Mohamed El Deeb

Aneurysmal bone cyst of the jaws. Report of a case associated with fibrous dysplasia and review of the literature.

A case of aneurysmal bone cyst (ABC) of the mandible, recurring for the third time and arising in conjunction with fibrous dysplasia, is reported. A comprehensive review of the literature and analysis of over 50 cases of ABC of the jaws yielded the following results: ABCs of the jaws constitute 1.5 % of all non-odontogenic and non-epithelial cysts of the jaws, and 1.9 % of all ABCs of the skeleton. The mandible was affected in 55 % of the cases, the maxilla in 45 % of the patients. Females represented 53 % of the patients and males the remaining 47 %. Seventy-four percent of the ABCs occurred in patients 20 years old and younger. This lesion is regarded as non-neoplastic and as most likely secondary to a pre-existing bone lesion. Our review established that 21 % of the reported cases in the jaws had developed in association with various primary lesions of bone, including fibro-osseous lesions. The primary bone lesion initiates an osseous, arteriovenous fistula which, through its hemodynamic forces, creates a secondary reactive lesion, that is an aneurysmal bone cyst. We also established a recurrence rate of 26 %, based upon previously reported cases as well as our own. The treatment of choice is surgical curettage with cryosurgery and immediate packing with bone chips.

Hydroxylapatite granules and blocks as an extracranial augmenting material in rhesus monkeys

This study evaluates the use of the nonporous hydroxylapatite (HA) granules and blocks as an extracranial augmentation material in monkeys. Augmentation was performed in 12 Rhesus monkeys killed at three, six, and 12 months postoperatively. Clinical evaluation revealed that the HA granules become stable within three to four weeks, but there is loss of some augmented height due to settling of the material within the subpericranial pocket. The HA blocks maintained the augmented cranial contours, but 25% of them exhibited mobility. Histologic evaluation revealed no evidence of inflammation or bone resorption with either the HA granular or block form. The HA granules were separated from each other and from the bone interface by a layer of collagen fibers, and the blocks were also surrounded by a fibrous capsule. There was no evidence of bonding between the HA granules, and the bone-HA interface was separated by an intervening fibrous layer in all the HA granular specimens except for one in the one year group which showed evidence of bone formation in part of the HA bone interface. It was concluded that when used as an extracranial augmentation material, the nonporous HA granules were more stable than blocks; however, the blocks maintain a better contour.

Tissue response to facial contour augmentation with dense and porous hydroxylapatite in rhesus monkeys

Using extraoral incisions, subperiosteal pockets were created bilaterally over the zygomatic and mandibular areas in six rhesus monkeys. One side of each anatomic site received a dense block of hydroxylapatite (HA) implant, and the contralateral side received an equivalent-sized block of porous HA implant. Monkeys were killed at 3, 6, and 12 months, and the implants were manually tested for mobility. The implants were then retrieved in block specimens. Half of each specimen was decalcified, embedded in paraffin, and stained. The other half was embedded in plastic, and sections were stained or carbon coated for scanning electron microscope histometry. The dense HA implants showed complete fibrous encapsulation and they popped out when cut in half. The porous HA implants were attached to the underlying cortex by bone ingrowth. The porous implant volume sampled within 2.5 mm of underlying cortex contained 33.0% HA matrix and 35.7% bone. The surface area of the porous HA matrix (4.8 mm2/mm3) was 54.3% covered by bone ingrowth. It is hypothesized that micromotion may have accounted for the lack of osseointegration of the dense HA specimens. In contrast, the early ingrowth of fibrous tissue into the porous HA block might be responsible for reducing micromotion to levels acceptable for ingrowth of bone. The contrasting biologic response of implant sites to two variants of the same implant material supports the value of comparative studies to permit informed surgical selection decisions.

