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Biomedical subjects

J R Strub

Publications and source records attributed to J R Strub.

At least 37 records · Page 2Linked to original sources
PubMed1997

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Part IV. Evaluation of hydroxyapatite-coated implants.

The aim of this study was to evaluate clinically, histologically and histometrically the use of hydroxyapatite-coated dental implants in conjunction with maxillary sinus augmentation procedures. In 4 adult male Rhesus monkeys (Macaca mulatta) the 3 maxillary molars on 1 side of the jaws were extracted and the remaining bone between the alveolar crest and the floor of the sinus was reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed in each monkey and the sinuses were grafted with a porous hydroxyapatite bone graft (Interpore-200). At the same time, 2 hydroxyapatite-coated cylinder implants (IMZ) were immediately placed into the augmented sinuses (i.e. simultaneous-implants-loaded group). Four months later, 2 additional similar implants were placed into the previously augmented sinuses (i.e. delayed-implants-loaded group). After 4 months, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received the same treatment with the exception that removal of the maxillary molars was performed 7 months after those in the opposite side, and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous-implants-unloaded group and delayed-implants-unloaded group) were obtained. Clinically, all loaded and unloaded implants were stable the day of sacrifice. Histologically, the grafted sinuses exhibited a significant amount of new bone formation with integration of the porous hydroxyapatite graft particles and hydroxyapatite-coat of the dental implants to the new bone. Histometric analysis indicated that on the loaded side the implants placed simultaneously with the sinus lift procedure exhibited greater direct mineralized bone-to-implant contact than the delayed placed implants. In addition, the percentage of direct mineralized bone-to-implant contact was significantly greater in the residual bone in comparison to the augmented area in all groups. Loading of the implants exhibited a positive effect on the percentage of direct mineralized bone-to-implant contact in the augmented area. It could be concluded that hydroxyapatite-coated implants may be of benefit when used in conjunction with sinus augmentation procedures.

Alveolar Process↗
PubMed1997

Permeability of dentine after Nd:YAG laser treatment: an in vitro study.

The purpose of this investigation was to determine the effects of Nd:YAG laser treatment on the permeability of dentine. Forty dentine discs were prepared by horizontal sectioning through the middle coronal third of freshly extracted non-carious third molars. After the removal of the pulp the discs were finished with 600 grit and divided into three test groups and one control group (n = 10). For the test group three different laser power settings were chosen: test group A: 3 x 60 sec, 60 mJ; test group B: 3 x 60 sec, 90 mJ; test group C: 3 x 60 sec, 120 mJ. No laser treatment was performed on the control group. In a two-chamber system the filtration rate of dentine tubules from an exactly defined area of the specimens was measured using a radioactive Ringer solution under a pressure of 30 cm H2O. Permeability measurements were carried out three times prior to lasing, three times immediately following laser treatment and six times after the application of phosphoric acid. Analysis of variance showed a significant influence of the Nd:YAG laser treatment on the permeability of dentine (P < 0.001). The mean quotient of non-treated control vs. lased dentine was 2.19 +/- 0.86 for the 60 mJ beam, 1.49 +/- 0.88 for the 90 mJ beam, and 2.04 +/- 2.17 for the 120 mJ beam. Etching the lased surfaces had a statistically significant influence on the permeability of the dentine only in the 60 mJ group (P < 0.001). The data show that the Nd:YAG laser treatment often increases the permeability of smear layer covered dentine but moderates the increase of permeability after etching the surface with phosphoric acid.

Acid Etching, Dental↗
PubMed1996

Clinical comparison of postoperative sensitivity for a glass ionomer and a zinc phosphate luting cement.

In 60 patients, 120 partial and full-coverage restorations were cemented on vital abutment teeth with either a glass ionomer or a zinc phosphate luting cement. A split-mouth design and a patient blind data acquisition protocol were used. During an average observation period of 17.3 months there were no differences between the two types of luting cements in regard to subjective and clinical parameters. A high incidence of postoperative hypersensitivity, which is often said to accompany the use of glass ionomer luting cements, was not observed. With the cementation method used in this study, the glass ionomer cement Ketac-Cem Maxicap was an acceptable alternative to conventional zinc phosphate cement. Capsule systems make the clinical handling of glass ionomer luting cements safe and easy and should be used routinely in dental practice.

Adult↗
PubMed1996

Prosthetic rehabilitation in patients with temporomandibular disorders.

Decision-making in prosthetic dentistry and in the management of patients suffering from temporomandibular disorders is strongly influenced by the clinical and educational background of the dentist. The prosthetic rehabilitation of patients affected by one of the various subsets of temporomandibular disorders is a particularly challenging task, and the literature about this topic is limited. This article reviews the current situation and gives suggestions on how the dentist should proceed in the prosthetic treatment of these patients.

