Restricting facial bone growth with skeletal fixation: A preliminary study

Rigid Fixation of the Pediatric Facial Skeleton

Pediatric facial fractures are uncommon, and fortunately, the majority can be managed with conservative measures. Rigid fixation of the pediatric facial skeleton can potentially be associated with delayed hardware issues and growth inhibition. When appropriate, resorbable fixation is most commonly used for this purpose. Titanium plates and screws are advantageous when rigid fixation is a priority because properly placed hardware that respects natural suture lines is not thought to significantly inhibit growth. Furthermore, titanium fixation may be removed following healing.

Asymmetric Protrusion of the Midface in Young Adults

PURPOSE

This study evaluated midfacial asymmetry using an alternative method that involved comparing bilateral patterns of the zygomaticomaxillary prominence in a young adult population.

MATERIALS AND METHODS

Three-dimensional reconstructed images based on computed tomography scans of 100 Koreans (mean age, 24.7 years) were evaluated with reference to lines spaced at 30° intervals and radiating from the center of an interporion line in a superior view. The surface inclination of the zygomaticomaxillary region was quantified on the same reference lines using a 3-dimensional ruler.

RESULTS

The 30°-interval line (at the level of the zygomaticotemporal suture) was longer on the left side than the right side in both males and females, whereas the left 60°-interval line (at the level of the zygomaticofrontal suture) was longer in females. Comparing the surface protrusion revealed that the zygomaticomaxillary region was more prognathic and inflated on the left side.

CONCLUSION

Functional deviations are considered to be causes of asymmetric craniofacial growth. Postnatal growth allometry across the circummaxillary sutures as elucidated by this study could be useful information in craniofacial surgery.

[Multiple uses of skeletal anchorages: taking advantage of mini-screws to improve aesthetics with active and passive appliances]

INTRODUCTION

The main causes of failures in canine traction are anchorage defects, incorrect direction of force, uncontrolled forces. An adolescent female (10 years, 9 months) presents with two included canines on the maxillary arch, in a palatal position and her lateral incisors (12 and 22) are microdontic. Two mini-screws are inserted on the palate, in a mesial position to 16 and 26 to secure the traction of 13 and 23; in general, braces are bonded after this first step. After debonding, mini-screws remain to help stabilize the palatal plate during the retention period and to avoid unaesthetic metallic wires and hooks which sometimes cause occlusal interferences.

DISCUSSION

The alternatives are discussed: Ballista spring, mini-screw inserted in the palatal suture, Nance appliance… Conclusion: The multi-use of temporary anchorage devices during traction of palatally impacted canine(s) (especially in the case of bilateral inclusions) offer new alternatives by securing the canine displacement, eliminating almost all of the patient's compliance (no loss of sagittal anchorage). This type of small appliance increases the patient's comfort and decreases the complexity of activations. The global duration of treatment with braces can be decreased if no braces are needed during the first steps, and then retention can be more effective and more aesthetic, especially during smiling.

The effect of extracapsular injuries on growth and development of the mandible condyle: an experimental study in growing dogs

OBJECTIVE

To investigate the effects of condylar extracapsular injuries on the development of the mandibular condyle and try to find a way to treat condylar hyperplasia by electively using such injuries to restrict the overdeveloped mandibular condyle.

STUDY DESIGN

Sixty 6-month-old beagle puppies were divided randomly into five groups: blank control; unilateral fracture to the condylar neck; unilateral fracture to the condylar neck treated with rigid internal fixation; unilateral periosteum injury; unilateral decortication of the condylar neck. Computed tomography, ^{99 m}Tc single-photon emission computed tomography, and tetracycline-calcein double-labeling were performed after surgery. The puppies were sacrificed 12 and 24 weeks after surgery. Morphologic analyses and examination of growth activity were done.

RESULTS

Unilateral fracture of the condylar neck without fixation caused local morphologic changes during the early postoperative period, but compensatory growth of the condyle altered such changes after healing. The other types of injury failed to inhibit the growth of the condyle and the mandible, whereas functional deviation of the chin was found after unilateral fracture of the condylar neck with or without fixation.

