Hydroxyapatite as a bone substitute in the jaws.

Densely sintered calcium hydroxyapatite has previously been shown to be biocompatible and stable. Its possible role in jaw surgery was investigated using a clinically analogous animal model. The apatite was implanted into the mandible of twelve dogs for 12 weeks, and the healing assessed radiologically and histologically. The new bone which was deposited directly onto the surface of the implants bonded them firmly to the adjacent tissues. There was no fibrous tissue between implant and bone. This material appears to be a suitable substitute for autogenous bone when used as inert 'space filler' in maxillo-facial surgical procedures.

Subperiosteal behaviour of alginate and cellulose wound dressing materials.

A histological comparison was undertaken of the tissue response to a new sodium calcium alginate material (Kaltostat) and an oxidized regenerated cellulose wound dressing (Surgicel) when implanted between bone and periosteum in the jaws at intervals of up to 24 wk. Both biomaterials caused a foreign body reaction, persisting up to 12 wk after surgery. New bone formation occurred along the surface of the mandible in some specimens, but was not apparently related to the implants. It was concluded that the implantation of Kaltostat or Surgicel between bone and periosteum in the jaws caused a delay in wound healing, and had no effect on bone induction.

Dose response and safety of cizolirtine citrate (E-4018) in patients with pain following extraction of third molars.

The objectives of this study were to determine the dose response and safety of the oral analgesic cizolirtine citrate (E-4018) in patients with postoperative pain after third molar extraction. This was a placebo-controlled, double-blind, randomised, parallel-group study. Doses of E-4018 were 50 mg, 100 mg, or 150 mg. The primary outcome measure of efficacy was patient assessment of pain severity, determined from serial visual analogue scales (VAS) over a four-hour investigation period. Other efficacy measures included the number of patients taking escape analgesic and the time before it was taken, and an overall assessment of pain relief on a four-point categorical scale. There was no significant difference between any of the E-4018 treatment groups and placebo in terms of the AUC for VAS pain scores over time. The percentages of patients who took paracetamol within five hours of their dose were 100%, 95%, 78% and 82% for the placebo, 50 mg, 100 mg and 150 mg E-4018 groups, respectively. The time to first use of paracetamol was significantly different for the 100 mg and 150 mg E-4018 groups compared to placebo. There were 17 adverse events, of which five were possibly related to the study medication (one in the placebo group and four in the 150 mg E-4018 group). We conclude that there was a dose-related trend in the percentage of patients requiring paracetamol within five hours of their study medication, and in the percentage of patients that recorded the treatment as providing good or excellent treatment of pain. There was, however, no firm evidence of a dose-related analgesic effect over the dose range of Cizolirtine chosen for this study. E-4018 was well tolerated in all patients.

Glycosaminoglycans in human salivary-duct stones.

These were demonstrated using histochemical and biochemical techniques. The presence of hyaluronic acid and chondroitin sulphate was confirmed by enzymic digestion. These substances may arise from inflammation in peri-ductal tissue.

A comparative histological study of wound healing following CO2 laser and conventional surgical excision of canine buccal mucosa.

The histological changes following removal of 2 cm discs of buccal mucosa by CO2 laser and conventional surgery were studied over a period of 42 days. The laser wound differed from the conventional wound: there was minimal damage to the adjacent tissue; initially a coagulum of denatured protein formed on the surface; the inflammatory reaction was less; fewer myofibroblasts were present and there was little wound contraction; less collagen was formed and epithelial regeneration was delayed and more irregular.

Implant supported overdentures--the Birmingham experience.

OBJECTIVES: The use of an implant retained overdenture with magnets offers a simple treatment approach to the problem of instability of the complete denture. Advantages with magnets include a simplified clinical technique and reduced lateral stresses on the abutments. This paper reports on a long-term study undertaken at Wordsley Hospital and Birmingham Dental teaching hospital in the West Midlands. METHODS: Twenty-one patients received implant-retained overdentures with magnets over a 5-year period. The average age of the patients was 63 years (range 44-83 years). Seventy-eight Astra (Astra Tech AB, Mölndal, Sweden) implants were placed: 17 patients had four, two had three and two had two implants placed. RESULTS: During the 5-year study, 11 implants were lost, one from infection, and the remaining 10 were lost because of a failure of osseointegration. This equates to an 86% success rate which increases to 97% when implants shorter than 1 cm are discounted. Over this period, the average number of dentures constructed per patient was 2.3. The main reason for denture replacement was a loss of function of the magnets. When the steel casing around the magnets was breached, then corrosion resulted. The life expectancy of the magnets over the 5-year period was 77 weeks (+/-50 weeks). One denture was replaced due to problems of instability. Patient satisfaction with the treatment remains high, and all patients can now wear dentures satisfactorily. CONCLUSIONS: The use of a magnet retained overdenture offers a simple reconstructive approach to complete denture instability. Methods are currently being investigated to improve the clinical function and durability of the magnets. The success rate with the implants remains good after 5 years in function.