Osteogenesis in composite grafts of allogenic demineralized bone powder and porous hydroxylapatite

This study evaluated the osteoinductive capabilities of porous hydroxylapatite (PH) and the tissue response following intramuscular implantation of PH alone or in combination with demineralized bone powder (DBP). Six rhesus monkeys each received the implants in three separate soft tissue pockets created in the thoracic region. The implants consisted of 2 cc of either PH alone or DBP alone, or a 1:1 combination of DBP and PH. Two animals were killed at 2 weeks, two at 4 weeks, and two at 12 weeks postimplantation. Histologically, bone formation was seen in the DBP mixed with PH and in the DBP group as early as 4 weeks postimplantation; bone was also occasionally observed within the pores of the PH particles. The PH alone showed no evidence of formation of bone and the material was surrounded by a thick layer of fibrous tissue. It was concluded that PH is not osteoinductive, but can act as a scaffold for growth of bone, and that when mixed with an osteoinductive material, it allows for formation of bone within the implant.

Porous hydroxylapatite granules and blocks as alveolar ridge augmentation materials: A preliminary report

Porous hydroxylapatite (PHA) blocks and granules were used in the augmentation of 30 maxillary and mandibular ridges in 28 patients. The postoperative evaluation period was 2 years in all cases. The patients were evaluated clinically and radiographically, and by patient questionnaires. An increased incidence of dehiscence was noted with the blocks as compared with the granules. Overall prosthodontic assessment showed 95% improvement among the granule cases when compared with the preoperative ridge, and 88% improvement noted among the block cases. Patient rating of their general satisfaction with their dentures showed 82% improvement in the granule patients, and 55% in the block cases. Radiographically, the granules showed an average decrease of 8%. The results of this study show that PHA granules can be used as satisfactory alveolar ridge augmentation material, while the blocks show an increased number of complications and should be used only in very selected cases.

Orthognathic Surgery in the Young Cleft Patient: Preliminary Study on Subsequent Facial Growth

PURPOSE This study evaluated the long-term effects of orthognathic surgery on subsequent growth of the maxillomandibular complex in the young cleft patient. PATIENTS AND METHODS We evaluated 12 young cleft patients (9 male and 3 female patients), with a mean age of 12 years 6 months (range, 9 years 8 months to 15 years 4 months), who underwent Le Fort I osteotomies, with maxillary advancement, expansion, and/or downgrafting, by use of autogenous bone or hydroxyapatite grafts, when indicated, for maxillary stabilization. Five patients had concomitant osteotomies of the mandibular ramus. All patients had presurgical and postsurgical orthodontic treatment to control the occlusion. Radiographs taken at initial evaluation (T1) and presurgery (T2) were compared to establish the facial growth vector before surgery, whereas radiographs taken immediately postsurgery (T3) and at longest follow-up (T4) were used to determine postsurgical growth. Each patients lateral cephalograms were traced, and 16 landmarks were identified and used to compute 11 measurements describing presurgical and postsurgical growth. RESULTS Before surgery, all patients had relatively normal growth. After surgery, cephalograms showed statistically significant growth changes from T3 to T4, with the maxillary depth decreasing by -3.3 degrees +/- 1.8 degrees , Sella-nasion-point A by -3.3 degrees +/- 1.8 degrees, and point A-nasion-point B by -3.6 degrees +/- 2.8 degrees. The angulation of the maxillary incisors increased by 9.2 degrees +/- 11.7 degrees. Of 12 patients, 11 showed disproportionate postsurgical jaw growth. Maxillary growth occurred predominantly in a vertical vector with no anteroposterior growth, even though most patients had shown anteroposterior growth before surgery. The distance increased in the linear measurement from nasion to gnathion by 10.3 +/- 7.9 mm. Four of 5 patients operated on during the mixed dentition phase had teeth that erupted through the cleft area. A variable impairment of postoperative growth was seen with the 2 types of grafting material used. No significant difference was noted in the effect on growth in patients with unilateral clefts versus those with bilateral clefts. The presence of a pharyngeal flap was noted to adversely affect growth, whereas simultaneous mandibular surgery did not. After surgery, 11 of 12 patients tended toward a Class III end-on occlusal relation. CONCLUSIONS Orthognathic surgery may be performed on growing cleft patients when mandated by psychological and/or functional concerns. The surgeon must be cognizant of the adverse postsurgical growth outcomes when performing orthognathic surgery on growing cleft patients with the possibility for further surgery requirements. Performing maxillary osteotomies on cleft patients would be more predictable after completion of facial growth.

