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Biomedical subjects

N Claffey

Publications and source records attributed to N Claffey.

At least 19 recordsLinked to original sources
PubMed2006

Contents of stomatological curricula in Europe.

The present study focuses on dental education in the Accession Countries to the European Union. Comparisons were made with data from EU dental schools [Eur J Dent Educ 1 (1997) 35]. The findings show a large variation in the hours allocated to individual subjects, medical and dental, both within and between AC and EU dental schools. Stomatology derived from General Medicine and the stomatologist is viewed as a doctor responsible for one part of the body. This was explained by the large proportion of time dedicated to medical subjects, especially in the first 2/3 years of the undergraduate curriculum. The percentage of hours for dental sciences varied inversely to those for bio-medical sciences and increase continuously from the first year to the final year. Curricula in the Stomatological schools tend to have a discipline-structured approach, generally utilising a large number of individual departments, resulting in a multitude of subjects being taught. Curricular extensions from 5 to 6 years were introduced in some schools from 1990 onwards in order to accommodate new dental subjects.

Curriculum↗
PubMed2004

Formulation and preliminary in vivo dog studies of a novel drug delivery system for the treatment of periodontitis.

A novel drug delivery system for the treatment of periodontitis was developed using two components. The first was tetracycline base loaded into the microtubular excipient halloysite, which was coated with chitosan to further retard drug release. Encapsulation efficiencies of 32.5% were achieved with the loading procedure, with tetracycline base showing in vitro release for up to 50 days in simulated gingival crevicular fluid. The second component developed was a vehicle for the drug loaded coated halloysite, which was primarily based on the thermoresponsive polymer, poloxamer 407. A concentration of 20% was chosen with the thermoresponsivity of the system modified using PEG 20,000 so that the mobile product at room temperature would gel by temperature rise following syringing into a periodontal pocket. Retention of the overall system in the pocket was further improved by the addition of octyl cyanoacrylate (OCA). The thermoresponsivity of the poloxamer 407 system proved to be sensitive to the presence of added excipients with the levels of PEG 20,000 and OCA requiring modification in the presence of the halloysite component. A final formulation was developed which consisted of 200 mg of halloysite double loaded with tetracycline base and coated with chitosan, suspended in 1 ml of poloxamer 407 20% (w/w), PEG 20,000 0.5% (w/w), OCA 1.0% (w/w), water to 100%, adjusted to pH 4. The syringeability of this formulation at various temperatures was evaluated to ensure ease of delivery to the periodontal pocket. A stability study was performed to examine the change in thermoresponsivity over time, with the final formulation found to be stable for at least 9 months when stored at room temperature (approximately 20 degrees C). This formulation offered ease of delivery to the periodontal pocket and sustained release of the antibiotic for up to 6 weeks. The formulation had preliminary in vivo testing performed in dogs to determine levels of drug release, antimicrobial activity and retentive ability of the product. A wound pocket creation model was developed for the purposes of the trial. The product was easy to deliver to the pockets with application times of less than 1 min. Results showed the product was retained in the pocket for up to 6 weeks with effective tetracycline levels released locally over this time period, which achieved good antibacterial activity.

Aluminum Silicates↗
PubMed2004

The influence of some different factors on the accuracy of shade selection.

The purpose of this study was to elucidate some of the factors on which accurate shade taking depends. Custom shade tabs (0.5, 1.0 and 1.5 mm porcelain thickness) were fabricated from selected Vita and Shofu porcelains. Four main factors were investigated, namely, the difference between the two types of porcelain used, the effect of light quality, the effect of porcelain thickness and the experience of the observer. The chi-square test for independence at a probability level of P <0.05 was used to analyse the results. The results indicated that in ideal light there was no difference between the two porcelains (P=0.58). The experienced observers proved better than the novice observers in ideal light conditions (P=0.003). Thickness was also significant in the overall results (P=0.0001), in that thicker samples gave more accurate results. The results indicate that in adverse light, there was an overall difference between the two porcelains (P=0.046), but no difference between the experienced and novice observers. The thickness made no difference to the experienced or the novice observer in adverse light. These results indicate that the most influential factor on shade taking was the light quality (P <0.0001); better results were obtained overall for the ideal light situation. In ideal light thicker samples gave better results (P=0.0001).

Clinical Competence↗
PubMed2003

Essential oil mouthwashes: a key component in oral health management.