Decision Making↗
PubMed1996

Computerized axiographic evaluation of condylar movements in cases with fractures of the condylar process: a follow up over 19 years.

The treatment of fractures of the mandibular condylar process(es) can be conservative or surgical. However, in many cases, a definitive judgment on the functional long-term outcome of the chosen therapy can only be given many years after the intervention. As a result, it is clearly useful to be able to review the effects of treatment undertaken at least 15 years previously. Even so, only two such studies have been identified. Therefore, the aim of the present study is to evaluate the current functional capacity of the mandibular condyles of 20 subjects who had had an uni- or bilateral fracture of the condylar process, on average 19 years ago. The individuals, who all had been treated conservatively, were compared with a control group of healthy volunteers matched for gender and age. Besides measuring maximum mouth opening (MMO), computerized axiographies in the sagittal plane were made for each condyle during MMO, maximum protrusion and maximum mediotrusion. In spite of the high degree of inter-individual variability in both groups, the data showed that the amount of condylar movement was in most cases greater in the control group. In general, it appears that the risk of developing functional problems after conservative treatment is highest in the case of a fracture of the condylar process accompanied by condylar luxation, rather than by a condylar dislocation or without it.

Adult↗
PubMed1995

Extracellular matrix interactions during the in vivo degradation of collagen membranes in the rat skin: immunohistochemical distribution of collagen types IV, V, and VI.

The role of collagen implant material (CIM) in periodontology is of considerable interest to the clinical dentist because of the capacity of connective tissue (CT) regeneration and partial prevention of epithelial cell migration onto the root surface. The aim of this study was to demonstrate alterations of the CT matrix after the use of CIM in subcutaneous pockets in the rat skin. We used 15 rats in this study. After sedation, two subcutaneous pockets (2 cm in length) were surgically made in the animals' backs. Collagen membranes were implanted in one of the two pockets (test site). The other pocket served as control. Then, 4, 7, 14, 21, and 28 days after implantation, the animals were sacrificed and biopsies preserved for histologic and immunohistochemical examination. Incubation with antibodies against CT matrix components (collagen type IV, V, and VI) were used for immunostaining. Histologically, the CIM was migrated by inflammatory cells in the first 7 days. Newly formed fibroblasts and blood vessels (BV) were present 14 days postimplantation. Collagen type IV was localized in the basement membranes of the epithelium, BV, and nerves. An increase in the BV amount was demonstrated around (and later in) the implant material. Collagen type V was found in a filament pattern of distribution and was inserted into the implant after 4 weeks of healing. Collagen type VI showed a microfibrillar pattern of distribution with a delayed formation in the graft mass. The data showed the alterations of the matrix after implantation of collagen type I membranes in the rat skin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effects of Nd:YAG laser on wound healing processes: clinical and immunohistochemical findings in rat skin.

BACKGROUND AND OBJECTIVE: The clinical effects of the Nd:YAG laser in the rat skin as well as alterations of the extracellular matrix during healing were presented in this study. STUDY DESIGN/MATERIAL AND METHODS: This study evaluated the clinical effects of the Nd:YAG laser used with different energy parameters (low energy: 1.75 W and 20 pps/high energy: 3.0 W and 30 pps) in a duration 20-40 s in rat skin. Control incisions were performed with a scalpel blade. Rat skin incisions were examined over a period of 28 days by clinical photographs as well as by using immunohistochemical techniques in order to find the distribution and the amount of the extracellular matrix fibrillar components, i.e., collagen types I and III. RESULTS: Low energy laser treatment caused a rapid wound healing without scar tissue formation (compared to the high energy laser group) and clinical signs of scar tissue formation (compared to control incisions with the conventional scalpel). During the study period, the laser-induced lesions healed through reparative synthesis of the matrix proteins, which led to filling of the tissue defects. The regenerative processes were similar in the low-energy laser group and in the control incisions. In the high-energy lased tissues, we observed a delayed replacement of the defects by newly formed extracellular matrix proteins. CONCLUSIONS: This study showed a slower wound healing in the high-energy lased tissues. A similar healing in the low-energy lased tissues and in the incisions with the conventional scalpel was observed. The differences in the distribution of matrix proteins during healing and the coagulation of the tissues, which were exposed to low-energy laser treatment, might be the explanation for the minimal scarring, contraction, and pigmentation of the lased tissues as compared to conventional incisions.

Aluminum Silicates↗
PubMed1995

Influence of the suprastructure on the peri-implant tissues in beagle dogs.

