Cork University Dental School and Hospital - Doctoral Theseshttps://hdl.handle.net/10468/13592024-03-29T13:03:13Z2024-03-29T13:03:13Z301A randomised controlled trial to determine if the addition of capnography to standard monitoring results in a decreased incidence of hypoxaemia during conscious sedation for oral surgeryBrady, Paulhttps://hdl.handle.net/10468/49202023-04-04T07:31:41Z2017-01-01T00:00:00Zdc.title: A randomised controlled trial to determine if the addition of capnography to standard monitoring results in a decreased incidence of hypoxaemia during conscious sedation for oral surgery
dc.contributor.author: Brady, Paul
dc.description.abstract: Background: Data from procedural sedation suggest that capnography is a more sensitive measure of ventilation than standard modalities and detects respiratory depression before hypoxaemia occurs. However, the generalisability of published research is problematic. To date, there has been no dentistry-specific published data supporting the use of monitoring with capnography for dental sedation. Our aim was to determine if adding capnography to standard monitoring during conscious sedation with Midazolam in a dental setting would decrease the incidence of hypoxaemia. Methods: A randomised controlled trial was conducted in which all patients (ASA I & II with BMI < 35 kg/m2) received standard monitoring and capnography, but were randomised to whether staff could view the capnography (intervention) or were blinded to it (control). The primary outcome was the incidence of hypoxaemia defined as a fall in oxygen saturation (SpO2) ≤ 94%. Results: 190 patients, mean age 31.3 years (range 14–62 years) were enrolled. There were 93 patients in the capnography group and 97 in the control group. The mean cumulative dose of Midazolam titrated was 6.94 mg (SD 2.31, range 3–20 mg). Six (3%) patients, three in each group, required temporary supplemental oxygen. There was no statistically significant difference between the capnography and control groups for the incidence of hypoxaemia: 34.4% vs 39.2% (p=0.5149, OR=0.78, 95% CI: 0.38–1.63). Conclusions: We were unable to confirm an additive role for capnography to prevent hypoxaemia during conscious sedation with Midazolam in a dental setting for patients not routinely administered supplemental oxygen. Clinical trial registration: ClinicalTrials.gov NCT01949012.
2017-01-01T00:00:00ZAccuracy of computer-aided design/computer-assisted manufacture (CAD/CAM) fabricated dental restorations: a comparative studyNasruddin, Mohd Faizhttps://hdl.handle.net/10468/22482023-04-04T07:17:44Z2015-01-01T00:00:00Zdc.title: Accuracy of computer-aided design/computer-assisted manufacture (CAD/CAM) fabricated dental restorations: a comparative study
dc.contributor.author: Nasruddin, Mohd Faiz
dc.description.abstract: Introduction: Computer-Aided-Design (CAD) and Computer-Aided-Manufacture (CAM) has been developed to fabricate fixed dental restorations accurately, faster and improve cost effectiveness of manufacture when compared to the conventional method. Two main methods exist in dental CAD/CAM technology: the subtractive and additive methods. While fitting accuracy of both methods has been explored, no study yet has compared the fabricated restoration (CAM output) to its CAD in terms of accuracy. The aim of this present study was to compare the output of various dental CAM routes to a sole initial CAD and establish the accuracy of fabrication. The internal fit of the various CAM routes were also investigated. The null hypotheses tested were: 1) no significant differences observed between the CAM output to the CAD and 2) no significant differences observed between the various CAM routes. Methods: An aluminium master model of a standard premolar preparation was scanned with a contact dental scanner (Incise, Renishaw, UK). A single CAD was created on the scanned master model (InciseCAD software, V2.5.0.140, UK). Twenty copings were then fabricated by sending the single CAD to a multitude of CAM routes. The copings were grouped (n=5) as: Laser sintered CoCrMo (LS), 5-axis milled CoCrMo (MCoCrMo), 3-axis milled zirconia (ZAx3) and 4-axis milled zirconia (ZAx4). All copings were micro-CT scanned (Phoenix X-Ray, Nanotom-S, Germany, power: 155kV, current: 60µA, 3600 projections) to produce 3-Dimensional (3D) models. A novel methodology was created to superimpose the micro-CT scans with the CAD (GOM Inspect software, V7.5SR2, Germany) to indicate inaccuracies in manufacturing. The accuracy in terms of coping volume was explored. The distances from the surfaces of the micro-CT 3D models to the surfaces of the CAD model (CAD