This Supplement provides clear evidence that essential oil (EO) mouthwashes can be a beneficial, safe component of daily oral health routines. However, despite the wealth of supporting evidence, several issues are worthy of discussion. Patient compliance is a clear issue with oral home-care routines, and the emphasis is on dental professionals to communicate the importance of adherence. The reasons for each step of the oral-care routine (i.e. brushing, flossing, rinsing) should be clearly explained, and if required, additional motivation should be provided. Most mouthwashes contain denatured alcohol as a delivery vehicle, and some concern has been raised about the association of alcohol with oral cancer. However, a review by the Food and Drug Administration and American Dental Association found that the supporting evidence to date is inconsistent and contradictory. Some mouthwashes have a pH below 5.5, and some researchers believe that this can lead to tooth erosion. Studies have shown that although the pH of an EO mouthwash is below 5.5, salivary pH remains above 5.5 following rinsing and for 15 min postrinse.

Anti-Infective Agents, Local↗
PubMed2002

The effect of Nd:YAG radiation at nanosecond pulse duration on dentine crater depth.

The effect of laser parameters on laser-dentine interaction is little known. The aim of this in vitro study was to determine the effect on dentine crater depth of Nd:YAG laser radiation in relation to pulse repetition rate, total delivered energy, dentine site and the presence or absence of a dye. One hundred and forty-four sound third molars were extracted and sectioned transversely to provide 288 upper and lower cut surfaces. The upper surfaces were painted with a layer of dye (IR5) suitable for absorption at 1064 nm. The specimens were divided into 12 sub-groups each containing 12 upper and 12 lower specimens. These were exposed to a Nd:YAG laser with a 30 nanosecond (ns) pulse duration. This laser operated in a non-contact mode (spot diameter 165 microm) with pulse repetition rates of 2.5, 5.4 and 10.5 Hz. Four total energies were delivered at each repetition rate; 2.3, 3.63, 3.96, 4.29 joule (J) at 2.5 Hz repetition rate; 2.3, 2.64, 3.63, 4.29 J at 5.4 and 10.5 Hz repetition rates. Five outer and three inner sites were irradiated on each specimen. Each dentine crater depth was measured five times using a Reflex Microscope and a three-dimensional centre of gravity derived. An upper and lower specimen were taken from each sub-group and viewed under a scanning electron microscope (SEM). ANOVA was applied: total delivered energy and dyed/undyed were found to have a statistically significant effect on crater depth (p<0.0001). In general increasing energy and the presence of dye produced deeper craters. Inner/outer dentine location and repetition rate were not found to be statistically significant. All craters were carbonised.

Dentin↗
PubMed2002

Tensile strength, histological and immunohistochemical observations of periodontal wound healing in the dog.

This study was designed to study wound strength at the dentine/connective tissue interface and at the bone/connective tissue interface following full thickness flap surgery. Flaps of uniform dimension were outlined in four young adult beagle dogs using a standardised double bladed knife and vertical incisions 10 mm apart, which extended 8 mm apical to the gingival margin. Bone was removed from half the sites (eight sites in each dog), giving 32 flaps replaced on dentine and 32 sites on bone. A tensile force was applied using a microprocessor force gauge at 1, 2, 3, 7, 10, 14, 21, and 28 days. Mean tensile strengths were markedly weaker for the dentine/flap interface. At 7 days the value for flaps to dentine was 1.82 N, in contrast to 5.08 N for flaps replaced on bone. Inflammatory cell counts tended to fall markedly at 3 days for both modalities, but were higher for the dentine/flap modality at all time points. Fibroblast density peaked at 7-14 days but did not vary with type of flap over the time points studied. The amounts of fibrin were greater for the dentine/flap interface at all time points but decreased for both flap types as time progressed. Collagen type V was localised to the basement membrane and blood vessels and tended to show more foci for flaps replaced on dentine. Procollagen levels showed little change over the healing interval for both flap/bone and flap/dentine interfaces. Type III collagen synthesis was at peak levels during the first week. These findings would support efforts to stabilise periodontal flaps at early time points, especially those on dentine.

Alveolar Process↗
PubMed2001

The effect of Nd:YAG pulse duration on dentine crater depth.

