Tooth loss and implant outcomes in patients refractory to treatment in a periodontal practice

Aim: The aim of this study was to investigate the factors associated with continued significant tooth loss due to periodontal reasons during maintenance following periodontal therapy in a specialist periodontal practice in Norway.
Material and Methods: A case-control design was used. Refractory cases were patients who lost multiple teeth during a maintenance period of 13.4 (range 8-19) years following definitive periodontal treatment in a specialist practice. Controls were age- and gender-matched maintenance patients from the same practice. Characteristics and treatment outcomes were assessed, and all teeth classified as being lost due to periodontal disease during follow-up were identified. The use of implants in refractory cases and any complications relating to such a treatment were recorded.
Results: Only 27 (2.2%) patients who received periodontal treatment between 1986 and 1998 in a specialist practice met the criteria for inclusion in the refractory to treatment group. Each refractory subject lost 10.4 (range 4-16) teeth, which represented 50% of the teeth present at baseline. The rate of tooth loss in the refractory group was 0.78 teeth per year, which was 35 times greater than that in the control group. Multivariate analysis indicated that being in the refractory group was predicted by heavy smoking (p=0.026), being stressed (p=0.016) or having a family history of periodontitis (p=0.002). Implants were placed in 14 of the refractory patients and nine (64%) of these lost at least one implant. In total, 17 (25%) of the implants placed in the refractory group were lost during the study period.
Conclusions: A small number of periodontal maintenance patients are refractive to treatment and go on to experience significant tooth loss. These subjects also have a high level of implant complications and failure. Heavy smoking, stress and a family history of periodontal disease were identified as factors associated with a refractory outcome.

Modern management of head injuries

Management of the head-injured patient is designed to prevent secondary injury and to provide the neurosurgeon with a live patient who has some hope of recovery. This review sets out the background essentials for the non-neurosurgeon dealing with the initial care of a head-injured patient.

Epidemiology of Adolescent Rugby Injuries: A Systematic Review

OBJECTIVE: Despite recent increases in the volume of research in professional rugby union, there is little consensus on the epidemiology of injury in adolescent players. We undertook a systematic review to determine the incidence, severity, and nature of injury in adolescent rugby union players.

DATA SOURCES: In April 2009, we performed a computerized literature search on PubMed, Embase, and Cochrane Controlled Trials Register (via Ovid). Population-specific and patient-specific search terms were combined in the form of MEDLINE subject headings and key words (wound$ and injur$, rugby, adolescent$). These were supplemented with related-citation searches on PubMed and bibliographic tracking of primary and review articles.

STUDY SELECTION: Prospective epidemiologic studies in adolescent rugby union players.

DATA SYNTHESIS: A total of 15 studies were included, and the data were analyzed descriptively. Two independent reviewers extracted key study characteristics regarding the incidence, severity, and nature of injuries and the methodologic design.

CONCLUSIONS: Wide variations existed in the injury definitions and data collection procedures. The incidence of injury necessitating medical attention varied with the definition, from 27.5 to 129.8 injuries per 1000 match hours. The incidence of time-loss injury (>7 days) ranged from 0.96 to 1.6 per 1000 playing hours and from 11.4/1000 match hours (>1 day) to 12-22/1000 match hours (missed games). The highest incidence of concussion was 3.3/1000 playing hours. No catastrophic injuries were reported. The head and neck, upper limb, and lower limb were all common sites of injury, and trends were noted toward greater time loss due to upper limb fractures or dislocations and knee ligament injuries. Increasing age, the early part of the playing season, and the tackle situation were most closely associated with injury. Future injury-surveillance studies in rugby union must follow consensus guidelines to facilitate interstudy comparisons and provide further clarification as to where injury-prevention strategies should be focused.

Local delivery of chlorhexidine using a tooth-bonded delivery system

Films containing 20% w/w chlorhexidine base (particle size 63-125 mu m) in poly(epsilon-caprolactone), MW 35 000-45 000, were prepared by solvent evaporation and sections attached to the mesio-lingual and mesio-buccal surfaces of the lower first molar in healthy volunteers. Saliva (

Risk factors for falls and injuries in a long-term care facility in Ontario

Objective: To identify risk factors for falls and injuries among seniors living in a long-term care facility. Method: Case-control study of 335 residents living at St. Joseph's Villa, Dundas, Ontario. Cases were defined as residents who fell between July 1, 1996 and June 30, 1997; controls were those who did not fall. To identify risk factors for injury, cases were defined as those with completed incident injury forms and controls as those without. Results: The most important risk factors for falls included: having fallen in the past three months; residing in a secured unit; living in the facility for two or more years; having the potential to cause injury to others; and having an illness, disease or behaviour that may cause a fall. The most important risk factor for injury among those who fell was altered mental state. Conclusion: The risk factors identified may be helpful to those planning falls prevention initiatives within long-term care settings.

Surveillance of severe chemical corneal injuries in the UK

AIM: To estimate the incidence of severe chemical corneal injuries in the UK and describe presenting clinical features and initial management.

