Types Of Dental Restorations Research Articles

ASSESSMENT OF RADIATION SCATTER AND ATTENUATION BY DENTAL RESTORATIONS IN HEAD AND NECK RADIOTHERAPY: A DOSIMETRIC STUDY

This dosimetric study investigates the impact of scattered and attenuated radiation by dental restorations in head and neck radiotherapy. Dental restorations, including fillings, crowns, and implants, can alter the distribution of radiation doses during radiotherapy treatments, potentially affecting treatment efficacy and normal tissue toxicity. The research employs advanced dosimetric techniques to quantify the extent of radiation scatter and attenuation caused by various types of dental restorations. Through phantom studies and Monte Carlo simulations, the study evaluates the magnitude and spatial distribution of radiation perturbations in the vicinity of dental restorations. The findings contribute to improving treatment planning accuracy and patient safety in head and neck radiotherapy by providing insights into the dosimetric effects of dental restorations.

THE RELATIONSHIP BETWEEN PERIODONTAL HEALTH AND FIXED PROSTETHIC RESTORATIONS

Periodontal health and various types of dental restorations are very closely related. On the one hand, periodontitis is a multifactorial disease. The main etiological factor is the microflora found in dental plaque. Plaque retentive factors - both natural and iatrogenic - are extremely important for the development of an inflammatory process of the periodontium. Among the most common iatrogenic plaque retentive factors are overhanging interproximal restorations (direct and indirect) and not precisely made prosthetic fixed structures. On the other hand, for restorative dentistry to be successful, it is necessary to first achieve periodontal health in the respective area, which should be maintained after the fabrication and placement of the dental restoration.

Development and validation of a 3D anthropomorphic phantom for dental CBCT imaging research.

Optimization of dental cone beam computed tomography (CBCT) imaging is still in a preliminary stage and should be addressed using task-based methods. Dedicated models containing relevant clinical tasks for image quality studies have yet to be developed. To present a methodology to develop and validate a virtual adult anthropomorphic voxel phantom for use in task-based image quality optimization studies in dental CBCT imaging research, focusing on root fracture (RF) detection tasks in the presence of metal artefacts. The phantom was developed from a CBCT scan with an isotropic voxel size of 0.2mm, from which the main dental structures, mandible and maxilla were segmented. The missing large anatomical structures, including the spine, skull and remaining soft tissues, were segmented from a lower resolution full skull scan. Anatomical abnormalities were absent in the areas of interest. Fine detailed dental structures, that could not be segmented due to the limited resolution and noise in the clinical data, were modelled using a-priori anatomical knowledge. Model resolution of the teeth was therefore increased to 0.05mm. Models of RFs as well as dental restorations to create the artefacts, were developed, and could be inserted in the phantom in any desired configuration. Simulated CBCT images of the models were generated using a newly developed multi-resolution simulation framework that incorporated the geometry, beam quality, noise and spatial resolution characteristics of a real dental CBCT scanner. Ray-tracing and Monte Carlo techniques were used to create the projection images, which were reconstructed using the classical FDK algorithm. Validation of the models was assessed by measurements of different tooth lengths, the pulp volume and the mandible, and comparison with reference values. Additionally, the simulated images were used in a reader study in which two oral radiologists had to score the realism level of the model's normal anatomy, as well as the modelled RFs and restorations. A model of an adult head, as well as models of RFs and different types of dental restorations were created. Anatomical measurements were consistent with ranges reported in literature. For the tooth length measurements, the deviations from the mean reference values were less than 20%. In 77% of all the measurements, the deviations were within 10.1%. The pulp volumes, and mandible measurements were within one standard deviation of the reference values. Regarding the normal anatomy, both readers considered the realism level of the dental structures to be good. Background structures received a lower realism score due to the lack of detailed enough trabecular bone structure, which was expected but not the focus of this study. All modelled RFs were scored at least adequate by at least one of the readers, both in appearance and position. The realism level of the modelled restorations was considered to be good. A methodology was proposed to develop and validate an anthropomorphic voxel phantom for image quality optimization studies in dental CBCT imaging, with a main focus on RF detection tasks. The methodology can be extended further to create more models representative of the clinical population.

