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Biomedical subjects

V G Kokich

Publications and source records attributed to V G Kokich.

At least 37 records · Page 2Linked to original sources
PubMed1988

Uses of implants in orthodontics.

In recent years, endosseous implants have become practical and reliable adjuncts for dental rehabilitation. That same technology can and will be used in orthodontics to provide anchorage for tooth and bone movement. As anchors for dental movement, osseointegrated implants particularly are useful in patients who are partially edentulous; the implants subsequently can be used as bridge abutments. As anchors for bone movement, implants will be used to modify facial growth. Although implants have not yet been used for this purpose in children, there are no unsolvable technological problems.

Animals↗
PubMed1987

Atelencephalic microcephaly: craniofacial anatomy and morphologic comparisons with holoprosencephaly and anencephaly.

This is the first detailed report of the craniofacial anatomy of atelencephaly. Comparisons were made with a control specimen and others with holoprosencephaly, anencephaly, and anencephaly with holoprosencephalic facial features. In the atelencephalic fetus, severe microcephaly, flattened calvaria, and partial synostosis of the metopic suture were apparent. The cranial fossae were much smaller than usual; lesser wings of the sphenoid were folded into a rounded basal mass. Facial features were pronounced, and orbits were hyperteloric, lowset, and rounded. Ethmoidal cartilages, nasal bones, and maxillary structures were distorted and elongated. The secondary palate was displaced inferiorly and cleft. Because major components of the craniofacial complex were generally present, although misshapen, changes in the atelencephalic skull seem to be deformations rather than malformations. Differences in the cranial morphology of associated disorders--holoprosencephaly and anencephaly--can be construed as aberrations of separate developmental fields. Relationships between atelencephaly and these fields are unclear.

Abnormalities, Multiple↗
PubMed1987

Displacement of the glenoid fossa: a cephalometric evaluation of growth during treatment.

Pretreatment and posttreatment lateral cephalograms of 175 orthodontically treated patients were evaluated to determine the change in position of articulare. The sample was arbitrarily subdivided according to the direction of facial growth during treatment (vertical, V; horizontal, H; intermediate, H/V) measured at pogonion. The cephalograms were superimposed on anterior cranial base and a Cartesian coordinate system was devised to measure changes in the position of articulare over time. The results clearly show that articulare is displaced posteriorly and inferiorly during craniofacial development with treatment. Significant differences in the amount of displacement were noted between groups. Patients with vertical growth patterns showed significantly greater posterior displacement of articulare than patients with horizontal growth patterns. Because articulare represents the point of intersection of the temporal bone and the neck of the condyle, this investigation suggests that the temporal bone and glenoid fossa are displaced posteriorly during facial development with treatment and that the amount of displacement can affect mandibular position.

Adolescent↗
PubMed1987

Long-term effect of root proximity on periodontal health after orthodontic treatment.

The present investigation was done to evaluate the incidence and distribution of root proximity after orthodontic treatment and to test the hypothesis that interproximal areas with thin interdental bone provide less resistance against marginal periodontal breakdown than areas with normal width of bone between the roots. Only adult patients were examined at least 16 years after active orthodontic treatment. The distance between the roots was measured directly on periapical radiographs. Gingival health, level of connective tissue attachment, and clinical scores for bone levels in sites with thin interdental bone and neighboring or contralateral sites with normal width of bone between the roots were compared. Among the 400 patients studied, 25 had unilateral or bilateral areas with root proximity. Root proximity was diagnosed between maxillary central and lateral incisors in 18 patients, between mandibular central and lateral incisors in two patients, and between maxillary lateral incisor and canine, maxillary first and second molars, mandibular canine and first premolar, mandibular first and second premolars, or mandibular first and second molars in only one patient. No statistically significant differences in inflammation, level of attachment, and bone level were observed between root proximity sites and control sites. The results indicate that anterior teeth are not predisposed to more rapid periodontal breakdown when roots are in close proximity. Too few molar sites were included to draw conclusions regarding such areas.

Adult↗
PubMed1986

Long-term effect of thin interdental alveolar bone on periodontal health after orthodontic treatment.

The present experiment was undertaken to determine if an interproximal area with a thin interdental bone septum following orthodontic treatment provides less resistance against marginal periodontal breakdown than an interproximal area with a normal width of bone between the roots. Only adult patients, at least 16 years after active orthodontic treatment, were studied. The distance between the roots was measured directly on periapical radiographs. Gingival health, level of attachment and bone level in sites with thin interdental bone were compared with neighboring or contralateral sites with a normal width of bone between the roots. No statistically significant differences in inflammation, level of attachment and clinical scores for bone level were observed. When measured radiographically the distance from the cementoenamel junction to the alveolar bone was significantly shorter in neighboring control sites (P less than 0.05). This discrepancy was most likely due to radiographic distortion. The results of this investigation suggest that in anterior areas marginal periodontal breakdown is unrelated to the thickness of bone between the roots. Too few molar sites were included to draw conclusions regarding such areas.

