terms were used in the search strategy on PubMed, refined by selecting the term
Inclusion and exclusion criteria
Eligibility criteria included clinical human studies, either randomized or not, comparing implant failure rates in any group of patients receiving submerged versus immediately loaded non-submerged dental implants. Only the studies immediately
loading all non-submerged implants were considered. For the studies publishing more than one paper but with different follow-up periods, only the publication with the longest (the last) follow-up period was considered, as long as the sample size had remained the same. For this review, implant failure represents the complete loss of the implant. Exclusion criteria were case reports, technical reports, animal studies, in vitro studies, and review papers. Study selection
The titles and abstracts of all reports identified through the electronic searches were read independently by the three authors. For studies appearing to meet the inclusion criteria, or for which there were insufficient data in the title and abstract to make a clear decision, the full report was obtained. Disagreements were resolved by discussion between the authors. Quality assessment
The quality assessment was performed using the recommended approach for assessing risk of bias in studies included in Cochrane reviews.10 The classification of the risk of bias potential for each study was based on the four following criteria: sequence generation (random selection in the population), allocation concealment (steps must be taken to secure strict implementation of the schedule of random assignments by preventing foreknowledge of the forthcoming allocations), incomplete outcome data (clear explanation of withdrawals and exclusions), and blinding (measures to blind study participants and personnel from knowledge of which intervention a participant received). Incomplete outcome data would also be considered addressed when there were no withdrawals and/or exclusions. A study that met all the criteria mentioned above was classified as having a low risk of bias, a study that did not meet one of these criteria was classified as having a moderate risk of bias, and when two or more criteria were not met, the study was considered to have a high risk of bias. Data extraction and meta-analysis
The following data were extracted from the studies included in the final analysis, when available: year of publication, study design, single centre or multi-centre study, number of patients, patient age, follow-up, days of antibiotic prophylaxis, use of mouth rinse, implant healing period, failed and placed implants, and postoperative
Immediately loaded non-submerged versus delayed loaded submerged dental implants: A meta-analysis infection. Contact was made with authors to obtain possible missing data. Implant failure and postoperative infection were the dichotomous outcome measures evaluated. Weighted mean differences were used to construct forest plots of marginal bone loss, a continuous outcome. The statistical unit for the outcomes was the implant. Whenever outcomes of interest were not clearly stated, the data were not used for analysis. The I2 statistic was used to express the percentage of the total variation across studies due to heterogeneity, with 25% corresponding to low heterogeneity, 50% to moderate and 75% to high. The inverse variance method was used for the random-effects or fixed-effects model. In the case of statistically significant (P < 0.10) heterogeneity, a random-effects model was used to assess the significance of treatment effects. Where no statistically significant heterogeneity was found, analysis was performed using a fixed-effects model.11 The estimates of an intervention were expressed as the risk ratio (RR) and as the mean difference (MD) in millimetres for continuous outcomes, both with a 95% confidence interval (CI). Statistical significance was set at P< 0.05. Only if there were studies with similar comparisons reporting
Fig. 1. Study screening process.
the same outcome measures was a metaanalysis to be attempted. A funnel plot (plot of effect size versus standard error) was drawn. Asymmetry of the funnel plot may indicate publication bias and other biases related to sample size, although the asymmetry may also represent a true relationship between trial size and effect size. The data were analysed using the statistical software Review Manager (version 5.2.8; The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark, 2014). Results Literature search
The study selection process is summarized in Fig. 1. The search strategy resulted in 1328 papers. One hundred and eighty-four were cited in more than one research of terms. The three reviewers independently screened the abstracts to identify articles related to the focus question. The initial screening of titles and abstracts resulted in 1144 full-text papers; 1050 were excluded for not being related to the topic. Assessment of the full-text reports of the remaining 94 articles led to the exclusion of 66
495