CONCLUSIONS

The four types of extracapsular injury described here failed to inhibit the growth of the mandibular condyle and could not be selected as alternatives to treat condylar hyperplasia.

The effects of altered maxillary growth on patterns of mandibular rotation in a pig model

OBJECTIVES

A thorough understanding of influence of maxillary growth on patterns of mandibular rotation during development is important with regard to the treatment of skeletal discrepancies. In the present study, we examined whether experimentally altered maxillary position has a significant influence on patterns of mandibular rotation in a pig model.

DESIGN

Maxillary growth was altered in a sample of n=10 domestic pigs via surgical fixation of the circummaxillary sutures. We compared the experimental group to control and surgical sham samples and assessed the effects of altered maxillary growth on mandibular form using geometric morphometric techniques. We tested for significant differences in mandibular shape between our samples and examined axes of morphological variation. Additionally, we examined whether altered mandibular shape resulting from altered maxillary position was predictably associated with morphological changes to the condylar region.

RESULTS

There was a statistically significant difference in mandibular shape between the experimental and control/sham groups. As a result of vertical displacement of the snout, mandibles in the experimental sample resulted in greater anterior rotation when compared to the control/sham pigs. Variation in rotation was correlated with morphological changes in the condyle including the shape of the articular surface and condylar orientation indicative of greater anterior mandibular rotation.

CONCLUSIONS

Vertical displacement of the maxilla had a significant effect on mandibular shape by encouraging anterior mandibular rotation. This result has important implications for understanding the effects of altered mandibular posture on condylar remodeling the treatment of skeletal discrepancies such as the correction of hyperdivegent mandibular growth.

Geographic Variation in Zygomaxillary Suture Morphology and its Use in Ancestry Estimation

Angled/curved zygomaxillary suture coding is widely employed in cranial assessments of ancestry. However, the efficacy of this method has not been extensively evaluated across diverse populations. In this study, zygomaxillary suture morphology was assessed on a total of 411 human crania from six populations (European, Native American, African, Asian, Arctic Circle, and Aboriginal Australian) using a novel 3D coordinate landmark method. Our results indicate a predominance of angled sutures among native peoples of the Arctic and North America (85-86%), a prevalence of curved sutures among Africans and Aboriginal Australians (77-81%), and essentially equal proportions of both configurations in Asians and Europeans (50-56%). Statistically, angled/curved coding generally discriminates poorly between groups, except when populations with antithetically high frequencies of the two configurations (e.g., African vs. Native American) are compared. Moreover, comparisons across previous studies reveal conflicting frequencies for many populations, further suggesting limited utility of this trait in ancestry estimation.

Pediatric nasoorbitoethmoid fractures

The pediatric craniofacial trauma literature largely focuses on the management of mandible fractures, with very little information focusing on pediatric midface fractures, specifically nasoorbitethmoid (NOE) fractures. Because the diagnosis and surgical treatment plan for adult NOE fractures is well established in the literature, the treatment algorithms for NOE are essentially a transfer of adult practices to pediatric patients. This article reviews the differences between the pediatric and adult facial skeleton and the pathology and presentation of NOE fractures in the pediatric craniomaxillofacial skeleton. It also presents the effects of NOE fractures on the growth and development of the pediatric facial skeleton and describes the current surgical management for NOE fractures.

Incremental growth of the maxillary tuberosity from 6 to 20 years-A cross-sectional study

OBJECTIVES

Although the maxillary tuberosity (MT) is a major growth site of the maxilla, its time-related growth was not fully investigated. The objectives of the study were to evaluate the MT growth from 6 to 20 years of age defining the peak growth age and to assess time-related indicators.

DESIGN

Panoramic radiographs from 189 patients were divided in a cross-sectional study into six age groups. A special panoramic analysis was developed including 18 parameters and 3 time-related indicators, i.e., chronological age, crown/root development stages of the maxillary second (M(2)) and third (M(3)) molars and eruption stages.

