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Biomedical subjects

I M Brook

Publications and source records attributed to I M Brook.

At least 19 recordsLinked to original sources
PubMed1992

Characterisation of the ultrastructure of glass-ionomer (poly-alkenoate) cement.

Set glass-ionomer cements were sectioned with a diamond knife and examined in the transmission electron microscope. Their appearance was in accordance with the theoretical structure of these materials, close examination revealing glass particles surrounded by a siliceous layer set in a hydrogel matrix. The elemental composition of each region was determined by X-ray microanalysis (energy dispersive). The results of microanalysis supported the ultrastructural observations, with ions that originated from the glass particles being detected throughout the matrix of the set cement. It was suggested that the mobility of these ions in the matrix phase was important in determining the biocompatibility and adhesive properties of glass-ionomer cements.

Electron Probe Microanalysis↗
PubMed1992

Bone cell interactions with a granular glass-ionomer bone substitute material: in vivo and in vitro culture models.

The interface between bone and a synthetic bone substitute constructed from glass-ionomer cement (ionomeric microimplant) was studied in diffusion chambers implanted in a primate baboon model (Papio ursinus) and in in vitro primary bone organ cultures derived from neonate rat calvaria. In both models osteoblast-like cells colonized the surface of the implant producing a collagenous extracellular matrix. An electron-dense bonding zone similar to that reported for hydroxyapatite and titanium was seen in both models but was a more constant feature of the tissue/implant interface in calvarial culture.

Animals↗
PubMed1991

Oxygen saturation during third molar removal with local anaesthetic alone and in combination with intravenous sedation.

Oxygen saturation was recorded in 96 adults undergoing removal of third molar teeth in the dental surgery. Half the patients received local anaesthetic alone; the remainder received, in addition, intravenous midazolam. Patients receiving sedation sustained the greatest falls in oxygen saturation. However, in 10 out of 48 patients undergoing third molar removal with LA alone, oxygen saturations in the range of 93-89% were recorded. The results of this study suggest that all patients undergoing removal of third molars are at risk of hypoxia. Short episodes of hypoxia may be of little consequence in healthy patients, but in compromised patients early detection may avoid serious complications.

Adult↗
PubMed1991

Controlled intraoral delivery of hydrocortisone sodium succinate.

Controlled release of hydrocortisone sodium succinate from a device consisting of a drug containing a core of polymethyl methacrylate was achieved by the use of a design incorporating impermeable barriers to drug diffusion and the use of a semipermeable membrane. Initial in vivo study showed sustained intraoral delivery of hydrocortisone sodium succinate during a 6-day period.

Administration, Oral↗
PubMed1991

In vitro interaction between primary bone organ cultures, glass-ionomer cements and hydroxyapatite/tricalcium phosphate ceramics.

Primary organ cultures derived from neonate rat calvaria were maintained for 2 wk and used to study in vitro response of osteoblast and periosteal cells to the component and composite forms of three different glass-ionomer (polyalkenoic) cements, comparing them to densely sintered hydroxyapatite and tricalcium phosphate ceramics. Qualitative analysis by scanning and transmission electron microscopy revealed that osteoblasts colonized all the solid test materials, although there was a less favourable response to materials with a rough surface topography and to unset and fluoride-containing glasses. On solid materials migrated cells maintained their tessellated morphology and exhibited numerous micro-appendages anchoring them to the surface of the test materials. A collagen-containing extracellular matrix was elaborated on to the ceramics and set glass-ionomer cements, except for one (AquaCem). Mineralization of the extracellular matrix was seen adjacent to hydroxyapatite and tricalcium phosphate ceramics, that adjacent to the latter morphologically resembling bone.

Animals↗
PubMed1991

Management of the atrophic anterior maxilla by combined hydroxyapatite augmentation and vestibuloplasty: a pilot study.

A technique is described to overcome the problem of the grossly resorbed maxillary alveolus and improve denture wear, by combining augmentation and increased soft tissue cover of the alveolar ridge. Manipulation and placement of the hydroxyapatite was facilitated by use of a hydroxyapatite/collagen composite (HAC) block. The procedure has been carried out in ten patients where extensive resorption contraindicated the use of permucosal implants. Six cases have been followed up for 2 to 3 years. After some initial compaction of HAC the improvement in ridge height has been maintained and long term improvement in denture function obtained.

Alveolar Bone Loss↗
PubMed1990

Inhibition of tissue prostaglandin synthesis during third molar surgery: use of preoperative fenbufen.

Preoperative administration of a non-steroidal anti-inflammatory drug (fenbufen) reduced immediate postoperative pain in a group of 38 patients undergoing removal of mandibular third molars, compared to placebo. However, overall pain experience and morbidity were not significantly improved suggesting that there was no clinical benefit derived from interference with tissue prostaglandin synthesis at the time of surgery.

Adult↗
PubMed1990

A comparative in vitro study of fixation of mandibular fractures with paraskeletal clamps or screw plates.

The use of porcine rib pairs as an in vitro analog for the edentulous mandible is described. Using this model, the relative degree of fixation achieved with a screw plate (Champy) and a paraskeletal clamp plate (Mennen) has been evaluated. The fractured plated ribs failed at significantly lower bending forces than the non-sectioned controls. However, no statistically significant difference in force at failure between the two different methods of plate fixation could be demonstrated.

Animals↗
PubMed1989

Tissue response to subperiosteal implantation of dense hydroxyapatite: case report.

Hydroxyapatite is becoming a popular implant material, yet reports on the tissue response it evokes in humans have been few in number and are based on relatively short periods of implantation. In the present case, implant material became available when it proved necessary to modify an alveolar ridge augmentation procedure carried out 18 month previously. Histology showed that whilst some parts of the implanted material were embedded only in fibrous tissue, others had become fully integrated within partly remodelled bony trabeculae. These findings confirm the status of hydroxyapatite as a biocompatible implant material and provide further evidence of its bone-bonding and osteoconductive capacities.

Adult↗
PubMed1989

Two-stage combined vestibuloplasty and partial mandibular ridge augmentation with hydroxyapatite.

The preliminary results of a new two-stage technique for partial augmentation of the edentulous mandibular ridge with hydroxyapatite are reported. The technique, which has been applied to five patients, can be performed under local analgesia, and involves initial placement of temporary silicone spacers, together with submucous vestibuloplasty to preserve sulcus depth. The spacers are later replaced by dense particulate hydroxyapatite, and the connective tissue capsules that remain after removal of the spacers allow control of particle migration and minimize the amount of hydroxyapatite required.

Alveolar Ridge Augmentation↗
PubMed1988

Comparison of sedation with temazepam by mouth and diazemuls i.v. for dental surgery. Variability in absorption may influence clinical effect.

Temazepam elixir 30 mg by mouth was compared with i.v. Diazemuls titrated to a maximum dose of 20 mg in a double-blind study of 50 patients undergoing elective minor oral surgery. The treatments produced a similar reduction in anxiety score and similar degrees of patient relaxation and co-operation. The diazepam group had greater amnesia during surgery, but also showed significant slowing of reaction time at the time of discharge. Patients given temazepam elixir showed wide variations in plasma concentrations. Patients with low plasma temazepam concentrations at the time of surgery showed no significant reduction in anxiety scores.

Administration, Oral↗