because they did not meet the inclusion criteria: 39 reported the non-submerged group being submitted to early or delayed loading, nine did not report the number of failures and/or the number of implants in each group, eight comprised earlier follow-up of the same study, four were animal studies, two were reviews, one was a finite element analysis study, one applied extraoral implants, one did not evaluate implant failure, and one reported two-stage implants being inserted in a one-stage procedure. Thus, a total of 28 publications were included in the review. Description of the studies
Detailed data of the 28 studies included are listed in Tables 1 and 2. Six randomized clinical trials (RCT),3,12–16 14 controlled clinical trials (CCT),6,17–29 and eight retrospective analyses30–37 were included in the meta-analysis. Only three of them were multi-centre studies.15,19,21 Nine studies had a maximum follow-up of 12 months,3,6,13,15,19,20,25,29,35 eight studies had a maximum follow-up ranging from 13 to 36 months,12,14,16,17,21–24 nine studies had a maximum follow-up ranging from 37 to 120 months,18,26–28,30–32,34,36 and one study had a follow-up of more than 10 years;37 one study did not report the follow-up period.33 Three studies did not report patient age.18,28,31 Of the studies with data available for patient age, three included non-adults patients.22,35,37 Only seven studies provided information on postoperative infection,12,15,16,18,23,28,36 with six occurrences in a total of 663 patients receiving 1530 implants. Some of the patients were smokers in 16 studies.6,12,13,15,17,19,21–24,26,27,29,32,35,36 Ten studies inserted some of the implants in fresh extraction sockets,17,22,25,26,28,29, 32,34,36,37 whereas in another, all implants were inserted in fresh extraction sockets.16 Four studies included only patients who received single-implant restorations3,13–15 and two included only patients who received overdentures.12,36 Some14,33,36 or all16 implant sites underwent grafting procedures in some studies. Seven studies included only edentulous patients,12,18,19, 21,24,27,33 five inserted implants only in the maxilla,3,6,13,14,27 five studies inserted implants only in the mandible,15,19,21,23,24 and one study only in the pterygomaxillary region using a stereolithographic surgical guide.37 Some patients17,26,32 or all patients16,25 had periodontal disease in some studies. Diabetic patients were included in three studies.17,29,36 The most common period of healing before the loading of implants in the
496
Table 1. Detailed data of the studies included. Patient age range (average) (years)
Follow-up visits (or range)
Antibiotics/ mouth rinse (days)
Failed/ placed implants (n)
Implant failure rate (%)
RA (single centre) RA (single centre) CCT (single centre) RA (single centre) CCT (single centre) RA (single centre) RCT (single centre) CCT (multicentre) CCT (single centre) CCT (multicentre) CCT (single centre) CCT (single centre) RCT (single centre) CCT (single centre)
7a
48–71 (NM)
42 Months
NM
535 (106 G1; 429 G2)b 10a
NM
10 Years
NM
45–70 (55)
NM
10 (NM)
48–78 (NM)
12 And 18 months 10 Years
10 (G1 + G2)
NM
14 (NM)
40–83 (NM)
20 (10 G1; 10 G2)
44–73 (58.4)
82 (52 G1; 30 G2)
NM (64.9)
6, 12, And 24 months 1 Year
7a
50–72 (60)
6 Months
108 (78 G1; 30 G2)
NM (64.9)
2 And 3 years
40 (20 G1; 20 G2)
58–87 (73) (G1) 50–80 (64) (G2) 17–83 (53)
3, 6, And 12 months 1 And 2 years
5/NM
23–71 (43)
1 Year
NM
12 (Split-mouth)
NM (51)
6 Weeks, 3, 6, 9, 12, 18, and 24 months 6 Months to 11 years (4.05 years)
0/7
3/20 (G1) 0/26 (G2) 75/421 (G1) 150/1137 (G2) 8/40 (G1) 4/90 (G2) 4/28 (G1) 0/35 (G2) 2/69 (G1) 1/38 (G2) 4/140 (G1) 0/17 (G2) 1/40 (G1) 1/40 (G2) 14/208 (G1) 3/120 (G2) 0/14 (G1) 0/28 (G2) 21/312 (G1) 3/120 (G2) 1/123 (G1) 0/120 (G2) 6/484 (G1) 3/521 (G2) 1/14 (G1) 0/14 (G2) 0/36 (G1) 0/36 (G2)
15 (G1) 0 (G2) 17.8 (G1) 13.2 (G2) 20 (G1) 4.4 (G2) 14.3 (G1) 0 (G2) 2.9 (G1) 2.6 (G2) 2.9 (G1) 0 (G2) 2.5 (G1) 2.5 (G2) 6.7 (G1) 2.5 (G2) 0 (G1) 0 (G2) 6.7 (G1) 2.5 (G2) 0.8 (G1) 0 (G2) 1.2 (G1) 0.6 (G2) 7.1 (G1) 0 (G2) 0 (G1) 0 (G2)
NM
1/15 (G1) 7/29 (G2)c
6.67 (G1) 24.14 (G2)
1 Week, 1, 3, and 6 months, 1 and 2 years
NM
2, 4, And 8 weeks, 3, 6, and 12 months 12 Months
7/7
2/30 (G1) 2/20 (G2, 1 week) 2/20 (G2, 4 months) 10/42 (G1) 2/23 (G2)
6.7 (G1) 10 (G2, 1 week) 10 (G2, 4 months) 23.8 (G1) 8.7 (G2)
46/477 (G1) 106/2349 (G2) 1/24 (G1) 2/25 (G2)
9.6 (G1) 4.5 (G2) 4.2 (G1) 8 (G2)
Authors
Study design
Schnitman et al.30
1990
31
Dietrich et al.
1993
Balshi and Wolfinger17 Schnitman et al.32
1997
Tarnow et al.18
1997
33
1997
Horiuchi et al.
2000
Chiapasco et al.12
2001
Engquist et al.19
2002
Lorenzoni et al.20
2003
21
Engquist et al.
2005
¨ stman et al.6 O
2005
Degidi et al.22
2006
3
371 (130 G1; 241 G2) 28 (14 G1; 14 G2)
Hall et al.
2006
Romanos and Nentwig23
2006
Balshi et al.34
2007
RA (single centre)
39 (NM)
29–82 (58.5)
De Smet et al.24
2007
CCT (single centre)
30 (10 G1; 10 G2, 1 week; 10 G2, 4 months)
Horwitz et al.25
2007
CCT (single centre)
19 (NM)
44–68 (58) (G1) 57–86 (69) (G2, 1 week) 33–72 (64) (G2, 4 months) 34–79 (NM)
Susarla et al.35
2008
De Rouck et al.13
2009
RA (single centre) RCT (single centre)
855 (178 G1; 677 G2) 49 (24 G1; 25 G2)
15–91 (53) (G1) 17–92 (53) (G2) NM (55 G1; 52 G2)
1, 2, 3, 4, And 5 years NM
3, 6, And 12 months
NM NM NM 3/4 7–10/7–10 4/‘postoperatively’ 7–10/7–10 10/10
NM NM
P-value (for failure rate)
Postoperative infection
NM
NM
NM
NM
NM
NM
0.022
NM
NM
0 (G1) 1 (G2) NM
NM
NM
1 (G1) 0 (G2) NM
NM
NM
NM
NM
NM
NM
0.267
NM
NM
NM
NM
0 (G1) 0 (G2)
‘‘not statistically significant at this sample size’’ NM
NM
NM
NM
NM
0.05
Chrcanovic et al.
