Cre-mediated gene inactivation demonstrates that FGF8 is required for cell survival and patterning of the first branchial arch.
In mammals, the first branchial arch (BA1) develops into a number of craniofacial skeletal elements including the jaws and teeth. Outgrowth and patterning of BA1 during early embryogenesis is thought to be controlled by signals from its covering ectoderm. Here we used Cre/loxP technology to inactivate the mouse Fgf8 gene in this ectoderm and have obtained genetic evidence that FGF8 has a dual function in BA1: it promotes mesenchymal cell survival and induces a developmental program required for BA1 morphogenesis. Newborn mutants lack most BA1-derived structures except those that develop from the distal-most region of BA1, including lower incisors. The data suggest that the BA1 primordium is specified into a large proximal region that is controlled by FGF8, and a small distal region that depends on other signaling molecules for its outgrowth and patterning. Because the mutant mice resemble humans with first arch syndromes that include agnathia, our results raise the possibility that some of these syndromes are caused by mutations that affect FGF8 signaling in BA1 ectoderm. (+info)
A sella turcica bridge in subjects with severe craniofacial deviations.
In earlier studies, a sella turcica bridge was stated to occur in 1.75 to 6 per cent of the population. The occurrence of a sella turcica bridge has not previously been studied in a group of patients with craniofacial deviations treated by surgery. Profile radiographs from 177 individuals who had undergone combined orthodontic and surgical treatment at the Copenhagen School of Dentistry were studied. A sella turcica bridge was registered in those subjects where the radiograph revealed a continuous band of bony tissue from the anterior cranial fossa to the posterior cranial fossa across the sella turcica. Two types of sella turcica bridge were identified. A sella turcica bridge occurred in 18.6 per cent of the subjects. (+info)
Bilateral hyperplasia of the mandibular coronoid processes associated with the nevoid basal cell carcinoma syndrome in an Italian boy.
In this report we present a subject affected by nevoid basal cell carcinoma syndrome (NBCCS), showing also bilateral mandibular coronoid processes hyperplasia, a hitherto unreported association. Our observation of bilateral hyperplasia of the mandibular coronoid processes in a boy with NBCCS may prompt a retrospective and prospective review of other patients affected by this syndrome in order to establish if this anomaly is part of it. (+info)
Developing an index of restorative dental treatment need.
The process undertaken to establish an initial pilot index for restorative dental treatment is described. Following consultation with a wide range of clinicians and others, an outline framework for the index was developed and comprised three main components: 1. Patient identified need for treatment: the data from the patient perceived need questionnaire were inconclusive; 2. Complexity of treatment (assessed by clinicians): this was found to be a practical tool capable of being used by a range of dentists. A booklet has been produced which describes the process of using the scoring system; 3. Priority for treatment (assessed by clinicians): three levels of priority were identified; the highest priority was assigned to patients with inherited or developmental defects that justify complex care (eg clefts of the lip and palate). The initial development of the index has had some success in a difficult area. The treatment complexity component is the most developed and may allow both referrers and commissioners of specialist restorative dentistry to determine appropriate use of skilled clinicians' expertise. (+info)
Craniofacial variability and its relationship to disharmony of the jaws and teeth.
Examination of size and shape changes in the skulls of growing dogs and related canidae indicates that dental irregularity and jaw disharmony result when the growth pattern of the skull as a whole departs too widely from the norm. (+info)
2,3,7,8-Tetrachlorodibenzo-p-dioxin toxicity in the zebrafish embryo: altered regional blood flow and impaired lower jaw development.