Adolescent↗
PubMed1985

Ankylosed teeth as abutments for maxillary protraction: a case report.

It has been recognized that using the maxillary teeth to deliver extraoral force to the maxilla not only results in sutural remodeling but also periodontal remodeling and tooth movement. In patients with severe maxillomandibular malrelationships, the potential for tooth movement often limits the amount and duration of extraoral force and, consequently, affects the success of treatment. This case report describes a technique to intentionally ankylose deciduous teeth in a patient with severe maxillary retrusion. The ankylosed teeth were used as abutments to deliver an anteriorly directed intermittent extraoral force. After 12 months of treatment, the anterior crossbite was nearly corrected. At that point the ankylosed teeth loosened because of root resorption and the treatment was terminated. Cephalometric superimposition demonstrated that the occlusal correction was the result of anterior maxillary movement with little mandibular growth and no movement of the ankylosed teeth. The results suggest that intentionally ankylosed teeth may be used as abutments for extraoral traction in patients with a severe disturbance in maxillary growth.

Acrocephalosyndactylia↗
PubMed1985

Evaluation of cranial bone suture autotransplants in the growing rabbit.

A coronal bone suture segment was autotransplanted into an experimentally created defect in the nongrowing portion of the nasal bone in 12 5-week-old male New Zealand white rabbits. The animals were sacrificed 90 days postoperatively. In most specimens the transplants were well incorporated into the recipient site. The transplanted sutures appeared narrower radiographically, and the bony projections of the sutures were not as long as those seen in control sutures. In each case the transplanted sutural ligament had atrophied, and six of the transplants showed bony union across the sutural space. The results suggest that growth and biomechanical stresses are important for maintenance of the sutural ligament and for the stimulation of bone deposition.

Animals↗
PubMed1985

Fetal alcohol syndrome: an examination of craniofacial dysmorphology in Macaca nemestrina.

The purpose of this investigation was to evaluate the craniofacial features in nonhuman primate models exposed in utero to moderate and high weekly binge doses of ethanol. While the high-dosed animal did have unusual craniofacial dysmorphology, she did not exhibit the typical facial pattern seen in human fetal alcohol syndrome. The high-dosed specimen displayed a scaphocephalic head shape secondary to synostosis of the sagittal suture. The brain of this monkey was grossly abnormal and microcephalic.

Animals↗
PubMed1984

Gingival contour and clinical crown length: their effect on the esthetic appearance of maxillary anterior teeth.

Fractured, congenitally missing, or avulsed maxillary incisors can often jeopardize the esthetic appearance of the remaining maxillary anterior teeth after orthodontic treatment. In many cases the unesthetic appearance is related to the irregular clinical crown lengths of either the fractured teeth or those that have been substituted for the missing teeth. The results of five cases with either fractured or traumatically avulsed central incisors are reported. Selective tooth intrusion and restorative techniques were used during the finishing stages of orthodontic treatment to improve the final esthetic result. The advantages and disadvantages of the intrusion technique are discussed.

Adolescent↗
PubMed1983

Experimental craniosynostosis in growing rabbits. The role of the periosteum.

Reports on the role of the periosteum in premature sutural synostosis have been contradictory. The present study summarizes a series of six experiments designed to clarify these previously conflicting findings. Twenty-five male New Zealand White rabbits were divided into six experimental groups. In four of the groups, methyl-2-cyanoacrylate was used to glue the frontal and parietal bones together and temporarily immobilize the coronal suture. In the other two groups, the sutures were not immobilized. Polyethylene was used to separate the cyanoacrylate from the periosteum in two of the groups. The experiments were performed at 5 weeks of age, and the animals were killed at either 30, 45, or 180 days postoperatively. Metallic implants were placed in the frontal and parietal bones for monitoring growth and/or sutural immobilization. Sutural fusion was confirmed radiographically or histologically. Based upon the findings it seems that mechanical immobilization of a suture does not induce fusion of that suture in rabbits. Furthermore, it appears that the mere application of methyl-2-cyanoacrylate to the periosteum overlying a suture will consistently cause the formation of a bony bridge in growing rabbits but not in nongrowing animals. The adhesive does not consistently induce synostosis if the periosteum is excised.

Animals↗
PubMed1982

Cyclopia: an anatomic and histologic study of two specimens.

The craniofacial complex of two neonatal, human, cyclopic specimens was studied in detail. Both specimens exhibited a single ocular opening and one had a prominent probosics positioned in the midline directly superior to the ocular aperture. No external nasal development was noted in the other specimen. The most remarkable finding was the lack of development of all skeletal derivatives of the ethmoidal cartilage(cribriform plate, perpendicular plate, superior and middle nasal conchae, medial orbital walls, and nasal septal cartilage) in both specimens. Since these bones normally form the medial, lateral, and superior walls of the nasal passage, this cavity was also absent. The two posterior halves of the maxillae were directed superiorly, medially, and with the vomer merged in the midline as a thick mass of bone. As a result the right and left alveolar portions of the maxillae were joined superiorly in the midline. With the absence of the nasal cavity, the right and left medial pterygoid plates merged medially with the palatal and pyramidal processes of the palatine bone to obstruct the junction between the oropharynx and nasopharynx(choanal atresia). The role of the skeletal parts of the ethmoid during maxillofacial growth and development is discussed.