Deviation) were investigated after creating surface colour deviation maps. Localised digital sections of the deviations (Occlusal, Axial and Cervical) and selected focussed areas were then quantitatively measured using software (GOM Inspect software, Germany). A novel methodology was also explored to digitally align (Rhino software, V5, USA) the micro-CT scans with the master model to investigate internal fit. Fifty digital cross sections of the aligned scans were created. Point-to-point distances were measured at 5 levels at each cross section. The five levels were: Vertical Marginal Fit (VF), Absolute Marginal Fit (AM), Axio-margin Fit (AMF), Axial Fit (AF) and Occlusal Fit (OF). Results: The results of the volume measurement were summarised as: VM-CoCrMo (62.8mm3 ) > VZax3 (59.4mm3 ) > VCAD (57mm3 ) > VZax4 (56.1mm3 ) > VLS (52.5mm3 ) and were all significantly different (p presented as areas with different colour. No significant differences were observed at the internal aspect of the cervical aspect between all groups of copings. Significant differences (p< M-CoCrMo Internal Occlusal, Internal Axial and External Axial 2 ZAx3 > ZAx4 External Occlusal, External Cervical 3 ZAx3 < ZAx4 Internal Occlusal 4 M-CoCrMo > ZAx4 Internal Occlusal and Internal Axial The mean values of AMF and AF were significantly (p M-CoCrMo and CAD > ZAx4. Only VF of M-CoCrMo was comparable with the CAD Internal Fit. All VF and AM values were within the clinically acceptable fit (120µm). Conclusion: The investigated CAM methods reproduced the CAD accurately at the internal cervical aspect of the copings. However, localised deviations at axial and occlusal aspects of the copings may suggest the need for modifications in these areas prior to fitting and veneering with porcelain. The CAM groups evaluated also showed different levels of Internal Fit thus rejecting the null hypotheses. The novel non-destructive methodologies for CAD/CAM accuracy and internal fit testing presented in this thesis may be a useful evaluation tool for similar applications.
2015-01-01T00:00:00ZAdolescent and parent perceptions of expected benefits of orthodontic treatment: a mixed-methods studySmyth, Joshua Peter Richardhttps://hdl.handle.net/10468/118982023-04-04T11:01:54Z2021-06-30T00:00:00Zdc.title: Adolescent and parent perceptions of expected benefits of orthodontic treatment: a mixed-methods study
dc.contributor.author: Smyth, Joshua Peter Richard
dc.description.abstract: Aims:
1: To investigate expected benefits of orthodontic treatment from both an adolescent and parent perspective.
2: To rank the expected benefits of orthodontic treatment identified by adolescents and parents in order of perceived importance.
Materials and Methods:
Ethical approval was granted to carry out both parts of this study.
Part 1 used qualitative methodology with one-to-one semi-structured interviews by a trained interviewer. Twenty adolescents (10 males; 10 females) referred for orthodontic assessment and their parents (8 males; 12 females) were interviewed independently to explore expectations of the benefits of orthodontic treatment. Interviews were transcribed verbatim and interpretive phenomenological analysis carried out.
Part 2 quantitatively assessed the benefits identified in Part 1. Twelve additional adolescents (6 males; 6 females) who were referred for orthodontic assessment and a parent (6 males; 6 females), completed a card ranking exercise to determine the rank order of the perceived importance of each benefit. The mean rank was then calculated and a two-sample t-test, with the level of significance set at P < 0.05, used to determine if a difference existed between adolescents and parents for the mean rank of any of the expected benefits.
Results:
The expected benefits of orthodontic treatment from both adolescent and parent perspectives included 11 benefits which could be grouped into four categories: oral health (improved appearance of teeth; ease of maintaining good oral health; improved jaw alignment; aiding dental development), psychosocial (improved self-confidence; improved perception of dental appearance by others), functional (improved ability to chew food; improved speech) and behavioural change (improved oral hygiene habits; improved diet; cessation of bad habits). Adolescents and parents placed a similar level of importance on these benefits with “improved self-confidence” ranked highest and “improved speech” ranked lowest. The only benefit where the mean rank differed significantly between adolescents and parents was “improved ability to chew food” (two-sample t-test; P = 0.042) which was ranked higher by adolescents.
