Autologous Platelet Rich Plasma (PRP)

Stephen L. Wheeler, D.D.S.
320 Santa Fe Drive, Suite #304 Encinitas, Calif. 92024
(760) 942-1333
Steve@Wheelerdds.com

Purpose: Autologous Platelet Rich Plasma (PRP) has the features of a non-toxic, non-immune reactive accelerator of existing wound healing pathways. Specific studies with PRP have identified several factors which can initiate bone regeneration and sustain long term healing and bone formation. Unfortunately there are few quantification studies to validate this premise. A prospective study was started in the summer of 1998 using PRP along with a xenograph (Bio-Oss®) and/or particulate autogenous bone harvested from the iliac crest in sinus lift cases prior to implant placement. The purpose of this study was to see if histomorphometric analysis would evidence a larger volume of bone formation in those grafts using PRP, and if there were differences in the effects of PRP when an alloplast was used instead of autogenous bone.

Methods: Fifteen healthy patients were selected for the study who had between 3-5mm of residual crestal bone in the posterior maxilla and required sinus grafting to place implants of adequate length. Both unilateral and bilateral cases were accepted. Bilateral cases would be used to compare a graft on one side with PRP and on the other side without. Cores were harvested after six months of healing and compared on bilateral cases and with previous sinus graft cases without PRP using histomorphometric analysis.

Results: Histomorphometric results showed an average of 17.3% vital bone formation in grafts using Bio-Oss alone (3 cores, 15-21% range), 32.25% average vital bone formation when adding PRP to the xenograft (12 cores, 13-54% range), and 37% average vital bone formation when PRP was added to particulate bone harvested from the iliac crest (5 cores, 10-52% range). In one case, bilateral sinus grafts were done using BioOss alone on one side and BioOss with PRP on the opposite side. Results showed a 41% increase in bone formation on the side where PRP was added (21% vs. 36%). Interestingly, the ranges of bone volumes were very similar between both the BioOss and PRP and autogenous bone and PRP (13-54% and 10-52%) with final averages only 15% apart. Thirty-six implants were placed in these grafts and have now been followed for up to three years with no failures

Predisposing conditions for retrograde peri-implantitis, and treatment suggestions

Clinical Oral Implants Research Volume 16 Issue 5 Page 599 - October 2005
Marc Quirynen1, Roel Vogels1, Ghada Alsaadi1, Ignace Naert2, Reinhilde Jacobs3 and Daniel van Steenberghe1*

Background: Recent case reports introduced the term retrograde peri-implantitis as a lesion (radiolucency) around the most apical part of an osseointegrated implant. It develops within the first months after insertion. This retrospective study aimed to find predisposing conditions for such peri-apical lesions and to evaluate treatment strategies.
Methods: All single implants (426 in the upper, 113 in the lower jaw, all Brånemark system® type) placed at the department of Periodontology of the University Hospital (Catholic University Leuven) were included in this retrospective evaluation to check the incidence of retrograde peri-implantitis. Eventual predisposing factors such as patient characteristics (age, medical history), recipient site (local bone quality and quantity, cause of tooth loss), periodontal and endodontic conditions of neighboring teeth, implant characteristics (length, surface characteristics), and surgical aspects (guided bone regeneration, osseous fenestration, or dehiscency) were considered. Moreover, implants with retrograde peri-implantitis were followed longitudinally to verify their treatment outcome by means of different parameters (Periotest® values (PTV), marginal bone level, radiological size of peri-apical defect).

Results: Seven implants in the upper (1.6%) and 3 in the lower jaw (2.7%) showed retrograde peri-implantitis, before or at abutment connection. In comparison with successful implants, such peri-apical lesions occurred preferably at sites with a history of an obvious endodontic pathology of the extracted tooth to be replaced. The incidence of retrograde peri-implantitis was significantly higher (P<0.0001) name="h4">

Conclusions: Within the limitations of a retrospective study, these results seem to indicate that retrograde peri-implantitis is provoked by remaining scar or granulomatous tissue at the recipient site: endodontic pathology of extracted tooth (scar tissue-impacted tooth) or possible endodontic pathology from a neighboring tooth.

Immediate Implantation in Fresh Extraction Sockets

Immediate Implantation in Fresh Extraction Sockets. A Controlled Clinical and Histological Study in Man
Michele Paolantonio et al.

