Advances in orthodontic anchorage with the use of mini-implant techniques.

Orthodontic mini-implants (OMIs) represent a new form of anchorage provision and appear to provide a variety of benefits for both anchorage-demanding and complex orthodontic cases. This paper reports the latest perspectives on OMIs in terms of the emerging clinical evidence base coupled with their varied clinical applications.

Use of mini-implants in orthognathic surgery.

We report a case in which mini-implants were used for intraoperative maxillomandibular fixation and for postoperative elastic traction in the treatment of a 20-year-old woman with mandibular prognathism.

Combined cephalometric and stent planning for palatal implants.

Several aspects of palatal implant usage are technique sensitive. In particular, problems during the insertion stage may compromise implant osseo-integration, or its subsequent ease of handling and effectiveness. This paper describes a systematic approach to combined cephalometric and model planning, and subsequent stent fabrication for Orthosystem palatal implants. The authors recommend this protocol in order to optimize three-dimensional control of implant positioning, and to both simplify and standardize the insertion stage.

The accuracy of preoperative orthognathic predictions.

We assessed the accuracy of preoperative OPAL trade mark orthognathic predictions by retrospective analysis of 25 Class II patients who had had orthodontic treatment combined with mandibular advancement osteotomy. Preoperative and postoperative lateral cephalographs were digitised and surgical predictions generated using OPAL software. Each prediction was compared with the corresponding clinical changes. We also made a method error study by doing a random retracing of 25 cephalographs. Predictions of some of the principal OPAL values (SNA, ANB, LAFH%, OJ, OB) were reasonably accurate in terms of mean values. However, there were large individual variations for most variables and predictions of the vertical skeletal, incisor, and Wits measurements were imprecise. In particular, there was a bias towards under-prediction of the vertical skeletal changes when there was more backward mandibular rotation than anticipated. Immediate postoperative cephalographs were also affected by a 2.1mm mean downward displacement of the mandible as a result of the surgical wafer.

The validity of computerized orthognathic predictions.

OBJECTIVE: utilizing OPAL cephalometric prediction software. DESIGN: A retrospective investigation involving the random selection of Class II orthognathic patients from surgical records. SUBJECTS: These 25 cases had undergone treatment aimed at producing Class I incisors. This involved fixed orthodontic appliances and a mandibular advancement osteotomy with rigid internal fixation. METHODS: Lateral cephalographs from three key stages were digitized and processed using the OPAL software. Pre-treatment predictions were generated and compared with the actual clinical changes. RESULTS: Prediction of some of the principal OPAL variables (SNA, ANB, LAFH%, OJ, OB) was reasonably accurate in terms of mean values. However, there were large individual variations for most measurements, and prediction of Wits, MxP/MnP, LAFH, and LPFH was prone to systematic error. In particular, there was a tendency towards over-prediction of the surgically-induced backward mandibular rotation. CONCLUSION: In lieu of further validation caution should be exercised with the interpretation of individual OPAL predictions, especially vertical skeletal changes, and an explanation given to patients that orthognathic predictions are based on generalizations.

An audit of the Yorkshire Regional Cleft Database.

This study assessed the validity of the Yorkshire regional orofacial cleft database by comparing the computer-based records with locally collated records of primary surgical events for babies born over a 2-year period (1994-1995). One-hundred-and-thirty-two infants with clefts (excluding submucous cleft palate) were identified from the latter source with an equal proportion of unilateral cleft lip/palate and isolated cleft palate births. However, only 62 per cent of cases were recorded on the database and the reporting rate of individual cleft units was highly variable (43-85 per cent). In addition, there was a significant under-reporting of both cleft lip and isolated cleft palate cases (42 and 50 per cent ascertainment, respectively). Consequently, the database figures understated the prevalence of all cleft births, but especially of these two cleft subtypes. Conversely, the relative frequency of combined cleft lip and palate cases was exaggerated. The reasons for such discrepancies and possible improvements to data collection are discussed.

Current concepts in the understanding and management of hemifacial microsomia.

Hemifacial microsomia (HFM) is a complex congenital condition. This review discusses recent research findings which affect all aspects of HFM, and addresses some prevailing misconceptions. Firstly, the broad phenotype is outlined, with an emphasis on the facial anomalies which are important for diagnosis, classification and treatment. The range of HFM anomalies and their possible embryology also account for the varied terms used in the literature. In addition, consideration of causation helps to shape our understanding of HFM as a clinical entity. Aetiology is described with particular emphasis on the involvement of genetic factors, although at present this is largely hypothetical. Finally, the principles of HFM management are reviewed. Attention is given to the integrated planning and team approach necessary to treat such patients. In addition, the possible attributes of new treatments, such as distraction osteogenesis, are highlighted.

