Elsevier

Journal of Dentistry

Volume 47, April 2016, Pages 8-17
Journal of Dentistry

Review article
Short dental implants versus standard dental implants placed in the posterior jaws: A systematic review and meta-analysis

https://doi.org/10.1016/j.jdent.2016.01.005Get rights and content

Abstract

Objective

The purpose of the present systematic review and meta-analysis was to compare short implants (equal or less than 8 mm) versus standard implants (larger than 8 mm) placed in posterior regions of maxilla and mandible, evaluating survival rates of implants, marginal bone loss, complications and prosthesis failures.

Data

This review has been registered at PROSPERO under the number CRD42015016588. Main search terms were used in combination: dental implant, short implant, short dental implants, short dental implants posterior, short dental implants maxilla, and short dental implants mandible.

Source

An electronic search for data published up until September/2015 was undertaken using the PubMed/Medline, Embase and The Cochrane Library databases.

Study selection

Eligibility criteria included clinical human studies, randomized controlled trials and/or prospective studies, which evaluated short implants in comparison to standard implants in the same study.

Conclusion

The search identified 1460 references, after inclusion criteria 13 studies were assessed for eligibility. A total of 1269 patients, who had received a total of 2631 dental implants. The results showed that there was no significant difference of implants survival (P = .24; RR:1.35; CI: 0.82–2.22), marginal bone loss (P = .06; MD: −0.20; CI: −0.41 to 0.00), complications (P = .08; RR:0.54; CI: 0.27–1.09) and prosthesis failures (P = .92; RR:0.96; CI: 0.44–2.09). Short implants are considered a predictable treatment for posterior jaws. However, short implants with length less than 8 mm (4–7 mm) should be used with caution because they present greater risks to failures compared to standard implants.

Clinical significance

Short implants are frequently placed in the posterior area in order to avoid complementary surgical procedures. However, clinicians need to be aware that short implants with length less than 8 mm present greater risk of failures.

Introduction

Implants are often used as a treatment option for partially or totally edentulous patients [1]. The success is directly related to the osseointegration process [2], and the use of standard implants allows a larger contact area with the bone tissue, which supports the osseointegration process [3], [4]. Tooth loss in the posterior jaws favors the resorption process of bone tissue [5], causing greater proximity to the inferior alveolar nerve and maxillary sinus, limiting the use of longer implants [3], [6].

To overcome these problems, bone grafts or maxillary sinus lifting have been indicated to reestablish the height of restored bone tissue and allow for placement of standard implants. However, these techniques are associated with increased postoperative morbidity, higher costs, and higher risks of complications during patient rehabilitation [5], [7]. Thus, short implants are used, which are considered to be simpler and more effective for rehabilitating atrophic ridges later [8].

As there is no consensus about the definition of short implants, with some authors considering them to be <10 mm [9], [10], while others consider short implants ≤8 mm [4], [11]. Current clinical tendencies consider implants with 7 mm length or less as short or extra-short implants [12]. The discrepancy in the crown-to-implant ratio can increase the risk of mechanical problems, but it did not increase the risk of peri-implant marginal bone loss [13].

Another important aspect to consider is the implants installation area, because the chances of failure are higher when the implants are installed in low-density bone, such as in the posterior maxilla [14]. However, there is no consensus on the survival rate of short implants in the posterior maxilla and mandible [15]. Some authors have shown low success rates [6], [16], while others have found high success rates for short implants [17], [18], [19].

The aim of this study was to evaluate the survival rate of short implants (equal or less than 8 mm) compared to standard implants (larger than 8 mm) in the posterior jaws. The null hypotheses are: (1) there are no differences between short implants and standard implants with regard to survival rates of implants and (2) there are no differences in marginal bone loss, complications, and prosthesis failures between short implants and standard implants.

Section snippets

Registry protocol

This systematic review was structured following the PRISMA checklist [20] and in accordance with models proposed in the literature [14], [21], [22], [23]. Moreover, the methods for this systematic review were registered with PROSPERO (CRD42015016588).

Eligibility criteria

The eligible studies should present the following characteristics: (1) randomized controlled trials, (2) prospective studies, (3) with at least ten patients, (4) studies published within last 10 years, (5) comparisons between short implants and

Literature search

The search in the databases retrieved 1460 references, including 1171 from PubMed/MEDLINE, 272 from Embase and 17 from The Cochrane Library. After duplicate references were removed, a detailed review was done on the titles and abstracts of the selected comparative studies, and after applying the inclusion/exclusion criteria, 30 full papers were selected for the eligibility assessment (Fig. 1). After reading the full texts of these articles, 13 studies [6], [25], [26], [27], [28], [29], [30],

Discussion

Recently, some revisions have verified that short implants are a predictable alternative treatment for the edentulous in the posterior region [10], [54]. However, the present systematic review only included studies with direct comparisons between short and standard implants, in order to reduce bias.

Short implants are considered an alternative for rehabilitation that reduces the complexity of the treatment, mainly in the posterior jaws. This is due to bone resorption maintaining proximity to

Conclusion

Short implants showed marginal bone loss, prosthesis failures and complication rates similar to standard implants, being considered a predictable treatment for posterior jaws, especially in cases that require complementary surgical procedures. However, short implants with length less than 8 mm (4–7 mm) should be used with caution because they present greater risks for implant failures when compared to standard implants.

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