Changing trends in the microvascular reconstruction and oral rehabilitation following maxillary cancer

PurposeThe maxillectomy defect is complex and the best means to achieve optimal reconstruction, and dental rehabilitation is a source of debate. The refinements in zygomatic implant techniques have altered the means and speed by which rehabilitation can be achieved and has also influenced the choice regarding ideal flap reconstruction. The aim of this study is to report on how the method of reconstruction and oral rehabilitation of the maxilla has changed since 1994 in our Institution, and to reflect on case mix and survival.MethodsConsecutive head and neck oncology cases involving maxillary resections over a 27-year period between January 1994 and November 2020 were identified from hospital records and previous studies. Case note review focussed on clinical characteristics, reconstruction, prosthetic rehabilitation, and survival.ResultsThere were 186 patients and the tumour sites were: alveolus for 56% (104), hard palate for 19% (35), maxillary sinus for 18% (34) and nasal for 7% (13). 52% (97) were Brown class 2 defects. Forty-five patients were managed by obturation and 78% (142/183) had free tissue transfer. The main flaps used were radial (52), anterolateral thigh (27), DCIA (22), scapula (13) and fibula (11). There were significant changes over time regarding reconstruction type, use of primary implants, type of dental restoration, and length of hospital stay. Overall survival after 24 months was 64% (SE 4%) and after 60 months was 42% (SE 4%).ConclusionThese data reflect a shift in the reconstruction of the maxillary defect afforded by the utilisation of zygomatic implants.

The Effect of Patient Specific Factors on Occlusal Forces Generated: Best Evidence Consensus Statement.

The purpose of this Best Evidence Consensus Statement was to search the literature to determine if there is a relationship between patient specific factors and occlusal force. A literature review was conducted in the following databases: Evidence-Based Medicine Reviews (EBMR), Cochrane Database of Systematic Reviews, Embase, and Ovid MEDLINE(R) and Epub Ahead of Print. Articles on patient factors and occlusal force were compiled by using a combination of the key words: "bite force," "occlusal force," "partial and complete edentulism," "bruxism," and "orthognathic class." Inclusion criteria included meta-analyses, systematic reviews, randomized controlled trials, case series, and journal articles. Exclusion criteria were case reports, studies in children, animals, and bench studies. Of the 1502 articles that met the initial search criteria, 97 related to patient-specific factors affecting occlusal forces. These articles were evaluated, rated, and organized into appropriate categories addressing questions of foci. The range of occlusal force is highly variable among subjects correlated to patient specific factors such as age, gender, partial and complete edentulism, the presence of a maxillofacial defect, location of edentulous area, orthognathic profile, and magnitude of occlusal vertical dimension. Tooth replacement therapies targeted at increasing occlusal contact seem to have a positive effect on increasing occlusal force. Bruxism does not necessarily demonstrate higher occlusal powering but may have greater tooth contact time. Occlusal force is not clearly affected by the type of dental restoration or restorative material used. The clinical significance of the changes in occlusal forces is yet to be determined.

Biological complications in patients with implant-supported dental restorations

Introduction. Biological complications are the most common type of complications around dental implants. They appear in two forms, peri-mucositis and peri-implantitis. The aim of our research was to analyze the above-mentioned complications regarding the time elapsed from implantation and implant loading, as well as regarding the type of dental restoration. Material and methods. 18 patients with self-reported complications were examined at the Department of Periodontology and Oral medicine, School of Dental medicine, University of Belgrade. Each patient filled an anamnestic questionnaire. Clinical examination, including photographic and radiographic documentation have been performed. Results. Clinical examination included 18 patients and 97 implants in total (70% female patients and 30% male patients). The average time elapsed from implants placement was 7.5 years and the average from final dental restoration was 7 years. Periodontitis was diagnosed in 85% of the patients. Complications were more common among the patients with cement-retained restorations. Conclusions. Due to the limitation of our study, we can assume that periodontal disease and cement-retained restorations are the risk factors for genesis and development of the complications around dental implants. The results of our study are in consent with data found in the literature, but in order to confirm these results it is necessary to perform analysis on a larger sample and with longer follow-up.

