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Biomedical subjects

J C Maltha

Publications and source records attributed to J C Maltha.

At least 73 records · Page 4Linked to original sources
PubMed1991

The effect of low-level laser treatment on maxillary arch dimensions after palatal surgery on beagle dogs.

The effect of low-level laser treatment on maxillary arch dimensions after palatal surgery was investigated in Beagle dogs at an age of 12 weeks. A total of 30 dogs was used, and they were assigned to either a control group (Group C, n = 6) or one of two experimental groups (Group L, n = 12; and group LL, n = 12). After Von Langenbeck's palatal repair in the two experimental groups, denuded bony areas in the LL group were irradiated with a continuous Ga-As-Al laser beam (830 nm) and energy output set at 30 mW. A dosage of 1 J/cm2 wound surface area was used. Treatment was carried out three times a week, with a total of ten treatments. The animals of the L group served as non-treated control animals. Dental casts were made of all animals of all groups at regular intervals until they reached 25 weeks of age. Maxillary arch dimensions were studied. Dental arch dimensions in the deciduous dentition of both experimental groups were not disturbed by surgery, but after eruption of permanent teeth, mainly transverse maxillary arch dimensions in the premolar region increased less in both experimental groups than in the control group. It was concluded that low-level laser treatment under the conditions used in this study did not decrease the adverse iatrogenic effects of palatal surgery on maxillary arch dimensions.

Analysis of Variance↗
PubMed1991

[The arrangement of trans-septal fibers in rotated and non-rotated emerged teeth in beagle dogs].

Transseptal fibers of the periodontal ligament are thought to play a role in relapse after orthodontic correction of rotated teeth. The aim of this study was to compare the location of the attachment site and the arrangement of the transseptal fibers in rotated emerged and non-rotated emerged teeth. In five dogs, unilaterally, the first upper premolars were reimplanted into a rotated position, before emergence. Histological evaluation showed that in the experimental as well as in the control specimens transseptal fibers developed. In all cases transseptal fibers bridged the shortest distance between two adjacent teeth. It was concluded that the attachment site of the transseptal fibers is not determined by tooth anatomy itself, but by the tooth position and its orientation in the dental arch during transseptal fiber development.

Animals↗
PubMed1990

Spirochetes in early lesions of necrotizing ulcerative gingivitis experimentally induced in beagles.

The presence of spirochetes and other bacteria during the induction of necrotizing ulcerative gingivitis (NUG) in beagle dogs was studied by transmission electron microscopy. NUG was induced by application of dental debris from diseased dogs to 4 beagles treated with corticosteroid. Biopsies of interdental papillae were collected during a period of 7 weeks. Spirochetes and other bacteria were observed in enlarged intercellular spaces between non-keratinized epithelial cells. Intracellular bacteria were found with and without surrounding vesicular spaces. The invasive spirochetes were mainly intermediately sized and of flagellar "4-8-4" configuration or higher. Bacterial invasion of the sulcular epithelium occurred before clinical evidence of NUG could be observed. It is concluded that invasion by intermediate spirochetes and other bacteria plays a role in initiating ulcerative gingivitis in beagles.

Animals↗
PubMed1990

[The regulation of tooth eruption].

The aim of the present publication is to provide a broad survey of the current concepts on the regulation of tooth eruption. There is increasing evidence that tooth eruption is a multifactorial process. The bone resorption occlusal to an erupting tooth is probably induced by the occlusal part of the follicle, and allows the tooth to erupt. The occlusal movement it self is likely to be regulated by a localized increase in tissue fluid pressure in the apical area. The bone deposition which is often observed apical to an erupting tooth is more likely to be a reaction to the eruption than a source of eruptive forces.

Bone Resorption↗
PubMed1989

Maxillary arch dimensions after palatal surgery at different ages on beagle dogs.

Changes of maxillary arch dimensions were studied longitudinally until maturity, after palatal surgery was performed on 37 beagle dogs at different ages. The dogs were divided into three experimental groups, a sham group, and a control group. At the age of 6, 16, or 25 weeks in the experimental groups, we created a soft-tissue cleft in the medial region of the palate, made relaxation incisions, and elevated and closed the mucoperiosteum in the midline, thus leaving two areas of denuded bone adjacent to the dentition. We made dental casts regularly until the age of 37 weeks, and studied maxillary arch dimensions. Surgery performed before or during the transition of teeth did not change maxillary arch dimensions in the deciduous dentition, but after the transition, the increase in arch width in the pre-molar region was reduced. Surgery performed after completion of the permanent dentition did not change maxillary arch dimensions. Delay of palatal surgery until the transition of teeth was completed favored normal development of the maxillary dental arch.

Age Factors↗
PubMed1989

[Implants with plasma spray coatings of hydroxyapatite: an experimental study in alveolar bone].

