Objectives. The aim of this study was to compare internal bacterial colonization in two implant systems, one screw root form (SRF) with an external hexagon connection and one plateau root form (PRF) with a Morse taper internal connection.... more
Objectives. The aim of this study was to compare internal bacterial colonization in two implant systems, one screw root form (SRF) with an external hexagon connection and one plateau root form (PRF) with a Morse taper internal connection. Materials and methods. Thirty-two implants; 12 SRF and 20 PRF, were sampled in 15 patients. All implants had been in function for at least 6 months prior to sampling. The implant restoration was removed and 10 µl of sterile saline was introduced into the implant well via a sterile glass syringe. The saline was drawn back up and transferred to the laboratory for microbiological analysis. The number of aerobic and anaerobic colony forming units per millilitre was determined and the dominant micro-organism in each sample was identified by 16s rRNA gene amplicon sequencing. Results. There was a significant difference between bleeding on probing around the SRF implants (3%) and the PRF implants (28%) (p = 0.0496). Bacterial colonization was identified a...
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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... more
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...
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Research Interests: Dentistry and Endodontics
... (Modified from Friedman (27)). These aims were later elaborated by Palmer & Floyd (61) to include correction of mucogingival deformities and the treatment of advanced periodontitis lesions that require reconstructive or... more
... (Modified from Friedman (27)). These aims were later elaborated by Palmer & Floyd (61) to include correction of mucogingival deformities and the treatment of advanced periodontitis lesions that require reconstructive or regenerative therapy. ...
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Lack of retention/resistance form in the clinical preparation of teeth for resin-bonded retainers may lead to clinical failure. This study investigated the effect of proximal grooves on the retention/resistance of cast resin-bonded... more
Lack of retention/resistance form in the clinical preparation of teeth for resin-bonded retainers may lead to clinical failure. This study investigated the effect of proximal grooves on the retention/resistance of cast resin-bonded retainers for maxillary and mandibular second molar teeth. 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. 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). 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.
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Debonding of resin-bonded fixed partial dentures has been partly resolved with modification of tooth preparations. Tooth preparations for resin-bonded retainers were completed on a maxillary central incisor, a lateral incisor, and a... more
Debonding of resin-bonded fixed partial dentures has been partly resolved with modification of tooth preparations. Tooth preparations for resin-bonded retainers were completed on a maxillary central incisor, a lateral incisor, and a canine. Fifteen metal replicas were constructed (five of each tooth morphotype). The three tooth morphotypes were then modified with proximal grooves prepared parallel to the long axes, and another 15 metal replicas were prepared. Cast metal retainers were constructed and cemented to the replicas with a resin cement. Tensile shearing dislodging loads were applied at 20 degrees to the long axes of the teeth with a testing machine. The addition of proximal grooves made statistically significant differences in resistance to debonding forces for all three tooth morphotypes (p < 0.01). An increase of 76.7% was seen in dislodging forces for lateral incisors with proximal grooves compared with incisors without grooves.
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Evidence for a link between periodontal disease and several systemic diseases is growing rapidly. The infectious and inflammatory burden of chronic periodontitis is thought to have an important systemic impact. Current evidence suggests... more
Evidence for a link between periodontal disease and several systemic diseases is growing rapidly. The infectious and inflammatory burden of chronic periodontitis is thought to have an important systemic impact. Current evidence suggests that periodontitis is associated with an increased likelihood of coronary heart disease and may influence the severity of diabetes. This paper represents a UK and Ireland cross-specialty consensus review, undertaken by a group of physicians and dentists. The consensus group reviewed published evidence (PubMed search for review and original articles), focusing on the past 5 years, on the contributory role of periodontal disease to overall health. In particular, evidence relating to a role for periodontal disease in cardiovascular disease and in diabetes was considered. Initial studies of large epidemiological data sets have sought to find links between periodontitis and systemic disease outcomes, but a causal relationship still needs to be demonstrated between periodontal disease, cardiovascular disease and diabetes through prospective studies. There is a need for prospective studies assessing the association between periodontal disease and patients at particular risk of cardiovascular events which will allow assessment of both cardiovascular disease clinical endpoints and surrogate markers of cardiovascular risk. Of note, periodontal disease is also often more severe in subjects with diabetes mellitus, a group at already increased risk for cardiovascular events. While further research is needed to define the population-attributable risk of periodontal disease to both cardiovascular diseases and to diabetes control and progression, health education to encourage better oral health should be considered as part of current healthy lifestyle messages designed to reduce the increasing health burden of obesity, cardiovascular disease and diabetes.
