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[Morphofunctional aspects of the stomatognathic apparatus in the totally edentulous patient. Prosthetic rehabilitation].

The authors examined the morphofunctional aspects of the various structures of the stomatognathic apparatus in the totally edentulous patient with the aim of carrying out and incorporating full prosthetic restoration. The following aspects are evaluated: 1) the reactive behaviour or resilience of the fibromucous support in the various areas under the functional load and its functional conditioning; 2) the vertical and horizontal intermaxillary ratios. Its modifications in an edentulous subject; 3) the evaluation and optimisation of the verticentre, namely the correct stable functional centre reference; 4) the regulation of muscle strength in relation to the length of contraction of muscle fibre; 5) type 3 lever mechanism in mandibular function and the creation of a balance distribution of occlusal forces in the centre. A suitable functional occlusive scheme in the total prosthesis achieves a correct adjustment of muscle contraddiction and a balanced distribution of load forces on the supporting tissues and on the temporomandibular joints. It constitutes a functional centre reference which centralises and stabilises the jaw and the prosthesis. In addition to correct technical installation, this also depends on a detailed preliminary diagnostic evaluation of the anatomofunctional conditions of all the structures in the stomatognathic apparatus of the subject to be treated.

Dental Prosthesis↗

New formation of periodontal tissues around titanium implants in a novel dentin chamber model.

Direct bone-to-implant contact, defined as "osseointegration", is considered most optimal for long-term stability and survival of dental implants. However, the possibility of the formation of a tooth-like attachment apparatus around implants has also been demonstrated. The purpose of this study was to explore the formation of periodontal tissues around titanium implants using a novel and unique experimental model. After resection of the crowns of the maxillary canine teeth in nine mongrel dogs, the roots were hollowed to a depth of 5 mm leaving a thin dentinal wall. Slits were prepared in the cavity wall to create passages from the chamber to the periodontal ligament area. A custom-made, titanium implant was placed into the center of each chamber. Machined, titanium plasma sprayed (TPS) and sand blasted with large grit and acid attacked (SLA) surfaces were used. A collagen barrier was placed over the submerged chamber. Following 4 months of healing, jaw sections were processed for histology. Newly formed periodontal ligament, alveolar bone, and root cementum filled the space between the implant and the wall of the chamber. Ingrown bone was neither in contact with dentin nor with the implant. Thus, an interposed soft connective tissue layer was present. Healing by fibrous encapsulation was observed around most implants. However, cellular cementum was deposited on one TPS and one SLA implant and on the dentinal walls of the chamber. This study shows a remarkable capacity for new periodontal tissue formation at a site where no such tissues ever existed. Maintenance of original periodontal tissue domains most likely prevented osseointegration of the implants. The cementum layer deposited on two implants was likely formed through cementoconductivity rather than by differentiation of periodontal ligament cells upon contact with the implant surface.

Animals↗

The effect of topical fluorides, after acid etching of enamel, on the bond strength of directly bonded orthodontic brackets.

This study tests the hypothesis that the beneficial effects of topical fluoride can be realized without reducing the bond strength of the resin adhesive. Twenty-eight groups of four teeth (third molars and premolars) were extracted from twenty-eight patients and stored in distilled water. Twin brackets on Ormesh pads were bonded to all teeth with Endur adhesive. One tooth from each group was bonded according to the manufacturer's instructions. These teeth, Subgroup I, served as controls. Subgroup II teeth were etched for 4 minutes with 50% phosphoric acid containing 2 percent sodium fluoride. Subgroup III teeth received a 3-minute application of a basic phosphate fluoride solution (10(-2)M NA3PO4, 10(3) ppm F) after 1 minute of etching with 50 percent phosphoric acid. Subgroup IV teeth received a 4-minute application of 8 percent stannous fluoride solution after 1 minute of etching with 50 percent phosphoric acid. Each tooth was mounted in a block of improved dental stone; guide wires were used to reproduce bracket orientation. The M.T.S. materials-testing apparatus was used to generate a torsional moment on the bracket at a rate of 1 degree per second. Fluoride uptake by enamel has been shown to be greater in an acid medium or after acid etching. The application of directly bonded orthodontic brackets and pit-and-fissure sealants requires acid etching of the enamel surface. This study supports the use of topical fluoride after acid etching, a procedure that achieves the benefits of increased fluoride uptake without changing the bond strength of the resin adhesive.

Acid Etching, Dental↗

[Dental assisted distraction osteogenesis of the mandible. Results of an animal experimental study and initial clinical application].

