“Early bone formation in human bone grafts treated with platelet-rich plasma: preliminary histomorphometric results” by Thor A, Franke-Stenport V, Johansson C, Rasmusson L. Int J Oral Maxillofac Surg. 2007;36:1164–1171.
This study evaluated the efficacy of using platelet rich plasma (PRP) on the healing of autogenous sinus grafts. Eleven patients had bilateral lateral wall approach sinus grafts using autogenous bone obtained from the iliac crest. Prior to augmentation the bone was particulated in a bone mill and on one side PRP was added to the graft. At 3 months time bone biopsies were obtained from the grafts and 2 microimplants were placed bilaterally in the area of the cortical window used for grafting (implants measured 2 × 5 mm). After 3 more months of healing, the microimplants were retrieved with a trephine bur and implants were placed. The biopsy samples and the microimplant-bone cores were subjected to histologic and histomorphometric analysis. The results indicated similar bone volumes for both grafting groups. At 3 months time there was significantly greater new bone formation in the PRP group. At 6 months there was no significant difference between the groups. This study suggests that PRP only affected early bone healing. The authors concluded that PRP has limited value in autogenous maxillary sinus grafts.
“Oral bisphosphonate-induced osteonecrosis: risk factors, prediction of risk using serum CTX testing, prevention and treatment” by Marx R, Cillo J, Ulloa J. J Oral Maxillofac Surg. 2007;65:2397–2410.
This paper provided valuable advice for the treatment and prevention of bisphosphonate-induced osteonecrosis of the jaw (BONJ). It prospectively examined 30 cases of oral bisphosphonate-induced osteonecrosis and compared it to data accumulated on 116 cases of intravenous (I.V.) BONJ. A detailed history and clinical examination of the exposed bone was performed. Each patient had fasting morning blood drawn to examine the levels of C-terminal telopeptide (CTX), a bone turnover marker. The BONJ was treated with nonsurgical methods and where necessary surgical debridement or resection was performed when the levels of CTX were appropriate. The majority of the cases (90%) were found to be from Fosamax use (Merk, Whitehouse Station, NJ). The majority of the cases occurred in the mandible (96.7%). Spontaneous exposure of the bone occurred in 50% of cases (majority lingual of mandibular molars), the remainder due to surgical insults including dental implant placement. The length of time patients had taken bisphosphonates varied from 3.3 to 10.2 years. It was noted that discontinuation of bisphonates (drug holiday) for 6 months increased the value of CTX from a mean of 72.9 pg/mL to a mean of 228 pg/mL. Longer drug holidays were correlated with improving levels of CTX. The authors speculated on the predominance of Fosamax use in the cases presented. This was partly due to the potency of oral Fosamax which is as potent as the I.V. form of other bisphonates. It may also be due to a longer half life of the medication in bone. To induce BONJ with oral bisphosphonates it appears that the medication must be taken for at least 3 years. In contrast I.V. use can induce BONJ in 9 to 14 months. The presence of pain with BONJ was correlated to the presence of infection. The severity of the BONJ was correlated to the length of time the drugs were taken. Several recommendations were presented. To prevent BONJ patients prescribed bisphonates should be referred by their MD to a dentist to have their oral condition evaluated. It appears safe to perform any necessary surgery (including implant placement) within a 3 year window after starting bisphosphonate therapy. However proper consent must be obtained even in this period. For those patients already taking bisphosphonates and requiring dental surgery in is advised to get CTX levels if bisphonate use is greater than 3 years or if it is less than 3 years but there is concomitant use of corticosteroids or chemotherapy. It may also be advisable to suggest a drug holiday prior to the procedure. Surgery should be avoided in patients with CTX levels less than 150 pg/mL. A 4 to 9 month drug holiday may be required to bring CTX levels up. Treatment of BONJ includes discontinuing the bisphosphonate, chlorhexidine rinses for those presenting without pain, and antibiotics for those in pain. Surgical intervention should be avoided and delayed until the drug holiday has been observed and CTX levels are above 150 pg/mL.