Study of Electrochemical Behavior of Some Dental Alloys

The purpose of the study is to investigate the electrochemical behavior of two dental alloys: palladium alloy (Palidor) and Ni-Cr alloy (Verasoft) in three types of artificial saliva. Determination of corrosion potential and recording of linear and cyclic polarization curves were performed with PGP201 potentiostat (VoltaLab 21- Radelkis Copenhagen. In order to study the modifications produced on the surface of the electrodes, a complex optical microscope MC 1 research type (IOR, Romania) was used, adapted to a digital camera, which was connected to a computer for the digital acquisition of images . Two metal alloys based on Ag-Pd and Ni-Cr were used for the experiments. The materials used came from different types of dental restorations removed from the oral cavity of the patients after a 5-15 years period. As corrosion environments, three artificial saliva were used: Fusayama, Afnor and Rondelli. The Pd-Ag dental alloy exhibits a very good corrosion resistance and the treatment in the Afnor saliva does not affect the surface of the alloy. Electrochemical behavior in Fusayama-Meyer�s saliva of the alloy surface results in a series of spots representing deposits of insoluble salts resulting from the oxidation process, while in the Rondelli saliva there is a series of small corrosion points on the alloy surface. The behavior of the Verasoft alloy in the Afnor and Rondelli saliva is similar; In both solutions, the potential breakthroughs are very close, but in Fusayama-Meyer�s saliva, the potential for initiation of corrosion points is very low (206 mV), a potential that can be encountered in the oral cavity. All metals and metal alloys, even the noble and semi-precious ones, are susceptible to corrosion, forming compounds with properties different from those of the metal or base alloy, which change their surface condition. Metallic dental restorations are permanently affected by the factors of the oral environment (physical-mechanical, chemical and biological), being subjected to a continuous process of degradation.

A Comparison Among Additive Manufactured Polymeric Complete Dental Models Resulting from Intraoral Scans: an in Vivo Study

The use of intraoral scanners and Additive Manufacturing (AM) techniques in dentistry is increasing, and such technologies are integrated in daily workflows for the production of various types of dental restorations. Thus, it is clinically sensible to assess the accuracy of these systems. This in vivo study presents a comparison, in term of accuracy, among three commercially available AM systems, used to rapid prototype models obtained from intraoral scans data. Eight patients with a complete dentition were selected. Complete-arch scans of both upper and lower jaws were obtained using the 3Shape Trios 3 color intraoral scanner. The corresponding CAD models were created by means of the 3Shape Dental System software, and three AM systems, Photocentric LC10 (AM1), Zortrax M 200 (AM2) and Prusa I3 (AM3) were used to manufacture them. The manufactured fourty-eight models were scanned with the 3Shape Trios 3 color scanner, by the same operator. Scans of the manufactured models were aligned and compared to the reference intraoral scan by means of a Reverse Engineering software (Geomagic Studio). The comparison between the scans of the manufactured models and the reference intraoral scans, for the eight patients, shows a standard deviation (SD) in the range 0.11 – 0.27 mm for AM1, in the range 0.04 – 0.26 mm for AM2 and in the range 0.07 – 0.26 mm for AM3. The results of this research show that Prusa I3 and Zortrax M 200 are statistically more accurate than Photocentric LC10. Nevertheless, if we consider the amount of difference in accuracy, this may be not relevant from a clinical point of view. Thus, the three AM systems can be used in some dental applications which are compatible with the reported accuracy.

The opinion of children and their parents about four different types of dental restorations in a public health service in Brazil.

To investigate the opinion of children and their parents of four different types of restoration placed in primary molars. A mixed method study in which both children and their parents were involved. In the quantitative study, children and parents gave their opinion using a face scale about four different types of restoration immediately after placement, evaluating how satisfied they were. In the qualitative part, children and their parents were interviewed to report their preference among the four types of restoration using dental models and photos. In the quantitative study, 1045 restorations were placed, being conventional restorations (198 with amalgam and 205 with composite resin) and atraumatic interventions [408 with glass ionomer: ART, atraumatic restorative treatment, and 234 with preformed metal crowns (PMCs): Hall technique]. Almost all participants (children and parents) gave a positive opinion (from 94.9 to 100%) on the four types of restoration placed in the children's teeth. There was no statistical significant difference in opinion in terms of acceptance of the four types of restoration placed (Chi square test, p value>0.05). In the qualitative approach, 18 children and 11 parents were interviewed. If they could choose, children (16/18) preferred the PMCs, while parents (10/11) preferred aesthetic materials such as composite resin and glass ionomer cement. A high degree of satisfaction was observed with children and their parents in the four types of restoration after placement. However, if it could be chosen in advance, children prefer the PMCs and parents a tooth-coloured material.