Abnormalities, Multiple↗
PubMed1982

Neuroanatomic examination of spina bifida aperta and the Arnold-Chiari malformation in a 130-day human fetus.

A 130-day human female fetus with the Arnold-Chiari malformation and thoracolumbar myeloschisis revealed evidence of neuroectodermal-mesodermal spatial dyssynchrony. The rhombencephalon and the cervico-medullary junction appear most affected. The phylogenetic and ontogenetic development of the transition zone between brain and spinal cord is reviewed. It is hypothesized that the etiologic event responsible for the Arnold-Chiari malformation is the caudal "displacement" of the site of initial fusion of the neural folds. This is believed to result in the posterior displacement of the cervico-medullary junction and myeloschisis (the Arnold-Chiari malformation, type II).

Arnold-Chiari Malformation↗
PubMed1982

The cloverleaf skull anomaly: an anatomic and histologic study of two specimens.

Two neonatal human specimens exhibiting the cloverleaf skull anomaly were studied in detail using gross, radiographic and histologic techniques. Both specimens exhibited premature fusion of the right and left coronal sutures, right and left lambdoidal sutures, and midsagittal sutures. Although the specimens grossly exhibited a similar trilobed appearance of the craniofacial complex, the interrelationship and spatial orientation of their respective articular and skeletal components differed markedly. The development of the cranial base in one specimen appeared normal, while in the other specimen, the synchondroses between the supraoccipital, exoccipital, basioccipital, basisphenoid, and presphenoid bones were prematurely obliterated histologically, resulting in a substantial decrease in the length of the cranial floor. The latter specimen also exhibited micromelic shortening of the limbs with abnormal chondrocyte proliferation and maturation at the epiphyseal growth plates. The alterations in the size and shape of the calvarial bones subsequent to premature sutural synostosis were more severe in the specimen with premature closure of the cranial base synchondroses. The striking differences observed in the anatomic and histologic analysis of the specimens demonstrated tha the cloverleaf skull malformation must be etiologically and pathogenetically heterogeneous.

Abnormalities, Multiple↗
PubMed1981

The facial features of holoprosencephaly in anencephalic human specimens. I. Historical review and associated malformations.

At least 19 human anencephalic specimens have been published which have the facial features of holoprosencephaly. All categories of holoprosencephaly are represented except ethmocephaly, the rarest form. Because of current scientific and clinical interest in both neural tube defects and holoprosencephaly it seems important to establish whether or not this association occurs by chance alone. The study of human embryos with holoprosencephaly by Matsunaga and Shiota ('78) and the anencephalic collection of Lemire et al ('78) suggests the association may be real.

Abnormalities, Severe Teratoid↗
PubMed1981

The facial features of holoprosencephaly in anencephalic human specimens. II. Craniofacial anatomy.

The craniofacial anatomy of two anencephalic human specimens with the facial features of holoprosencephaly is reported. Many of the malformations have distinctly holoprosencephalic or anencephalic features. Absence of the entire ethmoid complex, observed in both specimens of the present study, has rarely been described and, to our knowledge, has never been confirmed histologically. The significance of agenesis of the ethmoid bone in the development of normal and holoprosencephalic facial features has not been considered previously. On the basis of several morphological variations in the two specimens described, it is evident that the ethmoid bone provides integral support in multiple planes for tissues of the median face. It is postulated that the spatial relationships of the bony and soft tissue components of the median face are guided and maintained by the ethmoid complex during morphogenesis. Specifically, hypotelorism and superiorly displaced structures of the nose and upper lip may well represent migration of embryonic tissues into areas normally occupied by the ethmoid bone. Absence of the sella turcica and pituitary gland is ascribed to the holoprosencephalic process. A variant of choanal atresia, due to collapse of the pterygoid plates, is described.

Anencephaly↗
PubMed1981

The effects of early Le Fort I osteotomies on craniofacial growth of juvenile Macaca nemestrina monkeys.

Le Fort I osteotomies were performed on three juvenile Macaca nemestrina monkeys with midface deficiencies from prior extraoral traction. The maxillas of these monkeys were moved anteriorly an amount necessary to achieve about 8 mm. of horizontal overjet. Interosseous wires were used to stabilize the segments; the animals were not placed in intermaxillary fixation. Craniofacial growth in the three experimental monkeys and in three control monkeys was monitored for 2 years with serial cephalometric radiographs. Compared to the controls, the maxillas of the experimental animals demonstrated less anterior growth, and this was manifested clinically in anterior dental cross-bite relationships. Histologic examination of the circummaxillary sutural complex revealed normal morphology. It is concluded, therefore, that early Le Fort I osteotomies significantly affect subsequent maxillary growth in monkeys and that this effect probably is due to formation of scar tissue.

Animals↗