Hyrax application as a tooth-borne distractor for maxillary advancement

Experimental Design of Vertical Distraction Osteogenesis Using Simple 3 Screws

Distraction osteogenesis devices are complicated. To simplify these devices, we used 3 simple screws and 1 rubber band to realize the idea and analyzed histologic changes induced by mechanical forces. Ten female New Zealand white rabbits were studied. A left or right side of the mandible was randomly selected as the experimental side (ES). The unilateral mandible was distracted, and 2 fixation screws and 1 traction screw were implanted. When the traction screw was rotated downward, the opposite force made the osteotomy block move in opposite directions to increase the bone height. The control side (CS) was not processed. The results were assessed after 20 days of traction. Bone height in the ES increased by 5 mm. Toluidine blue staining showed that the number of osteoblasts per unit area on the ES was higher than that of the CS (P<0.01). PerkinElmer showed that the expressions of proliferating cell nuclear antigen (P=0.016) and collagen-I (P=0.000) on the ES were higher than those on the CS. Transmission electron microscopy showed that the number of mitochondria, endoplasmic reticulum, and Golgi apparatus on the ES was significantly greater than the CS. The results confirmed that the 3 screws vertically increase the bone height. Mechanical force signals stimulate tissue activity and lead to significant cell proliferation and differentiation in the traction zone. Collagen-I may induce osteogenesis in the early stage of traction.

Cephalometric changes in nasopharyngeal area after anterior maxillary segmental distraction versus Le Fort I osteotomy in patients with cleft lip and palate

OBJECTIVE

The present study was designed to compare the effects of two surgical methods, anterior maxillary segmental distraction (AMSD) versus conventional Le Fort I osteotomy, on cephalometric changes of velopharyngeal area of patients with cleft lip and palate.

MATERIALS AND METHODS

This study was conducted on 20 CLP in two groups. The first group had classic Le Fort I maxillary advancement and the second group had AMSD with a modified hyrax as an intraoral tooth-borne distractor. In the second group, 1 week after the surgery, activation of hyrax screw was started with the rate of 2 times a day for about 10 days. Initial and final lateral cephalograms were traced and analyzed by OrthoSurgerX software.

RESULTS

The changes in variables evaluating velopharyngeal status showed a significant difference between the two groups. In Group A (conventional), the mean of nasopharyngeal area and Nasopharynx floor length showed a significant increase (P < 0.05) after the surgery, while in Group B (DO), the trend of changes was vice-versa. The changes in SNA, overjet, and soft-tissue convexity were similar in both groups.

CONCLUSION

AMSD can improve facial profile, almost similar to the conventional Le Fort I advancement, while there is a significant decrease in nasopharyngeal; hereby there is no increase in the velopharyngeal sphincter.

Nasopharyngoscopic Analyses through Anterior Maxillary Distraction Osteogenesis for Adolescent Patients With Cleft Palate

Anterior maxillary distraction osteogenesis (AMDO) is a novel technique for correcting hypoplastic maxilla by sagittal expansion of the maxilla. Recent reports suggest that AMDO does not have an effect on fragile velopharyngeal function in patients with cleft palate. Furthermore, no studies have evaluated the impact of AMDO on velopharyngeal function.We adopted AMDO to correct severe hypoplastic maxilla in adolescent patients with cleft palate and evaluated its impact on velopharyngeal space and function in 8 patients aged 12 to 21 years who underwent AMDO from 2006 to 2014. All the patients had received treatment for cleft palate; however, they still exhibited marginal velopharyngeal insufficiency. The mean activation of the distractor was 10.9 ± 0.9 mm.We determined changes in velopharyngeal closure ratio and closure pattern via nasopharyngoscopy. Additionally, skeletal changes were evaluated using lateral cephalograms.The mean horizontal advancement in the cephalogram obtained 1 year after the distraction was +6.4 mm. Nasopharyngoscopic examination revealed that no deterioration of velopharyngeal gap had occurred after AMDO in all 8 patients. The velopharyngeal closure pattern changed from coronal to circular in 1 patient.Our results indicate that AMDO achieved correction of hypoplastic maxilla without deterioration in velopharyngeal gap and function. Therefore, AMDO is an effective and optimal approach for correcting hypoplastic maxilla especially in patients with fragile velopharyngeal function, such as those with cleft palate.

Use of anterior maxillary distraction osteogenesis in two cleft lip and palate patients

Distraction osteogenesis (DO) has become a mainstream surgical technique for patients with jaw deformities. The aim of this study was to report the effect of DO done by a hyrax screw incorporated in an acrylic plate in the treatment of two maxillary deficient cases with cleft lip and palate. Two patients, a 24-year-old female and a 29-year-old male who suffered from maxillary deficiency and cleft lip and palate, were treated by DO. After making vertical cuts between the premolars on both sides and horizontal cuts similar to Le Fort 1, a hyrax screw was mounted on an acrylic plate for the slow anteroposterior expansion of maxillary arch. The expansion was achieved by turning the hyrax screw 0.8 mm per day after the latency period. Treatment was discontinued after achieving satisfactory over jet and occlusion. This study showed that anterior maxillary distraction is a reliable technique for correction of midfacial deformity arising out of cleft lip and palate. Incidences of complications are negligible compared to total maxillary distraction.

Photometric Evaluation of Soft Tissue Changes in CLP Patients: Le Fort I Advancement Osteotomy (ALO) Versus Anterior Maxillary Distraction (AMD)

AIM

This paper is a comparative photometric evaluation of soft tissue changes in patients with CLP associated with maxillary deficiency treated with conventional Le Fort I advancement osteotomy (ALO) and anterior maxillary distraction (AMD).

MATERIALS AND METHODS

Twenty patients with maxillary hypoplasia associated with cleft lip and palate who had undergone either LeFort I osteotomy or distraction osteogenesis with maxillary advancement were included in this study. Frontal and profile photographs were used to ascertain the changes post-surgically. Photographs were obtained before treatment and 1 year after surgical correction in both groups.

RESULTS

Vertical as well as horizontal changes in pronasale was well observed in both groups. A substantial increase in nasal parameters was noted in case of AMD group in comparison to ALO group. Though maxillary advancement was quite evident in AMD and ALO groups, a significant and consistent change was observed in AMD group. Significant vertical and horizontal changes were seen with respect to subnasale and labrale superius in AMD group.

CONCLUSION

The hard and soft tissue changes produced by AMD by intra oral distractors were being evaluated so far. The results of the above studies have proved the excellence of AMD over conventional osteotomies. The present study goes hand in hand with the research outcomes till date.