Conclusions:
Adolescents and parents perceived 11 expected benefits from orthodontic treatment affecting oral health, psycho-social, functional and behavioural categories.
Adolescents and parents ranked the expected benefits similarly with psycho-social ranked highest. Within functional benefits, speech improvement was ranked lowest by both but improved masticatory function was ranked of significantly greater importance by adolescents.
2021-06-30T00:00:00ZAdult orthodontics: internet information and a national surveyMcMorrow, Siobhánhttps://hdl.handle.net/10468/28582023-04-04T07:24:00Z2015-01-01T00:00:00Zdc.title: Adult orthodontics: internet information and a national survey
dc.contributor.author: McMorrow, Siobhán
dc.description.abstract: Aims: 1. To investigate the reliability and readability of information on the Internet on adult orthodontics. 2. To evaluate the profile and treatment of adults by specialist orthodontists in the Republic of Ireland (ROI). Materials and methods: 1. An Internet search was conducted in May 2015 using three search engines (Google, Yahoo and Bing), with two search terms (“adult orthodontics” and “adult braces”). The first 50 websites from each engine were screened and exclusion criteria applied. Included websites were then assessed for reliability using the JAMA benchmarks, the DISCERN and LIDA tools and the presence of the HON seal. Readability was assessed using the FRES. 2. A pilot-tested questionnaire about adult orthodontics was distributed to 122 eligible specialist orthodontists in the ROI. Questions addressed general and treatment information about adult orthodontic patients, methods of information provision and respondent demographics. Results: 1. Thirteen websites met the inclusion criteria. Three websites contained all JAMA benchmarks and one displayed the HON Seal. The mean overall score for DISCERN was 3.9/5 and the mean total LIDA score was 115/120. The average FRES score was 63.1. 2. The questionnaire yielded a response rate of 83%. The typical demographic profile of adult orthodontic patients was professional females between 25-35 years. The most common incisor relationship and skeletal base was Class II, division 1 (51%) and Class II (61%) respectively. Aesthetic upper brackets and metal lower brackets were the most frequently used appliances. Only 30% of orthodontists advise their adult patients to find extra information on the Internet. Conclusions: 1. The reliability and readability of information on the Internet on adult orthodontics is of moderate quality. 2. The provision of adult orthodontic treatment is common among specialist orthodontists in the Republic of Ireland.
2015-01-01T00:00:00ZChildren and adolescents and modified twin block for Class II division 1 malocclusion compared to controls: quantitative and qualitative analysesO'Dwyer, Carolinehttps://hdl.handle.net/10468/119742023-04-04T10:41:49Z2021-07-01T00:00:00Zdc.title: Children and adolescents and modified twin block for Class II division 1 malocclusion compared to controls: quantitative and qualitative analyses
dc.contributor.author: O'Dwyer, Caroline
dc.description.abstract: Aims
• To evaluate the impact Modified Twin Block (MTB) treatment has on oral health related quality of life (OHRQoL), self-esteem, self-perception of aesthetic treatment need and 3D soft tissue facial changes in children with Class II division 1 malocclusion (II/1M) compared to children with II/1M awaiting treatment who served as controls.
• To assess the effect MTB treatment has on family quality of life (QoL) and on both the parent’s perception of their child’s OHRQoL and aesthetic treatment need compared to controls.
• To assess the level of agreement of child OHRQoL and perception of aesthetic treatment need by child and parent between groups.
Materials and methods
Following ethical approval, 60 subjects (31 males; 29 females) received MTB treatment (MTB group) and 47 subjects (22 males; 25 females) with II/1M awaiting treatment served as controls (Control group). At baseline (T1) and following MTB treatment/recall (T2) all subjects completed the Child Perception Questionnaire (CPQ11-14), Child Health Questionnaire short from (CHQ-CF45) and self-assessed aesthetic treatment need (IOTN-AC). Each child also had a 3D facial image captured at rest. At the same time points, a parent of each child completed the Parent-Caregiver Perception Questionnaire (P-CPQ) and assessed their child’s aesthetic treatment need (IOTN-AC). Comparisons of patient demographics were made using ANOVA and Chi-square tests. ANOVA was used for comparisons in CPQ, P-CPQ, CHQ-CF45 and 3D soft tissue facial changes at T1 and T2 between groups and paired t-tests were used within both groups. Bowker’s symmetry test was used to compare IOTN-AC within groups and Fisher’s Exact test was used between groups. ANOVA was used to test for associations between CPQ, CHQ, IOTN-AC, and 3D soft tissue facial change.
