Abstract
This thesis aims to investigate a possible approach to increase the volume of the area in which augmentation material can be inserted under oral soft tissues with self-inflating osmotic soft tissue expanders. This then allows more augmentation material to be inserted. The properties of the augmentation material inserted, will have impact to the bone genesis. Therefore, bone morphogenetic protein 2 (BMP-2), which is known to be osteo-conductive and osteo-inductive, is studied. It is unclear whether there is bone formation when using BMP-2 in the treatment of peri-implantitis. The most effective dose BMP-2 to promote bone formation when using an osseo-conductive coralline hydroxyapatite (CHA) coated with an osseo inductive layer biomimetic calcium phosphate (BioCaP) is not clear yet.
In order to describe the ideal properties of an expander for intra oral use, literature on tissue expanders used in general medicine was studied. Tissue expansion is indicated in cases where other surgical techniques aimed at gaining the soft tissue surface are inadequate. The use of tissue expanders requires extra time, extra surgical procedures, money and discomfort for the patient which limits its clinical use. The used self-inflating hydrogel Osmed ® expanders were enveloped in a silicone hull with a few small perforations, through which tissue fluids can be adsorbed by the hydrogel. Fixation of the expander, which is possible with a screw through the extension of the silicone envelope prevents dislocation. The histological findings showed no difference at comparing expanded and unexpanded tissue. The increase of the amount of soft tissue was clinically clearly visible, and no differences were found when following either the flap placement or the tunnel placement procedure. In a case report the use of two Osmed ® hydrogel soft tissue expanders enveloped in a silicone hull is described.
A critical sized bone defect is too large to heal spontaneously. Bone augmentation procedures can be performed to overcome this. BMP-2 needs to have a carrier and a delivery mode to be an effective. As a carrier octa calcium phosphate (OCP) can be used. BMP-2 can be adsorbed in the outer layer of OCP: biomimetic calcium phosphate (BioCaP) with adsorbed BMP-2, or incorporated only in the outer layer of OCP: BioCaP with incorporated BMP-2, or BMP-2 can be incorporated throughout the entire layer of OCP: BioCaP with inserted BMP-2. The optimal dose BMP-2 to induce bone formation is unknown.
Peri-implant bone defects can be considered as critical sized bone defects because they do not heal spontaneously. This study shows that when treating peri-implant bone defects in dogs with BioCaP containing adsorbed, incorporated or inserted BMP-2 they all generate bone. When BMP-2 has been incorporated in the entire volume of all BioCaP particles it performs the best.
Hydroxyapatite is a main component of our skeleton. Marine coral is used as a natural bone graft material and has a trabecular structure comparable to bone. Through a hydrothermal process its calcium carbonate skeleton converses from coral to hydroxyapatite, thus forming coralline hydroxyapatite (CHA). CHA alone does not induce bone formation in an ectopic site. By coating CHA with BioCaP containing BMP-2 osteo-inductive properties could be added to the augmentation material. All CHA samples coated with BioCaP containing incorporated BMP-2 show bone formation in ectopic sites, whereby the sample containing 5 µg BMP-2 induces the most bone formation.
It can be concluded that the tissue expanders looked promising but the research showed its limitations in volume increase, immediate expansion, costs involved and the extra surgery. BioCaP containing BMP-2 induces bone formation in animal studies in ectopic sites. The optimal BMP-2 concentrations per study are described.
Original language | English |
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Qualification | PhD |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 14 Dec 2022 |
Place of Publication | s.l. |
Publisher | |
Print ISBNs | 9789090367279 |
Publication status | Published - 14 Dec 2022 |
Keywords
- bone volume
- expansion
- intra oral
- tissue expander
- hydrogel
- BMP-2
- biomimetic
- calcium phosphate
- bone morphogenetic proteins
- hydroxyapatite
- osteoinduction