Intraoral wear of PICN CAD-CAM composite restorations used in severe tooth wear treatment: 5-year results of a prospective clinical study using 3D profilometry

OBJECTIVES

To evaluate, in a prospective clinical study over 5 years with ex vivo 3D profilometry analyses, the intraoral wear of Polymer-Infiltrated Ceramic Network (PICN) CAD-CAM composite restorations used in severe tooth wear treatment with the One-Step No-Prep technique.

METHODS

192 PICN (Vita Enamic) restorations on molars and premolars were included in a prospective clinical study involving patients treated according to the One-step No-prep protocol (n = 7). All patients showed clinical signs of bruxism. Replicas of restorations on molars and premolars were realized at each evaluation time (baseline and then every year up to 5 years) and scanned to perform 3D profilometry. Baseline and recall scans were superimposed with Geomagic Control software. The mean material wear was calculated for the full occlusal area (FOA) and for the occlusal contact area (OCA), respectively. Clinical evaluation of restorations was performed at recall.

RESULTS

At 5 years, the estimated mean material wear for FOA was inferior to the accuracy threshold of the profilometry measurement chain. For OCA, the estimated mean wear of the material was - 27.97 µm. This material wear was shown to be significantly influenced by time (p < 0.0001) and patient (p = 0.026), while the type of tooth (molar or premolar) had no influence. At 5 years, the survival and the success rates of restorations were 99.48% and 90.62%, respectively.

SIGNIFICANCE

The PICN material exhibits a low wear process in the treatment of severe tooth wear despite the presence of clinical signs of bruxism, and it constitutes a suitable material for the One-step No-prep technique.

Complete Denture Preclinical Training Program and Digital Tools: A Pilot Study

PURPOSE

To determine whether digital training improves conceptual skills acquisition for custom tray fabrication and tooth arrangement in the preclinical curriculum for complete denture fabrication.

MATERIALS AND METHODS

A crossover design study compared third-year student grades after conventional (manual) and digital training. Half the students were trained with conventional techniques prior to digital, while the other half were trained with digital techniques prior to conventional. The first part of the study (DP1) focused on custom tray fabrication and involved 154 students. The second part (DP2) focused on tooth arrangement with 204 students. The effect of preliminary digital training on conceptual skills was assessed by comparing the results of the students using a Student's t-test. Results were also analyzed by ranking on the students' Perceptual Ability Test (PAT) score. Finally, students' satisfaction with the training was investigated.

RESULTS

Students who completed the initial digital session achieved better custom tray fabrication and tooth arrangement in the subsequent manual sessions. For manual laboratory work, the most dexterous students (PAT1 group) demonstrated the best performance. However, PAT2 students had the best performance during the digital sessions during DP1, and PAT1 and PAT2 students had the best performance during the digital sessions during DP2. Additionally, 40% of DP1 and 12% of DP2 students expressed satisfaction with digital sessions.

CONCLUSION

With complementary manual and digital teaching, digital tools may be useful for enhanced student learning. Digital training has contributed to improve results in manual sessions but did not affect student satisfaction and remained a limited tool to detect learning difficulties.

Full-Mouth Rehabilitation of a 15-Year-Old Girl Affected by a Rare Hypoparathyroidism (Glial Cell Missing Homolog 2 Mutation): A 3-Year Follow-Up

OBJECTIVE

Familial isolated hypoparathyroidism is a rare genetic disorder due to no or low production of the parathyroid hormone, disturbing calcium and phosphate regulation. The resulting hypocalcemia may lead to dental abnormalities, such as enamel hypoplasia. The aim of this paper was to describe the full-mouth rehabilitation of a 15-year-old girl with chronic hypocalcemia due to a rare congenital hypoparathyroidism.

CLINICAL CONSIDERATIONS

In this patient, in the young adult dentition, conservative care was preferred. Onlays or stainless-steel crowns were performed on the posterior teeth, and direct or indirect (overlays and veneerlays) were performed on the maxillary premolars, canines, and incisors, using a digital wax-up. The mandibular incisors were bleached. The treatment clearly improved the patient's oral quality of life, with fewer sensitivities, better chewing, and aesthetic satisfaction. The difficulties were the regular monitoring and the limited compliance of the patient.