A new, short, specific questionnaire (QoLIP-10) for evaluating the oral health-related quality of life of implant-retained overdenture and hybrid prosthesis wearers

Objectives: This study aimed to validate a new questionnaire for assessing the oral health-related quality of life (OHRQoL) of implant-prosthesis wearers. Methods: A group of specialists designed the 10-item scale: ‘Quality of Life with Implant-Prostheses’ (QoLIP-10). After completing a pilot trial, 150 subjects wearing implant-prostheses or complete dentures who were not requesting dental treatment participated in the main investigation. They were divided into three groups (n=50 each) depending on the type of dental restoration. Group 1 (CD): complete denture wearers (control); Group 2 (IO): implant-retained overdenture wearers and Group 3 (HP): subjects with fixed implant hybrid prostheses. Participants answered the QoLIP-10 and the Oral Health Impact Profile (OHIP-20sp) questionnaires. Information on global oral satisfaction, socio-demographic, health-behavioural, clinical and prosthetic-related data were gathered. The psychometric characteristics of the QoLIP-10 were investigated. The Spearman's rank correlation test was used to determine the association between the total scores of the QoLIP-10 and OHIP-20sp. Descriptive and non-parametric probes were run to evaluate the impact scores obtained depending on the study variables. Results: The QoLIP-10 scale is reliable and valid. The factor analysis confirmed the existence of three dimensions and meaningful inter-correlations among the 10 items. HP wearers demonstrated better biopsychosocial QoL, as indicated by their answers to Item 1 (oral pain) and Item 3 (chewing difficulty). Conclusions: The QoLIP-10 index confirmed its psychometric capacity for assessing the OHRQoL of implant overdenture and hybrid prosthesis wearers. Overall, the participants were satisfied with their mouth and implant-restorations. Clinical significance: The QoLIP-10 may be recommended for determining the influence of implant-retained overdentures and hybrid prostheses on the well-being of future patients. Hybrid prostheses are the most predictable treatment option for improving patient satisfaction in terms of oral pain and chewing functionality when compared to implant overdentures and complete dentures.

OP036: Reconstruciton of bilateral maxillectomy defect

Purpose To study the outcome of reconstruction of bilateral maxillectomy defect with free fibula flap in our institute. Materials and methods Eight consecutive cases of bilateral maxillectomy defect reconstruction with free fibula flaps were reviewed. The period of study was from January 2006 to June 2012. All clinical data were analyzed, including primary diseases, types of bilateral maxillectomy defect, flap design, peri operative complications and follow up results. The main post operative functional indices, including oral diet, speech, type of dental restoration and aesthetic results were evaluated. Results Of the eight patients who underwent bilateral maxillectomy, six were having malignant etiologies while two were benign. Four patients were males and four females. Seven of them had bilateral upper alveolus defects while one had a high bilateral defect where the alveolus could be preserved. Free fibula flap was used in all patients. There was one flap failure. Post operatively recipient site wound infection occurred in two patients, one of which cleared with conservative treatment. In the other patient fibula got exposed on one side and had to be covered with free adiposofascial radial artery forearm flap, leading to delay in oral feeding by one month. In all other patients feeding was started orally within two weeks. Adequate oronasal separation, intelligible speech and good cosmesis could be achieved in all patients. All patients opted for conventional prosthesis, though the option of dental implants was available. Conclusion Reconstruction of bilateral maxillectomy defect is challenging. Free fibula is the most effective option for reconstructing this defect at present. Acceptable levels of cosmesis, good swallowing and speech functions with low peri operative morbidity can be achieved by reconstructing this defect using free fibula.

