Pharmacologic manipulation of postoperative labial wound contraction and midfacial growth in rabbits

Botulinum toxin type A: implications in wound healing, facial cutaneous scarring, and cleft lip repair

Botulinum toxin is a neurotoxin that has been utilized to induce chemo-denervation of muscles. Cutaneous wounds represent a special situation in which the tensile forces applied by these muscles on wound edges might have deleterious effects on the healing process. The aim of this review was to investigate such an effect and to review other mechanisms this toxin might have on the healing process. We also reviewed the role of botulinum toxin in the management of hypertrophic scars and cleft lip repair.

Effects of lip repair on maxillary growth and facial soft tissue development in patients with a complete unilateral cleft of lip, alveolus and palate

PURPOSE

To examine the relationship between lip repair and inhibition of maxillary growth, and to investigate the characteristics of upper lip in patients with complete unilateral clefts of lip, alveolus and palate.

MATERIAL AND METHODS

Lateral cephalometric radiographs and photographs (anterior-posterior and profile) were taken for 3 groups of patients: (1) 35 complete unilateral cleft lip, alveolus and palate cases in whom only a labioplasty was performed as infants; (2) 47 cases who had both lip and palate repaired; and (3) 37 non-cleft peers as controls.

RESULTS

There was maxillary retrusion in groups (1) and (2). Surface area and height of the upper lip was reduced in both these groups when compared with the normal controls.

CONCLUSION

Lip repair is a most important factor in the restraint of maxillary growth in patients with complete unilateral clefts of lip, alveolus and palate. And height and projection of the upper lip are reduced following lip repair.

Comparative cephalometric study of nasal cavity growth patterns in seven animal models

Although primates have been the craniofacial growth models of choice, recent circumstances have stimulated the search for nonprimate models. In a series of studies we have described changes in various regions of the craniofacial complex for seven commonly used animal models. The present study examined the bony nasal cavity. One hundred and forty-four serial and cross-sectional lateral head x-rays were obtained for unoperated controls from previous growth studies. The sample consisted of data from 26 rats, 21 rabbits, 21 domestic cats, 23 domestic dogs, 17 baboons, 16 rhesus monkeys, and 20 chimpanzees. Comparative human data was taken from the Bolton Standards. The samples were divided into three age categories based on dental and somatic development. Midsagittal nasal cavity measurements included length, height, shape index, and area. Analysis was based on the percent increase in measures from the infant condition. Three major shapes were discerned at adulthood (1) vertical quadrangles (humans and cats); (2) triangles (chimpanzees, rhesus monkeys, and baboons), and (3) horizontal quadrangles (rabbits, rats, and dogs). Results showed that overall shape was best modeled by the chimpanzee and, as a nonprimate model, the laboratory cat. Rabbits and rats also showed similar percent changes for length or height dimensions at different ages, suggesting that these animals may be acceptable, inexpensive alternatives to primates in some experimental situations.

Inhibition of collagen lattice contraction by pentoxifylline and interferon-alpha, -beta, and -gamma

The ability to control wound contraction is important in preventing disfiguring scarring in burn and trauma patients. Fibroblasts within the wound generate the mechanical forces that cause this contraction, and their interactions with various extracellular matrix components are thought to regulate this process. Because pentoxifylline and the interferons are believed to moderate fibroblast production of such matrix components, we assessed the effects of these agents on wound contraction in vitro, using a model wherein dermal fibroblasts are incorporated into a collagen lattice. Pentoxifylline and interferon-alpha, -beta, and -gamma inhibited lattice contraction in a dose-dependent manner and showed no effect on cell number or cell viability. These results suggest that pentoxifylline and the interferons may retard wound contraction in vivo and thus reduce scarring associated with severely contracted wounds. Further study is needed to determine the mechanism of action of these agents on the collagen lattice model.

Electromyographic analysis of lip muscle function in operated cleft subjects

EMG activity of the upper lip was measured with bipolar surface electrodes during speech and nonspeech tasks in order to assess labial function in subjects with repaired clefts. Eighteen patients between 15 and 23 years of age with repaired unilateral cleft lip (isolated or combined with repaired cleft palate) were compared to 24 matched noncleft subjects. Data analysis demonstrated that the amplitude of action potentials of the upper lip was significantly greater in the cleft group. We hypothesize that the enhanced activity of the repaired upper lip during function may contribute to the facial growth abnormalities usually seen in the cleft population.

A comparative study of mandibular growth patterns in seven animal models

The use of nonhuman primate experimental models has helped make significant contributions toward the clinical and surgical management of patients with craniofacial disorders. With concerns such as increasing cost, however, alternative models will have to be identified. The present comparative study describes baseline, age-related changes in mandibular growth patterns for seven commonly used animal models. The data was obtained from 144 serial and cross-sectional lateral head radiographs of unoperated control animals from a number of previous craniofacial growth studies. The sample consisted of 26 rats, 21 rabbits, 21 domestic cats, 23 domestic dogs, 17 baboons, 16 rhesus monkeys, and 20 chimpanzees. Comparative human data were taken from the Bolton Standards. The samples were divided into three age categories: infant, juvenile, and adult. Mandibular growth measurements included overall mandibular length, ramal height, and body height. Comparative analysis consisted of the calculation of percent increase from the infant condition. For all measurements, three major clusters could be discerned: 1) humans, chimps, and rhesus monkeys; 2) dogs and baboons; and 3) cats, rats, and rabbits. Results suggested that for the dimensions studied, long-term mandibular growth was best modeled by short-faced primates, and in particular, the chimpanzee. In addition, dogs and rats showed similar relative percent changes in different regions from juvenile through adulthood stages, which suggests that these animals may be acceptable, inexpensive alternatives to primates in certain experimental situations.

Superior orbicularis oris muscle activity in children with and without cleft lip and palate

An analysis of integrated electromyographic (IEMG) activity of the superior orbicularis oris muscle was undertaken in 15 children with cleft lip and palate who have undergone surgery compared to 10 children without clefts (control group). Bipolar surface electrodes were used for IEMG recordings of resting level activity and during the swallowing of saliva. Similar resting level activity was observed in both groups. During the swallowing of saliva, activity in children with cleft lip and palate was higher than in children without clefts (noncleft children). Moreover, in the cleft lip and palate group, children with abnormal lip seal showed the highest values for IEMG activity during the swallowing of saliva. This fact suggests that with each swallow of saliva, a greater counteracting effect of the superior orbicularis oris muscle could be produced on the growing maxilla. This may result in a significant long-term effect on the growth of the stomatognathic system, since the process of swallowing is a 24-hour function repeated between 600 and 2400 times each day.