Jaw Abnormalities Research Articles

Dental abnormalities associated with failure of tooth eruption in src knockout and op/op mice.

c-src knockout and op/op mice develop osteopetrosis as a result of defective osteoclast function and osteoclast formation, respectively. The mutant mice can be distinguished readily from their wild-type littermates around 10-12 days after birth because their incisors do not erupt, but the morphology of their teeth and surrounding bone has not been reported previously in detail. Histologic examination of jaws of src-mutant mice reveals unerupted, abnormal incisors within their bony crypts. The tooth roots are distorted by foci of haphazard proliferation of odontogenic epithelium associated with primitive tooth structures that strongly resemble the tumor-like lesions in humans, known as odontomas. The crowns of the incisors are fused to the adjacent bone, and the developing periodontal ligament is disordered and hypocellular. Osteoclasts are present in the bone surrounding the distorted teeth, but as in other bones in these mice they lack ruffled borders and thus do not resorb effectively. Similar odontogenic proliferation is present around unerupted incisors in op/op mice which form very few osteoclasts, but the amount is significantly less than in src mutant mice. Molars fail to erupt in both types of mutant mice, but they are not accompanied by aberrant odontogenic proliferation. These findings and previous reports of similar abnormalities in jaws from op/op rats suggest that failure of incisor eruption and associated proliferation of odontogenic epithelium in osteopetrotic rodents are a direct result of defective osteoclastic bone resorption.

Autosomal dominant osteosclerosisReport of a kindred

Autosomal dominant osteosclerosis (ADO), a rare inherited craniotubular bone disorder, is a generalized hyperostosis that manifests itself as increased cortical thickening of the skull, mandible, metacarpals, metatarsals, long bones, vertebral bodies, ribs, and clavicles. Jaw abnormalities, which clinically resemble the widening and deepening of the mandible seen in cherubism, begin in childhood and have been reported to stabilize after puberty. Teeth and alveolar bone are normal. ADO must be distinguished from Van Buchem’s disease, which is characterized by elevated serum alkaline phosphatase, neurologic complications, exopthalmos, periosteal excrescences, and an autosomal recessive pattern of inheritance, as well as from other craniotubular bone disorders such as osteopetrosis. We present clinical and radiographic documentation of members of a kindred representing 4 generations affected with ADO. At initial examination of the proband, a differential diagnosis included cherubism, fibrous dysplasia, osteopetrosis, and Paget’s disease. Radiographic examination revealed extensive radiopacity of the inferior border and basal bone of the mandible. The proband’s clavicles and humerus were also affected. All family members examined were similarly affected and had mandibular and palatal tori. Authors of a previously published report on the dental and dentoalveolar management of patients with craniotubular bone disorders have recommended prophylactic antibiotics to minimize risk of osteomyelitis in all such cases. The members of our kindred received extensive dental treatment before diagnosis, including extractions of severely carious teeth, preprosthetic dentoalveolar surgery, and endodontic therapy; there was no incidence of osteomyelitis or postsurgical complications. Therefore, the use of prophylactic antibiotics may not be warranted in patients with ADO who have otherwise normal medical histories. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:600-4)

Embryological development of sea turtles (Chelonia mydas, Caretta caretta) in the Mediterranean

Simple embryonic staging of Mediterranean sea turtles was developed after measuring a set of selected morphological characteristics. The frequency of gross abnormalities among the samples was also calculated. The most common abnormalities were supernumerary and subnumerary scutes, albinos, head and jaw abnormalities and twinning.

Trigeminal neuropathy: Improved imaging with a dental computed tomography software program

urpose: This study evaluated the use of images obtained by a dental computed tomography (CT) software program in the diagnosis and treatment of trigeminal neuropathy associated with jaw abnormality. Patients and Methods: Twelve patients with jaw abnormality associated with trigeminal neuropathy as the presenting symptom were studied by plain film radiography (PFR) and by a dental CT software program (DS) that displays multiple panoramic and cross-sectional views of the mandible and maxilla. The two modalities were compared for delineation of the integrity of mandibular foramen, mandibular canal, mental foramen, incisive foramen, and incisive canal. Also, displacement of the neurovascular bundle was evaluated and scored. Results: The DS was superior to PFR in showing the bony integrity of the foramina and canals in the jaws, as well as the degree of displacement of the neurovascular bundle. Conclusion: DS should be the study of choice for evaluating trigeminal neuropathy associated with abnormalities of the jaws.