CONCLUSION

Despite no clinical feedback in the literature, generalized hypomineralized/hypoplastic teeth due to hypoparathyroidism in a young patient can be treated as amelogenesis imperfecta (generalized enamel defects) with a conservative approach for medium-term satisfactory results.

HIGHLIGHTS

This study provides new insights into the management of enamel hypoplasia caused by familial isolated hypoparathyroidism, helping to improve patient outcomes in similar cases.

Concordance of judgement: A tool to foster the development of professionalism in dentistry

INTRODUCTION

Developing professionalism notably involves learning how to make professional judgements in ambiguous situations. The Concordance of Judgement Test (CJT) is a learning tool that was proposed to develop professionalism competencies, but it was never performed in dentistry or used with a synchronous methodology. The present study evaluated the feasibility of the use of CJT in the context of dental education, to foster professionalism and stimulate reflexivity and discussion.

MATERIALS AND METHODS

After different steps of optimization, a questionnaire presenting 12 vignettes was submitted to 33 Canadian students. Second, after an additional optimization, a questionnaire of 7 vignettes was submitted to 87 French students. An immediate educational feedback was proposed after each vignette to promote reflexivity and discussions during the experience.

RESULTS

The overall experience of the students was reported as good, thanks to the feedback of real-life situations. This promoted reflexivity and stimulated discussion between students and educators regarding professionalism issues. The students considered CJT as a relevant and well-adapted tool, and reported positive feelings regarding the inter-university aspect of the activity. The mean score of the panel members was close to 80/100 and the mean score of the students was 5 to 10 points lower, which is in agreement with docimological performance.

CONCLUSION

The results suggested that the use of CJT in a synchronous way was a feasible and relevant tool to motivate the students to improve their professionalism, and to stimulate their reflexivity and discussion. The students reported positive experience with CJT, and we believe that this tool can be integrated in the dental curriculum.

Use of digital tools for preclinical training in complete denture: A pilot study

INTRODUCTION

Advances in CAD-CAM complete dentures open up opportunities in preclinical laboratory education. A cross-over study was conducted to assess the benefit of digital training in custom tray fabrication. Hypotheses were that digital training improved conceptual skill acquisition and that assessment of digital work helps in the discrimination of students' difficulty.

MATERIALS AND METHODS

Third-year students were allocated either into group A and took the manual practical classes before the digital ones, or into group B (N = 154). Prior to the sessions, a motor skill test was conducted. The influence on the learning process was evaluated by comparing the groups' results to the manual lab work with a Student's t-test. The effectiveness of the assessment in discriminating manual aptitude and conceptual skill was studied through Spearman's rank coefficient between digital and manual scores in conceptual skill and with a subgroup analysis according to the results of the motor skill test. The level of significance was set up at .05. Students' satisfaction was also assessed with a questionnaire.

RESULTS

Students in group B achieved better scores. Spearman's rank coefficient test showed a weak correlation, R = .16. For manual lab work, the most manually skilled students did significantly better. In contrast, for the digital session, the medium manually skilled students did better. More than half of the students (55%) found the manual and digital sessions complementary, without identifying any difference depending on the learning sequence.

CONCLUSION

Digital training improved the students' results in the conventional practical exercise. Assessments of the digital and conventional custom trays were complementary in order to distinguish conceptual and motor skills.

Intraoral low-temperature degradation of monolithic zirconia dental prostheses: 5-year results of a prospective clinical study with ex vivo monitoring

OBJECTIVES

To investigate the 5-year intraoral evolution and kinetics of low-temperature degradation (LTD) of second-generation monolithic prostheses made of 3% molar yttrium-doped tetragonal zirconia polycrystal (3Y-TZP) and the influence of masticatory mechanical stresses and glaze layer on this evolution.

METHODS

A total of 101 posterior tooth elements were included in this prospective clinical study, which comprised ex vivo LTD monitoring (at baseline, 6 months, 1 year, 2 years, 3 years, and 5 years) using Raman spectroscopy (n = 2640 monoclinic phase measurement points per evaluation time) and scanning electron microscopy (SEM). Four types of areas (1-2 mm2 surface, six on molars, and four on premolars) were analysed on each element surface: occlusal, axial, glazed, or unglazed. Raman mapping, high-resolution SEM, and focused ion beam-SEM were performed on selected samples.

