## 2 Materials and Methods
### Case I  
A 57-year-old male patient visited the clinic with a chief complaint of tooth mobility and pain on the upper-right second premolar. The patient was systemically healthy. Thorough clinical and radiographical examination revealed full periodontal pocket depth (PPD) on the palatal aspect, with normal PPD on the buccal aspect, easy bleeding on probing (BoP), severe tooth mobility and apically involved intrabony defect with slight palatal marginal bone loss around the tooth (Figure 1e). The tooth had been diagnosed as Stage II, Grade B periodontitis [16] and the post-extraction socket configuration had been classified as subgroup E according to [PERSON] et al. study's classification of extraction socket defect [17]. During the next appointment, tooth extraction proceeded using a pre-molar extraction forcep without flap elevation (Figure 1a). After a thorough debridement, 0.25 g of collagenated deproteinized bovine bone mineral (collagenated DBBM; Bio-oss collagen\({}^{\circledR}\), Geistlich Pharma AG, Wollusen, Switzerland) was immediately grafted on the extraction socket and a resorbable collagen sponge (Teruplug, Olympus Terumo Biomaterials Corp., Tokyo, Japan) was adapted on top of the grafted site. The socket was sutured with 4-0 absorbable monofilament (Monosyn\({}^{\circledR}\), B. Braun, Melsungen, Germany). After the ARP procedure, a peri-apical radiograph was taken (Figure 1g). The patient was prescribed 250 mg of amoxicillin (Kymoxin, Yuhan pharmaceutical, Seoul, Korea), 200 mg of ibuprofen (Carol-F, lldong pharmaceutical, Seoul, Korea), and 100 mg of rehamipide (Mucosta, Korea Otsuka Pharmaceutical, Seoul, Korea), three times a day, for three days post-operative. Sutures were removed one week after the operation. For miscellaneous reasons, the patient failed to attend regular periodic follow-up schedules and revisited the clinic one-year post extraction for an implant surgery on the operation site. Cone-beam CT (CBCT) was taken for evaluation, and implant planning was proceeded using computer software (OnDemand3D, Cybermed, Seoul, Korea).  
During the operation, flaps were elevated after crestal and sulcular incision and the healing status of the surgical site was evaluated. Prior to implantation, a trephine (\(\O 3.0\) Trephine kit, Dentium, Suwon, Korea) with an inner diameter of 2.3 mm was drilled in the centermost area of the implant placement site to obtain the previously grafted bone tissue (6 mm depth). A 4.5 \(\times\) 10 mm SLA-surfaced implant (TS III, Osstem, Seoul, Korea) was placed with an insertion torque of 50 N/cm (Figure 1c) [18; 19]. Additional therapy was not performed, and a healing abutment (5.0 \(\times\) 4.0 mm, Osstem) was then connected to the fixture. Mesial and distal gingiva was sutured and the same previous medications (amoxicillin, ibuprofen and rebamipide) were prescribed for five days post-operation. Sutures were removed seven days post-operation and the patient attended the clinic monthly for regular follow-up. The implant stability was confirmed by Periotestvalues (Periotest\({}^{\circledR}\), Dentisystem, Budapest, Hungary) [20,21] three months post-operation, and the implant prosthesis was delivered. After a prosthesis delivery, the patient underwent a regular periodic follow-up program for any possible post-op complications.