Background: Early implantation may preserve the alveolar anatomy, and the placement of a fixture in a fresh extraction socket helps to maintain the bony crest. Although a number of clinical studies exist, no histological reports show the outcome of implantation in fresh extraction sockets without the use of membranes in humans compared to implants placed in mature bone.
Methods: Forty-eight healthy patients, receiving at least 4 fixtures in each of 2 symmetrical quadrants, underwent placement of 1 experimental fixture placed in a fresh extraction socket (TI) and 1 contralateral fixture in mature bone (CI). TI were placed after atraumatical tooth extraction, with a surgical site at the apex of the socket and a tight contact between the fixture and the socket?s walls, but without the use of filling materials or membranes. The flap was coronally repositioned to obtain primary wound closure. Immediately after surgical intervention, a standardized periapical radiograph was taken. Second-stage surgery was done after 6 months. Six months after the second surgery, a second standardized periapical radiograph was taken and clinical parameters (bleeding and plaque index) recorded. Marginal bone loss (MBL) from the time of implant placement to the time of fixture removal was calculated by comparing periapical radiographs. TI and CI were then removed by a hollow drill to obtain histological specimens. Non-demineralized sections were stained by acid fuchsin and toluidine blue, and by von Kossa to evaluate the degree of bone mineralization. The percentage of direct implant-bone contact (DBC) was calculated by a computerized microscopic digitizer.

Results: No significant differences in the clinical and radiographic parameters were observed between the 2 experimental categories. There was no statistically significant difference between TI and CI for DBC either in the maxilla or in the mandible. No connective or fibrous tissues were present around TI or CI. Bone resorption was not present in any of the histological sections.

Conclusions: The present study shows that when a screw-type dental implant is placed without the use of barrier membranes or other regenerative materials into a fresh extraction socket with a bone-to-implant gap of 2 mm or less, the clinical outcome and degree of osteointegration does not differ from implants placed in healed, mature bone. J Periodontol 2001;72:1560-1571.

Bucco-Lingual Crestal Bone Changes After Immediate and Delayed Implant Placement
Ugo Covani et al.

Background: Implants placed immediately after tooth extraction offer several advantages, but many authors have reported problems in filling the residual gap between the implant and the socket walls. Barrier and grafting techniques have been tested and yield varying results, so it has been suggested that the timing of implant placement may be important for success. The aim of this study was to analyze bone healing and coronal bone remodeling around 35 implants, 20 placed immediately after tooth removal and 15 placed 6 to 8 weeks after extraction.
Methods: All the implants were submerged and placed within the alveoli confines, leaving circumferential defects because the implants did not contact the bone at their coronal aspects; stabilization was achieved in the bone apically. After implant placement the mean distance from buccal bone to lingual bone was 10 mm (SD 1.522) for immediate implants and 8.86 mm (SD 2.356) for delayed implants. No membrane or filling materials were used. Primary flap closure was accomplished in all cases.

Results: At second-stage surgery all peri-implant defects were filled, and the mean distance from buccal bone to lingual bone was 8.1 mm (SD 1.334) for immediate implants and 5.8 mm (SD 1.265) for delayed implants. This pattern of coronal bone remodeling, showing a narrowing of the bucco-lingual width, was clinically similar for the two groups, although it should be noted that the delayed implants exhibited smaller bucco-lingual bone width already at the first measurement: it can be speculated that early remodeling may start immediately after tooth extraction and continue, non-uniformly, even after delayed implant placement.

Conclusions: This study suggests that circumferential defects could heal clinically without any guided bone regeneration (GBR) in both experimental groups, and that the procedure was virtually free from complications in the postoperative period, probably because of the absence of barrier membranes and/or grafting materials. Histologically, periimplant defects of over 1.5 mm heal by connective tissue apposition, rather than by direct bone-to-implant contact, but clinically this healing may be very successful. No histological analysis was carried out in the present study, but even the largest residual gaps were filled with hard tissue that could not be probed. Thus, such outcomes can be considered clinically successful. The different rate of bone remodeling around immediate or delayed implants could have implications for the preferred timing of implant placement in sites of high esthetic concern. J Periodontol 2004;75:1605-1612.

Hydraulic Sinus Condensing Technique

J Periodontol. 2005 Mar;76(3):482-91.An 8-year retrospective study: 1,100 patients receiving 1,557 implants using the minimally invasive hydraulic sinus condensing technique. Chen L, Cha J.

BACKGROUND:For many clinicians, inadequate alveolar bone height and anatomical features of the maxillary sinus complicate sinus lift procedures and placement of endosseous implants. We present a new internal crestal approach that addresses these issues.
METHODS:Sinus burs and condensers of increasing width are used in conjunction with pliable atraumatic bone grafting mixture and hydraulic pressure from a surgical handpiece. The risk of a membrane perforation is minimized when the surgeon's tactile skill is administered in a two-stage process to first loosen and then graft bone particulate under the Schneiderian membrane. Threaded implants can then be placed in the same visit and secured via primary closure.

RESULTS:A retrospective investigation of 1,100 cases showed that eight implants
14 required longer healing periods in patients with alveolar ridge heights varying between <1 to 5 mm.

CONCLUSIONS:Our experience suggests that hydraulic sinus condensing is a predictable and minimally invasive alternative for prosthetic rehabilitation of maxillary anterior and posterior regions in the presence of anatomical restrictions to implant placement.