David C Watts | The University of Manchester (original) (raw)
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Papers by David C Watts
Dental Materials Journal, 2017
Dental Materials, Dec 1, 2021
Dental materials : official publication of the Academy of Dental Materials, 2015
Dental Materials, Oct 1, 2018
Dental materials : official publication of the Academy of Dental Materials, Jan 8, 2018
To investigate the influence of implant design on the change in the natural frequency of bone-imp... more To investigate the influence of implant design on the change in the natural frequency of bone-implant system during osseointegration by means of a modal 3D finite element analysis. Six implants were considered. Solid models were obtained by means of reverse engineering techniques. The mandibular bone geometry was built-up from a CT scan dataset through image segmentation. Each implant was virtually implanted in the mandibular bone. Two different models have been considered, differing in the free length of the mandibular branch ('long branch' and 'short branch') in order to simulate the variability of boundary conditions when performing vibrometric analyses. Modal analyses were carried out for each model, and the first three resonance frequencies were assessed with the respective vibration modes. With reference to the 'long branch' model, the first three modes of vibration are whole bone vibration with minimum displacement of the implant relative to bone, with...
Dental Materials, Aug 1, 2013
European Journal of Orthodontics, Apr 1, 2004
Biomaterials, Aug 1, 2005
Journal of Oral Rehabilitation, 2005
The objectives of this study were to investigate the structural characteristics of orthodontic po... more The objectives of this study were to investigate the structural characteristics of orthodontic polyurethane elastomeric modules and their changes produced by mechanical and chemical ageing. Three products were tested (Generation II, Dentaurum, Alastic). For each product four groups of modules were studied under the following conditions: as-received (A(0)); after 3 weeks stretching at 50% elongation in air (B(0)); after 3 weeks immersion in an ethanol/water solution (3:1 v/v) to induce accelerated ageing (A(1)); and after 3 weeks immersion in the ethanol/water solution at 50% elongation, as above (B(1)). The chains and the solution extracts were characterized by micro-MIR FTIR spectroscopy. Specimens of group B(0) exhibited changes in peak intensities relative to the control group (A(0)), attributed to molecular orientation of poly (methylene glycol) soft segments and chain extenders such as butanediol. Moreover, group B(0) showed differences in the omega(CH(2))b peak at 1364 cm(-1), attributed to oxidative degradation of alpha-methylene groups by formation of ester, carboxylic acid or aldehyde groups due to hydrogen abstraction. Comparison of A(1) and B(1) groups with the controls (A(0), B(0)) showed no major differences between their respective spectra, apart from the loss of the 1639 cm(-1) peak attributed to ethylene NN bis (stearamide) wax. However, comparison of the spectra of the extracts from the elongated modules with the extracts of the controls revealed differences in the concentration of alcohol and alkene groups. The structural changes identified were the same in all the products tested and may indicate degradation mechanisms that could potentially hold intraorally.
Dental Materials Journal, 2017
Dental Materials, Dec 1, 2021
Dental materials : official publication of the Academy of Dental Materials, 2015
Dental Materials, Oct 1, 2018
Dental materials : official publication of the Academy of Dental Materials, Jan 8, 2018
To investigate the influence of implant design on the change in the natural frequency of bone-imp... more To investigate the influence of implant design on the change in the natural frequency of bone-implant system during osseointegration by means of a modal 3D finite element analysis. Six implants were considered. Solid models were obtained by means of reverse engineering techniques. The mandibular bone geometry was built-up from a CT scan dataset through image segmentation. Each implant was virtually implanted in the mandibular bone. Two different models have been considered, differing in the free length of the mandibular branch ('long branch' and 'short branch') in order to simulate the variability of boundary conditions when performing vibrometric analyses. Modal analyses were carried out for each model, and the first three resonance frequencies were assessed with the respective vibration modes. With reference to the 'long branch' model, the first three modes of vibration are whole bone vibration with minimum displacement of the implant relative to bone, with...
Dental Materials, Aug 1, 2013
European Journal of Orthodontics, Apr 1, 2004
Biomaterials, Aug 1, 2005
Journal of Oral Rehabilitation, 2005
The objectives of this study were to investigate the structural characteristics of orthodontic po... more The objectives of this study were to investigate the structural characteristics of orthodontic polyurethane elastomeric modules and their changes produced by mechanical and chemical ageing. Three products were tested (Generation II, Dentaurum, Alastic). For each product four groups of modules were studied under the following conditions: as-received (A(0)); after 3 weeks stretching at 50% elongation in air (B(0)); after 3 weeks immersion in an ethanol/water solution (3:1 v/v) to induce accelerated ageing (A(1)); and after 3 weeks immersion in the ethanol/water solution at 50% elongation, as above (B(1)). The chains and the solution extracts were characterized by micro-MIR FTIR spectroscopy. Specimens of group B(0) exhibited changes in peak intensities relative to the control group (A(0)), attributed to molecular orientation of poly (methylene glycol) soft segments and chain extenders such as butanediol. Moreover, group B(0) showed differences in the omega(CH(2))b peak at 1364 cm(-1), attributed to oxidative degradation of alpha-methylene groups by formation of ester, carboxylic acid or aldehyde groups due to hydrogen abstraction. Comparison of A(1) and B(1) groups with the controls (A(0), B(0)) showed no major differences between their respective spectra, apart from the loss of the 1639 cm(-1) peak attributed to ethylene NN bis (stearamide) wax. However, comparison of the spectra of the extracts from the elongated modules with the extracts of the controls revealed differences in the concentration of alcohol and alkene groups. The structural changes identified were the same in all the products tested and may indicate degradation mechanisms that could potentially hold intraorally.