Muscle-Specific Cell Ablation Conditional upon Cre-Mediated DNA Recombination in Transgenic Mice Leads to Massive Spinal and Cranial Motoneuron Loss

We describe here a binary transgenic system based on Cre-mediated DNA recombination for genetic cell ablation in mice that enabled us to obtain skeletal muscle-deficient embryos by mating two phenotypically normal transgenic lines. In those embryos, skeletal muscles are eliminated as a consequence of the expression of the gene encoding the diphtheria toxin A fragment. Cell ablation occurs gradually beginning approximately on embryonic day (E) 12.5, and by E18.5 almost all skeletal muscle is absent. Analysis of the consequences of muscle cell ablation revealed that almost all spinal motoneurons are lost by E18.5, providing strong evidence that survival of spinal motoneurons during embryogenesis is dependent on signals from their target tissue, skeletal muscle, and that trophic signals produced by nonmuscle sources are sufficient to support survival of no more than 10% of embryonic spinal motoneurons in the absence of muscle-derived signals. There was also substantial loss of cranial (hypoglossal and facial) motoneurons in the muscle-deficient embryos, thus indicating that cranial motoneuron survival is also dependent on trophic signals produced by their target tissue. Although spinal motoneurons are a major target of spinal interneurons, the loss of motoneurons did not affect interneuron survival. Muscle-deficient embryos had a cleft palate and abnormalities of the lower jaw, raising the possibility that they might serve as a mouse model for the human disorder, Robin sequence. The data reported here demonstrate the utility of a binary transgenic system for obtaining mouse embryos in which a specific cell population has been ablated, so that its role in embryonic development can be studied.

Evaluation of trigeminal nerve neuropathy in patients with jaw abnormality, using a dental CT software program

Evaluation of trigeminal nerve neuropathy in patients with jaw abnormality, using a dental CT software program

Speech and voice rehabilitation in selected patients fitted with a bone anchored hearing aid (BAHA)

With the Birmingham osseointegrated implant programme there have been several patients with severe pre-lingual conductive hearing loss. The majority of these have been patients with Treacher Collins syndrome. There are characteristic features of speech and voice in those with long-standing conductive hearing loss. In addition, the associated abnormalities of jaw, teeth and palate may amplify the problem. There may be spontaneous improvement in features such as voice pitch, quality and intensity following the fitting of a BAHA. However, in those with a pre-lingual hearing impairment, speech therapy may be necessary. Patients assessed as suitable for BAHA have a full assessment of communication skills including audio recording of speech and voice. Post-operative training improves auditory discrimination and perception and is followed by training in the production of the newly perceived speech sounds.

Clinical assessment of the Augustine Guide for endotracheal intubation

The Augustine Guide (AG) allows oral endotracheal intubations to be performed blindly; head and neck manipulation are unnecessary. It is a premolded device designed to fit in a lock and key fashion in the glottis, thus serving as a guide to allow blind laryngeal insertion of an endotracheal tube. Intubation success rate with the AG was studied in 100 adults intubated by the same individual; head and neck were held neutral. Intubations were described as easy if they were successful in the first attempt and difficult when more than one attempt to position the AG was necessary. Endotracheal intubation was successful 94% of the time and was easy in 71%. Repositioning of the AG was necessary in 23%. Patients with jaw abnormalities required repositioning more often (P < 0.05). Esophageal intubation did not occur. Minor trauma was noted in 18% of subjects. The AG is a safe and effective tool for blind orotracheal intubation.

Clinical assessment of the Augustine Guide for endotracheal intubation.

The Augustine Guide (AG) allows oral endotracheal intubations to be performed blindly; head and neck manipulation are unnecessary. It is a premolded device designed to fit in a lock and key fashion in the glottis, thus serving as a guide to allow blind laryngeal insertion of an endotracheal tube. Intubation success rate with the AG was studied in 100 adults intubated by the same individual; head and neck were held neutral. Intubations were described as easy if they were successful in the first attempt and difficult when more than one attempt to position the AG was necessary. Endotracheal intubation was successful 94% of the time and was easy in 71%. Repositioning of the AG was necessary in 23%. Patients with jaw abnormalities required repositioning more often (P < 0.05). Esophageal intubation did not occur. Minor trauma was noted in 18% of subjects. The AG is a safe and effective tool for blind orotracheal intubation.

