The quadrilateral analysis: a differential diagnosis for surgical orthodontics.

The integration of the diagnostic and treatment skills of both the orthodontist and the maxillofacial surgeon has become a standard procedure in the treatment of severe dentofacial dysplasias. Orthognathic surgery, surgery without prior tooth movement, is being replaced by an interdisciplinary approach as the treatment of choice. When a proper tooth-to-denture-base relationship is obtained, an ideal maxillomandibular relationship can be achieved surgically. The quadrilateral analysis enables the practitioner to obtain an individualized skeletal, dental, and soft-tissue assessment of each patient requiring treatment. It determines the direction and extent of the skeletal dysplasia in millimeter measurements and allows the clinician to outline the appropriate surgical orthodontic procedures. The quadrilateral analysis indicates that in a balanced facial pattern a 1:1 ratio exists between the maxillary bony base length (Max.Lth.) and the mandibular bony base length (Mand.Lth.); also that the average of the anterior lower facial height (ALFH) and the posterior lower facial height (PLFH) equals these bony base lengths. Simply stated, the Max.Lth. = Mand.Lth. = (formula; see text) An accurate diagnosis locates the area and quantifies the magnitude of skeletal dysplasia. Then the correct placement of a dentition within the denture bases and the appropriate surgery in the area of dysplasia can produce an individualized, balanced facial pattern.

The quadrilateral analysis: an individualized skeletal assessment.

There must be a change in our approach to orthodontic diagnosis, especially in those cases involving skeletal dysplasias. The orthodontic practice of today requires a more in-depth diagnostic approach before a realistic treatment plan can be developed. An understanding of the problem that exists is emerging as the essential ingredient before appliance therapy can begin. Diagnosis should dictate the direction of treatment for both the orthodontist and the surgeon. A cephalometric analysis should be able not only to detect but to locate the area of the skeletal dysplasia. Surgery, if at all possible, should be performed where the problem exists. In many cases, it becomes rather confusing to determine whether or not surgical orthodontic treatment is indicated, because most of the cephalometric measurements that are used do not reveal whether a skeletal problem exists, its location, or its magnitude. We believe that current cephalometric analyses do not completely recognize the extent of the dysplasia or where it is located within the jaws. Because of this, surgery is performed by repositioning bones to mask the defect rather than to restore a normal balance between the bones of the face. The only recourse the surgeon has is to achieve an acceptable facial profile by relying on cephalometric norms or to make the necessary correction on what appears visually to be an acceptable profile. The quadrilateral analysis offers an individualized cephalometric diagnosis on patients with or without skeletal dysplasias. We believe that it is a reliable and accurate method of assessing whether orthodontic treatment, surgical treatment, or a combination of both is required to achieve a satisfactory result.

The effect of topical fluorides, after acid etching of enamel, on the bond strength of directly bonded orthodontic brackets.

This study tests the hypothesis that the beneficial effects of topical fluoride can be realized without reducing the bond strength of the resin adhesive. Twenty-eight groups of four teeth (third molars and premolars) were extracted from twenty-eight patients and stored in distilled water. Twin brackets on Ormesh pads were bonded to all teeth with Endur adhesive. One tooth from each group was bonded according to the manufacturer's instructions. These teeth, Subgroup I, served as controls. Subgroup II teeth were etched for 4 minutes with 50% phosphoric acid containing 2 percent sodium fluoride. Subgroup III teeth received a 3-minute application of a basic phosphate fluoride solution (10(-2)M NA3PO4, 10(3) ppm F) after 1 minute of etching with 50 percent phosphoric acid. Subgroup IV teeth received a 4-minute application of 8 percent stannous fluoride solution after 1 minute of etching with 50 percent phosphoric acid. Each tooth was mounted in a block of improved dental stone; guide wires were used to reproduce bracket orientation. The M.T.S. materials-testing apparatus was used to generate a torsional moment on the bracket at a rate of 1 degree per second. Fluoride uptake by enamel has been shown to be greater in an acid medium or after acid etching. The application of directly bonded orthodontic brackets and pit-and-fissure sealants requires acid etching of the enamel surface. This study supports the use of topical fluoride after acid etching, a procedure that achieves the benefits of increased fluoride uptake without changing the bond strength of the resin adhesive.