Enabling dental implants: increasing the thickness of bone at the base of the sinus cavity

Maxillary_sinus_MRI_attrib Mark Hamilton

Attribution: Mark Hamilton, under Wikimedia Commons licence

This research seeks to determine whether and when it is necessary to increase the thickness of the bone layer (bone augmentation) at the base of the natural sinus cavity when inserting dental implants. The natural sinus cavity lies above the upper jaw, and can sometimes cause the bone at the back of the jaw to be too thin. This can become a problem when loading dental implants into the jaw. Dental implants offer an alternative way of replacing teeth; they look like screws and offer a stable base for artificial teeth to be anchored into.

When the bone is too thin to support the dental implants, there are a number of techniques that are used to create a thicker layer of bone at the base of the sinus cavity which are generally known as “sinus lift” procedures. These methods involve either taking bone from the patient (autogenous bone) or use of other biomaterials, or a combination of the two. Alternatively, a blood clot can be used as a base for the body to naturally form additional bone. Another option is to use short dental implants, if possible, these are 4 to 8.5mm long and do not require the same amount of bone for anchorage.

What was the research?

A systematic review of the evidence to assess the beneficial or harmful effects of augmenting the bone at the base of the sinus cavity, as opposed to no augmentation. Secondly, to compare the benefits and harms of different sinus lift techniques for dental implants.

Who conducted the research?

The research was conducted by a team led by Marco Esposito, on behalf of the Cochrane Oral Health Group. Pietro Felice and Helen V. Worthington were also on the team.

What evidence was included in the review?

Data was extracted from 18 randomised controlled trials, a total of 650 people participated in the trials. Four of the trials (102 participants) compared implants after sinus lift with short dental implants, where there is no sinus lift needed. The remaining 14 trials looked at different techniques to increase bone thickness.

What did the evidence say?

There is not enough evidence to show whether sinus lift techniques are more or less successful in reducing the number of dental implant failures when compared with short dental implants, however there is some limited evidence that short dental implants cause fewer complications. Complications include infections and bleeding; and when bone is taken from a patient, complications can also include nerve injuries and problems with walking.

The trials which compared different techniques did not provide enough evidence to conclude that one procedure led to more implant failures than another.

How good was the evidence?

There was moderate quality evidence on whether or not to use a sinus lift procedure, and low quality, insufficient evidence to determine which sinus lift technique was the best (for more information on different grades of clinical evidence and what is meant by high quality, moderate quality and low quality evidence, see the GRADE website).

What are the implications for dentists and the general public?

Given the lack of evidence to support one sinus lift procedure over another, clinicians should use their clinical judgement and take patient preference into account when choosing between procedures.

What should researchers look at in the future?

In order to understand when sinus lift procedures are needed and which technique is most effective, larger well-designed trials are needed. Such trials should include long-term follow-up and be reported according to CONSORT guidance. Priority should be given to those procedures which are simpler, less invasive and involve less risk of complications. Research efforts should concentrate on a few important clinical questions, and trials should use larger numbers of participants. Trials should focus on clinically important outcomes, such as how many implants fail or are lost, and how many complications are reported.


Esposito M, Felice P, Worthington HV. Interventions for replacing missing teeth: augmentation procedures of the maxillary sinus. Cochrane Database of Systematic Reviews 2014, Issue 5. Art. No.: CD008397. DOI: 10.1002/14651858.CD008397.pub2.