Results
Forty-two subjects (20 males; 22 females) completed MTB treatment (average duration 8.5 months; range 5-12 months) and 35 untreated II/1M subjects (15 males; 20 females) were recalled after an average time of 11 months (range 9-13 months). At T1, groups were similar in age (p=0.1402) and gender (p=0.2973) but overjet in the MTB group was slightly greater (p=0.0016). At T2, there was a significant improvement in the MTB group in overall OHRQoL (p<0.0001) and self-perception of aesthetic treatment need (p=0.018) but there was no change in self-esteem (p=0.144). Significant improvements occurred in family QoL (p=0.0001), in parent’s perception of both their child’s OHRQoL (p<0.0001) and aesthetic treatment need (p<0.0001). In the MTB and Control groups and at both time points, the level of agreement between child and parent perception of the child’s OHRQoL was poor with parents rating it worse [MTB group T1, p=0.0001; T2, p=0.003]; [Control group T1, p=0.001; T2, p=0.008]. At T1, parents rated the aesthetic treatment need to be greater than their child in the MTB group (p=0.054) and Control group (p=0.04). At T2, the level of agreement between the child and parent in their aesthetic treatment need was similar (p=0.262) but in the MTB group children perceived their aesthetic treatment need to be greater than their parents (p=0.019). From T1 to T2, significant 3D soft tissue changes occurred at Pogonion in the MTB group 4.26 mm (p= 0.001) and in the Control group 3.29 mm (p=0.002) but the mean difference between the groups (0.97 mm; p=0.011) was not clinically significant.
Conclusions
• MTB treatment significantly improved the OHRQoL and self-perception of aesthetic treatment need in children with II/1M but had no significant impact on self-esteem or 3D soft tissue facial changes compared to controls.
• MTB treatment significantly improved the family QoL and both the parent’s perception of their child’s OHRQoL and aesthetic treatment need compared to controls.
• In children following MTB treatment or awaiting treatment, poor agreement existed between the child and parent perception of OHRQoL and aesthetic treatment need.
2021-07-01T00:00:00ZComparison between local anaesthetic agents, lidocaine and bupivacaine, in patients undergoing third molar extraction in terms of patient satisfaction.McCarthy, Carolinehttps://hdl.handle.net/10468/22352023-04-04T07:28:59Z2016-01-01T00:00:00Zdc.title: Comparison between local anaesthetic agents, lidocaine and bupivacaine, in patients undergoing third molar extraction in terms of patient satisfaction.
dc.contributor.author: McCarthy, Caroline
dc.description.abstract: AIMS: (1) To determine if anaesthetic agent bupivacaine, has a prolonged effect on the period of acute postoperative pain when compared to lidocaine, a shorter acting agent. (2) To determine patient’s post-operative satisfaction and preference with regard to anaesthetic choice. METHODS: This double blind, randomised, interventional clinical trial included 85 patients. All patients had bilateral impacted lower third molars of removed under general anaesthetic. All patients received 0.5% plain bupivacaine on one randomly allocated side, with 2% lidocaine (with adrenaline) administered on the opposite side. Pain was measured using visual analogue scales at 0, 30, 60 minutes and 3, 4, 6 and 8 hours post-surgery. Pain was analysed for 1 week following surgery. Psychological evaluations and patient reported outcomes, including patient satisfaction were evaluated. RESULTS: A significant difference in pain (P=0.001) was seen during the 3-8 hour post-operative period. The upper limit of the 95% confidence interval was 10.0 or above at 3hours and 4 hours post-surgery. Two-thirds of patients preferred bupivacaine. CONCLUSION: Longer lasting anaesthetics such as bupivacaine offer a longer period of analgesia, and improve overall patient satisfaction.
