Correction of severe vertical maxillary excess with anterior open bite and transverse maxillary deficiency.

Patients requiring correction of large anterior open bites have historically been among the most challenging treatments for orthodontists. Adding to that fundamental challenge for the adult patient in this case was vertical maxillary excess, a severe transverse maxillary deficiency as well as an arch length inadequacy, even though the patient had prior orthodontic treatment. The prior orthodontist had included arch expansion and extracted four first bicuspids, which limited current treatment options. Various treatment modalities that have traditionally been used to correct transverse maxillary deficiency and the accompanying arch length inadequacy include extractions, labial and buccal dental tipping, segmental maxillary osteotomies, and rapid maxillary expansion with or without surgical assistance. Transverse maxillary distraction osteogenesis is a modification (ie, using a latency period and specific rate and rhythm of distraction) of the surgically assisted rapid maxillary expansion technique developed 25 years ago. This case demonstrates the relationship of transverse maxillary deficiency as well as vertical maxillary excess to apertognathia. Considerations regarding the use of segmental maxillary osteotomy vs transverse distraction osteogenesis are discussed. This case report illustrates the benefit of a team approach using transverse maxillary distraction osteogenesis, effective orthodontic mechanics, and orthognathic surgery to correct a severe dentofacial deformity.

Taking the guesswork out of mandibular symphyseal distraction osteogenesis.

Mandibular symphyseal distraction osteogenesis has recently been introduced as a means of resolving arch length deficiencies in the anterior segment and as a method of reducing large vestibular spaces related to a narrow mandible. Accurately relating the required distraction for a given anterior tooth mass and desired future anteroposterior location of the central incisors has not been possible until recently. The relationship between these 3 controlling factors has been mathematically described by the hyperbolic cosine function and a computer program designed for easy use by the clinician. Two clinical cases illustrate the application of the program. A Web site where the program can be downloaded at no cost is mentioned.

The relationship of the glenoid fossa to the functional occlusal plane.

The geometric relationship of the functional occlusal plane to the center of the glenoid fossa, as seen in the sagittal view, is described for males and females from age 7 through 25 years. This relationship is fully described by the distance from the geometric center of the glenoid fossa perpendicular to the functional occlusal plane (L, in millimeters) and its angulation (theta, in degrees) relative to a constructed Frankfort horizontal (SN-7 degrees ). Regression formulas with 95% confidence levels are described for L and theta for both genders combined. The differences between genders were found to be statistically insignificant. No correlation was found between these dimensions relative to the presence of temporomandibular joint dysfunction symptoms. A statistically significant difference in both L and theta was found in males who exhibited a Class III relationship compared with males exhibiting a Class II relationship.

The biomechanics of rapid maxillary sutural expansion.

Micro-displacements (fringe patterns) in the bones of the craniofacial complex as seen through laser holography during midpalatal sutural expansion with the Hyrax appliance are used to define the centers of rotation of the maxillary halves in both the frontal and occlusal views. Biomechanical analyses of the maxillary expansion force system are concomitant with the holographic findings and strongly suggest that the stainless steel wires joining the teeth to any expansion device be of the largest diameter possible. In addition, in the case of the Hyrax expansion device, it is recommended that the manufacturer increase the diameter of the activating screw as well as those of the 2 adjacent wire guides. And, importantly, the use of acrylic as a structural member to join the teeth to a sutural expansion device should be avoided if tipping of the maxillary halves is to be minimized, as the acrylic lacks sufficient rigidity.

The relationship of arch length to alterations in dental arch width.

An accurate method is presented for forecasting alterations in arch length related to various width increases in each dental arch. It is based on combined beta and hyperbolic cosine functions which express the expanded dental arches with correlation coefficients of r = 0.98, between measured data and representations of the dental arch. When the midpalatal suture is expanded, canine width and molar width alterations are not equal because the line of action of the expanding force is anterior to the center of resistance of the dentomaxillary complex. Therefore, canine to molar width ratio alterations of 1:1, 1.25:1, and 1.5:1 are examined, and simple linear functions are presented for purposes of predicting changes in arch length.

An evaluation of the shape of some popular nickel titanium alloy preformed arch wires.

The mathematical Beta function is shown to be an accurate planar representation of the natural human arch form defined by the spatial coordinates of the labial and buccal dental/bracket interfacing surfaces in the maxillary and mandibular arches. Graphic planar representations of the corresponding bracket base spatial coordinates of 33 popular preformed nickel titanium arch wires and bracket assemblies were superimposed on each of the relevant maxillary and mandibular natural forms. The arch forms of the preformed nickel titanium arch wires and bracket assemblies did not emulate the natural human arch form. The average mandibular natural human arch form first molar/canine width ratio is 2.38/1; the same preformed arch wire/bracket ratio is 1.87/1. These ratios for the maxillary arch are 1.92/1 and 1.54/1, respectively. The average canine width exceeded the natural canine width by 5.95 mm in the mandibular arch and 8.23 mm in the maxillary arch. The corresponding mandibular first molar and maxillary first molar widths exceeded the natural human first molar arch width by 0.84 mm and 2.68 mm, respectively. These findings have implications with respect to posttreatment stability and facial esthetics. "Round tripping" teeth resulting from subsequent change to stainless steel arch wires to restore a more natural human arch form and size may result in deleterious tissue effects.

