Innovation in skeletal II treatment including effective incisor root torque in a preliminary removable appliance phase

The Dynamax system: a new orthopaedic appliance and case report

The Dynamax appliance is a treatment modality for the correction of the Skeletal II malocclusion characterized by a mandibular retrusion. Progressive mandibular advancement, maxillary expansion, control of maxillary growth, incisor torque and control of vertical facial development are incorporated into a two-part appliance. The design facilitates laboratory construction, clinical handling and patient acceptability. A prefabricated spring module forms the basis of the appliance, allowing both maxillary expansion and mandibular advancement. An easily adjustable progressive forward position of the lower jaw makes a construction bite unnecessary. The spring module provides most of the structure of the appliance so that minimal acrylic is required and the appliance is fully contained within the freeway space. Contact between the upper and lower parts of the appliance occurs posteriorly in the lingual sulcus. Here the depth permits an extended vertical contact, to maintain a protrusive mandibular position throughout the range of mandibular opening, including during sleep. The lower portion of the appliance may be fixed or removable and multibracket treatment can be carried out in one or both arches at the same time as the orthopaedics.

Prospective clinical trial comparing the effects of conventional Twin-block and mini-block appliances: Part 1. Hard tissue changes

PURPOSE

The aim of this prospective clinical trial was to compare the dentoskeletal effects of a conventional and a modified Twin-block (TB) appliance. The conventional TB appliance was constructed with a large, single-step advancement. The modified appliance, termed the mini-block (MB), was incrementally advanced, incorporated a maxillary incisor torquing spring, and had a reduced bite-block height.

MATERIAL

Seventy patients were placed into age- and sex-matched pairs. Patients in each pair were allocated to opposing appliance groups. Active treatment lasted 9 months, irrespective of the final overjet attained, and final cephalometric records were taken at 12 months (+/-1 month). Both groups showed pretreatment equivalence for age, sex, overjet, and cephalometric variables.

RESULTS

The TB group experienced a significantly greater reduction in overjet (median, -8 mm; P = .02) compared with the MB group (median, -4 mm). This improved overjet reduction was associated with significantly greater forward movement of pogonion (median change, TB: 3.3 mm; MB: 2.1 mm; P = .02) and greater retroclination of the maxillary incisors (median change, TB: -5 degrees ; MB: -1.9 degrees ; P = .04). No significant intergroup difference was found for changes in total anterior facial height (median change, TB: 4.4 mm; MB: 4.3 mm) and mandibular incisor proclination (median change, TB: 1.3 degrees ; MB, 2.4 degrees ).

CONCLUSIONS

Progressive mandibular advancement was not associated with greater mandibular growth compared with single-step advancement. The maxillary incisor torquing spring seems to be effective at reducing maxillary incisor retroclination. Reduced bite activation in the MB group did not result in less mandibular incisor proclination. There was considerable individual variation in appliance effects within both groups.

Maxillary traction splint: a cephalometric evaluation

Orthodontists are particularly interested in knowing exactly what skeletal and dental changes are produced by headgear. With headgear and fixed appliances, part of the observed change is due to the headgear, part to the fixed appliances, and part to growth. Since the maxillary traction splint moves the teeth en masse, the dentoskeletal changes are due primarily to the headgear force. Selective mandibular dental changes can be produced by adjusting the mandibular occlusal contacts against the splint. In this study forty-seven patients with maxillary dentoalveolar protrusions and Class II, Division 1 malocclusions were treated with orthopedic headgear that attached to a full-coverage maxillary occlusal splint. Fifty-two patients were selected as a control for evaluation of growth changes versus treatment changes. Lateral cephalograms were taken before and after treatment, and the sagittal skeletal and dental changes were evaluated and quantified. The results of the investigation revealed (1) the establishment of a Class I posterior occlusion, (2) a significant overjet reduction, averaging 4.24 mm, (3) inhibition of vertical development of the maxilla and slight intrusion of the maxillary dentition, (4) overbite reduction by leveling of the mandibular dentition, (5) no indication that mandibular growth is accelerated, and (6) no significant increase in the mandibular plane angle. The maxillary traction splint is an effective means of correcting maxillary dentoalveolar protrusion in growing patients prior to fixed appliance therapy. The second phase of treatment with fixed appliances is necessary for individual tooth positioning and for detailing the occlusion.