Free-end saddle length influence on stress level in unilateral complex partial denture abutment teeth and retention elements

Different types of dental restorations are used for the therapy of unilateral free-end saddle edentulism. Unilateral complex partial denture is one of the indications for the Kennedy class II partial edentulism. The abscence of major connector and denture plate is an advantage compared to the conventional restorations, because of better comfort and shorter period of adaptation. The aim of the study was to analyse the influence of free-end saddle length change on the behaviour of unilateral complex partial denture supporting structures. Stress levels of the canine and the first premolar as retentional teeth and the attachments were tested under the influence of physiological forces with the loading point shifting distally in relation to the saddle length change. A virtual real size 3D model of the fixed part of the restoration (the canine and the first premolar with milled crowns) was created using the CATIA computer program. It was connected to the mobile part of partial denture with the SD snap in latch attachment. Mobile part of the restoration was designed in the region of 2, 3 and 4 lateral teeth (second premolar, first, second and third molar). By using the finite element method (FEM) stress levels analysis was performed under the load of physiological forces of 150 N in the free-end saddle teeth zone. The results of analysis show that physiological forces cause a different stress distribution on the abutment teeth and the attachment, depending on the saddle length. The stress level values obtained for the abutment teeth as well as the attachment are far lower than the marginal ones. The behaviour of the system changes under this defined stress, but no plastic deformation occurs.

Comparative study on the microbial adhesion to preveneered and stainless steel crowns

The extensive plaque formation on dental restorations may contribute to secondary caries or periodontal inflammation. Therefore, it is important to know how different types of dental restorations may prevent or promote the accumulation of microorganisms. The aim of this in vivo study was to evaluate the adhesion of Streptococcus mutans to preveneered and stainless steel crowns (SSCs) and to evaluate the effects of these restorations on the gingival health and oral hygiene. Twenty patients (age 3-5 years) were selected from the outpatient clinic of the pedodontics department, Faculty of Oral and Dental Medicine, Cairo University. The selected patients had (dmf) index for primary dentition ≤4, including lower right and left first primary molars. Each tooth was pulpotomy-treated and restored with either type of crowns (split-mouth technique). Then, ten swabs from the buccal mucosa, preveneered crown, and SSC surfaces were taken from each patient. Also, the gingival index (GI) and oral hygiene index (OHI-S) were measured at different times during the study. Mitis Salivarius Bacitracin agar (MSBA) was used as a selective medium for S. mutans growth. MSBA plates were taken in candle jar and incubated aerobically in 37°C for 48 h. Finally, bacteria were counted and expressed in colony forming unit (CFU). After 1, 2, and 4 weeks, mucosa and crown swabs of preveneered crown showed statistically significant higher mean CFU counts than SSC. Through the whole study period, the two restorations revealed a statistically significant decrease in mean CFU counts. Also, there was a statistically significant positive (direct) correlation between OHI-S, GI, and S. mutans counts on both restorations. The adhesion of S. mutans to preveneered crowns was higher than to SSC. Full mouth rehabilitation led to significant decrease in S. mutans count in the short term. An increase in S. mutans counts is associated with an increase in OHI-S and GI.

Maxillary Reconstruction with the Free Fibula Flap

The objective of this study was to evaluate the outcomes of using the free fibula flap in the reconstruction of maxillary defects. Thirty-four consecutive cases of maxillary reconstruction with the free fibula flap were reviewed. All clinical data were analyzed, including primary diseases, types of maxillary defect, free fibula flap design, perioperative complications, and follow-up results. The main postoperative functional indices, including oral diet, speech, type of dental restoration, and aesthetic results, were evaluated. Of the 34 patients who underwent maxillary reconstruction with the free fibula flap, the primary diseases were malignant tumor in 20 patients, benign tumor in 11 patients, and trauma in three patients. Free fibula flap transfer was successful in all cases. Postoperative complications occurred in five patients. Recipient-site wound infection occurred in two patients and donor-site wound dehiscence occurred in three patients. One patient with donor-site wound dehiscence had postoperative lameness. The oral and nasal cavities were separated well by the flap in all patients. The patients were able to take food orally and had no problems with speech intelligibility. Osseointegrated implants were placed in four patients, and complete conventional prostheses were applied in 19 patients. Excellent cosmetic results were obtained in 22 patients. Alveolar arch defects can be reconstructed successfully using free fibula flaps. This procedure also allows for dental implant rehabilitation, which can improve the patient's appearance and oral function and enhance the overall quality of life. The fibula free flap transfer has a high success rate and low perioperative complication rate, making it an ideal choice for maxillary defect reconstruction.