Sintered hydroxyapatite ceramic can be coated to a titanium core by means of a high temperature plasma spray procedure. The biological response of alveolar bone to an implant with such a coating of hydroxyapatite was evaluated in an animal experimental study. The results indicated that the plasma spray coating gave a very strong and direct bonding to cortical alveolar bone. The shear strength between bone and ceramic was greater than the shear strength between ceramic and titanium. From a radiological, macroscopic and microscopic point of view the conclusion could be drawn that the biological properties of a plasma spray coating of hydroxyapatite are the same as the properties of bulk hydroxyapatite ceramic. The outermost layer of the hydroxyapatite coating appeared to be unstable under the experimental conditions.

Animals↗
PubMed1988

Growth of the maxilla after soft tissue palatal surgery at different ages in beagle dogs: a longitudinal radiographic study.

This study investigated maxillary growth after palatal surgery at different ages in beagle dogs. Soft tissue clefts were created in the median region of the palate at the age of 6 (group 1), 16 (group 2), and 25 weeks (group 3). Relaxation incisions were made, and the mucoperiosteum was elevated and closed in the midline, leaving two areas of denuded bone adjacent to the dentition. Metallic implants were placed in the palate, and dorso-ventral and lateral radiographs were made until the age of 37 weeks to study sutural growth and overall growth of the maxilla. In groups 1 and 2, growth in the midpalatal suture was less, compared to the control, from 16 to 25 weeks and from 16 to 37 weeks of age. In group 2, less increase was also found in the transverse palatal sutures. Group 3, the sham group, and the control group did not show significant differences. None of the dimensions measured on the lateral radiographs showed any significant differences for any group. It was concluded that palatal surgery as performed in this study has no influence on vertical and antero-posterior maxillary growth; only transverse palatal growth is influenced to a minor degree, especially when surgery is performed before or during the eruption of the permanent posterior teeth.

Animals↗
PubMed1988

Lyophilized auricular cartilage as a replacement for the interarticular disc of the craniomandibular joint. An experimental study in guinea pigs.

Meniscectomy has major disadvantages and should be abandoned. Replacement of the removed interarticular disc is mandatory. As the harvesting of autogenous transplants requires the creation of a donor site defect, the use of preserved allogenic material seems justified. The interarticular disc of six young adult albino guinea pigs was replaced with preserved allogenic auricular cartilage. From the clinical and histological results we concluded that the postoperative clinical course of all animals paralleled the histological appearance of the joints. The transplants showed marked degree of resorption, but were replaced by fibrous connective tissue with focal cartilage formation. This newly formed structure resembled the original disc and protected the articular components of the joints, which, 24 weeks postoperatively, hardly differed from the controls. The role of the synovia in the formation of the "new disc" was quite evident.

Animals↗
PubMed1988

Replacement of the interarticular disc of the craniomandibular joint with fresh autogenous sternal or auricular cartilage. An experimental study in guinea pigs.

Meniscectomy has proved to be a disadvantageous therapeutic method for the surgical treatment of patients with internal derangement of the TMJ. A few authors have reported on the replacement of the removed disc with dermis, fascia and auricular cartilage in clinical reports. To the best of our knowledge no experimental work has ever been published on this subject. The interarticular disc of six young adult albino guinea pigs was removed and replaced with fresh autogenous sternal cartilage and in nine others with fresh autogenous auricular cartilage. After having been followed clinically, the animals were sacrificed after 3, 6, 12 and 24 weeks. Transplantation of sternal cartilage resulted clinically in moderate to marked discomfort. However, histologically no spectacular changes in the joints were found. The auricular cartilage transplants clinically did rather well. Histologically, some changes were found which became less pronounced with time. The use of sternal cartilage is not advisable as a replacement material because of technical reasons. The protective role of the auricular transplants could not be fully evaluated because of their tendency to warp and become displaced, although they retained their original microscopic structure and did not show reactive or resorptive changes. Further studies using larger groups of experimental animals and intermaxillary fixation are justified.

Animals↗
PubMed1988

Longitudinal growth of the rabbit femur after vascular and periosteal interference.

Results are presented of a radiological study with metallic implants concerning the growth in length of the rabbit femur following longitudinal sectioning of the periosteum, with and without stripping, circumferential periosteal division, with and without stripping, and vascular interference. Periosteal sectioning (except in the case of longitudinal sectioning) had the effect of increasing the ultimate length of the femur. The distal epiphysial plate was stimulated after longitudinal sectioning with stripping; both growth plates were stimulated after circumferential periosteal sectioning, with and without stripping. This stimulation was evident until fairly late in the growth period. There are no indications for any inhibition during the last phase of growth. Experimental interference of the subchondral vascularisation had no effect, whilst ligation of the nutrient artery had only a very limited curbing effect on the longitudinal growth due to restraining of the proximal growth plate. It was concluded that the growth stimulation following periosteal damage cannot be the result of vascular interference the diaphysial area. It was hypothesized that the periosteum plays a role as a local regulatory factor in the fine regulation of the growth of the epiphysial plates, acting as an intermediary and transmitting mechanical stimuli generated by other local factors to the epiphysial plates.

Analysis of Variance↗
PubMed1987

Mucoperiosteal migration after palatal surgery in beagle dogs. A longitudinal radiographic study.