RESULTS

From 6 to 20 years, the MT vertical growth was 5.17-fold greater than the horizontal. The horizontal growth covered 36% of the maxillary growth but was inadequate to secure space for third molar eruption despite a 51% increase in MT area. MT peak growth was between 8 and 9 years and 10-11 year. During these 14 years, the maxillary length increased by pneumatisation of the maxillary sinus (86%), growth of the MT (36%) and decrease of the anterior maxillary region (-22%). Of the 18 examined parameters, 83% showed dependency to the combination chronological age with M(2), M(3) crown/root development stage and 72% to the combination chronological age with M(2), M(3) eruption stage.

CONCLUSION

MT growth peak occurs with initiation of root development of M(2) and shortly before M(2) eruption (8-9 years to 10-11 years). Dental time-related indicators adjunct with the chronological age provide an effectual system to define MT growth potential.

Sutural growth restriction and modern human facial evolution: an experimental study in a pig model

Facial size reduction and facial retraction are key features that distinguish modern humans from archaic Homo. In order to more fully understand the emergence of modern human craniofacial form, it is necessary to understand the underlying evolutionary basis for these defining characteristics. Although it is well established that the cranial base exerts considerable influence on the evolutionary and ontogenetic development of facial form, less emphasis has been placed on developmental factors intrinsic to the facial skeleton proper. The present analysis was designed to assess anteroposterior facial reduction in a pig model and to examine the potential role that this dynamic has played in the evolution of modern human facial form. Ten female sibship cohorts, each consisting of three individuals, were allocated to one of three groups. In the experimental group (n = 10), microplates were affixed bilaterally across the zygomaticomaxillary and frontonasomaxillary sutures at 2 months of age. The sham group (n = 10) received only screw implantation and the controls (n = 10) underwent no surgery. Following 4 months of post-surgical growth, we assessed variation in facial form using linear measurements and principal components analysis of Procrustes scaled landmarks. There were no differences between the control and sham groups; however, the experimental group exhibited a highly significant reduction in facial projection and overall size. These changes were associated with significant differences in the infraorbital region of the experimental group including the presence of an infraorbital depression and an inferiorly and coronally oriented infraorbital plane in contrast to a flat, superiorly and sagittally infraorbital plane in the control and sham groups. These altered configurations are markedly similar to important additional facial features that differentiate modern humans from archaic Homo, and suggest that facial length restriction via rigid plate fixation is a potentially useful model to assess the developmental factors that underlie changing patterns in craniofacial form associated with the emergence of modern humans.

Effects of induced premaxillary suture fusion on the craniofacial morphology in growing rats

OBJECTIVE

Due to premaxillary rapid development and fusion with the maxilla at the fetus stage, the functions of the premaxillary suture still remain unclear. This study was designed to explore the effect of artificial induced premaxillary suture fusion on craniofacial morphology.

METHODS

Thirty Sprague Dawley rats were divided into control and experimental groups, with 3 week, 5 week and 8 week subgroups of five animals each. An incision was made in each rat along the premaxillary suture and cyanoacrylate was administered to immobilize the exposed premaxillary suture for experimental rats. No glue was applied to controls. Weights, dental impressions and radiographs were taken before and after surgery until sacrifice and used to determine the differences between groups using the one-way ANOVA test.

RESULTS

After immobilizing the premaxillary suture, significant changes in the craniofacial morphology were measured at the different time points. In the experimental groups, local changes occurred at the 3rd week. A global alteration in craniofacial morphology was apparent at the 8th week in the experimental group compared to the control. At each successive time point, craniofacial morphological alterations increased in rats with fused premaxillary sutures.

CONCLUSIONS

Induced premaxillary suture fusion can inhibit the growth of the premaxilla and cause extensive craniofacial morphological changes. These findings suggest that premaxillary suture fusion may be related to craniofacial malformation or malocclusion and to the formation of the flattened craniofacial profile in humans.