Number of patients (n per group)
Year published
5/NM
14–90 (58)
NM (47.5)
981 (NM)
155 (NM)
3–9 Months
25–94 (NM) 60 (30 G1; 30 G2)
2012
2012
2013
2014
¨ stman et al.28 O
Shibly et al.16
Balshi et al.37
Meizi et al.29
RA (single centre) CCT (single centre)
NM 46 (NM)
2012 Meloni et al.15
2011 Tealdo et al.
2011
RCT (single centre)
28–70 (46) 20 (Split-mouth)
49 (34 G1; 15 G2)
18–66 (38) (G1) 18–67 (40) (G2) NM (58.2) 27
2010
Vercruyssen et al.36 den Hartog et al.14
CCT (single centre) RA (single centre) RCT (single centre) CCT (single centre) RCT (multicentre) CCT (single centre) 2010 Siebers et al.26
CCT, controlled clinical trial; G1, immediately loaded non-submerged implants group; G2, delayed loaded submerged implants group; NM, not mentioned; RA, retrospective analysis; RCT, randomized controlled trial. a The patients received both non-submerged and submerged implants, but not in a split-mouth design. b A total of 690 patients were included in the study, but only those patients for whom it was clearly stated that implants were inserted using one technique or the other (non-submerged vs. submerged) and who were followed up for 10 years were considered (n = 535). c The authors evaluated 459 implants, but made a separate evaluation for non-submerged and submerged implants only in the group of implants without rotational primary stability (n = 44). These are the implants considered here. d Some patients received implants from both groups. e Unpublished information was obtained by personal communication with one of the authors.
NM 0.29
NM NM
4.1 (G1) 14.1 (G2) 3.8 (G1) 1.9 (G2) 32/783 (G1) 116/825 (G2) 7/184 (G1) 3/160 (G2) NM
0 (G1) 1 (G2) NM 3.3 (G1) 6.7 (G2) 1/30 (G1) 2/30 (G2)
NM Before surgery/ NM
7/14
NM
NM
10/14
(G1) (G2) (G1) (G2)e 0 0 2 0 NM
NM 0.42
>0.05
0 (G1) 1 (G2) NM 0.00007 NM (60.8)
495 (24 G1; 471 G2) 62 (31 G1; 31 G2)
NM
Mean of 38 months Mean of 88 months 6 And 18 months 36–47 Months (mean 40.5) 3, 6, 9, And 12 months 3 And 6 months, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 years 7 And 10 days, 3, 6, 12, and 24 months 16 Years 22–85 (52 13) 76 (45 G1; 51 G2)d
NM
5/111 (G1) 0/111 (G2) 6/35 (G1) 35/1015 (G2) 1/31 (G1) 0/31 (G2) 10/163 (G1) 4/97 (G2) 0/20 (G1) 0/20 (G2) 1/24 (G1) 0/97 (G2)e
4.5 (G1) 0 (G2) 17.1 (G1) 3.4 (G2) 3.2 (G1) 0 (G2) 6.1 (G1) 4.1 (G2) 0 (G1) 0 (G2) 4.2 (G1) 0 (G2)
0.024
NM
Immediately loaded non-submerged versus delayed loaded submerged dental implants: A meta-analysis
497
non-submerged group was 3 months in 10 studies,13,14,16,17,19,21,23,31,32,34 followed by loading after 6 months of healing in three studies6,20,25 and 4 months of healing in one study.30 One study did not report the period of healing before loading.22 In most other studies, loading of the submerged implants was performed within a range of time (e.g., between 3 and 6 months). In the 28 studies comparing the procedures, a total of 3918 dental implants were non-submerged and immediately loaded, with 263 failures (6.71%), and a total of 7194 implants were submerged, with 446 failures (6.20%). There was no implant failure in three studies.15,20,23 The most commonly used implants were the Bra˚nemark (Nobel Biocare, Go¨teborg, Sweden) in 13 studies,6,12,17–19,21,24,30,32–34, 36,37 but not exclusively in five studies,6,18,34,36,37 and the TiUnite (Nobel Biocare, Go¨teborg, Sweden) with an oxidized surface in nine studies.6,13–16,28,34,36,37 Ten studies reported whether there was a statistically significant difference or not in the implant failure rate between the four procedures;12,14,22,26,27,29,32,34–36 found a statistically significant difference favouring submerged implants.26,32,35,36 Twelve studies provided information on the use of prophylactic antibiotics6,12,15,16,19–23, 25,28,29 and nine studies about the use of chlorhexidine mouth rinse by the patients.6,12,15,16,19–21,23,25 Quality assessment
Each trial was assessed for risk of bias; the scores are summarized in Table 3. Twenty-three studies were judged to be at high risk of bias, whereas one study was considered at moderate risk of bias and four studies at low risk of bias. Meta-analysis
In this study, a random-effects model was used to evaluate implant failure in the comparison between the procedures, since statistically significant heterogeneity was observed (P < 0.00001; I2 = 76%). The insertion of dental implants through the two different techniques statistically affected the implant failure rate in favour of the submerged procedure (P = 0.02; Fig. 2). The RR of 1.78 (95% CI 1.12– 2.83) implies that failures are 1.78 times more likely to happen when implants are immediately loaded than when implants are submerged. Thus, the relative risk reduction (RRR) is 78%. The RRR is negative, i.e. immediately loaded nonsubmerged implants increase the risk of
498
Table 2. Further details of the studies included. Healing period/loading (G2)
Marginal bone loss (mean SD), (mm)
Schnitman et al.30
4 Months
NM
Dietrich et al.31
3 Months
NM
Balshi and Wolfinger17
3 Months
NM
Schnitman et al.32
3 Months
NM
Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden)
Tarnow et al.18
4–6 Months
NM
NM
Chiapasco et al.