2016-01-01T00:00:00ZComparison of statural height growth velocity with chronological age and dental development at different cervical vertebral maturation stages in a contemporary Irish populationCoffey, Diarmuid Johnhttps://hdl.handle.net/10468/119872023-04-04T10:55:51Z2021-07-01T00:00:00Zdc.title: Comparison of statural height growth velocity with chronological age and dental development at different cervical vertebral maturation stages in a contemporary Irish population
dc.contributor.author: Coffey, Diarmuid John
dc.description.abstract: Aim:
The aim of this study was to investigate if a correlation exists between CVM stage and statural height growth velocity, chronological age and dental development in a contemporary Irish population.
Materials and Methods:
Following ethical approval, a total of 269 subjects were recruited from the orthodontic treatment waiting list at Cork University Dental School and Hospital (CUDSH). All participants had a digital lateral cephalogram and DPT as part of their initial orthodontic records. Standardised standing height was also measured at this initial appointment and at subsequent 6 to 8 week intervals for approximately one year to calculate a mean annualised growth velocity (MAGV). A single calibrated observer assessed CVM stage from lateral cephalograms using the method described by Baccetti et al., (2005) and dental development stage of the mandibular second permanent molar from each DPT using Demirjian’s Index. Chronological age was determined from the subject’s chart. Statistical analysis of MAGV, chronological age and stage of dental development were performed using ANOVA, with CVM and gender as factors. Pairwise comparisons were made between CVM stages.
Results:
The final sample comprised of 218 subjects (121 females, 97 males), with a mean age of 14.02 (SD 1.97) years and age range of 8.82-18.77 years. Intra-observer (ĸ = 0.97) and inter-observer (ĸ = 0.94) reliability of CVM stage assessment were ‘almost perfect’. Intra-observer reliability for dental development stage was also ‘almost perfect’ (ĸ = 0.97). There was a statistically significant difference in MAGV between CVM stages (p<0.0001) and between genders (p<0.0001). The peak in statural height growth velocity occurred at CVM stage 3 in both males (mean age 13.39 (SD 0.75) years) and females (mean age 11.95 (SD 0.82) years). Chronological age exhibited significant differences between CVM stages (p<0.0001) and between genders (p<0.0001). There was also a statistically significant difference in the distribution of dental development stage between CVM stages (p<0.0001) and between genders (p=0.0292).
Conclusions:
• MAGV differed significantly between successive CVM stages in both males and females, with the peak in statural height growth velocity found at CVM stage 3.
• Chronological age differed significantly between CVM stages, and these differences were dependent on gender.
• The distribution of dental development stages differed significantly between CVM stages and between genders.
2021-07-01T00:00:00ZDentofacial parameters associated with the unilateral palatally impacted canineKoshak, Lamishttps://hdl.handle.net/10468/28752023-04-04T07:09:25Z2015-01-01T00:00:00Zdc.title: Dentofacial parameters associated with the unilateral palatally impacted canine
dc.contributor.author: Koshak, Lamis
dc.description.abstract: Aims To investigate the relationship between unilateral PIC and specific dentofacial parameters. Materials and methods A sample of 216 subjects, with 108 subjects in the retrospective and prospective samples respectively. Dental parameters: The following dental parameters were assessed: Inter-canine and intermolar width; palatal depth and palatal area; anterior Bolton tooth-size discrepancy (TSD); maxillary arch shape and ratio and maxillary central and lateral incisor shape and ratio. Facial parameters: Three-dimensional (3D) images were taken for subjects in the prospective sample only, and were used to assess the following facial parameters: Face shape; face ratio and 3D distances and angles. Results Dental parameters: Inter-canine width was significantly smaller in the test group compared to the control group in the retrospective (p= 0.0002) and prospective (p= 0.0018) samples respectively. Anterior Bolton TSD was significantly higher in the prospective test group compared to controls (p= 0.0070). Arch ratio was significantly smaller in the test group than the control group for the retrospective sample (p= 0.0029), whereas no significant difference was recorded in the prospective sample (p= 0.1017). Arch shape distribution was significantly different in the retrospective sample (p= 0.009). Tooth shape distribution was significantly different for the maxillary right central incisor in the retrospective sample (p= 0.030). Tooth ratio showed no significant difference for both samples. Facial parameters: Basal width was significantly smaller in the test compared to the control group (p= 0.0001). No significant difference was found in all other 3D distances and angles measured. Conclusion Inter-canine width was significantly smaller in unilateral PIC subjects compared to controls. Anterior Bolton TSD was significantly higher in prospective unilateral PIC compared to controls. Maxillary arch ratio was significantly smaller in retrospective subjects. Square/tapered tooth shape was significantly more common in the retrospective group. Basal width was significantly smaller in subjects with unilateral PIC than controls.