A reexamination of various extraoral appliances in light of recent research findings.

The location of the center of resistance of the dentomaxillary complex has recently been identified more accurately than before. Based on this new finding, various modifications of the common facebow are presented for use in protraction therapy. Clinical applications for specific treatment objectives are also reviewed. Orthopedic and biomechanical implications of various standard retraction type extraoral appliances are also analyzed.

Assessment, documentation, and treatment of a developing facial asymmetry following early childhood injury.

Prepubertal trauma is often implicated as the cause of asymmetric growth of the mandible. A series of photographs taken before and after early childhood injury to the orofacial complex illustrates the development of a three-dimensional dentofacial deformity in a patient. The diagnosis and combined surgical orthodontic treatment plan to correct the facial asymmetry and malocclusion are discussed.

Surgical correction of patients with asymmetries.

Facial asymmetry is quite common and, when sufficiently severe, can warrant surgical orthodontic intervention. The causes of facial asymmetry are numerous and can be generally classified as congenital, developmental, or subsequent to pathology or injury. A systematic and comprehensive examination, diagnosis, and treatment plan are requirements for successful correction of facial asymmetry. Several of the more common facial asymmetries presenting for treatment to the orthodontist and surgeon are discussed in this article. Some fundamental surgical and orthodontic principles for treating these deformities are described. The purpose of this article is to provide a brief overview of a surgical and orthodontic approach to the evaluation and treatment of some of the more common facial asymmetries.

The form of the human dental arch.

The human dental arch form is shown to be accurately represented mathematically by the beta function. The average correlation coefficient between measured arch-shape data and the mathematical arch shape, expressed by the beta function, is 0.98 with a standard deviation of 0.02. Forty sets of casts--15 Class I, 16 Class II, and 9 Class III--were examined. A precision machine tool device was used to record the X-, Y-, and Z-coordinates of selected dental landmarks on all casts to 0.001 mm accuracy. The coordinates were processed through a computer curve-fitting program. The Class III mandibular arches had smaller arch depth and greater arch width (beginning in the premolar area) than the Class I arches. The Class II mandibular arches exhibited generalized reduced arch width and depth compared with the Class I arches. Maxillary arch depths were similar in all three groups. However, the Class III maxillary arch widths were greater from the lateral incisor-canine area distally compared with the Class I maxillary arch, and the Class II maxillary arch form was narrower than the Class I arch form from the lateral incisor-canine area distally. The beta function more accurately described the dental arch form than representations previously reported.

Changes in occlusion related to the cant of the occlusal plane.

It is known that dental occlusion is influenced by changes in the cant of the occlusal plane. This study has defined the geometric and mathematical relationships between dental occlusion and rotations of the occlusal plane in the sagittal view. As a general clinical guide, each degree of rotation of the occlusal plane will result in a half millimeter change in the dental occlusal relationship. This is of importance, because changes in the cant of the occlusal plane are sometimes unintentional, as well as intentional, during orthodontic therapy. An earlier study has also documented that the occlusal plane rotates naturally upward and forward approximately 6 degrees during growth and development. This phenomenon tends to develop a Class II dental relation and therefore has important implications for the developing dentition.

Variable modulus orthodontics advanced through an auxiliary archwire attachment.

Reducing the load deflection rates of orthodontic springs is important, for it provides relative constancy of the moment-to-force ratio applied to the teeth with concomitant, forecastable dental movement. Increasing patient comfort and reducing the number of office visits while lowering potential tissue damage are additional features of lower load deflection rate springs. A simple auxiliary attachment, which can be crimped into position on an archwire or onto segments of an archwire, is described. This attachment permits the clinician to incorporate a relatively high rate stiff wire to enhance the anchorage of the reactive teeth in one area of the dental arch, while allowing the use of lesser stiffness (lower load deflection rate spring) to engage teeth targeted for movement. The auxiliary allows the clinician various stiffness through the use of wire of one modulus (stainless steel, for example) in one area of the arch, and wire of a differing modulus (NiTi, for example) in another area of the same arch. The advantages and disadvantages of choosing wires of differing moduli are reviewed. Alternative methods of transforming the spring rate through changes in wire cross-section or length are also reviewed. Practical clinical applications of the auxiliary attachment are shown.