4 Months (mandible), 6 months (maxilla) 4–8 Months
1 Year: 0.7 (G1), 1.5 (G2) 2 Years: 0.8 (G1), 1.2 (G2)
Several (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden; Bonefit, ITI, Waldenburg, Switzerland; TiOblast, Astra Tech, Mo¨lndal, Sweden; 3i, Implant Innovations, West Palm Beach, USA) Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden) Turned (Bra˚nemark System MKII, Nobel Biocare, Go¨teborg, Sweden)
Engquist et al.19
3 Months
0.09 0.05 (G1) 0.32 0.06 (G2)
Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden)
Lorenzoni et al.20
6 Months
Engquist et al.21
3 Months
Sandblasted and acid-etched (Frialit-2, Dentsply-Friadent, Mannheim, Germany) Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden)
¨ stman et al.6 O
6 Months
0.9 0.4 (G1) 0.33 0.34 (G2) 1.33 0.15 (G1; n = 120) 1.42 0.17 (G1; n = 88) 1.24 0.17 (G1; n = 104)a 1.68 0.12 (G2; n = 120) 0.78 0.90 (G1) 0.91 1.04 (G2)
Degidi et al.22
NM
0.9 (G1) 1.0 (G2)
Hall et al.3
26 Weeks
Romanos and Nentwig23
3 Months
Mesial 0.69 1.36 (G1) 0.56 1.90 (G2) Distal 0.58 0.95 (G1) 0.99 1.18 (G2) Information was provided, but not in mean SD
Horiuchi et al.33 12
Implant surface modification (brand)
Observations
Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden) Sandblasted (IMZ, Friedrichsfeld AG, Mannheim, Germany), TPS (?) Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden)
–
Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden; n = 11), oxidized (TiUnite, Nobel Biocare, Go¨teborg, Sweden; n = 232) Sandblasted and acid-etched (XiVE, DentsplyFriadent, Mannheim, Germany) Sandblasted (Southern Implants, Irene, South Africa)
Sandblasted and acid-etched (Ankylos, Dentsply-Friadent, Mannheim, Germany)
– Only in the mandible. 8 patients with moderate to advanced periodontal disease, 4 with bruxism, 2 smokers, 1 diabetic. 58 implants were inserted in fresh extraction sites 9 patients with periodontal disease. Some implants were inserted in fresh extraction sockets and some patients were smokers, but the exact number was not reported Only in totally edentulous jaws, minimum of 10 implants were placed in each patient’s arch
11 implants with bone grafting (all in G2), only edentulous patients Edentulous mandibles, overdentures. Patients who smoked
Meta-analysis Dental implants
Immediately loaded non-submerged versus delayed loaded submerged dental implants: A meta-analysis
B. R. Chrcanovica,, T. Albrektssona,b, A. Wennerberga a
Department of Prosthodontics, Faculty of Odontology, Malmo¨ University, Malmo¨, Sweden; bDepartment of Biomaterials, Go¨teborg University, Go¨teborg, Sweden
B.R. Chrcanovic, T. Albrektsson, A. Wennerberg: Immediately loaded non-submerged versus delayed loaded submerged dental implants: A meta-analysis. Int. J. Oral Maxillofac. Surg. 2015; 44: 493–506. # 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. The purpose of the present meta-analysis was to test the null hypothesis of no difference in the implant failure rate, postoperative infection, and marginal bone loss for patients being rehabilitated with immediately loaded non-submerged dental implants or delayed loaded submerged implants, against the alternative hypothesis of a difference. An electronic search without time or language restrictions was undertaken in March 2014. Eligibility criteria included clinical human studies, either randomized or not. The search strategy resulted in 28 publications. The inverse variance method was used for a random- or fixed-effects model, depending on the heterogeneity. The estimates of an intervention were expressed as the risk ratio (RR) and mean difference (MD) in millimetres. Twenty-three studies were judged to be at high risk of bias, one at moderate risk of bias, and four studies were considered at low risk of bias. The difference between procedures (submerged vs. non-submerged implants) significantly affected the implant failure rate (P = 0.02), with a RR of 1.78 (95% confidence interval (CI) 1.12–2.83). There was no apparent significant effect of non-submerged dental implants on the occurrence of postoperative infection (P = 0.29; RR 2.13, CI 0.52–8.65) or on marginal bone loss (P = 0.77; MD 0.03, 95% CI 0.23 to 0.17).
Introduction
Historically, the original Bra˚nemark protocol for placing dental implants prescribed a two-stage surgery with a submerged healing period of at least 3 months in the mandible and 6 months in the maxilla,1 allowing the implant to osseointegrate without being exposed to external forces. After bone healing, a second surgery is performed to connect a 0901-5027/040493 + 014
healing abutment. One of the main reasons for implant insertion in the two-stage procedure was to minimize the risk of infection, since the peri-implant tissue is allowed to heal separate from the oral microbial environment.2 Extended treatment times, the requirement for two surgical interventions, and the need for interim prostheses during healing are disadvantages of conventional implant treatment.3
Keywords: Dental implants; Submerged; Nonsubmerged; One-stage implant; Two-stage implant; Implant failure rate; Postoperative infection; Marginal bone loss; Meta-analysis. Accepted for publication 19 November 2014 Available online 23 December 2014
Over time, the concepts of implant placement in fresh extraction sockets,4,5 immediate loading, and non-submerged implants were introduced, focusing on shorter and less invasive procedures. To reduce the treatment time and offer the patient early function and aesthetics, it is necessary to use a one-stage surgical procedure and to load the implants as soon as possible. In the one-stage surgical approach (non-submerged implant), the coronal part
# 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
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Chrcanovic et al.
