Repair of craniofacial defects with hydroxyapatite cement.

PURPOSE: The objective of this study was to evaluate the course of healing of craniofacial bone defects when filled with hydroxyapatite cement and to determine whether adding various percentages by weight of demineralized bone powder to the cement will result in enhanced bone formation. MATERIALS AND METHODS: The model for the study was the canine calvarium. The implants were placed into cranial defects and harvested at 3 or 6 months for qualitative evaluation by light microscopy, microradiography, and quantitative histomorphometry. RESULTS: The implantation of hydroxyapatite cement resulted in characteristic replacement of the material with new bone ingrowth. The addition of demineralized bone powder to the hydroxyapatite cement appeared to improve the handling characteristics of the cement; however, improvement in the replacement of the material by bone was not observed. The implantation of only allogeneic demineralized bone showed limited new bone formation within the defect site. CONCLUSIONS: Hydroxyapatite cement formed an effective osseoconductive scaffold for bone replacement. The addition of demineralized bone powder to the cement to serve as a carrier of osseoinductive factors did not result in additional bone being formed.

Oral commissure burns in children.

Electrical burns of the mouth are relatively common in young children. Early intervention to prevent complications remains controversial. A chart review was conducted of 24 patients with oral commissure burns who were treated at the University of Iowa from 1975 to 1988. All of these patients were treated conservatively without splinting or early surgery. Only one patient underwent oral splinting before receiving care at the University of Iowa Hospitals and Clinics. While under our care, no patients suffered significant hemorrhage at eschar separation. Commissuroplasty and/or reconstructive lip surgery were performed at various times after the burn injury was healed and the functional or aesthetic impairment was established. Long-term follow-up was from 5 to 17 years, allowing for longitudinal evaluation of the postburn scars and their influence on facial growth. Our review revealed that (1) younger children with more severe burns have a less favorable outcome; (2) no hemorrhage was observed immediately after the burn or at eschar separation; and (3) conservative surgical treatment after scar maturation- and in some cases following steroid injections- resulted in a successful functional and esthetic outcome.

Cranioplasty in the growing canine skull using demineralized perforated bone.

This study was designed to test the hypothesis that demineralized perforated bone matrix implant from canine skull and tibia induces new bone formation within the calvarial defect comparable with the bone induced by autogenous graft. We also were interested in determining whether demineralized perforated bone matrix implants from membranous bone have greater osseoinductive capacity in the calvarial area than demineralized perforated bone matrix implants from endochondral bone. Forty 12-week-old purebred beagles were used. Group I consisted of animals with unrepaired surgically created calvarial defects healed by secondary intention (n = 10). Group II consisted of animals with surgically created calvarial defects in which the bone was removed and replaced with an autograft (n = 10). Group III consisted of animals with surgically created calvarial defects in which the bony defect was closed with a demineralized perforated bone matrix implant obtained from beagle calvaria (n = 10). Group IV consisted of animals with surgically created calvarial defects in which the bony defect was closed with a demineralized perforated bone matrix implant obtained from beagle tibia (n = 10). The two control groups (I and II) allowed us to isolate the inductive capacity of demineralized perforated bone matrix implants and compare it with the healing of the bone defects left unrepaired or repaired with calvarial autografts. Animals were sacrificed after 8 and 12 weeks. In the present study we were able to verify that demineralized perforated bone matrix implants are well accepted in the calvarial defects with little tissue reaction and remarkably little osteoclastic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Periosteum in regeneration of palatal defects.

The influence of the periosteum on the regeneration of palatal bone was investigated in this study. Eighty, 8-week-old, purebred beagle dogs were assigned randomly to four groups: (1) unoperated dogs as a group control; dogs in which the mid-third of the palate was surgically removed and (2) left unrepaired (unrepaired controls); (3) repaired with mucosal flaps; (4) repaired with mucoperiosteal flaps. Five animals from each group were killed at 4, 6, 8, and 12 weeks after surgery and coronal sections examined under light microscopy. Among the animals with complete soft tissue healing, 8 of 12 dogs from Group 2, 11 of 20 from Group 3, and 10 of 19 from Group 4 showed complete bone regeneration. No significant differences were found overall in bone thickness and bone density measurements between Group 3 and Group 4. Histologically, a well-differentiated periosteum was present on the maxilla at 4 weeks, even in animals in which the periosteum had not been preserved in the original flap. These results suggest that maintaining the periosteum at surgical closure does not influence bone regeneration in beagles up to 12 weeks of age. We suggest that osteoprogenitor cells, migrating from the undisturbed local periosteum adjacent to the defect, were responsible for the new bone growth in our study.