On the management of extraction sites.

Extraction sites may be needed to achieve specific orthodontic goals of positioning the dentition within the craniofacial complex. The fundamental reality that determines the final position of the dentition, however, is the control exercised by the clinician in closure of the extraction sites. A specific treatment objective may require the posterior teeth to remain in a constant position anteroposteriorly as well as vertically, while the anterior teeth occupy the entire extraction site. Another treatment objective may require the reverse, or any number of purposeful alternatives of extraction site closure. An appliance system developed over time, which provides this control, is described. The system takes advantage of aspects of continuous arch therapy that provides constant, positive orientation of the anterior and posterior groups of teeth to each other in three-dimensional space across an extraction site, combined with aspects of the segmented arch technique that permit definable and predictable force systems to be applied to these teeth. Consequently, the clinician has the ability to forecast treatment outcomes with confidence.

A cancellous marrow bone-cartilage composite autograft for maxillofacial reconstructive surgery. A case report.

Numerous experimental and clinical investigations have contributed to current protocol for the reconstruction of hard tissue defects of the face and jaws. Free transplantation of tissues from the same host is a viable option for these defects. This article includes a review of the literature for autogenous grafting and presents an example of this treatment with a 19-month follow-up. This approach is not the sole answer but is only one solution for this difficult problem.

Masseter muscle adaptation following surgical correction of vertical maxillary excess.

This study was designed to examine the adaptive response of the human masseter muscle following surgical correction of abnormal facial form. Biopsies of the deep surface of the anterior superficial masseter muscle were obtained from five patients demonstrating vertical maxillary excess (VME), one at the time of corrective surgery, and a second at a long-term postoperative time interval (mean, 8 months). Control biopsies were also obtained from five individuals (three cadavers and two patients) with normal dentofacial morphology. A standard regimen of histologic and histochemical staining was used to classify individual muscle fibers as either type 1, type 2, or intermediate. In both VME patients and normal subjects type 1 fibers predominated, with the control group displaying a higher percentage (50% vs. 43%). On the average, type 1 fibers also had the largest areas. Following surgery there was an increase in type 2 fibers (30% vs. 52%). Two patients receiving maxillary surgery only exhibited either no change in mean fiber area or only a slight increase. The three remaining patients who underwent concomitant maxillary and mandibular surgery all showed a significant decrease in mean fiber area. Two persons in the latter group also showed features consistent with a denervation-reinnervation process. The results of this study indicate that the human masseter responds to surgical manipulation of the jaws in a histochemically demonstrable manner, with the nature and magnitude of the response associated with the particular surgical procedure(s) performed.

Treatment of Class II deep bite by orthodontic and surgical means.

Conventional orthodontic correction of the Class II deep-bite deformity with a decreased lower anterior facial height tendency can be mechanically difficult, inefficient and, in many instances, impossible. Orthodontic treatment alone of either adults or adolescents with such deformities frequently can neither increase lower anterior facial height sufficiently to achieve ideal facial proportions nor achieve long-term occlusal stability. Despite the need for surgical intervention to achieve satisfactory occlusal and esthetic results, many patients with such deformities are still being treated in clinical practice by traditional orthodontic procedures, with less than ideal esthetic and/or occlusal results. The challenge to achieve efficient and stable treatment of this deformity has been met by the use of various surgical techniques in combination with orthodontic treatment. This combined surgical-orthodontic approach can provide increased treatment efficiency, long-term stability, and optimal esthetic results. The proper sequencing and correct selection of orthodontic mechanotherapy are essential to ensure the desired results. This article purposes to detail basic problems involved in diagnosis and treatment planning for the combined surgical-orthodontic approach to patients exhibiting Class II deep bite and decreased lower facial height. Orthodontic and surgical treatment objectives are explained, and representative case reports are presented and discussed to illustrate this method of treatment. Extraction patterns, control of the transverse dimension, arch wire selection, auxiliary wires, elastics, and extraoral appliance use are described. Surgically, the dentofacial disharmony associated with this deformity may defy treatment by surgical advancement of the mandible only. Genioplasty, Le Fort I osteotomy, symphyseal osteotomy, anterior or total mandibular subapical osteotomy, body osteotomy, submental lipectomy, and rhinoplasty are adjunctive procedures that are described and may be used in concert with mandibular advancement surgery.

Pulpal and radicular response to maxillary osteotomy in monkeys.

The purpose of this study was to examine the pulpal and radicular response to total maxillary osteotomy. The osteotomy was performed on four adult Macaca irus monkeys. Monkeys were killed after a postsurgical observation period of 150 days. Tissue blocks of the maxilla with teeth were cut and examined histologically. The pulp of the majority of the teeth from experimental animals showed cellular and circulatory pathologic changes, even in the presence of collateral circulation.