OBJECTIVES: The effect of alteration of laser parameters on laser-dentine interaction, in particular the effect of pulse duration, has not been well documented. The aim of this in vitro study was to determine the effect on dentine crater depth of Nd:YAG laser pulse duration, and total delivered energy, dentine site and the presence or absence of dye. METHODS: Ninety-six sound third molars were extracted and sectioned transversely to provide 192 upper and lower cut surfaces. The upper surfaces were painted with a layer of dye (IR5) suitable for absorption at 1064 nm. The specimens were divided into 16 sub-groups and exposed to two Nd:YAG lasers; one of pulse duration 7 ms and the second of pulse duration 35 ps. Both lasers operated in a non-contact mode (spot diameter 165 microm) with repetition rates of 10.5 and 10 Hz, respectively. Four total energies (2.28, 2.64, 3.6, 4.2 J) were delivered to eight dyed and eight undyed sub-groups. Eight outer and five inner sites were irradiated on each specimen. Dentine crater depth was measured five times using a Reflex Microscope and a three-dimensional centre of gravity derived. An upper and lower specimen were taken from each sub-group and viewed under a SEM. RESULTS: ANOVA and multiple regression analysis were applied and the following factors were found to have a statistically significant effect on crater depth (p<0.0001): total delivered energy, pulse duration and inner/outer location. CONCLUSIONS: Increasing energy and pulse duration produced deeper craters. Similarly inner dentine sites produced deeper crater depths. Only craters produced at the ms pulse duration were carbonised. It would appear that laser-dentine interaction has a non-thermal component at picosecond pulse duration.

Analysis of Variance↗
PubMed2001

Effect of groove placement on the retention/resistance of resin-bonded retainers for maxillary and mandibular second molars.

STATEMENT OF PROBLEM: Lack of retention/resistance form in the clinical preparation of teeth for resin-bonded retainers may lead to clinical failure. PURPOSE: This study investigated the effect of proximal grooves on the retention/resistance of cast resin-bonded retainers for maxillary and mandibular second molar teeth. MATERIAL AND METHODS: Two ivorine teeth (a maxillary and a mandibular second molar) were prepared for resin-bonded retainers. Twenty metal replicas of the prepared teeth were made (10 for each tooth morphotype). Resin-bonded retainers 0.5 mm thick were made for the 40 replicas and luted with Panavia EX cement. Forces for dislodgment of the retainers were applied along the long axes of the teeth. Forces recorded at the time of dislodgment were analyzed with 2-way analysis of variance and the post hoc Scheffé test. RESULTS: Grooves resulted in substantial increases in debonding forces for maxillary molars (P<.001). The effect of grooves on mandibular second molars was not significant (P=.13). CONCLUSION: Grooves placed in tooth preparations of maxillary molar teeth for resin-bonded retainers had a significant effect on retention/resistance. The effect of grooves on mandibular second molars was less pronounced.

Analysis of Variance↗
PubMed1999

Histological evaluation of repair using a bioresorbable membrane beneath a resin-modified glass ionomer after mechanical furcation perforation in dogs' teeth.

Resorbable barriers have been shown both clinically and histologically to produce favorable periodontal regenerative outcomes. The purpose of the present study was to evaluate the histological response to one such resorbable barrier (Atrisorb) when used as a matrix under a resin-modified glass ionomer (RMGI) sealant in the repair of furcation perforations in experimental animals. After anesthesia, pulp extirpation and filling of radicular canals with zinc oxide-eugenol cement, furcal perforations were made in 30 lower premolar (P2, P3, and P4) teeth of labrador dogs with a 1 mm diameter round bur in a conventional handpiece. The perforated teeth were randomly divided into two groups of 15 teeth. Group 1 teeth were treated with RMGI alone and group 2 with the resorbable barrier under RMGI. Six teeth without perforations served as negative controls. Pulp chambers of all teeth were filled with RMGI cement. Animals were sacrificed after 3 months. The teeth and the surrounding structures were processed for light microscopy. There were no differences found between results for glass ionomer alone and barrier with glass ionomer. The conclusion of this study is that placement of a resorbable barrier at the pulp chamber aspect of a furcation perforation did not result in superior healing, compared with the use of resin-modified glass ionomer alone.

Absorbable Implants↗
PubMed1998

The fit of cast and premachined implant abutments.