In recent years lengthening of the human mandible by distraction osteogenesis has become an accepted treatment for correction of severe mandibular disto-basal discrepancies. Using extra-oral and intra-oral distraction devices the technique of osseous anchorage is usually preferred. To avoid the disadvantages of this method it is the aim of many research groups to develop a tooth-borne distraction. In the present animal study, six minipigs were treated with a new solely dentally fixed orthodontic device for mandibular distraction osteogenesis. Following bilateral osteotomy in the dentigerous area of the mandibular body and a latent period of 2-7 days, a mandibular lengthening of 9 mm was reached within a period of 9 days. This situation was retained using the distraction device for 6 weeks. After the removal of the apparatus, there followed a period of another 6 weeks of consolidation. The callus and bone formation and potential dental, periodontal and nerval reactions were radiologically examined and histological examination was performed at the end of the experiment. At 12 weeks after the mandibular lengthening, the osteogenesis in the distraction areas was complete. No destructive processes were recognizable, either at the roots or at the periodontium of the teeth near the osteotomy gap. The mandibular nerve at the osteotomy site remained intact. The results justified transferring this procedure to humans. The clinical application of the device is presented.

Adult↗

Tooth-borne distraction of the mandible. An experimental study.

Two mini-pigs and 6 micropigs were fitted with a dentally fixed device for osteodistraction of the mandible. Following bilateral osteotomy and after a latency period of 7 days, the apparatus was activated 1 mm per day. A 9 mm lengthening of the mandible was achieved. After a retention period of 6 weeks, the device was removed followed by a consolidation period of 6 weeks. During the experiment, the callus and bone formation and potential dental and periodontal reactions were radiologically examined. Polychrome sequential labelling was performed by injecting calcein green and xylenol orange for histological assessment of bone. The animals were killed at the 14th postoperative week and the area of distraction and the roots of the adjacent teeth were histologically studied. After 12 weeks, the osteogenesis in the distraction gap was complete, showing lamellar bone. No detrimental effects at the roots or in the periodontium of the adjacent teeth were seen. Thus, lengthening or widening of the mandible using a tooth-borne distraction device seems feasible in selected cases.

Animals↗

An electron microscopic study of collagen formation in the dental pulp of the human premolar and rat incisor.

Collagen secretion and maturation were investigated at the ultrastructural level. Pulp tissue from the continuously growing incisor of the rat provided excellent material for studying the secretory aspects of the tropocollagen. More mature human pulp material proved valuable in viewing the collagen fibril. A networklike arrangement of fibroblasts and fibrocytes was noted. Various types of cell junction were found in all specimens. The finding of a nexus junction was particularly interesting. It is hypothesized that connected cell systems rather than single cells might be the functional units involved in collagen formation.

Adult↗

Salivary gland aplasia: an ectodermal disorder?

A case of a patient presenting with the symptoms of lifelong xerostomia is discussed. Clinical investigation demonstrated aplasia of all the major salivary glands, lacrimal gland hypoplasia and enamel hypoplasia. The management and aetiology of the case is discussed.

Adult↗

Relationship between oral alveolar bone loss and aging among African-American and Caucasian individuals.

BACKGROUND: The periodontal attachment apparatus consists of the periodontal ligament, alveolar bone, cementum and supra-crestal connective tissue. They are interdependent and provide protection and support to the dentition. It is theorized that the integrity of the periodontal apparatus can be maintained throughout life by exercising comprehensive oral hygiene practices and routine dental care. Additionally, it appears to be unaffected by aging. As a consequence, the investigators performed a study to determine the effects of chronological aging on alveolar bone loss. OBJECTIVE: The present study was conducted to determine the relationship between oral alveolar bone loss, oral hygiene, and aging among African-American and Caucasian populations. METHODS: The population consisted of 229 individuals. There were 131 men and 98 women. With respect to race there were 89 African-Americans and 140 Caucasians. Oral examinations, oral hygiene and missing teeth determinations and bitewing radiographs were performed on all the individuals. Radiographs were digitized and measurements were made from the cementum/enamel junction to the alveolar bone crest. Measurements were made for both the maxillary and mandibular jaws. RESULTS: The results of the study showed a significant multiple linear regression model relationship between oral bone loss and aging. Oral hygiene was a factor, but contributed only slightly to the overall model. Race, gender and the number of missing teeth were not significant variables in the overall model. CONCLUSION: The results of this study suggest age-related alveolar bone loss.

Adult↗

[Methods of treatment of preschool children used in the orthodontics department, Institute of Stomatology, Medical Academy in Warsaw].

The reported analysis was based on 288 clinical cards of patients aged 2 to 6 years, admitted for treatment in the years 1980-1985. The greatest group was that of children aged 3 years (28%), followed by those aged 6 years (25%). Abnormalities from the group of distocclusion prevailed (28%), followed by teeth abnormalities (26%), and cross-bite (16%). In 165 cases functional apparatus was used initially, in 66 cases Schwarz or Adams plates, in 31 cases dental prostheses, and in 22 cases chin sling. Four cases were observed after removal of malocclusion cause. Besides treatment with removable devices myotherapy and spatula exercises were used.

Child↗

Applicator for cyanoacrylate tissue adhesive.