The purpose of this study was to compare clinical, radiographic and histological differences around titanium oral implants loaded with either acrylic-veneered metal or ceramo-metal fixed prostheses. Five beagle dogs were used in this investigation. At the beginning of the study, all mandibular premolars and first molars were extracted. After 3 months of healing, 2 Brånemark implants were installed on each side of the mandibles. Three months later, abutments were inserted on each implant and a daily oral hygiene regime was initiated. One month after abutment connection, the implants on one side of the mandible were restored with an acrylic-veneered metal fixed prosthesis, whereas, on the other side a ceramo-metal fixed prosthesis was inserted. The prostheses were constructed in occlusion with the maxillary first molars. The following clinical parameters were measured around each implant at this time (i.e., baseline), and thereafter, at monthly intervals up to 5 months: Plaque Index; Gingival Index; implant mobility (using the Periotest); probing depth and clinical attachment level (using the Florida Probe). In addition, standardized radiographs were taken at baseline and 5 months after insertion of the prostheses and evaluated by subtraction radiography. Another Brånemark fixture was installed on each side of the mandibles 3 months before the end of the study. These implants remained unloaded and submerged for the entire study period. Five months after prosthesis insertion, the animals were killed, and implants with their supporting peri-implant tissues were processed for histological evaluation. Analyses of the clinical, radiographic and histometric parameters revealed no significant differences between the acrylic-veneered and ceramometal loaded implants.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylic Resins↗
PubMed1995

A comparative histological study of wound healing following Nd:YAG laser with different energy parameters and conventional surgical incision in rat skin.

Wound healing following the use of Nd:YAG laser with different frequencies and energy parameters (20 pps and 1.75 W/30 pps and 3.0 W), and the conventional scalpel incision were studied over a period of 4, 7, 14, 21, and 28 days in the rat skin. The low-energy laser wounds could not be significantly differentiated from the conventional incisions although less damage and inflammatory reaction, increased matrix production, and only a little wound contraction could be demonstrated. In the high-energy lased tissues extensive damage and an increased inflammatory reaction were present. The low-energy Nd:YAG and scalpel incisions established a normal wound healing without scar tissue formation compared to the high-energy Nd:YAG, where the necrosis was higher.

Animals↗
PubMed1995

Treatment of exposed implant threads using a synthetic bone graft.

The aim of this study was to evaluate clinically and histologically the use of a synthetic bone graft (Ionogran) alone and in combination with guided bone regeneration (GBR) to facilitate bone regeneration and augmentation around exposed implant threads. Five male Beagle dogs were used in this investigation. Prior to the study all 3rd and 4th premolars were extracted. After 3 months, a flap was elevated and two Brånemark implants were inserted in each quadrant in such a way that two-three threads remained exposed over the alveolar bone. On the control sites the synthetic bone graft was then placed around the exposed threads and the flaps were repositioned and sutured. On the test sites, the same procedure was performed, but an expanded polytetrafluoroethylene barrier was placed to cover the bone graft and implants. Three months after implant placement, the barriers on the test sites were removed, healing abutments were inserted on all implants, and a thrice weekly plaque control regime was initiated. The following clinical parameters were measured at 1, 2, and 3 months: Plaque Index, Gingival Index, Probing Depth and Clinical Attachment Level. Three months after abutment connection the animals were killed and specimens were obtained for histological evaluation. Clinical parameters revealed a significant improvement on the experimental sites compared to control sites during the 3 month loading phase. Histological analyses, however, could not determine a difference in the nature of the implant/tissue interphase between experimental and control sites.

Aluminum Silicates↗
PubMed1995

[The recognition of mandibular asymmetries in the panoramic tomogram. An example of the need for judging the value of a diagnostic procedure].

According to Habets et al. (1988), dental rotational panoramic radiographs can be used to diagnose vertical asymmetries between the right (R) and left (L) mandibular condyle and/or ramus. The difference in vertical height between the two sides is expressed by an asymmetry index which is calculated with the formula (R - L)/(R + L) x 100%. The aim of this paper is to investigate the accuracy of this diagnostic method with the help of the parameters sensitivity and specificity. For each of 25 fully preserved and macerated skulls with a stable occlusion. Two dental rotational panoramic radiographs were made. The values obtained for condylar and rami heights as well as for the asymmetry indices as proposed by Habets and al. (1988) were compared with the values received from the corresponding measurements on the skulls. For the determination of sensitivity and specificity, the five highest asymmetry values found on the skulls were classified as "high asymmetry present". In order to achieve an acceptable sensitivity (.8), an insufficient specificity must be accepted (for ramus height .25, condyle height .2), resulting in a very high rate of false positive diagnoses. The study emphasizes the necessity of a critical evaluation of the utility of diagnostic tests and procedures.