The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure on regional red blood cell (RBC) perfusion rate, as an index of blood flow, and lower jaw development were investigated quantitatively in zebrafish embryos (Danio rerio) during early development. As revealed by observation of live embryos and alcian-blue staining, TCDD retarded lower jaw development in a concentration-dependent manner with only a minor inhibitory effect on total body length. Both inhibitory effects were significant as early as 60 h postfertilization (hpf), at which time the area of goosecoid (gsc) mRNA expression was clearly reduced in the lower jaw. To examine effects of TCDD on RBC perfusion rate, time-lapse recording was performed using a digital video camera attached to a light microscope. TCDD did not show marked effects on RBC perfusion rate until 72 hpf, when vessel-specific effects emerged. TCDD severely inhibited RBC perfusion rate in intersegmental arteries of the trunk, but only modestly and slightly inhibited RBC perfusion rate in certain vessels of the head such as the central arteries and optic vein. Conversely, at both 72 and 84 hpf, TCDD significantly increased RBC perfusion rate in the hypobranchial artery branching to the lower jaw primordia, and then reduced it at 96 hpf. RBC perfusion rate in all vessels examined in TCDD-exposed embryos was inhibited at 96 hpf. The zebrafish aryl hydrocarbon receptor 2 (zfAhR2) mRNA was strongly expressed in the lower jaw primordia at 48 hpf, and expression of this transcript was augmented by TCDD treatment. Thus, TCDD exposure of the zebrafish embryo has a disruptive effect on local circulation and lower jaw cartilage growth. Initially, TCDD may act directly on the lower jaw primordia to impair lower jaw development. Reductions in hypobranchial RBC perfusion rate occurred well after the initial retardation in lower jaw development had become apparent, and may contribute further to the effect. (+info)
Severity of dentofacial deformity, the motivations and the outcome of surgery in skeletal Class III patients.
OBJECTIVE: To study the relationship between severity of skeletal Class III malocclusion and the patient's emotional status, as well as motivation for seeking surgical correction and satisfaction with the outcome of the surgery. METHODS: One hundred and forty consecutive Chinese patients with skeletal Class III malocclusion who had been treated with a combined orthodontic and surgical approach were studied. Sixty-seven percent (40 males and 54 females) responded to a questionnaire. Fifty-four percent had two jaw deformities, 32% mandibular hyperplasia and 14% maxillary hypoplasia. Surgical procedures: 77% received two jaw surgeries, 15% maxillary advancement and 8% mandibular setback. This was a retrospective study based on questionnaires with numerical scale ranked answers (0: not at all; 1: a little; 2: moderately; 3: quite a bit; and 4: extremely). RESULTS: ANB angle was significantly negatively correlated with feelings about the nickname related to their facial problems (embarrassment: gamma =-0.30, P < 0.01; worn out gamma =-0.32, P < 0.01; angry gamma =-0.24, P < 0.05). ANB angle also had a significant negative correlation with the reasons for having the surgery (pressure from their friends: gamma =-0.21, P < 0.05, and referred by physician: gamma =-0.24, P < 0.05). Changes in life style as a result of surgery were significantly negatively correlated with the ANB angle before treatment, positive influence on relationships with the opposite sex (gamma =-0.25, P < 0.05), positive influence in social activities (gamma =-0.22, P < 0.05). CONCLUSION: The psychological status before surgery and the outcome following orthognathic surgery in patients with skeletal Class III malocclusion were closely related to severity of the malocclusion. (+info)
Post-operative stability of the maxilla treated with Le Fort I and horseshoe osteotomies in bimaxillary surgery.
In this study, the post-operative change of the maxilla in six non-cleft patients who underwent combination (Le Fort I and horseshoe) osteotomy for superior repositioning of the maxilla was investigated. In all patients, the maxilla was first osteotomized and fixed with four Luhr plates. No iliac bone graft was applied to the maxilla. A bilateral sagittal split ramus osteotomy of the mandible (BSSRO) was then carried out and titanium screw fixation was performed. No maxillo-mandibular fixation (MMF) with stainless steel wire was used post-operatively in any patient. Lateral cephalograms were obtained pre-operatively, 5 days post-operatively, and 3, 6, and 12 months after surgery. The changes in anterior nasal spine (ANS), point A, upper incisor (U1), and point of maxillary tuberosity (PMT) were examined. The maxillae in the six subjects were repositioned nearly in their planned positions during surgery and no significant post-operative changes in the examined points of the maxilla were found. These results suggest that a combination of a Le Fort I and horseshoe osteotomy is a useful technique for reliable superior repositioning of the maxilla. The post-operative change in the maxilla using this combination osteotomy is comparatively stable. (+info)