Cyanoacrylate tissue adhesive (CTA) is very useful for emergency treatment of corneal perforations. Lack of Food and Drug Administration approval as well as concerns about toxicity from the application of large amounts of glue, however, have limited its use. It is difficult to apply a sufficiently small amount of glue or to achieve a water tight seal using published techniques of glue application. We have found a commercially available micropipette (used in dental work) to be more effective than other methods of CTA application. With this apparatus, precise and accurate placement of minimal amounts of CTA at the slit lamp is consistently possible.

Adult↗

[Accelerated orthodontic treatment with a device for one-way pushing of teeth].

A device for the treatment of dental-jaw deformities with teeth in medio- disto- and transposition is proposed. The device is successfully applied for pushing of teeth, in medio- and disto-position, to their normal place along the dentition. A modification of an intraoral apparatus, the device proposed is a combination of a palatal plaque with a segment guaranteeing one-way pushing of single teeth medially or distally, depending of the deformity. It is distinguished for its light technological manufacture of materials with low prime cost. Its better effectiveness and applicability than the so far known orthodontic apparatuses have been confirmed on the base of data reported about clinical, paraclinical and X-ray studies of children with dental-jaw deformities--healed.

Adolescent↗

[The physical properties of silicone impression materials with hydrophilicity and hydrophobicity. Wetting, water absorption, surface structure of dental stone and dimensional change on stone dies].

In order to compare the physical properties of the silicone impression materials with regard to their hydrophilicity and hydrophobicity, wetting and water absorption, the surface structure and dimensional changes of stone dies were investigated. The evaluation of wetting was performed on one kind of addition-type material with hydrophilicity, five kinds of addition-type materials with hydrophobicity and one kind of condensation-type silicone impression material. One kind of addition-type silicone impression material with hydrophilicity and hydrophobicity was used in other research. Wetting was assessed by measuring the contact angle between water and the impression materials. Water absorption was assessed by the change in weight of the impression materials after immersion in water. The surface structure of the dental stone was observed by SEM. The dimensional changes of stone dies were measured by means of an apparatus designed in this department. The results were as follows: 1. Wetting: The addition-type impression material with hydrophilicity had a 51.4 +/- 1.3 degree contact angle, and other impression materials varied from 84.6 +/- 6.1 degrees to 97.7 +/- 4.4 degrees. 2. Water absorption: The amount of water absorption of the hydrophilic type was greater than that of the hydrophobic type. 3. The surface structure of dental stone: In the case of Vermix stone, which was poured into water-immersed hydrophilic type material, the stone crystals became large, but Fujirock showed no change. 4. The dimensional change on stone dies: No difference was apparent between the hydrophilic type and the hydrophobicity type. 5. Hydrophilicity may affect the surface structure of the dental stone slightly but this is possible within the permissible clinical limits.

Absorption↗

A case of major salivary gland agenesis.

Major salivary gland agenesis is a rare disorder and only a few instances of the condition have been reported. The number of absent salivary glands and the degree of associated xerostomia vary between individuals. Salivary gland agenesis can cause profound xerostomia in children and there may be oral and upper respiratory tract sequelae, such as dental caries, candidiasis, ascending sialadenitis, laryngitis and pharyngitis. Salivary gland aplasia may be associated with other ectodermal defects, particularly abnormalities of the lacrimal apparatus. We report on the first observation of major salivary gland agenesis in South Korea. A child with xerostomia should be appropriately investigated and diagnosed, and careful attention should be paid to the prevention and treatment of sequelae.

Adult↗

Disturbances in the contraction and co-ordination pattern of the masticatory muscles due to dental restorations. An electromyographic study.

Recent Swedish publications report that a large number of patients suffer from the mandibular dysfunction syndrome. Some theories assume that this syndrome is the result of a disturbance in blood flow through the maxillary artery. The present authors suggest, that the syndrome is caused by a disturbance in the pattern of contraction of the masticatory muscles. This hypothesis is based on the assumption that the human periodontal membrane contains mechanoreceptors which are able to exert reflex control over the pattern of contraction of the muscles during chewing. If the pattern of stimulation of these receptors is modified following dental restoration, then this could result in a disturbance of the neuromuscular pattern of the masticatory apparatus. In order to test this hypothesis, an electromyographic study was carried out in three volunteers and eight patients. The results of this study support the view that there are receptors in the human periodontal membrane which are able to control the pattern of contraction of the masticatory muscles. The hypothesis that the mandibular dysfunction syndrome is the result of a disturbance in the pattern of contraction of these muscles is pursued further in the discussion.

Adult↗

Rigidity of dental local anaesthetic injection needles.

The objective of this study was to determine the rigidity of 11 different types (4 brands) of dental local anaesthetic injection needles available in South Africa. Twenty needles of each type were attached to a Zwick material testing apparatus and subjected to pressure testing. Stress vs deformation curves were obtained for each needle. The data obtained was logarithmically converted and subjected to an analysis of covariance. The results from this study showed that there were statistically significant differences in the rigidity of dental needles available on the South African market.

Anesthesia, Dental↗