Diagnostic Errors↗
PubMed1994

Influence of water storage and thermal cycling on the fracture strength of all-porcelain, resin-bonded fixed partial dentures.

The purpose of this in vitro study was to evaluate the influence of water storage and thermal cycling on the fracture strength of two designs of all-porcelain, resin-bonded fixed partial dentures made with the glass-infiltrated alumina ceramic In-Ceram. Forty frameworks of In-Ceram ceramic veneered with Vitadur-N porcelain were made to replace an upper central incisor bonded to extracted natural teeth. In 20 of the restorations the pontic was veneered only labially with Vitadur-N porcelain and no proximal box preparations were made (design A). The other 20 restorations had additional box preparations proximal to the pontic and the In-Ceram ceramic pontic framework was shifted to the labial aspect and veneered circumferentially with Vitadur-N porcelain (design B). Subgroups of 10 restorations were stored for 7 days in thymol solution or alternatively for 150 days in artificial saliva with thermal cycling for 18,750 cycles between 5 degrees and 55 degrees C. Restorations with design B had a statistically significantly higher fracture strength than restorations with design A. Storage in artificial saliva with thermal cycling significantly reduced the fracture strength of the resin-bonded In-Ceram fixed partial dentures. Therefore, the long-term clinical behavior of resin-bonded In-Ceram fixed partial dentures must be evaluated before general clinical use can be recommended.

Aluminum Oxide↗
PubMed1994

Titanium deposition in regional lymph nodes after insertion of titanium screw implants in maxillofacial region.

The deposition of titanium in regional lymph nodes was studied after insertion of endosseous, plasma-spray-coated titanium screw implants in a total of 19 beagle dogs. Five additional animals with no implants served as the control group. After killing the animals 9 months postoperatively, the regional lymph nodes were carefully excised, and samples were prepared for histologic examination. Other samples were used to identify foreign particles by energy-dispersive x-ray analysis and for measurement of the titanium concentration in the tissue by flameless atomic absorption spectroscopy. Very fine foreign-body particles could be seen in the histologic sections, and they were identified as titanium by energy-dispersive x-ray analysis. The atomic absorption analysis for titanium revealed a significantly higher concentration in the group with implants. The presence of very fine, poorly attached particles on the plasma-sprayed titanium surface suggests that these particles may be mechanically dislodged from the surface on insertion of the implants. This suggests that the fine particles may be transported by phagocytes to the regional lymph nodes, where they could be found without any signs of inflammation or foreign-body reaction.

Animals↗
PubMed1994

Bone augmentation using a synthetic bone graft in dogs.

The aim of this investigation was to evaluate clinically and histologically the use of a synthetic bone graft (Ionogran) alone and in combination with guided bone regeneration (GBR) for alveolar ridge augmentation. Five beagle dogs were used in this study. Prior to the augmentation procedure the maxillary and mandibular second, third and fourth premolars were extracted. Three months after the extractions, impressions from the area of the ridges were taken. Particles of Ionogran were then placed under mucoperiosteal flaps in each quadrant. On the experimental sites, an expanded polytetrafluoroethylene barrier was placed between the flap and the particles. Impressions were retaken at 1 and 3 months after surgery. Three months after surgery, the animals were sacrificed and specimens were prepared for histological evaluation. Computer-assisted volumetric analyses from the casts revealed an increase in ridge volume from baseline in both groups at 1 and 3 months. There was no difference in the height of the augmentation between the test and control sites. The histological results of this study indicate that this new synthetic bone graft appears to be a safe biocompatible grafting material. There were no apparent histological differences between the graft alone and graft/GBR sites. In both groups, however, graft particles were surrounded by dense fibrous connective tissue and bone formation was limited to the graft bone interface.

Aluminum Silicates↗
PubMed1993

Three-dimensional investigation of the accuracy of impression materials after disinfection.

The influence of the two new disinfection systems Hygojet/MD 520 and Impresept on the accuracy of eight impression materials was evaluated with a clinically relevant abutment arrangement. In addition, an "aseptic" irreversible hydrocolloid was tested under the same test conditions but without the disinfection procedure. The dimensional changes of all eight impression materials related to the disinfection procedures were small. Although statistically significant interactions of the impression materials and the disinfection systems were found, the influence of the two tested disinfection systems on the dimensional accuracy of the impressions does not seem to be clinically relevant. From the standpoint of impression accuracy, both tested disinfection systems and the tested "aseptic" irreversible hydrocolloid can be recommended for clinical and laboratory use.

Analysis of Variance↗