Orthopedic coordination of dentofacial development in skeletal Class II malocclusion in conjunction with edgewise therapy. Part II

This second of two articles describes the effects of mandibular growth enhancement in a comprehensive orthopedic approach to the correction of skeletal Class II malocclusion. Clinical and experimental evidence gives support to the concept, and case histories show the clinical mode of use of the appliance system. An initial 10- to 12-month orthopedic phase is followed by a second phase of similar duration in which full edgewise therapy is used to establish a gnathologically ideal occlusion. As the essential corrections are achieved in the orthopedic phase, the second phase is much reduced in complexity and is generally confined to alignment and final detailing. This combined approach to skeletal Class II treatment offers the possibility of better harmony of dental and facial features, with continued stability through the period of facial growth.

Orthopedic coordination of dentofacial development in skeletal Class II malocclusion in conjunction with edgewise therapy. Part I

The skeletal Class II malocclusion may be considered to develop as a failure of the coordinating process to maintain harmonious relationships within the developing dentofacial apparatus. If the skeletal elements are too far apart for adaptation to occur and/or if there are functional abnormalities of the orofacial musculature which inhibit coordination from taking place, a malocclusion will result. An orthopedic technique and appliance system has been developed with the intention of improving those factors responsible for the development and perpetuation of the skeletal Class II malocclusion in a primary stage of treatment. This is accomplished by means of restraint and redirection of forward maxillary growth and an increase in the velocity of mandibular growth. Concurrently, adverse soft-tissue influences are eliminated or ameliorated. Edgewise appliance therapy is subsequently carried out for the final correction. The subject is considered in two articles. This first article describes the effects of the restraint of maxillary growth on craniofacial development and the dental changes produced by a maxillary removable splint with extraoral traction and shows how they can be used clinically for correction of the skeletal Class II malocclusion. The experimental and clinical evidence supporting this approach is considered, and case histories show the clinical use of the maxillary splint. This form of maxillary therapy for the skeletal Class II malocclusion has limitations, and it is desirable for it to be incorporated into a comprehensive orthopedic system.

The palatal movement of the apices of upper incisors using intra-oral elastics: a case report

An appliance is described which uses elastics to move the apices of upper incisors palatally. No claims are made that this works better than existing appliance systems. However, a number of possible advantages have been listed and may be worthy of further investigation.

Dento-facial orthopaedics in the correction of class II malocclusion

An orthopaedic appliance system has been developed with the specific therapeutic intention of removing those factors responsible for the initiation or maintenance of the skeletal Class II malocclusion. This is accomplished by means of restraint and redirection of forward maxillary growth and induction of mandibular growth. Concurrently, adverse soft tissue influences are eliminated or ameliorated. Clinical and experimental evidence gives support to this concept and case histories show that clinical mode of use of the appliance system. An initial 10--12 month orthopaedic phase is followed by a second phase of similar duration, utilizing full Edgewise therapy to perfect the occlusion. The second phase is much reduced in complexity and is generally confined to alignment and final detailing as the essential corrections have been achieved in the orthopaedic phase. It is considered that this combined approach to Skeletal II treatment is more physiologic than conventional treatment and results in a better harmony of dental and facial features.

Upper torque/intrusion mechanics in deep bite cases using the upper utility wire and directional headgear

The problems of correcting deep bites are outlined and the advantages and usage of the upper utility wire are described with special reference to some case reports. High pull headgear direct to the arch Wire allows an orthopaedic force to be added if required, in addition to opposing the extrusive force vector applied by the torqueing mechanics. Treatment may be commenced with only two molars and four incisors banded and the edgewise system allows the incisor roots to be kept away from palatal and buccal plates during intrusion. This prevents the root resorption described recently when incisors roots have been allowed to contact the cortical plates of bone during movement. Use of Cobalt—Nickel—Chrome* wire and pre-torqued brackets allows the application of a light physiological force acting over a long period and this reduces patient visits. Overbite correction is achieved by true incisor intrusion and not by molar extrusion.