RESULTS

The dental prostheses developed a tetragonal-to-monoclinic transformation at the extreme surface of the material after six months in a buccal environment, and this process increased significantly over time. Over the five years of monitoring, the transformation developed nonuniformly with the presence of localised clusters of monoclinic grains. Tribological stresses generate grain pull-out from these clusters, which may raise questions regarding the release of 3Y-TZP nanoparticles into the body. The prosthesis fracture rate was 4.5% after 5 years.

SIGNIFICANCE

LTD developed in vivo on the surfaces of 3Y-TZP dental prostheses and progressed slowly but significantly over time, up to 5 years investigation. However, the effects of aging on the failure rate recorded and of zirconia nanoparticles released into the body require further investigation.

Implant Survival Rate in Mandible Reconstructed with Free Fibula Flaps After Oral Tumors: A Systematic Review and Meta-Analysis

PURPOSE

To assess the implant survival rate in mandibles reconstructed with free fibula flap after oral tumor resection after 1 year of prosthetic loading. A secondary objective was to compare immediate or delayed implant placement protocols in this population.

MATERIALS AND METHODS

Electronic and manual searches were performed on different databases for controlled and prospective trials that indicated implant survival rate. This systematic review followed PRISMA guidelines. Risk of bias was evaluated using Cochrane Collaboration tools. Meta-analyses heterogeneity source assessment and GRADE evaluation were performed among studies with identical follow-ups.

RESULTS

Among 305 primarily selected articles, 109 were eligible after reading the title and abstract, and 8 were included after full-text reading: 2 randomized controlled trials and 6 prospective studies comprising 140 patients and 507 implants. Meta-analyses estimated an overall survival rate of 97% (95% CI: 94% to 99%) after 1 year of prosthetic loading. The survival rate was 98% (95% CI: 94% to 100%) with immediate implantation and 97% (95% CI: 90% to 99%) with delayed implantation. Only 3 studies reported radiotherapy treatment, with no real impact on implant survival rate. Overall, 69% of tumors were benign.

CONCLUSIONS

Implant placement in vascularized fibula flaps in the mandible is recommended for patients undergoing segmental mandibular reconstruction after tumor resection. Within the limitations of this study, no significant difference in survival rates was found between immediate and delayed implant placement.

Accuracy of Complete-Arch Implant Digital Scans: Effect of Scanning Protocol, Number of Implants, and Scan Body Splinting

PURPOSE

To determine the effect of scanning protocol, number of implants, and implant splinting on the accuracy of digital scanning in the edentulous arch.

MATERIALS AND METHODS

A resin-based model of an edentulous mandible with six implants was scanned with a coordinate measurement machine as a reference and then with two intraoral scanner (IOS) systems (Trios 3 and Primescan). Ten scans were taken per IOS for three experiments, and each scan was compared to the reference data to evaluate trueness and precision. Analysis involved measurement of linear and angular discrepanices using engineering software. In experiment 1, three scanning protocols were compared (curvilinear, zigzag, and half-arch). In experiment 2, three clinical situations were simulated (6 implants, 4 implants-short arch, and 4 implants-long arch). In experiment 3, the effect of implant splinting with a suture thread was measured. Normal distribution of data was examined with Shapiro-Wilk test. Levene test was used for equality of variance (α = .05). Statistical differences in distance and angular deviations were analyzed using Student t test or ANOVA with post hoc Tukey test (α = .05).

RESULTS

The best results in terms of trueness and precision were obtained with a linear scanning protocol and six implants. The results were as follows: Trios 3: trueness = 52 μm/0.42 degrees, precision = 40 μm/0.26 degrees; Primescan: trueness = 24 μm/0.28 degrees, precision = 18 μm/0.27 degrees. The scanning protocol did not significantly affect distance or angular deviation accuracy. Trueness and precision significantly decreased with four implants using Primescan and TRIOS 3. Splinting implants negatively affected accuracy with both IOS devices.

CONCLUSION

Both IOS devices achieved clinically satisfying accuracy for distance (< 100 μm) and angular (< 0.5 degrees) deviations with six implants and a linear scanning protocol. With four implants, angular deviations sometimes differed between implants within the same group depending on the IOS and the clinical situation. Int J Prosthodont 2023;36:219-227. doi: 10.11607/ijp.7332.