Retrospective case series of primary and secondary microvascular free tissue transfer reconstruction of midfacial defects

Statement of Problem. Midfacial defects arising from tumor extirpation or trauma may involve any portion of the central area of the face, including the palate, maxilla, orbit, lip, and/or nose. Speech, mastication, swallowing, and cosmesis are significantly impaired and present a unique challenge to the reconstructive surgeon. Purpose. This study evaluated the functional and cosmetic success of both soft tissue and osteocutaneous free flap reconstruction of the midface. Material and Methods. A retrospective chart review of 34 patients who underwent primary and secondary free flap reconstruction of the midface was conducted. The main outcome measures were perioperative complications, diet, speech intelligibility, type of dental restoration, and cosmetic result. Results. Fifteen patients underwent soft tissue free flap reconstruction of the midface. Six of these patients also had additional nonvascularized free cranial bone grafts to improve restoration of the orbitozygomatic region. Nineteen patients who might have required osseointegrated implants to anchor a dental prosthesis underwent osteocutaneous free flap reconstruction. Thirty-three of 34 free flaps survived, and wound complications were minimal. After surgery, 20 patients were able to eat a regular diet and 14 a soft diet. All patients had intelligible speech over the telephone. Ten patients used a dental prosthesis (5 conventional and 5 implant-borne). Cosmesis was judged to be excellent in 12 patients, good in 15 patients, fair in 5 patients, and poor in 2 patients. Conclusion. In the patients reviewed, free flap reconstruction of the midface was completed in a single stage and created a reproducible, permanent separation of the oral and sinonasal cavities with adequate speech and swallowing. (J Prosthet Dent 2001;86:369-76.)

Microvascular free flap reconstructive options in patients with partial and total maxillectomy defects.

To evaluate and discuss the free flap reconstructive options for patients with partial and total maxillectomy defects. Retrospective review of cases. Two tertiary referral centers. Fifty-one patients had partial or total maxillectomy defects resulting from oncologic surgical resection, and 7 had partial maxillectomy defects resulting from trauma. Inferior or partial maxillectomy defects included 10 anterior arch and hemipalate defects and 12 subtotal or total palate defects. Total maxillectomy defects with and without orbital exenteration included 36 maxilla defects with hemipalate and malar eminence. There were 11 fibula, 14 rectus abdominis, 9 scapular, 10 radial forearm, 5 latissimus dorsi, and 13 combination latissimus dorsi and scapular flaps. Separation of the oral cavity from the sinonasal cavities, diet, type of dental restoration, type of orbital restoration, speech intelligibility, and complications. Only 1 flap failure was reported. There was loss of bone in 2 flaps and loss of the skin paddle in 1 flap. All palatal defects were sealed by the separation of the oral and sinonasal cavities. Thirty-eight patients were able to eat a regular diet while the remaining patients maintained a soft diet. All patients conversed on the telephone without difficulty in intelligibility. Eight patients had an implant-borne dental prosthetic, and 30 patients had a conventional partial prosthetic. Orbit restoration was achieved in 2 patients with an implant-borne prosthetic, and 6 patients retained a standard orbit prosthetic. Free flap reconstruction of the maxilla creates reproducible permanent separation of the oral and sinonasal cavities in a single-stage procedure. In addition, there exists the potential for dental rehabilitation with restoration of masticatory and phonatory function. Free flap reconstruction also provides a good cosmetic result, which improves patients' outlook and contributes to their overall well-being. Reconstructive flaps are designed to fit specific maxillary defects and patient needs to provide optimally functional and cosmetic results.

Causes of Failure of Various Types of Dental Restorations and Their Longevity

Causes of Failure of Various Types of Dental Restorations and Their Longevity