Patient selection
This prospective clinical trial was performed at one center in Korea. The Institutional Review Boards (IRB) of Dankook University Jukjeon Dental Hospital in Yongin approved the study protocol (JDH2011-001). All patients provided written informed consent before treatment initiation. From February 2011 to August 2013, 38 consecutive patients who required tooth extraction for endodontic or periodontal reasons or pericoronitis of third molar and dental implant restoration were included in this study. The reasons for bone grafting included the repair of vertical or horizontal alveolar bone defects to facilitate implant osseointegration. Patients with generalized aggressive periodontitis, severe general illness (over ASA Class III) were excluded.
Tooth extraction and preparation
Before surgery, all patients received intramuscular administrations of clindamycin phosphate (300 mg) and tramadol hydrochloride (50 mg). Local anesthesia was induced by nerve block or local infiltration using 2% lidocaine HCl (1:80,000 epinephrine) and additional bupivacaine HCl if required. Following clean tooth extraction, any soft tissue adherent to the root was removed using a surgical blade. The pulp tissue in the root canal(s) was then removed using a pear-shaped carbide bur (no. 330), and several small holes 2–3 mm apart for better contact to reagent were created from the outer surface of the tooth to pulp chamber.
Chairside preparation of the auto-FDT graft
The entire chairside preparation process, including demineralization, sterilization, and washing was completed within 2 h (block type) after extraction according to the manufacturer’s instructions using an ultrasonic device and reagents (VacuaSonic® and DecalSi-DM®; Cosmobiomedicare, Seoul, Korea). The final washing solutions for the processed teeth were sent to the Green Cross Clinical Laboratory (Yongin, Korea) for bacterial culture for monitoring.
Auto-FDT grafting and implant placement
The fresh extraction sockets were prepared for bone grafting. The auto-FDT graft was implanted as blocks or chips depending on the condition of the defect (Figure 1). The block was trimmed with a surgical blade or bone rongeur, while the chips and powder were prepared using a bone mill or crusher. The dental implant fixtures (TSII-CA, Osstem, Seoul, Korea) were placed simultaneously with or after graft placement. An absorbable or titanium sheet barrier membrane was used to cover the graft. Patients were prescribed antibiotics and non-steroidal anti-inflammatory drugs for 1 week and were given postoperative dental hygiene instructions.
Evaluation of new bone formation and implant stability
Postoperative wound healing and implant stability were clinically assessed. Radiographs, including panoramic views and cone beam computed tomography (CBCT) images, were obtained to confirm graft healing at 6 month postinsertion and 12 months after prosthesis delivery (postoperative 18 months). Implant stability was measured using a radio frequency device (Osstell Mentor, Integration Diagnostics, Göteborg, Sweden) before recording impressions. Prosthetic procedures were initiated 4–6 months after fixture placement depending on the type of defect and graft amount. The radio frequency value was measured twice in two directions (buccal and lingual or palatal; Figures 2A–K).
In some cases, small bone segments were acquired from the graft site of the osteotomy with a trephine bur during fixture placement or the graft over cover screws with the tissue punch during uncovering. Decalcified tissue sections were then prepared using routine procedures and stained with hematoxylin–eosin (H&E) and Masson’s trichrome (MT).
In-vitro assessment of the auto-FDT graft
Dried sample weighing and energy dispersive X-ray spectroscopy (EDS) were used to evaluate the degree of tooth demineralization. Extracted maxillary premolars (n = 5) were dried and their weight was measured. The teeth were then processed in an ultrasonic chamber as for clinical use, and their dry weight were measured again. EDS (TEAM System, EDAX Inc., NJ, USA) was used to check the relative calcium content (wt%) at 5 points up to a depth of 700 μm from the surface of the dentin. Data were collected in the 2θ range of 8°–90°, with a step size of 0.02° and a counting time of 20 s at each step. The data bank from the International Center for Diffraction Data was used in a search/match program for phase identification.
Scanning electron microscope (SEM) studies were performed using the Nanoscope IIIa instrument (Digital Instruments, Tonawanda, NY, USA) after coating samples with a gold–palladium alloy. The processed tooth materials and untreated tooth surfaces were then observed.
Statistical analysis
Wilcoxon signed rank test was used for in-vitro analysis of calcium using SPSS 20 software (IBM SPSS Inc., Chicago, IL, USA) with the significant level of 0.05, and the clinical data are described using descriptive statistics.