Hydroxyapatite as a biomaterial for alveolar ridge augmentation.

Hydroxyapatite is a useful biomaterial because of its excellent biocompatibility. It is extremely well tolerated by the hard and soft tissues of the mouth and jaws, and offers great potential for the future. This paper reviews the various physical forms of the material, both solid and porous, its biological behaviour in different implant sites, and the surgical techniques for its implantation. Some of the controversies and doubts about the material are discussed in relation to its use in alveolar ridge augmentation.

Surface analysis of titanium maxillofacial plates and screws retrieved from patients.

This investigation is a controlled human plate-retrieval study. The surface appearances and elemental composition of 50 titanium maxillofacial plates and associated screws retrieved from 39 patients were compared with a control sample of unused plates and screws using stereomicroscopy, scanning electron microscopy and energy dispersive X-ray analysis. There were two surface finishes, either anodized or non-anodized. Surface contamination was detected on both retrieved and control plates consisting of aluminium and silica and was more commonly present on non-anodized specimens. Manufacturing defects comprising rough metal edges and protuberances were identified on the unused controls and surgical damage was evident on the retrieved specimens. There were no signs of corrosion or surface deterioration on the retrieved plates and screws which had been in the tissues for between 1 month and 13 years. There was no evidence from this study to support the routine removal of titanium maxillofacial miniplates plates due to corrosion up to a period of 13 years.

Large calculi of the submandibular salivary glands.

Salivary calculi occur in the submandibular and parotid glands, and their ducts, and occasionally reach a large size. However, little information is available on the composition of these giant stones. 2 cases are reported of unusually large calculi of the submandibular salivary glands. The glands were excised, and the results of chemical and infrared analysis of the calculi are presented.

Human tissue response to porous hydroxyapatite implants. A case report.

Histological examination of 2 porous hydroxyapatite implants removed from a patient showed a pattern of ossification similar to that reported in a previous animal study. New bone was laid down on the surface of the hydroxyapatite but did not progress to occupy all the pores. Although porous hydroxyapatite blocks are biocompatible and well tolerated by the tissues, they are not recommended for augmentation of the resorbed alveolar ridge where the overlying mucosa is thin and atrophic, because of the risk of mucosal dehiscence and implant exposure. They are suitable in situations where they are deeply buried in the tissues and not subjected to direct trauma.

Effect of autogenous bone grafts on healing following Le Fort I maxillary osteotomies.

The healing of Le Fort I maxillary osteotomies was studied histologically in 12 adult rhesus monkeys to determine the effect of split autogenous rib grafts overlaying the osteotomy cuts on the lateral maxillary walls. The maxilla was advanced 8 mm in each animal, and examined at varying intervals up to 24 weeks after surgery. The results indicated that there were no obvious differences between the monkeys with and without the rib grafts. Both groups healed with good osseous union. It is concluded that autogenous rib grafts did not enhance bony healing.

In vivo surface analysis of titanium and stainless steel miniplates and screws.

This study was undertaken to characterize the surfaces of Champy titanium and stainless steel miniplates and screws that had been used to stabilize fractures of the mandible in an animal model. Miniplates and screws were retrieved at 4, 12, and 24 weeks after surgery. Low-vacuum scanning electron microscopy (SEM) of autoclaved unused (control) and test miniplates from the same production batches was undertaken. Energy-dispersive X-ray (EDX) analysis was used to identify compositional variations of the miniplate surface, and Vickers hardness testing was performed. At autopsy, clinical healing of all fractures was noted. SEM analysis indicated no perceptible difference in the surface characteristics of the miniplates at all time intervals. Aluminium and silicon deposits were identified by EDX analysis over the flat surfaces. There was extensive damage to some screw heads. It is concluded that there were no significant changes in the surface characteristics of miniplates retrieved up to 24 weeks after implantation in comparison with controls. Damage to the screws during insertion due to softness of the materials may render their removal difficult. There was no evidence to support the routine removal of titanium or stainless steel miniplates because of surface corrosion up to 6 months after implantation.

Release of metal in vivo from stressed and nonstressed maxillofacial fracture plates and screws.