LONG-TERM FOLLOW-UP OF THE USE OF NONPOROUS HYDROXYAPATITE FOR AUGMENTATION OF THE ALVEOLAR RIDGE

Particulate hydroxyapatite (HA) was used in the augmentation of 18 mandibular and four maxillary ridges in 21 patients whose cases were followed postoperatively for 5 to 7 years. Patients were evaluated clinically, radiographically, and through questionnaires. Prosthodontic assessment of retention and stability of dentures showed improvement 5 years postoperatively. Patients receiving HA rated their dentures favorably using parameters of the Cornell Medical Index. The results of this study show that particulate HA alone can be used as a satisfactory material for augmentation of the alveolar ridge.

Tissue response to hydroxylapatite in induced diabetic and nondiabetic rats: Histologic evaluation

This study evaluated the tissue response to the subcutaneous implantation of nonporous hydroxylapatite (HA) in 24 induced-diabetic (ID) and 24 nondiabetic (ND) rats. One cubic centimeter of HA was implanted subcutaneously in each rats chest. Subgroups of 6 rats from the ID and ND groups were killed at 3, 6, 12, and 24 weeks postimplantation. The implants were removed with the surrounding soft tissues and processed for histologic evaluation. This revealed that soft tissue inflammation was mild at each time interval. There was a decreased response at 6 months in ND rats and a persistent inflammatory reaction in ID rats. Collagen maturity and fibroplasia increased within ND rats, whereas the ID rats showed a marked delay in collagen maturity and density. No osteogenesis was observed in any specimen. Dystrophic calcification was observed at the HA-tissue interface in 37% of ND and 59% of ID specimens. It was concluded that HA elicited a greater inflammatory response in ID than in ND rats when implated subcutaneously.

Zygomatic and mandibular augmentation with Proplast and porous hydroxyapatite in Rhesus monkeys

Using an extraoral approach, subperiosteal pockets were created bilaterally over the zygomatic and mandibular regions in six Rhesus monkeys. One side of each animal received a Proplast I (Vitek Inc, Houston) implant and the contralateral side received an equivalent sized block of porous hydroxyapatite (HA). The animals were followed clinically and radiographically. Two animals were killed postoperatively at 3, 6, and 12 months, respectively. The implants were retrieved en bloc and halved. Half of each specimen was decalcified, embedded in paraffin, and stained. The other half was embedded in plastic, and sections were stained or carbon-coated for histometry scanning under electron microscopy. Clinical evaluation revealed that porous HA implants were more stable than Proplast implants. The Proplast implants showed complete encapsulation by infiltration with fibrovascular connective tissue, and progressive fragmentation with giant cell reactions. The porous HA implants were united to the underlying cortex by bony ingrowth. The volume of implants sampled within 2.5 mm of the underlying cortex contained 42.5% HA matrix and 23.8% bony ingrowth, and the surface area of the HA matrix (9.7 mm2/mm3) was 47.8% covered by bony ingrowth. No giant cell response, fragmentation, or biodegradation was observed or measured in the porous HA implants. The data from this primate model further substantiate previous canine studies and permit more reliable estimation of clinical performance. These results provide comparative data that can contribute to the decision-making process in selecting clinical implants.

A primate model for producing experimental alveolar cleft defects

A simplified surgical technique to create an alveolar cleft defect with oronasal communication was developed in 12 female rhesus monkeys. The defects fulfilled the following criteria: 1) a bilateral alveolar cleft with a minimal width of 1 cm; 2) presence of an oronasal communication lined by epithelium; 3) absence of any clinical signs of inflammation within the cleft defect area; and 4) presence of functional teeth on each side of the created defect.