STATEMENT OF PROBLEM: There is insufficient information regarding the adaptation of abutments to implants. PURPOSE: This study assessed the adaptation of premachined, cast, and laboratory modified premachined abutments to implants at two sites: abutment/implant interface and screw to screw seat. MATERIAL AND METHODS: Six combinations of abutments and implants were studied: CeraOne abutments joined to Nobel Biocare implants; STR (Implant Innovations Inc.) abutments joined to 31 implants; Cast UCLA (31) abutments subjected to porcelain firing cycles and joined to 31 implants; Cast UCLA abutments subjected to porcelain firing cycles and joined to Nobel Biocare implants; UCLA premachined abutments cast with gold palladium alloy and subjected to porcelain firing cycles (later joined to 31 implants); and UCLA premachined abutments joined to 31 implants. Each group contained five assemblies. RESULTS: The adaptation of abutments to implants was closer and the amounts of contact larger for assemblies with premachined and laboratory modified premachined abutments than for those with cast abutments. CONCLUSION: The finishing of custom-made abutments requires further refinement.

Analysis of Variance↗
PubMed1998

The use of 0.2% chlorhexidine in the absence of a structured mechanical regimen of oral hygiene following the non-surgical treatment of periodontitis.

The aim of the present study was to evaluate a 0.2% chlorhexidine mouthrinse following the non-surgical treatment of advanced human periodontitis in the absence of a structured mechanical oral hygiene regimen. 10 patients and a total of 1483 sites were used. Recordings for plaque, bleeding, pocket depth and attachment levels were made at baseline and at 3, 6, 9, and 12 months. Debridement was performed under local anaesthesia. No instruction or reinforcement in mechanical oral hygiene procedures was given at any time. However, at each visit the patients were instructed in the 2x daily use of 0.2% chlorhexidine mouthwash. The plaque indices, scored as % of sites with removable deposits, showed negligible improvement from baseline scores of 80%-100% for all categories of initial probing depth. Mean bleeding score was reduced to 10-20% irrespective of initial probing pocket depth, site location or tooth surface location. Sites > or = 7 mm at baseline demonstrated a reduction in mean probing pocket depth of 3.9 mm and a gain in mean probing attachment level of 2.5 mm. Moderately deep sites (4-6.5 mm) demonstrated a reduction in mean probing pocket depth of 2 mm and a gain in mean probing attachment level of 0.8 mm. Shallow sites (< or = 3.5 mm) demonstrated a reduction in mean probing pocket depth of 0.5 mm and a loss in mean probing attachment level of 0.2 mm. Site-specific attachment level analysis demonstrated that over 80% of losing sites were shallow with low bleeding frequency, indicating that the loss of attachment may have occurred for reasons other than inflammatory periodontal disease. The results indicate that chlorhexidine can be used as an adjunct to inadequate mechanical oral hygiene over an observation period of 1 year.

Adult↗
PubMed1998

Association of crevicular fluid elastase-like activity with histologically-confirmed attachment loss in ligature-induced periodontitis in beagle dogs.

Experimental periodontitis was induced using ligatures in 6 beagle dogs over 57 days. Levels of elastase like activity in healthy sites, gingivitis sites, and in sites ligated for different time points were analyzed with respect to levels of histologically confirmed attachment loss. Attachment loss increased with increasing periods of ligation and reached a maximum of 0.15 mm at 57 days. Maximum loss of histological attachment was found to coincide with the period of maximum enzyme activity; during the first 7 days of ligature. Spearman correlation analysis of enzyme activity with attachment loss yielded a significant correlation (0.73, p=0.0396). The healthy and gingivitis sites were found to have minimal levels of enzyme activity throughout. Thus, this prospective study in beagle dogs found a relationship between histologically confirmed attachment loss and increased levels of elastase like activity indicating the probable usefulness of this parameter, either alone or in conjunction with other markers, for disclosing active periodontitis.

Animals↗
PubMed1998

Investigation of the operative response of a group of general dental practitioners to varying extents of proximal caries.

The aim of this investigation was to assess the operative response of a representative sample of Irish General Dental Practitioners of various times since qualification to carious lesions of varying extent in both approximal surfaces of a lower left first molar tooth. 82 General Dental practitioners participated. The dentists were asked to treat 2 manikin teeth for minimal caries on both approximal surfaces extending to the enamel dentine junction, 2 teeth for caries extending approximately to half the thickness of the dentine and 2 teeth for caries extending more than 3/4 of the dentine thickness. Weight measurements were made of the tooth substance cut away. Mean volumes of tooth material removed ranged from 21 mm3 for minimal caries to 76 mm3 for the largest amount of caries. A two-factor analysis of variance revealed that the type of cavity preparation the dentist used had a significant effect on the volume of tooth material removed for all three extents of caries. Time since graduation had a significant effect on the volume of tooth material removed for the least extent of caries, but not for the other categories of carious involvement.