of the implant is positioned above the gingiva level in the case of single-part implants, or transmucosal healing abutments are placed in the case of two-part implants. In the one-stage surgical approach, the implant can be loaded immediately or not. The encouraging early experiences of immediate loading in the mandible and the development of new implant designs and surfaces have inspired researchers to further explore applications of immediate loading.6 Inserting implants in one stage has several advantages. Only one surgical intervention is required, which is convenient for the patient, especially for the medically compromised patient. In addition, there is a considerable cost-benefit advantage. The prosthetic phase can start earlier because there is no wound-healing period related to a second surgical procedure. Furthermore, the implants are accessible for clinical monitoring during the osseointegration period.7 It allows for a healed peri-implant mucosa at the time of prosthetic rehabilitation. Although immediate loading of implants shortens the treatment duration and also provides patients with an acceptable aesthetic appearance, there is concern that immediate loading may increase the risk of implant failure. The aim of this meta-analysis was to compare the survival rate, postoperative complications, and marginal bone loss of non-submerged immediately loaded dental implants with those of submerged delayed loaded implants. The present study presents a more detailed and in-depth analysis of the influence of the submerged and non-submerged approaches on implant failure rates previously assessed in a published systematic review.8 Materials and methods
This study followed the PRISMA Statement guidelines.9 A review protocol does not exist. The purpose of the present meta-analysis was to test the null hypothesis of no difference in implant failure rate, postoperative infection, and marginal bone loss for patients rehabilitated with immediately loaded non-submerged dental implants or delayed loaded submerged implants, against the alternative hypothesis of a difference.
‘dental journals’ in the filter ‘journal categories’: {Subject AND Adjective} {Subject: (dental implant [title]) AND Adjective: (submerged OR nonsubmerged OR non-submerged OR one-stage OR single-stage OR two-stage [title])}. The following terms were used in the search strategy on Web of Science, refined by selecting the term ‘dentistry oral surgery medicine’ in the filter ‘research area’: {Subject AND Adjective} {Subject: (dental implant [title]) AND Adjective: (submerged OR nonsubmerged OR non-submerged OR one-stage OR single-stage OR two-stage [title])}. The following terms were used in the search strategy for the Cochrane Oral Health Group Trials Register: (dental implant OR dental implant failure OR dental implant survival OR dental implant success AND (submerged OR nonsubmerged OR non-submerged OR one-stage OR single-stage OR two-stage)). A manual search of journals covering dental implant research was also done, including British Journal of Oral and Maxillofacial Surgery, Clinical Implant Dentistry and Related Research, Clinical Oral Implants Research, European Journal of Oral Implantology, Implant Dentistry, International Journal of Oral and Maxillofacial Implants, International Journal of Oral and Maxillofacial Surgery, International Journal of Periodontics and Restorative Dentistry, International Journal of Prosthodontics, Journal of Clinical Periodontology, Journal of Dental Research, Journal of Oral Implantology, Journal of Craniofacial Surgery, Journal of Cranio-Maxillofacial Surgery, Journal of Dentistry, Journal of Maxillofacial and Oral Surgery, Journal of Oral and Maxillofacial Surgery, Journal of Oral Rehabilitation, Journal of Periodontology, and Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology. The reference lists of the studies identified and relevant reviews on the subject were also scanned for possible additional studies. Moreover, online databases providing information on clinical trials in progress were checked (http://clinicaltrials.gov; http://www.centerwatch.com/ clinical-trials; http://www.clinicalconnection.com).
Search strategies
An electronic search without time or language restrictions was undertaken in March 2014 in the following databases: PubMed, Web of Science, and the Cochrane Oral Health Group Trials Register. The following terms were used in the search strategy on PubMed, refined by selecting the term
Inclusion and exclusion criteria
Eligibility criteria included clinical human studies, either randomized or not, comparing implant failure rates in any group of patients receiving submerged versus immediately loaded non-submerged dental implants. Only the studies immediately
loading all non-submerged implants were considered. For the studies publishing more than one paper but with different follow-up periods, only the publication with the longest (the last) follow-up period was considered, as long as the sample size had remained the same. For this review, implant failure represents the complete loss of the implant. Exclusion criteria were case reports, technical reports, animal studies, in vitro studies, and review papers. Study selection
The titles and abstracts of all reports identified through the electronic searches were read independently by the three authors. For studies appearing to meet the inclusion criteria, or for which there were insufficient data in the title and abstract to make a clear decision, the full report was obtained. Disagreements were resolved by discussion between the authors. Quality assessment
The quality assessment was performed using the recommended approach for assessing risk of bias in studies included in Cochrane reviews.10 The classification of the risk of bias potential for each study was based on the four following criteria: sequence generation (random selection in the population), allocation concealment (steps must be taken to secure strict implementation of the schedule of random assignments by preventing foreknowledge of the forthcoming allocations), incomplete outcome data (clear explanation of withdrawals and exclusions), and blinding (measures to blind study participants and personnel from knowledge of which intervention a participant received). Incomplete outcome data would also be considered addressed when there were no withdrawals and/or exclusions. A study that met all the criteria mentioned above was classified as having a low risk of bias, a study that did not meet one of these criteria was classified as having a moderate risk of bias, and when two or more criteria were not met, the study was considered to have a high risk of bias. Data extraction and meta-analysis
The following data were extracted from the studies included in the final analysis, when available: year of publication, study design, single centre or multi-centre study, number of patients, patient age, follow-up, days of antibiotic prophylaxis, use of mouth rinse, implant healing period, failed and placed implants, and postoperative
Immediately loaded non-submerged versus delayed loaded submerged dental implants: A meta-analysis infection. Contact was made with authors to obtain possible missing data. Implant failure and postoperative infection were the dichotomous outcome measures evaluated. Weighted mean differences were used to construct forest plots of marginal bone loss, a continuous outcome. The statistical unit for the outcomes was the implant. Whenever outcomes of interest were not clearly stated, the data were not used for analysis. The I2 statistic was used to express the percentage of the total variation across studies due to heterogeneity, with 25% corresponding to low heterogeneity, 50% to moderate and 75% to high. The inverse variance method was used for the random-effects or fixed-effects model. In the case of statistically significant (P < 0.10) heterogeneity, a random-effects model was used to assess the significance of treatment effects. Where no statistically significant heterogeneity was found, analysis was performed using a fixed-effects model.11 The estimates of an intervention were expressed as the risk ratio (RR) and as the mean difference (MD) in millimetres for continuous outcomes, both with a 95% confidence interval (CI). Statistical significance was set at P< 0.05. Only if there were studies with similar comparisons reporting
Fig. 1. Study screening process.