Descriptive terminology for jaw anomalies

A descriptive terminology for jaw abnormalities was developed and has been used for many years. This terminology was based primarily on inspection of patients and evaluation of cephalometric x-ray images and defines the anatomic location of abnormalities. It aids in communication between doctors of different specialties.

Oral Surgeons’ Considerations in Surgical Orthodontic Treatment

The orthognathic surgeon seldom has to consider further growth and development of the adult jaws. There are, however, limitations in the adult of certain orthodontic procedures that are effective in the young; rapid palatal expansion, for example. The surgeon and the orthodontist must be aware of other procedures that may be substituted. The adult patient has social, economic, and psychological demands that differ from the young. These may mandate a reversal of the traditional staging of orthodontics first, surgery to follow. Instead, consideration can be given to doing only that orthodontics needed to permit surgery, then surgery to correct the skeletal problems, followed by whatever orthodontics are necessary or desired. Various symptoms of MPD are present in most patients with jaw abnormalities and malrelationships. There must be an awareness that trying to provide relief without correcting the structural problem is treating only symptoms. There also must be realization, especially on the part of the patient, that correcting the jaw deformity does not necessarily mean that symptoms will be gone or, if gone, will not recur. Above all, the orthodontic and surgical team should strive to provide the patient with the maximum function compatible with the appearance the patient desires and do it with the least required amount of surgery and orthodontics.

Some Effects of Salinity and Temperautre on Early Development of Pacific Herring (Clupea pallasi)

Pacific herring (Clupea pallasi) eggs were incubated in the laboratory at 13 different salinity–temperature combinations (ranges: 5–45‰ S, 4–14 C). Data were obtained on rate of development, larval length at hatching, percent total hatch, and percent viable hatch. Subsamples of larvae, held in their incubation media, provided data on posthatching survival and larval size at yolk sac absorption. Maximum percent viable hatch, larval size at hatching, and maximum survival to yolk sac absorption occurred in a trial at 16.41‰ S, 6.85 C. Optimum conditions were calculated by response surface analysis — maximum total hatch: 12.01‰ S, 6.46 C; maximum viable hatch: 16.98‰ S, 8.33 C; maximum length of newly hatched larvae: 20.00‰ S, 5.54 C. Maximum percent viable hatch of largest larvae in the shortest incubation period is estimated to occur at or near 16.98‰ S, 8.7 C. Abnormalities of the lower jaw were present in larvae from eggs incubated at temperatures of 4.0 and 4.71 C. Pacific herring eggs are considered euryhaline and stenothermal. A comparison of laboratory and field observations suggests that occurrence and abundance of herring is related to the availability and extent of spawning salinities between 8 and 28‰. Moreover, catch statistics suggest that population abundance in North American waters is associated with spawning temperatures of 5–9 C, abundance is limited by temperatures of 9–10 C, and the maximum temperature for spawning is about 10 C. From the current study, survival of viable larvae to yolk sac absorption would place the lower limit of thermal tolerance of Pacific herring eggs between 4 and 5 C.

Jaw abnormalities caused by wrong position of the premaxilla and their therapeutic management possibilities

Jaw abnormalities caused by wrong position of the premaxilla and their therapeutic management possibilities

Measurement of models in diagnosing jaw abnormalities

Measurement of models in diagnosing jaw abnormalities

Malocclusion accentuating a facial deformity

In these days of beauty specialists so much can be done that the plain girl has now equal chances with girls more happily endowed, and in such a connection the help of the orthodontist may prove invaluable. In talking of facial deformities, we arc, I think, always inclined to visualize profile abnormalities, that is, defects in the anteroposterior jaw relationships, but, there is also a quite distinct group of lateral jaw abnormalities, with its corresponding anterior facial defect, which call for comment and treatment. The models of the case under review show a relatively simple Class 1 case with narrowed maxilla and slightly asymmetrical mandible, neither great in themselves, but intensified out of all proportion by the subsequent eruption of the teeth, and by the false biting posture t’hat has naturally ensued. (Fig. 1.)