Radiographic evaluation of a bone substitute material in alveolar ridge preservation for maxillary removable immediate dentures: A randomized controlled trial

STATEMENT OF PROBLEM

Maxillary bone resorption after multiple extractions can jeopardize the success of an immediate denture, but whether bone volume preservation techniques are effective is unclear.

PURPOSE

The purpose of this randomized controlled trial was to evaluate the efficacy of socket grafting with a xenogenic bone substitute in participants receiving maxillary immediate removable complete dentures in terms of bone volume preservation (height and width of the bone ridge).

MATERIAL AND METHODS

The study was a single-blinded, randomized controlled clinical trial with 2 balanced parallel arms. Thirty-six participants who had Kennedy Class I edentulous posterior areas bilaterally for at least 3 months and required maxillary immediate removable complete dentures were enrolled. Duplicates of the removable complete denture were made and converted into radiographic and surgical guides. Participants allocated to the test group received deproteinized bovine bone mineral blended with 10% porcine collagen (DBBM-C) in the extraction sockets, and participants in the control group received no grafting material. With a radiographic guide in place, cone beam computed tomography scans were made 10 days after tooth extraction, when the immediate removable complete denture was delivered (D10, baseline), after 3 months (D90), and after 1 year (D365). The scans were superimposed, and measurements were made on the cross-sectional plane of each extraction site. The influence of various prognosis factors associated with bone volume preservation, including the location of tooth extraction, smoking habits, periodontal disease, and operator team, were analyzed.

RESULTS

Of 36 participants, 3 were lost to follow-up. The mean ±standard deviation loss of height of the buccal crest was 1.2 ±1.8 mm in the control group and 0.3 ±1.2 mm in the test group after 3 months of healing (P<.001) and 2.1 ±2.0 mm in the control group and 0.7 ±1.4 mm in the test group after 1 year of follow-up (P<.001). Mean ±standard deviation horizontal ridge width change was 1.3 ±1.4 mm in the control group and 0.5 ±0.8 mm in the test group after 3 months (P<.001) and 2.2 ±1.4 mm in the control group and 0.9 ±1.1 mm in the test group after 1 year of follow-up (P<.001). None of the other prognostic factors had a significant effect at either time period.

CONCLUSIONS

Grafting DBBM-C into the extraction socket after removing anterior teeth for immediate removable denture therapy resulted in significantly less vertical buccal crest and horizontal ridge resorption as compared with spontaneous socket healing after 1 year of follow-up. This procedure may be useful for preserving bone, especially when a fixed implant-supported prosthesis is planned.

OSCEGame: A serious game for OSCE training

BACKGROUND

Objective Structured Clinical Examinations (OSCEs) are amongst the most anxiety-provoking competency assessment methods. An online serious game (OSCEGame) was developed and implemented within the OSCE curriculum. This study aimed to evaluate the usefulness of this serious game on preparedness and reducing OSCE-related stress.

METHODS

A serious game was designed to help dental students train for OSCEs. Two game courses (4 stations each) were designed according to year of undergraduate training (4^th and 5^th year), based on 6 pre-existing multi-competency OSCE stations. The OSCEGame was available online on a learning platform 4 to 6 weeks before the summative OSCEs. Game use was evaluated by analysing connection data. Preparedness, stress and time management skills were assessed using a questionnaire following the summative OCSEs. The results of 4^th -year students (OSCE naive population) were compared to those of 5^th -year students to assess usefulness and benefits of such preparation method.

RESULTS

In total, 97% and 60% of the students in 4^th year and 5^th year, respectively, used the game. The game was seen as an essential preparation tool to reduce anxiety (for 60% of all students) and increase time management skills (65% of all students). However, significant differences were observed between 4^th- and 5^th -year students (anxiety reduction: 65% vs. 22%, p < 0.001; time management skills: 59% vs. 41%, p < 0.05) suggesting that it is most useful for OSCE naive students.

CONCLUSION

This serious game is a useful time efficient online tool, for OSCE preparation, especially in OSCE naive students.

Script concordance tests: A call for action in dental education

The Script Concordance Test (SCT) is an educational tool that aims to assess the ability to interpret medical information under conditions of uncertainty. It is widely used and validated in health education, but almost unknown in dentistry. Based on authentic clinical problem-solving situations, it allows to assess clinical reasoning that experienced health workers develop over the years. A specific scoring system, dedicated to SCT, considers the variability of responses of practitioners in the same clinical situations. Finally, the scores generated by SCT reflect the respondents' ability to interpret clinical data compared to experienced clinicians. This article aims to familiarise the dental educators' community with SCT construction, optimisation and its possible applications.