the same outcome measures was a metaanalysis to be attempted. A funnel plot (plot of effect size versus standard error) was drawn. Asymmetry of the funnel plot may indicate publication bias and other biases related to sample size, although the asymmetry may also represent a true relationship between trial size and effect size. The data were analysed using the statistical software Review Manager (version 5.2.8; The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark, 2014). Results Literature search
The study selection process is summarized in Fig. 1. The search strategy resulted in 1328 papers. One hundred and eighty-four were cited in more than one research of terms. The three reviewers independently screened the abstracts to identify articles related to the focus question. The initial screening of titles and abstracts resulted in 1144 full-text papers; 1050 were excluded for not being related to the topic. Assessment of the full-text reports of the remaining 94 articles led to the exclusion of 66
495
because they did not meet the inclusion criteria: 39 reported the non-submerged group being submitted to early or delayed loading, nine did not report the number of failures and/or the number of implants in each group, eight comprised earlier follow-up of the same study, four were animal studies, two were reviews, one was a finite element analysis study, one applied extraoral implants, one did not evaluate implant failure, and one reported two-stage implants being inserted in a one-stage procedure. Thus, a total of 28 publications were included in the review. Description of the studies
Detailed data of the 28 studies included are listed in Tables 1 and 2. Six randomized clinical trials (RCT),3,12–16 14 controlled clinical trials (CCT),6,17–29 and eight retrospective analyses30–37 were included in the meta-analysis. Only three of them were multi-centre studies.15,19,21 Nine studies had a maximum follow-up of 12 months,3,6,13,15,19,20,25,29,35 eight studies had a maximum follow-up ranging from 13 to 36 months,12,14,16,17,21–24 nine studies had a maximum follow-up ranging from 37 to 120 months,18,26–28,30–32,34,36 and one study had a follow-up of more than 10 years;37 one study did not report the follow-up period.33 Three studies did not report patient age.18,28,31 Of the studies with data available for patient age, three included non-adults patients.22,35,37 Only seven studies provided information on postoperative infection,12,15,16,18,23,28,36 with six occurrences in a total of 663 patients receiving 1530 implants. Some of the patients were smokers in 16 studies.6,12,13,15,17,19,21–24,26,27,29,32,35,36 Ten studies inserted some of the implants in fresh extraction sockets,17,22,25,26,28,29, 32,34,36,37 whereas in another, all implants were inserted in fresh extraction sockets.16 Four studies included only patients who received single-implant restorations3,13–15 and two included only patients who received overdentures.12,36 Some14,33,36 or all16 implant sites underwent grafting procedures in some studies. Seven studies included only edentulous patients,12,18,19, 21,24,27,33 five inserted implants only in the maxilla,3,6,13,14,27 five studies inserted implants only in the mandible,15,19,21,23,24 and one study only in the pterygomaxillary region using a stereolithographic surgical guide.37 Some patients17,26,32 or all patients16,25 had periodontal disease in some studies. Diabetic patients were included in three studies.17,29,36 The most common period of healing before the loading of implants in the
496
Table 1. Detailed data of the studies included. Patient age range (average) (years)
Follow-up visits (or range)
Antibiotics/ mouth rinse (days)
Failed/ placed implants (n)
Implant failure rate (%)
RA (single centre) RA (single centre) CCT (single centre) RA (single centre) CCT (single centre) RA (single centre) RCT (single centre) CCT (multicentre) CCT (single centre) CCT (multicentre) CCT (single centre) CCT (single centre) RCT (single centre) CCT (single centre)
7a
48–71 (NM)
42 Months
NM
535 (106 G1; 429 G2)b 10a
NM
10 Years
NM
45–70 (55)
NM
10 (NM)
48–78 (NM)
12 And 18 months 10 Years
10 (G1 + G2)
NM
14 (NM)
40–83 (NM)
20 (10 G1; 10 G2)
44–73 (58.4)
82 (52 G1; 30 G2)
NM (64.9)
6, 12, And 24 months 1 Year
7a
50–72 (60)
6 Months
108 (78 G1; 30 G2)
NM (64.9)
2 And 3 years
40 (20 G1; 20 G2)
58–87 (73) (G1) 50–80 (64) (G2) 17–83 (53)
3, 6, And 12 months 1 And 2 years
5/NM
23–71 (43)
1 Year
NM
12 (Split-mouth)
NM (51)
6 Weeks, 3, 6, 9, 12, 18, and 24 months 6 Months to 11 years (4.05 years)
0/7
3/20 (G1) 0/26 (G2) 75/421 (G1) 150/1137 (G2) 8/40 (G1) 4/90 (G2) 4/28 (G1) 0/35 (G2) 2/69 (G1) 1/38 (G2) 4/140 (G1) 0/17 (G2) 1/40 (G1) 1/40 (G2) 14/208 (G1) 3/120 (G2) 0/14 (G1) 0/28 (G2) 21/312 (G1) 3/120 (G2) 1/123 (G1) 0/120 (G2) 6/484 (G1) 3/521 (G2) 1/14 (G1) 0/14 (G2) 0/36 (G1) 0/36 (G2)
15 (G1) 0 (G2) 17.8 (G1) 13.2 (G2) 20 (G1) 4.4 (G2) 14.3 (G1) 0 (G2) 2.9 (G1) 2.6 (G2) 2.9 (G1) 0 (G2) 2.5 (G1) 2.5 (G2) 6.7 (G1) 2.5 (G2) 0 (G1) 0 (G2) 6.7 (G1) 2.5 (G2) 0.8 (G1) 0 (G2) 1.2 (G1) 0.6 (G2) 7.1 (G1) 0 (G2) 0 (G1) 0 (G2)
NM
1/15 (G1) 7/29 (G2)c
6.67 (G1) 24.14 (G2)
1 Week, 1, 3, and 6 months, 1 and 2 years
NM
2, 4, And 8 weeks, 3, 6, and 12 months 12 Months
7/7
2/30 (G1) 2/20 (G2, 1 week) 2/20 (G2, 4 months) 10/42 (G1) 2/23 (G2)
6.7 (G1) 10 (G2, 1 week) 10 (G2, 4 months) 23.8 (G1) 8.7 (G2)
46/477 (G1) 106/2349 (G2) 1/24 (G1) 2/25 (G2)
9.6 (G1) 4.5 (G2) 4.2 (G1) 8 (G2)
Authors
Study design
Schnitman et al.30
1990
31
Dietrich et al.
