Osseointegrated dental implants have been available since the 1970s and initially it was recommended to keep them load free during the healing period. Since then early loading protocols have been adopted with studies showing good implant survival with both immediate and early loading protocols regardless of the type of prosthesis.

The aim of this review was to compare the outcomes of early and delayed loading of dental implants

Methods

Searches were conducted in the Medline, Embase and Ovid databases. Two reviewers independently screened and selected studies. Randomised controlled trials (RCTs) involving at least 10 patients comparing early loading to delayed loading and published in English were considered. Early loading was defined as 1 to 6 weeks after implant placement while delayed loading for after 8 weeks. The main outcomes were implant survival and changes in marginal bone level (MBL). Two reviewers extracted data independently and assessed study quality using the Cochrane risk of bias tool.  Continuous parameters were presented as mean differences (WMDs) with 95% confidence interval (CI) and dichotomous outcomes as risk ratios (RRs) with 95% CI.

Results

• 18 RCTS reported in 23 papers were included.
• A total of 790 patients (386 early, 404 delayed) with 1907 implants (842 early 1065 delayed) were included in the meta-analysis
• 13 studies were considered to be at a high risk of bias and 5 at a moderate risk. No studies were at a low risk of bias.
• No implant failure was reported in 8 of the 18 RCTs.

For implant as statistical unit

• Implant survival in early group was 91% and 89.4% in the delayed group
• No statistical difference in implant survival RR = 1.03 (95%CI; 0.99 to 1.07) [14 studies].
• There were also no differences in subgroup analyses (see table below).

Subgroup	Risk ratio (95% CI)
Fixed prostheses	1.028 (0.989 to 1.068)
Overdentures	1.065 (0.935 to 1.212)
Delayed implant	1.032 (0.992 to 1.073)
Occlusal contact	1.034 (0.993 to 1.077)
No occlusal contact	1.024 (0.938 to 1.117)
Single missing tooth	0.974 (0.912 to 1.040)
Free-hand surgery	1.028 (0.991 to 1.068)
Surgical guide	1.152 (0.920 to 1.443)
Non-submerged technique	1.039 (0.992 to 1.089)

For patient as statistical unit

• Mean survival rate was 91.8% in the early loaded implant group 91.6% in the delayed group.
• Meta-analysis showed no difference between early and delayed loading RR=1.009 (95%CI; 0.944 to 1.078) [13 studies].
• Similarly, no differences were seen in the subgroup analyses (see table below)

Subgroup	Risk ratio (95% CI)
Fixed prostheses	1.015 (0.948 to 1.088)
Overdentures	0.969 (0. 784 to 1.198)
Delayed implant	1.005 (0.926 to 1.090)
Occlusal contact	1.005 (0.926 to 1.090)
No occlusal contact	1.024 (0.938 to 1.117)
Single missing tooth	0.970 (0.898 to 1.048)
Free-hand surgery	0.999 (0.932 to 1.071)
Surgical guide	1.152 (0.920 to 1.443)
Non-submerged technique	1.038 (0.954 to 1.130)

• No difference in MBL change was shown between the early and delayed groups (WMD=0.044; 95%CI; -0.042 to 0.131) when the outcomes from all implant positions were pooled.
• No difference in MBL was seen between early and delayed groups for any of the subgroups ( see table below).

Subgroup	WMD (95% CI)
Fixed prostheses	0.091 (-0.037 to 0.218)
Overdentures	-0.001 (-0.042 to 0.04)
Delayed implant	0.052 (-0.041 to 0.146)
Occlusal contact	0.075 (-0.033 to 0.184)
No occlusal contact	-0.061 (-0.266 to 0.143)
Single missing tooth	0.037 (-0.033 to 0.108)
Free-hand surgery	0.043 (-0.047 to 0.133)
Surgical guide	0.060 (-0.114 to 0.260)
Non-submerged technique	0.032(-0.022 to 0.086)

Conclusions

The authors concluded: –

Early and delayed loading protocols had similar clinical outcomes with regard to the survival rate of implant and MBL change.

Comments

A 2013 Cochrane review (Dental Elf – 10^th Apr 2013) looked at different loading time for dental implants including 26 RCTs and concluding,

Overall there was no convincing evidence of a clinically important difference in prosthesis failure, implant failure, or bone loss associated with different loading times of implants.

Although they did recommend interpreting the findings with caution because the evidence was considered to be of low quality. Since then, there have been other reviews on the topic and the most recent we have looked were in the Dental Elf – 14^th Oct 2019 and Dental Elf – 20^th Jul 2022. The 2019 Chen review (Dental Elf – 14^th Oct 2019) 49 studies concluding,

Compared with early loading, immediate loading could achieve comparable implant survival rates and marginal bone level changes. Compared with conventional loading, immediate loading was associated with a higher incidence of implant failure.

This new review searched a number of major databases but has only included RCTs published in English so may have excluded some relevant studies. It includes 18 RCTs compared with the 39 studies included in the Chen review with only a small number of studies (4) common to both reviews.  The follow up period for the included studies ranged from 4 to 120 months with 8 (44%) of the included studies have a follow up of 12 months or less and 3 studies (17%) have a follow up period of 5 years or more. While it is argued that the first 4 months is a key period for osteointegration 8 of the included studies reported no implant failures which may be related to the follow up times. Most of the studies are conducted in a university or secondary care setting and the low rates of implant failures mean that larger sample sizes would be needed to see if clinically important differences exist in loading protocols. With far greater numbers of implants being placed in primary dental care setting studies in their settings should also be conducted. International agreement and use of clear definitions regarding immediate, early and delayed loading would also be helpful.

Links

Primary Paper

Zhang W, Huang S, Ye Q, Wei D, Zhou X. Clinical efficacy of early and delayed loading implants: A systematic review and meta-analysis. J Prosthet Dent. 2022 Aug 10:S0022-3913(22)00423-1. doi: 10.1016/j.prosdent.2022.05.033. Epub ahead of print. PMID: 35963711.

Other references

Dental Elf – 10^th Apr 2013

No convincing evidence of a clinically important difference with different loading times of implants

 Dental Elf – 14^th Oct 2019

Dental implants: Immediate, early or conventional loading?

Dental Elf – 20^th Jul 2022

Single implant restorations – Immediate v non-immediate loading