Study population and design
This was a retrospective observational study of autotransplantation of third molars into fresh first or second molar extraction sockets simultaneously using a 3D replica and grafting with autogenous bone mixed with concentrated growth factor (CGF) in 10 patients (8 males and 2 females) (ages ranging from 19 to 42 years) between September 2016 and August 2017. All the patients were consecutively collected from Department of Oral and Maxillofacial Surgery, Affiliated Stomatological Hospital of Fujian Medical University. All patients were informed about the surgical treatment procedure. The study design was performed in accordance with the Helsinki Declaration (revised in 2008).
The patients included in this study reach the following criteria:
- First or second molar need to be extracted.
- Third molar with mature root need to be extracted.
- Recipient site without local acute inflammatory.
- The rest bone height of the recipient site is enough for the donor tooth (the height from alveolar ridge crest to inferior alveolar nerve).
- Systemic diseases such as diabetes mellitus and hypertension, which is not suit for oral surgery, were absent.
All patients received a cone-beam computed tomography (CBCT) examination to analysis the compromised teeth and the donor teeth (the stage of the root development and the shape of the root), then the mesio-distal and bucco-lingual dimension and height of the donor tooth and the recipient site were measured to evaluate the adaptability of the donor tooth to the fresh extraction sockets as it showed in Fig 1. Whether the extraction socket need to be prepared or GBR to filled the gap between the donor tooth and the extraction socket can be known. All patients underwent a low-dose CBCT imaging using the NewTom GiANO (NewTom, Italy) with voxel size 0.150 mm, tube voltage of 90 kV, current of 7.00 mA, and exposure time of 9 s. The CBCT data was imported into Materialize Proplan software, this allowed the segmentation of the donor tooth as it show in Fig 2. Then 3D replica of the donor teeth, made of resin material, was fabricated by a 3D printer (Vida, Envision TEC) according to the segmentation data from the CBCT. All patients underwent an overall dental hygiene assessment, teeth washing or scaling, and root planning one week before surgery, if necessary.
All the surgical proceduces were performed by the same surgeon, who had more than 20 years of experience in oral surgery. Block anesthesia of the inferior alveolar nerve was performed when the donor teeth and the recipient site were in the mandibular; local anesthesia was performed when the donor teeth or the recipient site were in the maxillary. Local anesthesia was achieved with articaine chlorhydrate 4% and adrenaline 1:100 000. A crevicular incision was made from second premolar to third molar, and the vertical releasing incision in distal side was made if necessary. The compromised molar was extracted by minimally invasive maneuver, using high-speed fissure bur (SINOL) and a dental elevator or forceps (Stoma). The preparation of recipient site was done by piezosurgery according the root shape of the 3D replica of the donor teeth, which was sterilized by ethylene oxide before surgery. Meanwhile, the bone fragment was collected during the preparation of the recipient site if the recipient site need bone graft. The impacted tooth was also extracted by minimally invasive technique, using a dental elevator or forceps (Stoma) after the 3D replica of the donor teeth try-ins into the recipient socket. We put the donor teeth into the recipient socket and checked whether it achieve an optimal fit. If there were bone defect around the donor tooth, we grafted the autogenous bone which was collected during the socket preparation process, mixed with concentrated growth factors (CGFs) which was done immediately before surgery. Whole blood drew from the patient was centrifuged using a tabletop centrifuge (Medifuge, Silfradenstsr, S. Sofia, Italy) and it was divided into four layers as described by Bozkurt et al. The CGF layer, which was the second growth factor and stem cell layer of the four layers, was separated using sterile scissors. Then the bone graft area was covered by CGF membrane which was also done before surgery. Finally, the flap was repositioned and sutured. All the transplanted teeth were stabilized with splints attached to the adjacent teeth which were carried out with a multi-layer fiber-glass band. The brief surgical procedure of the tooth autotransplantation was showed in Fig 3.
After surgery, all the patients received mouth rinsing for 1 week. After 1 week, the sutures were removed and the wound was cleaned by normal saline. The preparation of the root canal was performed 2 weeks after surgery and the filling of the root canal was done 5 weeks after surgery. The multi-layer fiber-glass band was removed 5 weeks after surgery.
Follow-up recalls were scheduled for1, 2, 4 weeks and for 3, 6,12, 24 months. At each time of the follow-up the mobility and percussion were checked, while the probing depth of the mesial-buccal, buccal, distal-buccal, mesial lingual, lingual, and distal-lingual of the autotransplantation teeth and the masticatory function were checked 1, 3, 6, 12 and 24 months after surgery. The radiography examination was taken before surgery and immediate, 1, 3, 12, 24 months after surgery. We defined the masticatory function as the patient’ ability to chew normal food without pain or discomfort. The primary success criteria of the transplanted tooth were followed according to the described by Tsukiboshi. In terms of the radiography (1) normal space of the parodontium; (2) no sign of progressivity absorb of the root; (3) the exist of the lamina dura. In terms of clinical examination (1) normal mobility; (2) normal percussion sound; (3) no periodontal pocket; (4) no sign of inflammation; (5) no discomfortable; (6) normal function of chewing.