1993
Balshi and Wolfinger17 Schnitman et al.32
1997
Tarnow et al.18
1997
33
1997
Horiuchi et al.
2000
Chiapasco et al.12
2001
Engquist et al.19
2002
Lorenzoni et al.20
2003
21
Engquist et al.
2005
¨ stman et al.6 O
2005
Degidi et al.22
2006
3
371 (130 G1; 241 G2) 28 (14 G1; 14 G2)
Hall et al.
2006
Romanos and Nentwig23
2006
Balshi et al.34
2007
RA (single centre)
39 (NM)
29–82 (58.5)
De Smet et al.24
2007
CCT (single centre)
30 (10 G1; 10 G2, 1 week; 10 G2, 4 months)
Horwitz et al.25
2007
CCT (single centre)
19 (NM)
44–68 (58) (G1) 57–86 (69) (G2, 1 week) 33–72 (64) (G2, 4 months) 34–79 (NM)
Susarla et al.35
2008
De Rouck et al.13
2009
RA (single centre) RCT (single centre)
855 (178 G1; 677 G2) 49 (24 G1; 25 G2)
15–91 (53) (G1) 17–92 (53) (G2) NM (55 G1; 52 G2)
1, 2, 3, 4, And 5 years NM
3, 6, And 12 months
NM NM NM 3/4 7–10/7–10 4/‘postoperatively’ 7–10/7–10 10/10
NM NM
P-value (for failure rate)
Postoperative infection
NM
NM
NM
NM
NM
NM
0.022
NM
NM
0 (G1) 1 (G2) NM
NM
NM
1 (G1) 0 (G2) NM
NM
NM
NM
NM
NM
NM
0.267
NM
NM
NM
NM
0 (G1) 0 (G2)
‘‘not statistically significant at this sample size’’ NM
NM
NM
NM
NM
0.05
Chrcanovic et al.
Number of patients (n per group)
Year published
5/NM
14–90 (58)
NM (47.5)
981 (NM)
155 (NM)
3–9 Months
25–94 (NM) 60 (30 G1; 30 G2)
2012
2012
2013
2014
¨ stman et al.28 O
Shibly et al.16
Balshi et al.37
Meizi et al.29
RA (single centre) CCT (single centre)
NM 46 (NM)
2012 Meloni et al.15
2011 Tealdo et al.
2011
RCT (single centre)
28–70 (46) 20 (Split-mouth)
49 (34 G1; 15 G2)
18–66 (38) (G1) 18–67 (40) (G2) NM (58.2) 27
2010
Vercruyssen et al.36 den Hartog et al.14
CCT (single centre) RA (single centre) RCT (single centre) CCT (single centre) RCT (multicentre) CCT (single centre) 2010 Siebers et al.26
CCT, controlled clinical trial; G1, immediately loaded non-submerged implants group; G2, delayed loaded submerged implants group; NM, not mentioned; RA, retrospective analysis; RCT, randomized controlled trial. a The patients received both non-submerged and submerged implants, but not in a split-mouth design. b A total of 690 patients were included in the study, but only those patients for whom it was clearly stated that implants were inserted using one technique or the other (non-submerged vs. submerged) and who were followed up for 10 years were considered (n = 535). c The authors evaluated 459 implants, but made a separate evaluation for non-submerged and submerged implants only in the group of implants without rotational primary stability (n = 44). These are the implants considered here. d Some patients received implants from both groups. e Unpublished information was obtained by personal communication with one of the authors.