METHODS: All patients with severe chemical corneal injury in the UK from December 2005 to November 2006 inclusive were prospectively identified using the British Ophthalmological Surveillance Unit. Reporting ophthalmologists provided information regarding presentation and follow-up.

RESULTS: Twelve cases were identified, giving a minimum estimated incidence in the UK of severe chemical corneal injury of 0.02 per 100,000. 66.7% of injuries were in males of working age, 50% occurred at work, and alkali was causative in 66.7%. Only one patient was wearing eye protection at the time of injury, 75% received immediate irrigation. Six patients required one or more surgical procedures, most commonly amniotic membrane graft. At 6 months' follow-up, the best-corrected visual acuity was 6/12 or better in five patients, and worse than 6/60 in two.

CONCLUSION: The incidence of severe chemical corneal injury in the UK is low. The cases that occur can require extended hospital treatment, with substantial ocular morbidity and visual sequelae. Current enforcement of eye protection in the workplace in the UK has probably contributed to a reduced incidence of severe ocular burns.

Focal irradiation of perforating eye injuries

Plaques constructed with 125I were used to irradiate the sites of perforating ocular injuries in rabbits. An approximate dose of 16Gy given over a period of 6 days was shown to significantly reduce intraocular cellular proliferation when irradiation was commenced within 24 hours after injury. If irradiation was delayed until day 5, this reduction in cellular proliferation and intraocular membrane formation did not occur. Smaller radiation doses of approximately 6Gy given within 24 hours post-injury and administered over 6 days also reduced the extent of cellular proliferation but was not as effective as the 16Gy dose.

Fracture strength of machined ceramic crowns as a function of tooth preparation design and the elastic modulus of the cement

Objectives: To determine, by means of static fracture testing the effect of the tooth preparation design and the elastic modulus of the cement on the structural integrity of the cemented machined ceramic crown-tooth complex. 
Methods: Human maxillary extracted premolar teeth were prepared for all-ceramic crowns using two preparation designs; a standard preparation in accordance with established protocols and a novel design with a flat occlusal design. All-ceramic feldspathic (Vita MK II) crowns were milled for all the preparations using a CAD/CAM system (CEREC-3). The machined all-ceramic crowns were resin bonded to the tooth structure using one of three cements with different elastic moduli: Super-Bond C&B, Rely X Unicem and Panavia F 2.0. The specimens were subjected to compressive force through a 4 mm diameter steel ball at a crosshead speed of 1 mm/min using a universal test machine (Loyds Instrument Model LRX.). The load at the fracture point was recorded for each specimen in Newtons (N). These values were compared to a control group of unprepared/unrestored teeth. 
Results: There was a significant difference between the control group, with higher fracture strength, and the cemented samples regardless of the occlusal design and the type of resin cement. There was no significant difference in mean fracture load between the two designs of occlusal preparation using Super-Bond C&B. For the Rely X Unicem and Panavia F 2.0 cements, the proposed preparation design with a flat occlusal morphology provides a system with increased fracture strength. 
Significance: The proposed novel flat design showed less dependency on the resin cement selection in relation to the fracture strength of the restored tooth. The choice of the cement resin, with respect to its modulus of elasticity, is more important in the anatomic design than in the flat design. © 2013 Academy of Dental Materials.

Effect of the crown design and interface lute parameters on the stress-state of a machined crown-tooth system: A finite element analysis

The effect of preparation design and the physical properties of the interface lute on the restored machined ceramic crown-tooth complex are poorly understood. The aim of this work was to determine, by means of three-dimensional finite element analysis (3D FEA) the effect of the tooth preparation design and the elastic modulus of the cement on the stress state of the cemented machined ceramic crown-tooth complex. The three-dimensional structure of human premolar teeth, restored with adhesively cemented machined ceramic crowns, was digitized with a micro-CT scanner. An accurate, high resolution, digital replica model of a restored tooth was created. Two preparation designs, with different occlusal morphologies, were modeled with cements of 3 different elastic moduli. Interactive medical image processing software (mimics and professional CAD modeling software) was used to create sophisticated digital models that included the supporting structures; periodontal ligament and alveolar bone. The generated models were imported into an FEA software program (hypermesh version 10.0, Altair Engineering Inc.) with all degrees of freedom constrained at the outer surface of the supporting cortical bone of the crown-tooth complex. Five different elastic moduli values were given to the adhesive cement interface 1.8 GPa, 4 GPa, 8 GPa, 18.3 GPa and 40 GPa; the four lower values are representative of currently used cementing lutes and 40 GPa is set as an extreme high value. The stress distribution under simulated applied loads was determined. The preparation design demonstrated an effect on the stress state of the restored tooth system. The cement elastic modulus affected the stress state in the cement and dentin structures but not in the crown, the pulp, the periodontal ligament or the cancellous and cortical bone. The results of this study suggest that both the choice of the preparation design and the cement elastic modulus can affect the stress state within the restored crown-tooth complex.