Robert P. Carmichael

Bisphosphonate Associated Osteonecrosis of the Jaw

In 2003, the first reports describing osteonecrosis of the jaw (ONJ) in patients receiving bisphosphonates (BP) were published. These cases occurred in patients with cancer receiving high-dose intravenous BP; however, 5% of the cases were in patients with osteoporosis receiving low-dose bisphosphonate therapy. We present the results of a systematic review of the incidence, risk factors, diagnosis, prevention, and treatment of BP associated ONJ. We conducted a comprehensive literature search for relevant studies on BP associated ONJ in oncology and osteoporosis patients published before February 2008.All selected relevant articles were sorted by area of focus. Data for each area were abstracted by 2 independent reviewers. The results showed that the diagnosis is made clinically. Prospective data evaluating the incidence and etiologic factors are very limited. In oncology patients receiving high-dose intravenous BP, ONJ appears to be dependent on the dose and duration of therapy, with an estimated incidence of 1%–12% at 36 months of exposure. In osteoporosis patients, it is rare, with an estimated incidence < 1 case per 100,000 person-years of exposure. The incidence of ONJ in the general population is not known. Currently, there is insufficient evidence to confirm a causal link between low-dose BP use in the osteoporosis patient population and ONJ. We concluded BP associated ONJ is associated with high-dose BP therapy primarily in the oncology patient population. Prevention and treatment strategies are currently based on expert opinion and focus on maintaining good oral hygiene and conservative surgical intervention.

Quantification of bone harvested from the iliac crest using a power-driven trephine

PURPOSE This study describes an alternate approach for harvesting cancellous bone from the anterior iliac crest and quantifies the amount of bone removed using a power-driven trephine without the need for an open procedure. The safety of this technique is also evaluated. MATERIALS AND METHODS Twenty-five adult cadavers were used to determine the volume and weight of bone that could be harvested using a motorized trephine. A total of 50 anterior iliac crests were sampled. Core samples of cancellous bone were measured, weighed, and the volume calculated. The harvested sites were then dissected and evaluated for perforations. These data were compared with the measurement of the first 40 consecutive cores trephined from patients requiring grafts. RESULTS The bone harvested took the form of a compact core measuring, on average, 33.5 mm in length and 4.0 mm in diameter. The average weight of each core was 0.44 g, and the average volume was 0.42 cm3. Perforation to the medial aspect occurred in 4 of 50 hips, and lateral perforations occurred in 7 of 50 hips. The greatest number of perforations occurred at depths greater than 30 mm and were found in the most atrophic cadavers. The 40 cores obtained from patients averaged 34.1 mm in length and 0.46 g in weight. The average volume per core was 0.45 cm3. CONCLUSIONS The amount of trephinated autogenous cancellous bone procurable by means of a motor-driven trephine is suitable for cases of sinus lifting or to fill an alveolar cleft defect. Although the yield of cadaveric bone is slightly less than the amount obtainable from patients, it is a useful model to evaluate potential complications and estimate yields.

Dental Implants, Growth of the Jaws, and Determination of Skeletal Maturity

In this article, the authors examine the optimal time for dental placements in young individuals and emphasize the importance of ensuring skeletal maturity has been reached, except in some situations where dentoalveolar growth is expected to be minimal or where the value afforded by an anchored prosthesis outweighs the disadvantage of local growth inhibition. They offer examples of the difficulties encountered in implants placed in a growing individual, including loss of integration, diminishment of posterior function, and excessive wear or fracture of restorative materials in the anterior region. Because individual growth cessation varies by up to 6 years within each gender, chronologic age cannot be used as a guide in planning implants; rather, analysis of skeletal development can be made from carpal radiographs or from superimposition of serial lateral cephalograms.

Dental implants placed into alveolar clefts reconstructed with tongue flaps and bone grafts

OBJECTIVE The aim of this study was to describe a case series using surgical and prosthodontic modifications of tongue flaps necessary to adapt them for use in the reconstruction of large cleft deformities refractory to customary measures using dental implants and to study their outcomes in patients with complex cleft lip and palate deformities. STUDY DESIGN Five patients were treated with iliac crest bone grafts and covered by anteriorly based tongue flaps divided at either 3 or 4 weeks after surgery. The patients were followed clinically and radiographically for 3-12 years after placement of their dental implants to monitor implant survival and success. RESULTS One of the 5 patients suffered a partial tongue flap detachment, graft dehiscence, and recurrence of an oronasal fistula, which was successfully treated by shifting the tongue flap tissue from its new location in the palate. A total of 18 dental implants were placed into bone-grafted tissue covered by the tongue flaps. There was 1 implant failure. There were no cases of periimplantitis or bone loss in the 17 surviving implants. CONCLUSIONS Tongue flaps are rarely used clinical entities with a very narrow range of indications. Tongue flaps are useful in the preprosthetic reconstruction of select cases with large residual oronasal fistulae with soft tissue deficits due to scarring from previously failed surgery. Tongue flaps are extremely stressful procedures for patients to endure. Patient selection is of the utmost importance.