Clinical results of pharyngeal flap surgery: the Iowa experience.

Sixty-five patients with cleft palate, with or without cleft lip, who received previous pharyngeal flap surgery for chronic velopharyngeal dysfunction in our department, were examined for velopharyngeal status, speech production patterns, and evidence of nasal airway obstruction. Of the 65 subjects, 54 (83.1 percent) showed velopharyngeal function within normal limits, 43 (66.1 percent) showed normal or near-normal speech production, and 58 (89.2 percent) reported snoring sometimes or often. Of the 58 reporting snoring, electrocardiogram (ECG) data for 33 were examined for evidence of right ventricular hypertrophy. Only one (3 percent) of the 33 showed such possible indication. We conclude that by our methods, pharyngeal flap surgery is an effective treatment for velopharyngeal dysfunction. After surgery, patients may report symptoms of nasal airway obstruction during sleep but are not expected to show ECG changes in cardiac function resulting from oxygen deprivation.

The effects of lip repair with and without soft-tissue undermining and delayed palate repair on maxillary growth: an experimental study in beagles.

Undermining of the soft tissue on the surface of the maxilla at the time of cleft lip repair remains a controversial issue in cleft management. Using 64 eight-week-old beagles, we tested the hypothesis that lip repair with soft-tissue undermining contributes more to maxillofacial growth aberrations than lip repair without these additional procedures. Animals were assigned to four groups: unoperated controls, unrepaired controls, and two experimental groups (with and without undermining). Defects simulating cleft of the lip, alveolus, and palate were surgically created in the unrepaired and experimental animals. At 36 weeks of age, 11 measurements were made directly on the cleaned maxillae. Analysis revealed that all groups with surgically created defects were significantly different from normal; however, animals with undermining exhibited the greatest group deviation from normal. These findings reaffirm our earlier conclusions that undermining of the soft tissue on the surface of the maxilla is detrimental to maxillofacial growth.

A comparative study of the effects of biodegradable and titanium plating systems on cranial growth and structure: experimental study in beagles.

An experimental study was conducted in beagles to assess the effects of biodegradable and titanium plating systems on cranial growth and structure. Forty-eight 9-week-old purebred beagles were used in this study. To avoid any effects of sexual dimorphism, we used only female beagles. The animals were divided in three groups: sham-operated controls, n = 16; beagles implanted with commercially available titanium plates and screws, n = 16; and beagles implanted with biodegradable plates and screws, n = 16. The biodegradable plating system developed by Storz Instrument Company (St. Louis, Mo.) for use in the craniofacial skeleton does not require another procedure to remove plates and screws once the healing process is completed. To assess the dynamics of changes in cranial growth under the influence of two different plating systems, we conducted two identical studies during two different time periods: 6 weeks and 12 weeks. Using two different time frames allowed us to assess changes in the biodegradable material and in the bone and soft tissue surrounding this material. Statistical analysis revealed no significant differences in the gross cranial structure among the three groups. This finding suggests that the biodegradable plating system has no adverse effect on cranial growth. The material does resorb and/or disintegrate between 6 and 12 weeks after insertion. The rate of resorption is approximately 5.3 microns per day. The bone and soft tissue surrounding the biodegradable implant exhibited very limited inflammation and foreign body reaction. Bony overgrowth was frequently found over the plating system.

Relationship between the sequence of lip and palate repair and maxillary growth: an experimental study in beagles.

The present study was designed to evaluate the relationship between varying sequences of lip and palate repair and maxillary growth. To investigate this problem, an experimental study using beagles was conducted to assess the influence of three different sequences of lip and palate repair. The first sequence constitutes the commonly accepted approach of lip repair first, palate repair second. The second sequence was reversed: palate repair first, lip repair second. The third sequence consisted of simultaneous lip and palate repair. Using 70 eight-week-old beagles, we tested the following hypothesis: The sequence of lip repair first and palate repair second is less detrimental to maxillary growth than the other two sequences. The animals were assigned to two control groups (unoperated and unrepaired animals) and three experimental groups, in which three different sequences of repair were executed. Upon sacrifice, 11 maxillary variables were measured directly from cleaned skulls and analyzed by univariate and multivariate techniques. The most important finding from this analysis is that the commonly accepted sequence of cleft lip and palate repair (lip first, palate second) is less detrimental to maxillary growth than repairing the palate first and the lip second or simultaneous closure of both defects.