Intraoral low-temperature degradation of monolithic zirconia dental prostheses: Results of a prospective clinical study with ex vivo monitoring

OBJECTIVE

To investigate the intraoral development and kinetics of low-temperature degradation (LTD) in second-generation 3 mol.% yttria-doped tetragonal zirconia polycrystal (3Y-TZP) monolithic prostheses, as well as the influence of masticatory mechanical stress and glaze layer on it.

METHODS

A total of 101 posterior tooth elements were included in a prospective clinical study, which included ex vivo LTD monitoring (at baseline, 6 months, 1 year, and 2 years) using Raman spectroscopy (n = 2640 monoclinic phase measurement points per evaluation time) and SEM. Four types of areas (1-2 mm² surface, 6 on molars, and 4 on premolars) were analyzed on each element surface: occlusal, axial, glazed, or unglazed. Raman depth mapping and high-resolution SEM were performed on the selected samples.

RESULTS

LTD developed in 3Y-TZP monolithic restorations 6 months after intraoral placement and progressed with time. After two years, the tetragonal-to-monoclinic transformation was non-uniform, with the presence of localized clusters of transformed grains. In axial areas, the grain aspect was typical of the classical nucleation-growth process reported for LTD, which progresses from the surface to a depth of several tens of microns. However, in occlusal areas, tribological stress generated surface crushing and grain pull-out from the clusters, which induced an underestimation of the aging process when the evaluation was limited to monoclinic phase quantification. Glazing cannot be considered a protection against LTD.

SIGNIFICANCE

If LTD occurs in dental prostheses in the same way as in orthopedic prostheses, its clinical impact is unknown and needs to be further studied.

Clinical behavior of second-generation zirconia monolithic posterior restorations: Two-year results of a prospective study with Ex vivo analyses including patients with clinical signs of bruxism

OBJECTIVES

This study aimed to investigate (1) clinical outcomes of second-generation zirconia restorations, including patients with bruxism clinical signs, and (2) the material wear process.

METHODS

A total of 95 posterior monolithic zirconia tooth-elements in 45 patients were evaluated, 85 on implants and 10 on natural teeth, and 20.3% of restorations being fixed partial dentures (FPDs). Occlusal contact point areas were determined and half of those areas were left unglazed and just polished. Restorations were clinically evaluated following criteria of the World Dental Federation and antagonistic teeth were examined at each evaluation time. Wear ex vivo analyses using SEM and 3D laser profilometry were performed at baseline and after 6 months, 1 year, and 2 years respectively, temporarily removing the prostheses.

RESULTS

The Kaplan-Meier survival rate of restorations was 93.3% (100% for FPDs) and the success rate was 81.8%, with 4 abutment debondings, 3 tooth-supported crown debondings (provisional cement use), 1 restoration fracture, 1 minor chipping, 1 core fracture, 1 root fracture, and 2 implant losses. 80% of catastrophic failures occurred in patients with clinical signs of bruxism (61.7% of patients). Complications were also observed on antagonistic teeth (3 catastrophic failures). Clinical evaluation of the restorations showed good results from the aesthetic, functional, and biological perspective. Zirconia wear was inferior to 15 μm, while glaze wear was observed on all occlusal contact areas after 1 year.

CONCLUSIONS

Monolithic zirconia FPDs are promising but the failure rate of single-unit restorations was not as high as expected in this sample including patients with bruxism clinical signs.

CLINICAL SIGNIFICANCE

Within study limitations, FPDs showed excellent short-term results but further research is needed for single-unit restorations considering samples, which do not exclude bruxers. The weak link is the restoration support or the antagonist tooth, one hypothesis being that zirconia stiffness and lack of resilience do not promote occlusal stress damping.

Mechanical Properties of CAD/CAM Denture Base Resins

PURPOSE

To evaluate the influence of fabrication processes on the mechanical properties of denture base resins.

MATERIALS AND METHODS

Flexural strength, fracture toughness, and Vickers hardness were measured on a conventional pack-and-press resin (PRO), a resin for injection molding (CAP), and a CAD/CAM disc (CAD).