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Our present method for clinical evaluation of marginal periodontal tissues involves examination for bleeding and suppuration and the measurement of probing depth. There is little doubt that this method provides useful guidelines for... more
Our present method for clinical evaluation of marginal periodontal tissues involves examination for bleeding and suppuration and the measurement of probing depth. There is little doubt that this method provides useful guidelines for evaluation of the overall periodontal status of dentitions. On an individual-site basis, however, it has limitations in the identification of locations prone to disease progression. So far, there is no reliably clinical, microbiologic, or other method to predict or identify sites with disease activity (i.e., ongoing loss of attachment). Therefore, there are no clear guidelines for distinguishing between active and arrested lesions. A treatment resulting in a plaque-free mouth with nonbleeding and shallow probing depths throughout the dentition will reduce the risk of residual, active disease. Such a result, although desirable, is not realistic for many patients. Therefore, the clinician is faced with the delicate task of evaluating sites with various grades of involvement using current clinical methods of examination.
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The effect of laser parameters on laser-dentine interaction has not been explored fully. This in vitro study investigated the effect on dentine crater depth of Nd:YAG laser radiation with varying repetition rates, total delivered energy,... more
The effect of laser parameters on laser-dentine interaction has not been explored fully. This in vitro study investigated the effect on dentine crater depth of Nd:YAG laser radiation with varying repetition rates, total delivered energy, and dentine site either dyed or undyed. One hundred forty-four caries-free third molars were sectioned transversely to provide 288 upper and lower cut surfaces. The upper surfaces were dyed (IR5). These upper and lower cut surfaces were exposed to an Nd:YAG laser with a 7 millisecond (msec) pulse duration, pulse repetition rates (RR) of 2. 5, 5.4, and 10.5 Hz, and four total energies (2.28, 2.64, 3.6, 4.2 joules). Dentine crater depth was measured by using a Reflex microscope. Results were statistically analysed with analysis of variance. Crater depth increased with increase in total delivered energy and in dyed and inner dentine sites (P<0.0001) but decreased with increasing repetition rate (P< 0.0001). Increasing energy, dyed, and inner dent...
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106 sites with probing pocket depths 7 mm or greater from 14 patients were treated with plaque control instruction and 1 episode of root planing. Sites in each patient were either irrigated with 2% chlorhexidine or left as non-irrigated... more
106 sites with probing pocket depths 7 mm or greater from 14 patients were treated with plaque control instruction and 1 episode of root planing. Sites in each patient were either irrigated with 2% chlorhexidine or left as non-irrigated controls. Irrigation immediately followed root planing and was repeated daily, by the patient, for 24 weeks. Clinical measurements were made at 12 and 24 weeks, as were gingival washings for determining the number and % of spirochetes. Results at 24 weeks demonstrated that bleeding scores decreased from 91% to 9%; the % of spirochetes dropped from approximately 9% to less than 1%; probing pocket depths decreased from 7.5 to 4.5 mm, and probing attachment levels gained 1.1 to 1.4 mm. The chlorhexidine irrigated experimental group and the non-irrigated control group did not differ significantly in any of the studied parameters. Thus, daily patient-administered chlorhexidine irrigation of deep pockets did not augment the effects of non-surgical periodontal therapy.
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Tissue engineering using cell-seeded biodegradable scaffolds offers a new bone regenerative approach that might circumvent many of the limitations of current therapeutic modalities. The aim of this experiment was to study the early... more
Tissue engineering using cell-seeded biodegradable scaffolds offers a new bone regenerative approach that might circumvent many of the limitations of current therapeutic modalities. The aim of this experiment was to study the early healing events around mesenchymal stem cell-seeded collagen-glycosaminoglycan scaffolds. The 5-mm critical size defects were created in the calvarial bones of 41 Wistar rats. The defects were either left empty to serve as controls (n = 11), filled with cell-free scaffolds (n = 12), cell-seeded scaffolds that were maintained in standard culture medium (n = 9), or cell-seeded scaffolds that were maintained in osteoinductive factor-supplemented medium (n = 9). The animals were sacrificed at 7 days after surgery, and specimens were prepared for histological analysis. Early healing events such as host cell penetration, blood vessel in-growth, and scaffold integration were observed. The degree of inflammatory cell infiltrate was assessed. While defects in the control group healed with a thin fibrous tissue, the collagen-glycosaminoglycan scaffold in the test groups preserved the three-dimensional form of the defects. After 7 days in vivo, the scaffold maintained its integrity and appeared populated with host cells. The cell-seeded scaffold induced more inflammatory response compared to the cell-free scaffolds. New blood vessels and areas of early bone formation were also evident in the cell-seeded scaffolds. In conclusion, the findings show that mesenchymal stem cell-seeded collagen-glycosaminoglycan scaffolds have good tissue tolerance and exhibit an osteoinductive effect as indicated by early stage healing.
