Soft tissue expansion: principles and inferred intraoral hydrogel tissue expanders

Background: Tension-free closure of the intraoral site is a prerequisite at bone augmentation procedures. Dental surgeons mainly use a technique called soft tissue mobilisation. The soft tissue expander has not yet been used in the daily practice. However, in plastic surgery, soft tissue expansion is often used to create a surplus of soft tissue. The experience gathered in plastic surgery can be extrapolated into intraoral surgery. Especially the new small-sized hydrogel soft tissue expanders can be used intraorally in implant dentistry. Purpose: This paper presents systematically the principles of soft tissue augmentation. Its purpose is to summarize the general knowledge about soft tissue expanding and the characteristics of tissue expanders. Experience gathered in plastic surgery is transformed to intraoral use. It outlines the advances of tissue expansion and its possible role using hydrogel soft tissue expanders in dental implant therapy. Materials and methods: The electronic data bases Science Direct, PubMed, High Wire and Google Scholar were searched for articles published until March 2015. The related terms were used. Result and discussion: Intraoral tissue expansion seems useful and practicable, although complication rates are still high, which could be caused by poor clinical experience. A decision tool is given to decide whether intraoral soft tissue expansion is a treatment option. Although the studies for intraoral use are minimal, the technique is absolutely valid. Correspondence to: Henri J.J. Uijlenbroek, Academic Centre of Dentistry Amsterdam (ACTA), Department of Oral Implantology and Prosthetic Dentistry, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, The Netherlands, Tel: +31 513 411988, Fax: +31 513 411972; E-mail: [email protected] Received: November 10, 2015; Accepted: December 04, 2015; Published: December 06, 2015 Introduction Soft tissue expansion is a natural phenomenon seen in pregnancy, obesity, tumour growth and (ancient) tribal rituals. In reconstructive plastic surgery tissue expansion has become a common surgical procedure to grow extra skin through controlled mechanical overstretch. It creates skin that matches the colour, texture, and thickness of the surrounding tissue, while minimizing scars and risk of rejection [1]. The goal of tissue expansion is to develop donor tissue by tissue expansion adjacent to [2,3] or in the centre [4] of the site of reconstructive surgery. In 1957 Neumann [5] introduced a rubber balloon to expand soft tissue in order to reconstruct an ear. In 1984 Radovan [2] placed an expander adjacent to the defect and doubled the size of the donor flap by intermittent injections of normal saline into the expander. The tissue expanders used had an external port to fill them. In 1982 Austad et al. [6] described a self-inflating tissue expander. He used a permeable silicone balloon filled with a saturated NaCl solution. The disadvantages were the long inflation period of 8 to 14 weeks and the risk of rupture, which could result in necrosis of the overlying tissue. Wiese et al. [79] researched the use of hydrogels for tissue expansion to overcome these problems. This led to the Osmed® hydrogel expander. Hydrogels can imbibe water or biological fluids and thus increase in volume. The smaller-sized Osmed® hydrogel expanders can be used intraorally. Hydrogel based soft tissue expanders are used in plastic surgery with moderate [10,11] to good [12-15] results as well as in ophthalmology [9,16]. The use of intraoral soft tissue expanders was first described in 2007 [17] as small hydrogel expanders became available. Animal studies [18,19] as well as human studies [20] have been done. In this paper we present the history of tissue expansion, the surgery needed in soft tissue expansion procedures and is related problems. The intraoral applications are discussed with their limitations and an indication is provided for the future application in implant dentistry.