2015-01-01T00:00:00ZDetermining competence in prosthodontics in undergraduate dental school programmes: an international studyAl Khalaf, Khaleelhttps://hdl.handle.net/10468/140602023-04-04T10:44:50Z2022-12-09T00:00:00Zdc.title: Determining competence in prosthodontics in undergraduate dental school programmes: an international study
dc.contributor.author: Al Khalaf, Khaleel
dc.description.abstract: Background and aims: In an era of increased attention on patient safety, as well as
increased student mobility between many countries, it is of interest to investigate
contemporary international trends in the teaching and assessment of prosthodontics.
The aims of this PhD project were to investigate the teaching and assessment methods
of the prosthodontics domains and to determine if it is possible to agree on competency
standards in prosthodontics.
Structure and methods: This thesis includes an introductory chapter (Chapter 1), a
narrative review of relevant educational and prosthodontic literature (Chapter 2), four
original quantitative (questionnaire-base) studies to assess the contemporary teaching
and assessment methods of prosthodontics on international basis (Chapters 3-6), and
a mixed-method Delphi approach among prosthodontic/restorative dentistry experts
to obtain a consensus on the most suitable undergraduate teaching and assessment
methods (Chapter 7). Chapter 8 includes a qualitative study using one-to-one interview
to explore the perspectives and opinions of senior dental academics that did not reach
consensus using the Delphi method. Chapter 9 contains a systematic review
synthesising the response rates in dental literature of questionnaire-base studies.
Finally, a brief conclusion of the thesis was presented (Chapter 10).
Results: Narrative review: there was significant divergence among prosthodontic
curricula in dental schools in terms of teaching methods, assessment criteria and how
student competence is determined.
Quantitative studies: Our findings from the quantitative studies reinforced the findings
of the narrative review; there was a significant international divergence of undergraduate teaching and assessment trends among dental schools, including the preclinical and clinical course, of the prosthodontics divisions (complete denture, removable partial denture, fixed prosthodontics and dental implants). Divergence was evident in dental schools even within the same country.
Mixed-method Delphi and qualitative studies: A total of 23 senior academic experts
from 11 countries participated in the Delphi study. There was a high level (92.6%, 175
statements out of 189) of consensus agreement over three iterative rounds, whereas 14
statements (7.4%) did not achieve a consensus. A total of 12 senior dental academics
from seven countries participated in semi-structured interviews, it was agreed that
academic professors, consultants, or specialists were the most suitable staff members
to supervise students during preclinical hands-on sessions in removable and fixed
prosthodontics. In addition, participants mentioned the availability of suitable patients
for treatment, dental schools’ curriculum and the level of students’ skills as factors
influencing the starting point of clinical sessions in fixed prosthodontics. We also found differences among the participating schools in regard to course contents and extent of teaching on dental implants. The experts suggested tailoring the curriculum according to what is expected from the graduating dentists and allowing students to observe dental implant cases before treating simple cases.
Systematic review of response rate: Overall, 133 studies with 149 response rates were
included. The median response rate across the included studies was 77%, a significant
negative correlation was observed between the response rate and the actual number of
distributed questionnaires (sample size) (r = -0.4127; P<0.001). there was an association between the response rate and the area of distribution (e.g., national or international, P= 0.0012). Yet, it was unclear whether if there are correlations between
the response rate and other variables (e.g., piloting, number of questions and the journal impact factor).
Conclusions: This thesis highlighted the current divergence in teaching and assessment methods of undergraduate prosthodontics. However, this divergence can be minimized, and the international harmonization of the dental curricula is highly possible by reassessing and tailoring the dental curricula. We presented a list of senior academics’ consensus statements on the teaching and assessment methods of prosthodontics. In addition, multiple recommendations and challenge resolutions were suggested and introduced. Thus, our findings can be considered as guidelines and references to develop recommendations for stakeholders involved in undergraduate curricula among dental schools worldwide and in consistence with the local dental council recommendations, which will ensure dentists with the same level of competence at graduation.