NM 0.29
NM NM
4.1 (G1) 14.1 (G2) 3.8 (G1) 1.9 (G2) 32/783 (G1) 116/825 (G2) 7/184 (G1) 3/160 (G2) NM
0 (G1) 1 (G2) NM 3.3 (G1) 6.7 (G2) 1/30 (G1) 2/30 (G2)
NM Before surgery/ NM
7/14
NM
NM
10/14
(G1) (G2) (G1) (G2)e 0 0 2 0 NM
NM 0.42
>0.05
0 (G1) 1 (G2) NM 0.00007 NM (60.8)
495 (24 G1; 471 G2) 62 (31 G1; 31 G2)
NM
Mean of 38 months Mean of 88 months 6 And 18 months 36–47 Months (mean 40.5) 3, 6, 9, And 12 months 3 And 6 months, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 years 7 And 10 days, 3, 6, 12, and 24 months 16 Years 22–85 (52 13) 76 (45 G1; 51 G2)d
NM
5/111 (G1) 0/111 (G2) 6/35 (G1) 35/1015 (G2) 1/31 (G1) 0/31 (G2) 10/163 (G1) 4/97 (G2) 0/20 (G1) 0/20 (G2) 1/24 (G1) 0/97 (G2)e
4.5 (G1) 0 (G2) 17.1 (G1) 3.4 (G2) 3.2 (G1) 0 (G2) 6.1 (G1) 4.1 (G2) 0 (G1) 0 (G2) 4.2 (G1) 0 (G2)
0.024
NM
Immediately loaded non-submerged versus delayed loaded submerged dental implants: A meta-analysis
497
non-submerged group was 3 months in 10 studies,13,14,16,17,19,21,23,31,32,34 followed by loading after 6 months of healing in three studies6,20,25 and 4 months of healing in one study.30 One study did not report the period of healing before loading.22 In most other studies, loading of the submerged implants was performed within a range of time (e.g., between 3 and 6 months). In the 28 studies comparing the procedures, a total of 3918 dental implants were non-submerged and immediately loaded, with 263 failures (6.71%), and a total of 7194 implants were submerged, with 446 failures (6.20%). There was no implant failure in three studies.15,20,23 The most commonly used implants were the Bra˚nemark (Nobel Biocare, Go¨teborg, Sweden) in 13 studies,6,12,17–19,21,24,30,32–34, 36,37 but not exclusively in five studies,6,18,34,36,37 and the TiUnite (Nobel Biocare, Go¨teborg, Sweden) with an oxidized surface in nine studies.6,13–16,28,34,36,37 Ten studies reported whether there was a statistically significant difference or not in the implant failure rate between the four procedures;12,14,22,26,27,29,32,34–36 found a statistically significant difference favouring submerged implants.26,32,35,36 Twelve studies provided information on the use of prophylactic antibiotics6,12,15,16,19–23, 25,28,29 and nine studies about the use of chlorhexidine mouth rinse by the patients.6,12,15,16,19–21,23,25 Quality assessment
Each trial was assessed for risk of bias; the scores are summarized in Table 3. Twenty-three studies were judged to be at high risk of bias, whereas one study was considered at moderate risk of bias and four studies at low risk of bias. Meta-analysis
In this study, a random-effects model was used to evaluate implant failure in the comparison between the procedures, since statistically significant heterogeneity was observed (P < 0.00001; I2 = 76%). The insertion of dental implants through the two different techniques statistically affected the implant failure rate in favour of the submerged procedure (P = 0.02; Fig. 2). The RR of 1.78 (95% CI 1.12– 2.83) implies that failures are 1.78 times more likely to happen when implants are immediately loaded than when implants are submerged. Thus, the relative risk reduction (RRR) is 78%. The RRR is negative, i.e. immediately loaded nonsubmerged implants increase the risk of
498
Table 2. Further details of the studies included. Healing period/loading (G2)
Marginal bone loss (mean SD), (mm)
Schnitman et al.30
4 Months
NM
Dietrich et al.31
3 Months
NM
Balshi and Wolfinger17
3 Months
NM
Schnitman et al.32
3 Months
NM
Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden)
Tarnow et al.18
4–6 Months
NM
NM
Chiapasco et al.
4 Months (mandible), 6 months (maxilla) 4–8 Months
1 Year: 0.7 (G1), 1.5 (G2) 2 Years: 0.8 (G1), 1.2 (G2)
Several (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden; Bonefit, ITI, Waldenburg, Switzerland; TiOblast, Astra Tech, Mo¨lndal, Sweden; 3i, Implant Innovations, West Palm Beach, USA) Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden) Turned (Bra˚nemark System MKII, Nobel Biocare, Go¨teborg, Sweden)
Engquist et al.19
3 Months
0.09 0.05 (G1) 0.32 0.06 (G2)
Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden)
Lorenzoni et al.20
6 Months
Engquist et al.21
3 Months
Sandblasted and acid-etched (Frialit-2, Dentsply-Friadent, Mannheim, Germany) Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden)
¨ stman et al.6 O
6 Months
0.9 0.4 (G1) 0.33 0.34 (G2) 1.33 0.15 (G1; n = 120) 1.42 0.17 (G1; n = 88) 1.24 0.17 (G1; n = 104)a 1.68 0.12 (G2; n = 120) 0.78 0.90 (G1) 0.91 1.04 (G2)
Degidi et al.22
NM
0.9 (G1) 1.0 (G2)
Hall et al.3
26 Weeks
Romanos and Nentwig23
3 Months
Mesial 0.69 1.36 (G1) 0.56 1.90 (G2) Distal 0.58 0.95 (G1) 0.99 1.18 (G2) Information was provided, but not in mean SD
Horiuchi et al.33 12
Implant surface modification (brand)
Observations
Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden) Sandblasted (IMZ, Friedrichsfeld AG, Mannheim, Germany), TPS (?) Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden)
–
Turned (Bra˚nemark, Nobel Biocare, Go¨teborg, Sweden; n = 11), oxidized (TiUnite, Nobel Biocare, Go¨teborg, Sweden; n = 232) Sandblasted and acid-etched (XiVE, DentsplyFriadent, Mannheim, Germany) Sandblasted (Southern Implants, Irene, South Africa)
Sandblasted and acid-etched (Ankylos, Dentsply-Friadent, Mannheim, Germany)
– Only in the mandible. 8 patients with moderate to advanced periodontal disease, 4 with bruxism, 2 smokers, 1 diabetic. 58 implants were inserted in fresh extraction sites 9 patients with periodontal disease. Some implants were inserted in fresh extraction sockets and some patients were smokers, but the exact number was not reported Only in totally edentulous jaws, minimum of 10 implants were placed in each patient’s arch
11 implants with bone grafting (all in G2), only edentulous patients Edentulous mandibles, overdentures. Patients who smoked