Multidisciplinary treatment results for patients with isolated cleft palate.

Fifty-eight patients with cleft palate only who had received treatment in the Department of Otolaryngology-Head and Neck Surgery at the University of Iowa were examined for treatment results. Forty-one (70.7 percent) of the 58 patients showed a syndrome or suggestive factors. An unusually high percentage (36 percent) of the 58 patients required secondary surgery for velopharyngeal dysfunction or showed indications for surgery at examination. Some but not all of the relatively low success rate appears related to surgical experience. Speech proficiency, hearing acuity, and dental status were within normal limits or nearly so. The 20 patients with pharyngeal flap surgery were doing well, with minimal indications of functional obstruction.

A comparative study of facial growth following lip and palate repair performed in sequence and simultaneously: an experimental study in beagles.

This study was designed to assess the effects of the commonly accepted sequence of cleft lip and palate repair on subsequent maxillofacial growth and to compare these effects with those resulting from simultaneous lip and palate repair. Using 62 eight-week-old normal beagles, we tested the hypothesis that sequential repair (lip first, palate second) of surgically induced lip and palate defects is less detrimental to maxillofacial growth than simultaneous repair of both surgically created defects. Animals were assigned to one of four groups: two control groups (unoperated and unrepaired) and two experimental groups. Defects simulating cleft of the lip, alveolus, and palate were surgically created in the unrepaired controls and in the experimental animals. In one experimental group, the lip and palate defects were repaired immediately and simultaneously. In the other experimental group--simulating current clinical practice--the lip defect was repaired first at the time that it was created, while closure of the palatal defect was delayed 4 weeks. After the animals were killed at 36 weeks of age, 11 maxillary variables were measured directly from cleaned skulls and analyzed by using univariate and multivariate techniques. Animals that had lip and palate defects closed in sequence had less severe maxillofacial aberrations than animals with simultaneously closed defects. Sequential closure of the defects also had identifiable effects on maxillofacial form. The growth aberrations observed among animals with sequential closure, however, are primarily attributable to surgical creation of the defects and not to the surgical repair. Delaying palate repair is less traumatic to the subsequent growth of the maxillary complex than simultaneous repair of lip and palate defects.

Demineralized perforated bone implants in craniofacial surgery.

Between July 1990 and September 1991, demineralized perforated allogeneic bone implants (Pacific Coast Tissue Bank, Los Angeles, CA) were placed in 72 patients. Because many patients received more than one implant, a total of 248 implants were used in 80 procedures. The technology of processing demineralized bone implants is described in detail. All patients were operated on by one surgeon (K.E.S.) at the Humana Craniofacial Institute in Dallas, Texas. Forty-one patients had craniofacial deformities, 16 had secondary deformities following cleft lip and palate repair, 8 had bony defects following removal of tumors, and 10 had various skeletal deformities following trauma. Of the 72 patients, 6 had two surgical procedures during which additional implants were inserted. Implants placed in the cranial vault and the maxillary complex, including alveolar grafts, were inlay grafts, whereas implants placed in the orbital, nasal, paranasal, temporal, and malar areas were onlay grafts used for contouring, augmentation, or both. Complications were limited to delayed wound healing in 6 patients. According to our observations, demineralized perforated bone implants represent an encouraging alternative to autogenous bone grafting. Further clinical and experimental studies are necessary to obtain more information about this material.

Results of multidisciplinary management of bilateral cleft lip and palate at the Iowa Cleft Palate Center.

Bilateral cleft of the lip and palate is by many standards the most complex and severe form of the defect. The complexity and severity of the defect require an unusual degree of cooperation among all specialists and especially between the surgeon and the orthodontist. There are no published findings that we know about in which comprehensive data from a number of disciplines are reported for the same group of bilateral cleft patients. Fifty randomly selected patients with bilateral complete clefts were examined by the Iowa team and two orthodontists from other institutions. The evaluations revealed that a large number of patients over the age of 10 have multiple residual problems requiring further treatment. Only 23 percent of the older patients studied were judged to have had treatment completed by the surgeon, speech pathologist, and orthodontist. It is very difficult to state whether the results obtained by our team can be considered satisfactory because there are no comparable studies that have attempted to evaluate the same parameters in multidisciplinary management.