Midfacial Distraction Osteogenesis

George K.B. Sándor, MD, DDS, PhD, Dr. Habil, FRCDC, FRCSC, FACS*, Leena P. Ylikontiola, DDS, PhD, Willy Serlo, MD, PhD, Pertti M. Pirttiniemi, DDS, PhD, Robert P. Carmichael, DMD, MSc, FRCDC Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, Ontario M5G 2M7, Canada The Hospital for Sick Children, S-525, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada Bloorview Kids Rehab, Suite 2E-285, 150 Kilgour Road, Toronto, Ontario M4G 1R8, Canada Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario M5G 1P6, Canada Regea Institute for Regenerative Medicine, University of Tampere, Biokatu 12, Tampere 33520, Finland Department of Oral and Maxillofacial Surgery, Institute of Dentistry, University of Oulu, Box 5281, Oulu 90014, Finland Institute of Dentistry, University of Oulu, Oulu University Hospital, Box 5281, FIN-90014, Oulu, Finland Division of Pediatric Surgery, Department of Pediatric Surgery, University of Oulu, Oulu University Hospital, Box 23, FIN-90029 OYS, Oulu, Finland

Reconstruction of Ablative Defects Using Dental Implants

Benign and malignant conditions can result in the need for ablative surgery where segments of the tooth-bearing portions of the jaws require removal for adequate disease control. Aggressive cystlike lesions of the jaws may result in destruction of large areas of the alveolus and underlying structures, resulting in the loss of teeth. Tumors such as ossifying fibroma, aggressive fibromatosis, central giant cell granuloma, and ameloblastoma may lead to defects that are challenging to restore. This article examines the reconstruction of such ablative defects and those areas of deficient growth induced by radiotherapy in childhood to treat tumors such as rhabdomyosarcoma, retinoblastoma, or neuroblastoma.

The plasticizing effect of temporary soft lining materials on polymerized acrylic resins

A patient requesting replacement complete dentures will usually have old dentures that are unsatisfactory in one or more respects. Before constructing replacement dentures, modifications to the existing dentures may be necessary.’ These modifications can be extensive, involving a combination of border correction and tissue conditioning. When an autopolymerizing acrylic resin is used to extend denture flanges that are subsequently relined with a temporary soft liner, the acrylic resin additions may become flexible after 1 week of wear. It was the possibility of an interaction between these two groups of materials that prompted this investigation. Its object was to evaluate the ability of two commonly used temporary soft liners to alter the physical properties of two equally common autopolymerizing acrylic resins and of a heat-cured acrylic resin.

Dental Implants in the Management of Nonsyndromal Oligodontia

Oligodontia has been reported to be the most or one of the most common developmental dental anomalies. The severity and pattern of oligodontia has been shown to affect craniofacial morphology, a situation with obvious implications for preprosthetic orthodontic treatment. Given the associations between developmental pathways and tissue homeostasis, it is fascinating that oligodontia may be used as a marker for malignancy and hitherto unreported congenital malformations. This article discusses the etiology, prevalence, and consequences of oligodontia, followed by a review of approaches to treatment depending on the presentation of the patient.

Facilitation of Orthodontics and Orthognathic Surgery Using Dental Implants

Conditions requiring orthodontic treatment and replacement of missing teeth in young patients are by their very nature complex. The treatment approach must be multidisciplinary, requiring the close cooperation of a triad of prosthodontist, orthodontist, and oral and maxillofacial surgeon. The advantage of absolute anchorage provided by an ankylosed dental implant was recognized by orthodontists early in the years following the advent of osseointegration. In more recent years, microimplants have enjoyed a certain level of popularity due to their novelty and ease of placement, however, their acceptance is waning somewhat with the realization by practitioners that they have a high failure rate. Intraosseous screws and bone plates offer the opportunity for secure orthodontic anchorage, although they are obviously more invasive. Dental implants used to obtain orthodontic anchorage have the advantage of being useable as part of the final prosthodontic restoration if the treatment has been properly planned and executed. Dental implants intended to provide orthodontic anchorage can be placed either in an extraalveolar location, outside of the tooth-bearing parts of the jaws, or in an intra-alveolar location within. This distinction is an important one as it pertains to growth of the young patient. Extra-alveolar fixtures can be placed in the palate (Fig. 1), the tuberosities of the maxilla, the zygomatic arches, or the retromolar areas of the mandible (Fig. 2). These fixtures can be placed in growing children because they are temporary and may be removed after the conclusion of the orthodontic treatment. Such implants are particularly useful in patients with oligodontia who have significantly reduced dental anchorage options due to their missing teeth. Intra-alveolar implant fixtures require careful planning. They are generally placed after skeletal maturity because they would otherwise interfere with alveolar development. Once placed, the position of these implants is final, and the orthodontist and prosthodontist must prescribe their locations with adequate forethought. The normal treatment sequence in patients requiring multidisciplinary therapy begins with orthodontic idealization of the alignment of the teeth, implant placement, and, finally, prosthodontic treatment. When implants are needed to provide anchorage consideration must be given to the length of time required to achieve osseointegration so as not to interupt timely delivery of orthodontic treatment. The issue of wait time for osseointegration to take place is,

Distraction Osteogenesis Using Dental Implants

Alveolar distraction osteogenesis may offer several advantages over bone grafting alone in the treatment of vertical alveolar defects. No donor site is required; distraction of bone and surrounding soft tissue occurs simultaneously; and the transport segment is a form of pedicled graft that is never separated from its blood supply, maximizing vitality and minimizing resorption. It has the potential for better control of vertical height, esthetics, and biomechanical loading.