Age Factors↗
PubMed1997

Bond strengths of maxillary anterior base metal resin-bonded retainers with different thicknesses.

PURPOSE: This study evaluated the effect of three different thicknesses of base metal resin-bonded retainers on retention/resistance. MATERIAL AND METHODS: Three ivorine teeth, a central incisor, lateral incisor, and canine, were prepared to receive resin bonded retainers. Fifteen metal replicas of prepared teeth were made (five for each tooth morphotype). A total of 45 metal retainers were cast in three different thicknesses, 0.3, 0.5, and 0.7 mm, with 15 for each thickness. Retainers were cemented to metal die replicas with Panavia EX luting agent. After 24 hours, forces to dislodge the retainers were applied at 45 degrees to the vertical mesiodistal plane at the proximolingual line angle. RESULTS: An increase in thicknesses resulted in elevation of dislodging forces that were almost linear for the three thicknesses of canine retainers. The central incisor exhibited the greatest increase in resistance to dislodgment between retainers that were 0.3 and 0.5 mm thick, whereas increased thickness for the lateral incisor retainer resulted in minimal or no benefit.

Analysis of Variance↗
PubMed1997

A comparison of the dimensional accuracy of the splinted and unsplinted impression techniques for the Bone-Lock implant system.

STATEMENT OF PROBLEM: The precise transfer of intraoral relationships of implants to laboratory working models is central to the success of implant prostheses. PURPOSE: In this study a stone master model incorporating five implants (Bone-Lock) was used to compare the dimensional accuracy of a splinted impression technique with an unsplinted impression technique. METHODS: A three-factor analysis of variance was used to examine the effect of technique, relative position of the implant on the cast, and plane of measurement. RESULTS: All three factors had a significant effect on dimensional accuracy. CONCLUSIONS: The splinted technique exhibited more deviation from the master model than the unsplinted technique did. This was primarily associated with rotational discrepancies around the long axes of the implants for the splinted technique.

Analysis of Variance↗
PubMed1996

Supracrestal bone growth around partially inserted titanium implants in dogs. A pilot study.

8 titanium implants (Nobel Biocare, Göteborg, Sweden) were inserted into edentulous lower premolar areas of 4 dogs so that 6 threads of the implant protruded from the bone crest. Newly-developed perforated dome-shaped titanium space maintainers were fixed to the implant with cover screws. Autogenous bone fragments were placed under the space maintainers. On one side of the arch, the space maintainer was covered with a non resorbable cell occluding barrier. The implant/space maintainers were submerged under coronally positioned flaps. Following a 3-month healing period, there was a mean gain of new bone amounting to 2.5 mm for all specimens. A greater height of bone was found for those sites in which an ePTFE membrane was used; 3.1 mm vs. 1.9 mm (p < 0.05). This study demonstrated the potential of coronal bone growth of the alveolar bone in a protected space around crew implants with exposed treads when placed in the dog.

Alveolar Process↗
PubMed1996

Histological and microbiological aspects of ligature-induced periodontitis in beagle dogs.

This study was designed to investigate, using 6 beagle dogs, the levels of selected putative pathogens in healthy sites, in gingivitis sites, and in sites with histologically confirmed attachment loss. Levels of attachment loss increased with increasing periods of ligation and reached a maximum of 0.15 mm at 57 days. Both histological attachment level and histological pocket depth were found to vary significantly with health/disease status (p < 0.0001). Higher numbers of total colony-forming units were seen for ligated sites than for healthy and gingivitis sites. Levels of Porphyromonas gingivalis and Prevotella intermedia also changed significantly with health/disease status (p < 0.001). These organisms showed their greatest increases at the time of the most intense attachment loss. Higher levels of Fusobacterium nucleatum were seen in the gingivitis sites than in healthy or ligated sites. Low levels of Campylobacter rectus and Capnocytophaga spp. were detected throughout. The morphometric microbiological analysis revealed unexpectedly high %s of motile rods, while spirochetes were found in very low %s. The total number of bacterial cells detected using phase contrast microscopy was not found to vary significantly. None of the morphotypes were demonstrated as showing significant changes with health/disease status.

Analysis of Variance↗