Research Interests: Tissue Engineering, Bone Regeneration, Inflammatory Immune Response, Oral and Maxillofacial Surgery, Collagen, and 13 moreAnimals, Skull, Male, Mesenchymal Stem Cell, Glycosaminoglycan, Experimental Study, Glycosaminoglycans, Rats, Three Dimensional, Wistar Rats, Bone Formation, Blood Vessel, and Control Group
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Periodontal sites which had undergone probing attachment loss were identified in 16 advanced periodontitis patients subjected to initial periodontal treatment and monitored every 3rd month for 42 months. Many sites with probing attachment... more
Periodontal sites which had undergone probing attachment loss were identified in 16 advanced periodontitis patients subjected to initial periodontal treatment and monitored every 3rd month for 42 months. Many sites with probing attachment loss showed no increase in probing depth and bled on probing at a few of the examinations during maintenance. Others showed increase in depth, frequent bleeding and suppuration. An arbitrary classification of &#39;questionable periodontitis&#39; sites was used and included sites with the following characteristics: probing depth at 42 months &lt; or = 3.5 mm + bleeding on probing at no more than 5 of the 14 examinations 3-42 months + no suppuration on probing 3-42 months. The % sites in this category ranged from 21-35%, depending upon method used to determine probing attachment loss. Widely varying characteristics of sites identified with probing attachment loss were evident for all surface locations and all subgroups of initial probing depth. From a traditional viewpoint, a significant proportion of the losing sites might not have been afflicted with periodonitis. On the other hand, deterioration does not necessarily have to be coupled with obvious inflammation, particularly following therapy.
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There are insufficient data on the accuracy of resin indexing materials for the assembly of implant prostheses in vivo. This in vitro study assessed the fit of an implant framework with the use of 2 common acrylic resins. A standardized... more
There are insufficient data on the accuracy of resin indexing materials for the assembly of implant prostheses in vivo. This in vitro study assessed the fit of an implant framework with the use of 2 common acrylic resins. A standardized type IV gold alloy cast framework with 3 stainless steel implant replicas secured to 3 premachined gold cylinders placed 200 mm apart using a parallelometer was fabricated on a flat type IV stone model. Wax was placed around the center of each bar section, and a silicone matrix was fabricated to enable the same quantity of material to be used for each assembly. Each bar was sectioned at the center of the matrix, and indices (n=20) were fabricated from Duralay and GC Pattern acrylic resins. The materials were allowed to polymerize for 15 minutes before the assemblies were removed from the model. Frameworks were visually assessed for fit after an additional 15 minutes, after 2 hours, and after 24 hours, using the Sheffield 1-screw test. Observational outcomes are presented indicating visually perceived fit relative to the type of indexing resin. Both indexing materials were judged to be visually accurate at the 15-minute time interval only. Within the limitations of this in vitro study, both resin-indexed implant assemblies were judged visually accurate for fit 15 minutes after polymerization but not at subsequent test intervals.
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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... more
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 &gt; 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 (&lt; 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.
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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... more
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 &lt;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 &lt;0.0001); better results were obtained overall for the ideal light situation. In ideal light thicker samples gave better results (P=0.0001).
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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... more
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. 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. ANOVA and multiple regression analysis were applied and the following factors were found to have a statistically significant effect on crater depth (p&amp;amp;lt;0.0001): total delivered energy, pulse duration and inner/outer location. 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.
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Recordings of patient satisfaction with provision of dental implant treatment are scarce. This study aimed to evaluate satisfaction amongst patients attending for provision of implant treatment by training undergraduate and postgraduate... more
Recordings of patient satisfaction with provision of dental implant treatment are scarce. This study aimed to evaluate satisfaction amongst patients attending for provision of implant treatment by training undergraduate and postgraduate students at Dublin Dental School and Hospital (DDSH). A questionnaire was formulated and distributed to 100 individuals randomly selected from records of patients who had received implant treatment via student clinics in the previous 5 years. The response rate was 68%. Results showed a high overall level of satisfaction with treatment received.
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The purpose of this study was to examine the effectiveness of conventional pre-clinical training in dentistry and to determine if evaluation of a dental procedure at the beginning of dental training can be a predictor for future... more
The purpose of this study was to examine the effectiveness of conventional pre-clinical training in dentistry and to determine if evaluation of a dental procedure at the beginning of dental training can be a predictor for future performance. A group of second year dental students with no previous experience in operative dentistry were asked to prepare a conventional class I cavity on a lower first molar typodont. Their first preparation was carried out after an introductory lecture and a demonstration and their second at the end of conventional training. The prepared typodonts were coded and blindly scored for the traditional assessment criteria of outline form, retention form, smoothness, cavity depth and cavity margin angulation. Once the codes were broken, a paired t-test was used to compare the difference between the means of before and after scores (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.0001) and a Pearson&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s linear correlation to test the association (r=0.4). From the results of this study, we could conclude that conventional preclinical training results in a significant improvement in the manual skills of the dental students and that the dental procedure used had only a limited predictive value for later performance at the preclinical level.