2022-12-09T00:00:00ZEndodontic access in all-ceramic dental restorative crown materialsGorman, Catherine M.https://hdl.handle.net/10468/62882023-04-04T07:35:19Z2018-01-01T00:00:00Zdc.title: Endodontic access in all-ceramic dental restorative crown materials
dc.contributor.author: Gorman, Catherine M.
dc.description.abstract: A diagnosis of irreversible pulpitis can occur after a crown has been permanently cemented. This necessitates the need for endodontic treatment, often with the crown in situ. Increasing trends indicate that all-ceramic crowns are provided as the preferred restorative option to metal-ceramic crowns. This is because modern all-ceramic restorations can now provide excellent aesthetic solutions combined with high mechanical strength properties, compared with earlier, weaker ceramic materials. It is a considerable operative challenge for the dental practitioner to prepare an endodontic access cavity in vivo, due to the high mechanical properties of modern dental ceramic materials. The inherent nature of ceramic materials is that they are brittle, sensitive to damage and moisture, with failure occurring in an unpredictable manner. The difficulties in performing endodontic treatment in all-ceramic crowns and subsequently repairing the access cavity is relatively unexplored in the dental literature, more research is needed to inform clinical practice in this area. A systematic review of the literature aimed to identify influential treatment factors of endodontically accessed and repaired all-ceramic crowns and report the evidence of damage around the endodontic access cavity as a result of preparing the cavity in an all-ceramic crown. Eight studies were selected to address the aims. The inadequate volume of literature was highlighted with, the earliest relevant publication identified in 1962 and since the last electronic search (2016) only 26 additional references were identified in the subject area. Potentially noteworthy strength controlling factors were identified to be related to the crown material, its baseline strength, the grit size of the diamond bur used to create the access cavity, the ratio of access cavity to crown dimension, the cement used to lute the crown and the presence of radial cracks after access cavity preparation. The effect of two variables, namely, cavity dimension and modulus of elasticity of the resin composite repair material on the equibiaxial flexural strength of lithium disilicate glass-ceramic (IPS e.max® Press, Ivoclar Vivadent) material was investigated. Disc specimens with representative access cavities were used as a model system to examine these variables. Within the study limitations, the results indicate that cavity size and not the repair material, influence the equibiaxial flexural strength. The shear bond strength of the resin composite material used to repair the access cavity in a lithium disilicate glass-ceramic was determined to be comparable to those values as found in the literature (see Appendices). Model mandibular first molar crowns were fabricated from lithium disilicate glass-ceramic to examine the impact of cavity size on failure load. The failure load for the intact crowns and crowns with a rhomboidal (based on the presence of three-canals) or rectangular (based on the presence of four-canals) endodontic access cavity, with and without a resin composite repair were measured and analysed statistically. Within the limitations, the results show that a rectangular access cavity significantly reduces the failure load which was then restored to the original values upon repair with resin composite. The preparation of a rhomboidal access cavity did not reduce the failure load compared with the intact crown. The novel use of Finite Element Analysis (FEA) was successfully demonstrated in this subject area. Solid geometric models of lithium disilicate glass-ceramics (LDGC) crowns with three endodontic access options repaired with a resin composite (Tetric EvoCeram®, Ivoclar Vivadent) were modelled. The models were subsequently subjected to clinically relevant loads and a stress analysis was performed using FEA. This work showed that high curvature access cavity designs produced the highest stress scenario and therefore should be avoided. In an attempt to compliment the in vitro study computer models of LDGC discs were modelled using Finite Element (FE). The models were successfully validated, similar variables were modelled and concentric ring loading conditions were applied as per the in vitro study. It was determined that the size and not the stiffness of the repair material was more critical to the strength of LDGC discs. In conclusion, this study has addressed some of the aspects of problems encountered when endodontic access cavities are prepared in all-ceramic dental crowns, however it is an area where substantial literature is lacking and therefore further research is warranted.
2018-01-01T00:00:00Z