Original study - ZZI 03/2011

Immediate Function in a Dental Practice

D. Siebers1, P. Gehrke2, H. Schliephake3

Objectives: The aim of this study was to clarify whether immediate function or immediate loading in a private practice may be regarded as a safe treatment protocol for selected cases. This question is addressed using a longitudinal case control study of patients in a private practice.

Material and Methods: All 111 implants that had been treated according to an immediate function protocol between 2001 and 2004 were followed up. 111 implants with parameters as similar as possible served as controls. 96 parameters in 76 patients were recorded and analyzed. These included numerous risk factors mentioned in the literature, implant and denture parameters, and clinical and radiographic parameters. The implant success rate was evaluated and an aesthetic assessment of a reasonable proportion was performed.

Results: Five of the 222 implants were lost during the healing period (survival rate 97.7 % after 3.25 years on average). The Kaplan-Meier analysis showed statistically significantly better results for the control group (survival rate 100 %) compared with the test group (survival rate 95.5 %, p = 0.024) as well as for implantation in healed sites (99.4 %, p = 0.0055) compared with immediate implantation (93.1 %). Evaluation of implant success resulted
in a success rate of 97.75 % (Gettleman/Schnitman) and 95.5 % (Buser/Naert). The success rate was statistically significantly higher with delayed compared with immediate implantation (p = 0.017). The test group had significant advantages aesthetically compared with the control group (p = 0.0074).

There were also advantages for immediate compared with delayed implantation (p = 0.0076) and for the test group compared with the control group (p = 0.0092). The probing depth was less in the test group than in the control group (p = 0.011) and with immediate loading compared with the immediate restoration group (p = 0.025).

Conclusions: Immediate function of dental implants is a therapy with a high success rate of 95.5 % and high aesthetic potential. However, there is evidence that immediate function and immediate implantation are associated with a higher risk of failure. Therefore, an accurate risk analysis is required for each patient to avoid risk accumulation.

Keywords: dental implants; immediate function; immediate loading; immediate restoration; immediate implantation; clinical parameters; risk factors; risk accumulation; success; aesthetic evaluation

Introduction

Unloaded closed healing of implants for four to six months [12, 13] has now been a functioning concept in dental implantology for some decades and was for a long time regarded as
a „conditio sine qua non“. However, this concept was queried early from the aspect of improving patient comfort [51, 52]. Currently, there are two concepts for shortening the duration of treatment [22, 71]. They differ according to the time of implant insertion and the time of loading. Immediate function
is divided into two forms of loading [22, 71]. Immediate loading, in which a restoration in occlusion with the opposing teeth is fitted within 48 hours after implant insertion, contrasts with immediate restoration, which involves prosthetic restoration within the same period after implant insertion but without contact with the opposing teeth. Other authors use terms such as direct and indirect occlusal contacts [6] or immediate functional as opposed to immediate nonfunctional loading [27].

The available literature reviews, review articles, meta-analyses and consensus papers [3, 6, 21, 23, 33, 48, 60, 61] show a great degree of variation. Good to very good success rates of 90 % or more are recorded in all publications. In particular, immediate loading with interforaminal mandibular implantation is well documented scientifically [3, 21, 33, 70] and demonstrates a high success rate regardless of the implant type, surface structure and prosthesis design. There is less evidence for the maxilla and partially dentate situations [5, 21, 33]. In 2005, Attard et al. [6] confirmed the biological success of immediate loading. Glauser et al. [37] examined the available literature for the associations between marginal soft tissues and the loading protocol in a meta-analysis in 2006. They found that immediately restored and loaded implants after successful osseointegration demonstrate a soft tissue reaction with regard to periodontal and morphological aspects that is comparable with that seen with conventionally loaded implants. Many authors deplore the poor methodological quality of the studies [5, 21, 22, 37] and demand more long-term investigations with a stricter study design, greater implant numbers and longer follow-up periods. Data from private dental practices are extremely rare.

There is consensus that primary stability must be achieved with the insertion of implants that are to be restored immediately in order to limit relative movements at the implant-bone interface to physiologically acceptable levels. As practicing implantologists have few aids at their disposal for obtaining information about the structure and density of the local bone, apart from the relatively imprecise radiology, another measure for these parameters must be found. The only validated control mechanism for this is the insertion torque. The close correlation between bone density and the final insertion torque has been demonstrated [41, 54, 57]. Today, many authors therefore recommend final insertion torques between 25 and 40 Ncm [14, 26, 44], as these suggest adequate bone density. Other important requirements are careful case selection [29] and the use of adequate surgical techniques to spare the peri-implant tissue during tooth extraction [6, 7].

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