OBJECTIVES: To analyze the release of metal into the adjacent tissues from stressed and nonstressed titanium and stainless steel miniplates and screws. STUDY DESIGN: Two miniplates were inserted into the cranial vaults of 12 beagle dogs while they were under general endotracheal anesthesia. One miniplate was shaped to fit the curvature of the skull (control). Another miniplate, made of the same material, was bent in a curve until the midpoint was raised 3 mm above the ends. Screws were inserted and tightened until the plate conformed to the skull curvature, creating stresses in the system. Four animals (2 each, having titanium or stainless steel plates and screws) were killed after 4, 12, and 24 weeks. Metallosis of adjacent soft tissues was assessed qualitatively. Miniplates and screws were removed, and adjacent soft tissue and bone was excised. Titanium, iron, chromium, nickel, and aluminum levels were assayed by ultraviolet/visible light and atomic absorption spectrophotometry. Nonparametric statistical methods were used for data analysis. RESULTS: There was no clear relationship between pigmentation of soft tissue adjacent to the miniplates and screws and the concentrations of metal present. The data did not demonstrate any consistent differences in the concentrations of metallic elements next to stressed and nonstressed (control) miniplates and screws of either material. CONCLUSION: Stresses arising through poor contouring of miniplates do not appear to influence the extent of release of metal into the adjacent tissues.

Participatory continuing dental education.

The significance of continuing education for the development of a professional person is indisputable. There is evidence that participatory continuing education is the most effective form for this activity to take in relation to dentists and clinical practice. Working Group 15, appointed by the FDI Commission, specifically studied this form of continuing education by use of a questionnaire to 26 representative national dental associations. The majority of countries surveyed have at least some education of this sort although it forms only a small proportion overall. Little evaluation seems to take place to measure the subsequent value to the practitioners attending. The results of the information gathered are discussed and recommendations are made.

Sharps injuries involving a sheathed needle.

Two dental nurses each sustained a sharps injury while attempting to remove the sheathed needle from a used dental local anaesthetic syringe. The needle had been bent inadvertently during use. Neither of the dental nurses were aware that the needle had perforated the side of the sheath during resheathing. This incident emphasises the need for constant vigilance during the disposal of sharps and for the routine avoidance of direct contact with sheathed or unsheathed needles and other sharps after use.

Dental practitioner attendances at postgraduate courses in a dental school.

The attendance pattern of dental practitioners who resided in the West Midlands and attended postgraduate courses at Birmingham University Dental School was studied. Data were collected from the participants as to their name, the location of their practice and the type of course that they attended. Other information such as their qualifications or their attendance at other postgraduate courses was sought from appropriate records. The percentage of West Midlands' dentists who attended postgraduate courses at Birmingham University Dental School was found to be 41%, although this figure was higher amongst Birmingham (53%) and Wolverhampton (51%) practitioners. It is known that practitioners participated in other types of continuing educational activities elsewhere. The majority of dentists attending courses had been qualified for less than 15 years. There were multiple attendances from participants who were already involved in other postgraduate activities such as the MGDS. This study also highlighted the important role of university employed staff in providing postgraduate education for general dental practitioners.

Second year general professional training for dentists: the West Midlands regional scheme one year on.

the West Midlands regional scheme offers new dental graduates the opportunity to undertake a 2-year period of general professional training prior to embarking on their chosen career pathway. Ideally experience should be gained in primary and secondary care. This paper describes the second year of the West Midlands scheme introduced a year ago, which combines house officer and general practice experience.

Second year vocational training in the West Midlands region.

January 1994 saw the start of a pilot second year VT scheme in the West Midlands combining house officer/GDP associateship experience as an integral part of general postgraduate training in dentistry. The scheme is funded by a grant from the W.M. Board of Postgraduate Medical and Dental Education. The availability of such a course in each region would be beneficial for those dentists who wish to experience hospital practice following their mandatory vocational training.

Practice visits.

This article reviews the practice visiting procedures employed in vocational training. The particular usage examined is that employed in the West Midlands region after a 10-year development period, although most regions employ a similar format. It is hoped that the article will be of particular assistance to practitioners contemplating an application to become a trainer.

Recommendations for improving the assessment of postgraduate dental education.

This paper makes recommendations for the improvement of assessment in postgraduate dental education. The recommendations are based on a twelve-month study conducted in 1998/99 which evaluated the strengths and weaknesses of the existing assessment systems. Evidence was taken from examination syllabi, assessments and records. Semi-structured interviews were conducted with representatives from national bodies and with trainers and trainees in the West Midlands. Strengths in parts of the system include: commitment and professional experience; commissioned work; opportunity to share experience; a monitoring framework; procedures for maintaining standards and examples of broadbased assessments. Weaknesses include: lack of assessment of quality; existence of some forms of unregulated assessment; lack of transparency and lack of clarity between training and assessment. Development is recommended in three broad areas: a competence-based model of assessment; distinguishing assessment from the analysis of educational needs and quality assurance. The introduction of a competence-based model is the most significant and is addressed in some detail. Specific proposals for consideration by national regulatory bodies and education providers include: strengthening the management of assessment; national leadership in the development of a competence model of assessment; widening the assessment base; clearer criteria for inspection; revisions to how vocational training, HO/SHO training and general professional training are assessed and training for trainers.