Diagnosis of hemifacial microsomia.

Early diagnosis of the developmental anomaly hemifacial microsomia is essential for the optimal management of affected patients. However, for a number of reasons this condition is often difficult to recognize. This article discusses the diagnostic problems and gives relevant points for the clinical assessment of facial asymmetry.

Post-operative infection of Proplast facial implants.

Proplast is an ultra-porous composite material that has been used widely to augment the facial skeleton. In recent years, however, the popularity of this material has declined because of complications associated with its use. This paper presents a retrospective study of 36 cases treated with 88 Proplast implants at one unit over a nine-year period. The results suggest that infection of the implant is the most common post-operative complication. Infection may occur at any time following implantation and appears to be more likely when implantation is associated with an osteotomy procedure. In addition, the overall rate of infection in this study (16%) was higher than reported previously and the male-female ratio was 2:1. The possible factors involved in infection are discussed.

A comparison of two classification systems for hemifacial microsomia.

The classification of hemifacial microsomia (HFM) aids in diagnosis, treatment planning, prognostic predictions and data evaluation. The aetiological and phenotypic heterogeneities of HFM, however, make its classification problematic. This study used data from 50 patients to examine the classification of HFM and to compare two systems: OMENS and SAT. The results were concordant with current literature and demonstrated the phenotypic heterogeneity of HFM. Essentially, both classifications embody the major craniofacial defects, but the OMENS system appears to be further refined by its differentiation between soft tissue and nerve defects, and between orbital and mandibular defects. Neither system, however, records deafness or grades auricular tags, although tags occurred in 34% of cases and two patients with otherwise 'normal' ears had tags. Therefore, it is suggested that auricular tags be graded as minor ear malformations. Furthermore, the OMENS system could be strengthened by the addition of an asterisk to the acronym in cases with serious non-craniofacial anomalies, for example OMENS*. This adds little complexity to the acronym, but immediately indicates when a patient's features lie towards the more generalised oculoauriculovertebral end of the phenotypic spectrum.

Hemifacial microsomia: developmental consequence of perturbation of the auriculofacial cartilage model?

The cause of hemifacial microsomia (HFM) is currently the subject of much investigation. Despite a large body of clinical and experimental data, little is certain other than the heterogeneity of this malformation complex. Here we suggest that some of the cases previously designated as being multifactorial in origin may be interpreted instead as resulting from a single-gene mutation, by applying a stochastic single-gene model. A variety of models of the pathogenesis of HFM have been described, including the proposal that local embryonic haemorrhage is a causal mechanism. More recently, it has been suggested that an interference in chondrogenesis is primarily responsible for the HFM phenotype. In this paper direct experimental evidence, based on surgical interference of mandibular development in the chick embryo, is applied in favour of the latter concept. In particular, asymmetrical perturbation of Meckel's cartilage has been shown to result in asymmetry of the mandible, and it is proposed that, irrespective of cause, the skeletal pathogenesis of HFM primarily involves the auriculofacial cartilage model.

The effects of surgical section of the embryonic chick mandibular arch.

The embryonic chick mandibular arch was surgically sectioned in ovo on day 7 of incubation and the subsequent wound healing of the arch, together with the response of Meckel's cartilage to fracture, was examined. The repair process observed (in contrast to that in adults) was characterised by minimal haematoma formation or cell death and the absence of formation of either cellular blastema or fracture callus. re-epithelialisation was complete within 48 h with no scar tissue formed. Continuity of Meckel's cartilage, together with restoration of its histological appearance and that of the surrounding soft tissues, was re-established within 24 h in 88% of cases. In the case of the cartilage this was due to fusion of the matrix followed apparently by chondrocytic and perichondrial proliferation. This differs from the repair of embryonic long bone cartilages. In 12% of cases, however, mal-union or non-union of the cartilage resulted in mandibular arch deviation. This observation suggests that mandibular arch growth and morphogenesis may parallel the development of Meckel's cartilage. Where cartilaginous non-union occurred, some irregularities in the pattern of the developing mandibular bones were evident, and it is argued that deformity in the cartilage may ultimately affect the length and shape of the adult mandible.