In this study, the effect of palatal surgery on the mucoperiosteum was investigated radiographically. 33 beagle dogs were used, divided into 3 experimental groups, a control group and a sham operated group. At the age of 6, 16 or 25 weeks in the experimental groups, a soft tissue defect was created in the median region of the palate by excising a standardized elliptical mucoperiosteal flap. This defect was closed according to the Von Langenbeck technique. Metallic implants were placed in the mucoperiosteum. Dorso-ventral radiographs were taken until the age of 37 weeks. Increments of distances between these mucoperiosteum markers were calculated. Wound contraction in the denuded areas, recorded as the approaching of the opposite metallic implants followed the same pattern for all experimental groups and was restricted to the first 2 experimental weeks. In all experimental groups, the anterior and posterior overall palatal width diminished during the early wound healing compared to the control group. The largest initial effect was found in the anterior region of the palate. The margins of the mucoperiosteal tissue in the median region of the palate moved towards the denuded areas during the first postoperative week. Palatal surgery as performed did not influence antero-posterior distances on the palatal mucoperiosteum.

Animals↗
PubMed1987

Wound healing of the palatal mucoperiosteum in beagle dogs after surgery at different ages.

The aim of this study was to investigate macroscopic wound healing after palatal surgery at three different ages. A total of 37 beagle dogs was used, divided into three experimental groups, a control group and a sham-operated group. Palatal surgery was performed at the age of 6, 16 or 25 weeks respectively. The animals of the sham group and the control group were studied from the age of 6 weeks on. All animals were studied longitudinally over a period of six weeks. The three experimental groups were compared mutually and the youngest experimental group was compared with the sham group and the control group. Clinically the wound healing in the median region was complete after two weeks in all animals. In the denuded areas the wound healing continued for the youngest experimental group for 2 to 3 weeks postoperatively and for the two older age groups for 4 to 5 weeks postoperatively. The wound contraction in the denuded areas, recorded as the increasing approximation of the opposite tattoo points was larger in the two older age groups than in the youngest one and was restricted mainly to the first postoperative week. This effect seemed to be permanent because no compensating increase in distance was found later on. It was concluded that shortly after operation wound contraction was mainly responsible for the reduction of the surface area of the denuded bone, but later on, epithelial cell proliferation was the predominant factor.

Age Factors↗
PubMed1987

The influence of vascular and periosteal interferences on the histological structure of the growth plates of long bones.

Investigations have been carried out on the histological structure of the growth plates of the rabbit femur following interferences of the vascular blood supply in the metaphysial/diaphysial area and following 3 different types of periosteal division. Trepanation of the cortex had no observable effect on the growth plate. Following the other vascular interferences the reaction of the growth plates was characterised by a total or a partial thickening due to an accumulation of hypertrophic cells followed by a period of regeneration until 40 d p.o. Following periosteal intervention only small differences between operated and non-operated femur were observed. It was concluded that the fibrous periosteum, in contrast to the vascular supply of the metaphysial/diaphysial area plays a role in the local growth regulation of the epiphysial plate, probably by affecting the rate of mitosis of the germinal cells.

Animals↗
PubMed1986

The reaction of the periodontium to different types of splints. (I). Clinical aspects.

To study the influence of splints on the periodontia over a period of time, Obwegeser and Merkx splints were applied on beagles. Clinical evaluation using different periodontal parameters was carried out before, and 48 h, 3 weeks and 6 weeks after splinting. It was shown that both splints act as plaque-retentive devices and provoke gingival inflammation. A statistically significant difference between both splints could, however, only be demonstrated for the plaque index.

Animals↗
PubMed1986

The reaction of the periodontium to different types of splints. (II). Histological aspects.

To study the influence of splints on periodontal tissues, Obwegeser and Merkx splints were applied to beagles. Histological evaluation was performed after splinting periods of 48 h and 6 weeks. After 48 h, gingivitis had developed when using both types of splints. After 6 weeks, the adverse effects of the splints were more predominant. Gingivitis had become severe and mild periodonitis had developed. In the case of Merkx splints, the periodontal ligament appeared to be somewhat less affected but the condition of the gingiva appeared to be somewhat worse than in the case with Obwegeser splints. For both types of splints, it is important that clinical application should be attended by measures not only to reduce plaque accumulation, but also to minimize trauma due to their application and continuous mechanical irritation of the tissues.

Alveolar Process↗
PubMed1986

Adherence of oral treponemes and their effect on morphological damage and detachment of epithelial cells in vitro.

The present study shows adherence of Treponema denticola L12D and Treponema vincentii RitzA to guinea pig ear epithelial cells in vitro. The number of adhering organisms was positively related with the treponemal concentration and contact time. Incubation of washed T. denticola L12D and T. vincentii RitzA organisms or their culture supernatants with the epithelial cells induced morphological damage and detachment of these cells. In addition, indications for inhibition of epithelial cell proliferation were found. The activity of the supernatants was dose dependent, heat sensitive, and sensitive to sulfhydryl-containing components, suggesting the presence of enzymatic activity that might be of importance in the pathogenicity of these oral treponemes.

Adhesiveness↗