Blood flow in expanded tissue treated with an anticontractile agent.

The present study investigates blood flow at several stages of expansion with and without enhancement by anticontractile agents (papaverine). Twelve 1-kg guinea pigs were divided into two groups. In group 1 were six animals undergoing tissue expansion without anticontractile agents, and in group 2 were six animals treated with a saturated solution of papaverine prior to expansion. Laser-Doppler velocimetry was used to monitor the changes in blood perfusion that occurred with each expansion. Animals pretreated with papaverine (group 2) maintained higher blood flow following inflation of the expander than untreated animals (group 1). This study provides physiologic evidence of the benefits of pharmacologic enhancement of the expansion process. Agents of this type may have a future role in the prevention of ischemic complications.

Reflections on research.

The authors present their reflections on several of the major topics related to research. The subjects discussed include the quantity and quality of research; the motivation for research; the research process; research paradigm; restraints of research; and freedom to research. They point out that the haste to achieve success and to publish in most cases has precluded the learning process about the substance and methodology of research. An attempt is made to relate general problems of research and its methodology to research in the area of congenital facial deformities.

Does interference with mucoperiosteum and palatal bone affect craniofacial growth? An experimental study in beagles.

This study was designed to assess the effects of raising mucoperiosteal flaps and exposing palatal bone at the time of palatoplasty. Using 62 beagle puppies as subjects, we tested the hypothesis that raising mucoperiosteal flaps does not interfere with craniofacial growth. We further hypothesized that the size of the area of bone exposed following palatoplasty does affect subsequent craniofacial growth. The animals were divided into four groups: two control groups (unoperated and unrepaired) and two experimental groups. In the first experimental group, two-flap palatoplasty was used to close the surgically induced palatal defect, leaving narrow strips (0 to 2.5 mm) of bone exposed lateral to the flaps. In the second group, one flap was raised to close the defect, leaving a wide area (5 to 6 mm) of palatal bone exposed on one side. Thirty-four direct craniometric measurements were analyzed. Animals that had elevation of both mucoperiosteal flaps with narrow strips of denuded bone on both sides had less severe craniofacial growth aberrations than those in which the defect was left unrepaired or was repaired with one mucoperiosteal flap leaving a wider area of bare bone exposed. These findings suggest that raising mucoperiosteal flaps is less detrimental to craniofacial growth than leaving large areas of exposed palatal bone.

Serial measurement of blood flow in expanded tissue by laser Doppler velocimetry.

This study provides additional information about changes in blood flow in expanded tissue as measured by laser Doppler. Five one-kilogram albino Hartley guinea pigs were implanted with commercially available hemispheric expanders. The expanders were inflated every 3 days on four successive occasions. Blood flow measurements were taken on each animal just before each inflation, immediately after inflation, and then at 1, 2, 3, 4, and 24 hours after expansion. Measurement of flow changes immediately after each inflation of the expander showed that, initially, blood flow in the tissue overlying the expander recovered quickly, but as the expansion process was continued, the flow did not return to baseline values so rapidly. This might be an indication that tissue expansion in patients could be carried out more rapidly during the initial inflations, with increasing recovery periods between inflations as the expansion process continued.

Enhancement of expansion of guinea pig skin by local delivery of an anticontractile agent using a new bilumen expander.

We have shown previously that anticontractile agents used with tissue expanders provide significantly more rapid expansion in an animal model than in controls without these agents. We describe an improved method of delivery involving a perforated concentric envelope enclosing a tissue expander (type 2) in place of the single circumferential perforated catheter (type 1) used previously by us. Eleven guinea pigs received a type 1 expander and ten received a type 2 expander. The anticontractile agent theophylline was delivered in saline around each expander, and all the expanders from both groups were inflated to a similar pressure every three days for twelve days. Significantly greater expansion, in terms of total volume delivered to the expander, was noted using the type 2 expander. We conclude that the concentric device offers further improvement, probably as a result of more uniform distribution of the agent in the tissue around the expander.