“Immediate loading of single SLA implants: drilling vs. osteotomes for the preparation of the implant site” Stavropoulos A, Nyengaard J, Lang N, Karring T. Clin Oral Impl Res. 2008;19:55–65.
This paper compared the healing of bone adjacent to implants placed by either conventional drilling or osteotomes. Six dogs had their second, third, and fourth premolars extracted bilaterally in the mandible. After 3 months of healing 4 implants were placed. In 3 animals the osteotomies were prepared using the manufacturer's drills in a stepwise fashion. In the other 3 animals the osteotomies were prepared entirely with the use of osteotomes. The initial osteotome was a “cutting” osteotome with a sharp tip that was used to perforate the cortical bone using a mallet. The subsequent osteotomes employed were a “condensing” variety with a round tip pressed into position with a reciprocating motion. The implants placed were screw type one-stage implants, 3.3 mm wide x 10 mm long. After implant placement, transfer impressions were taken, healing collars placed and flaps sutured. Screw retained crowns were placed 4 days later. Resonance frequency analysis was employed to assess implant stability at placement, at crown placement, and after sacrifice. The animals were killed at 2, 4, and 12 weeks post loading and the jaws harvested for histologic processing. The results indicated that cracks appeared in the bone with the osteotome technique. All of the implants placed with the osteotome technique were lost prior to sacrifice. None of the implants placed with drilling were lost and were found to integrate in a standard fashion. This study suggests that the use of osteotomes is contraindicated. However the technique employed for the osteotomes was not the technique commonly employed which combines initial drill(s) with osteotomes. Due to this, these results are suspect.
“Influence of platform switching on crestal bone changes at non-submerged titanium implants: a histomorphometrical study in dogs” Becker J, Ferrari D, Herten M, et al. J Clin Periodontol. 2007;34:1089–1096.
This study evaluated the effect of platform switching on the bone healing in nonsubmerged implants in a dog model. Nine dogs had the second, third, and fourth premolars and first and second molars extracted bilaterally in the mandible. After 3 months of healing, 5 mm x 11 mm implants were placed at or below the osseous crest. The implants had an identical endosseous portion but had either flat connection to a healing collar or an experimental beveled connection that allowed a healing collar with a horizontal mismatch of 0.5 mm (platform switching). Each animal had 3 of each type of implant placed with healing collars placed to allow nonsubmerged healing. At 7, 14, and 28 days the animals were killed and subjected to analysis. Measurements were made between the implant shoulder (IS), the apical extension of the long junctional epithelium, the most coronal level of bone in contact with the implant (CLB) and the level of the alveolar bone crest (BC). The results indicated that the platform switching implants had significantly less apical epithelial downgrowth. However both groups suffered increased bone loss at the buccal at 28 days. There was no significant difference in the IS-CLB and IS-BC between the groups. These results suggest that platform switching did not result in different crestal bone changes during healing.
“Correlation between early perforation of cover screws and marginal bone loss: a retrospective study” Assche V, Collaert B, Coucke W, Quirynen M. J Clin Periodol. 2008;35:76–79.
This retrospective study examined the relationship between early exposure of implant coverscrews and crestal bone loss. Sixty implants of the same brand were placed by the following protocol: 40 via a two-stage protocol with a cover screw placed and 20 via a one-stage protocol where a healing collar was placed at surgery. Twenty of the two-stage implants had their cover screws exposed due to spontaneous perforation of the gingival tissues. The crestal bone levels were compared radiographically at the time of surgery and at three months post placement (at the time of second stage uncovery surgery in the two-stage implants). The results indicated that the implants that had early perforation suffered significantly greater crestal bone loss compared to both the one-stage implants and the two-stage implants that did not suffer premature exposure. There was no difference between the one-stage group and the two-stage implants that did not suffer premature exposure. These results suggest that early spontaneous exposure of implants placed in a two-stage manner causes increased crestal bone loss. Long term follow up of these patients would be valuable.