RESULTS

For maximal flexural strength, PRO (97.31 MPa) was stronger than CAD (87.98 MPa) and CAP (79.35 MPa). CAD displayed hardness similar to PRO and high fracture toughness.

CONCLUSION

CAD/CAM denture base resin mechanical properties result from the evolution of denture base materials, combining high-impact fracture toughness and improved flexural strength and hardness.

Immediate Loading of Two Unsplinted Implants in Edentulous Patients with Mandibular Overdentures: A 10-year Retrospective Review of Patients from a Previously Conducted 1-year Cohort Study

PURPOSE

This 10-year retrospective study aimed to report implant bone changes in completely edentulous patients after a mandibular immediate loading protocol using two ball attachments.

MATERIALS AND METHODS

This study was initially designed as a prospective 1-year cohort study, then extended with a 10-year retrospective evaluation of implant bone change. In the first part of the study, 43 edentulous patients wearing satisfactory maxillary and mandibular dentures for at least 3 months were included. Two interforaminal implants (Brånemark system, Nobel Biocare) were placed symmetrically in the anterior mandible using a surgical template and a torque greater than 40 Ncm. Immediately following surgery, 2.25-mm-diameter ball abutments were screwed to the implants, and their matrices (Dalbo Plus, Cendres et Métaux) were incorporated in the denture base. In an initial 1-year study, clinical recalls were scheduled 3, 6, and 12 months after implant placement with a team of two investigators. The follow-up consisted of a clinical examination and a standardized radiographic assessment of the vertical bone change. Implant stability was then monitored. The patient satisfaction was evaluated with a questionnaire before and 3 months after loading. The second part of the study occurred 10 years after the inclusion, as patients were recalled for an implant bone change monitoring.

RESULTS

The included patients were 28 to 80 years of age (mean: 61 ± 11.4 years). Three out of 86 implants failed during the healing phase (survival rate of 96.5% [90.1%, 99.2%]). Implant stability was maintained all along the 1-year follow-up (Δ = 73.33, 95% CI [72.39 to 74.26], P = .032). The mean radiographic bone loss was 0.27 ± 0.35 mm at 3 months after surgery, 0.47 ± 0.42 mm after 1 year, and 0.95 ± 0.98 mm after 10 years. General visual analog scale satisfaction was increased by 25 units with the treatment. No patients were lost to follow-up at 1 year, but five were lost at 10 years.

CONCLUSION

This protocol of immediate loading of two unsplinted mandibular implants in overdenture patients using ball attachments is a clinically viable treatment with a high implant success rate and improved satisfaction.

Zirconia abutments in the anterior region: A systematic review of mechanical and esthetic outcomes

STATEMENT OF PROBLEM

The success of single, anterior, implant-supported restorations relies on mechanical and esthetic outcomes. Titanium has been the most commonly used material for abutments, but zirconia is increasingly chosen for its appearance despite its unclear mechanical performance. Today, manufacturers market prefabricated, computer-aided design and computer-aided manufacturing (CAD-CAM) custom and zirconia abutments with titanium connections.

PURPOSE

The purpose of this study was to systematically review the mechanical and esthetic outcomes of implant zirconia abutments used in the anterior region, considering the design changes of the past 5 years.

MATERIAL AND METHODS

An electronic search was conducted in Medline (PubMed) for studies on zirconia abutments. All clinical studies with at least a 1-year follow-up and case series (>5 abutments) published after 2013 were included. Mechanical and esthetic outcomes were collected.

RESULTS

Of the 231 retrieved studies, 20 remained for quantitative analysis. Twelve described mechanical outcomes, and 15 focused on esthetics, using mainly the pink esthetic score. Five articles reported abutment fractures and no chipping. No difference was found between prefabricated and custom abutments or internal and external implant connections regarding fractures or screw loosening. All authors reported "good to excellent" esthetic integration in terms of restorations and soft-tissue color and the presence and height of papillae. The most difficult esthetic parameters to achieve were root convexity, soft-tissue color, and texture and level of mucosa.

CONCLUSIONS

Esthetics remain the major advantage of zirconia abutment when compared with titanium, despite reservations concerning the risk of mechanical complications. Data are lacking for zirconia abutments with titanium inserts, although the prospects for this design are promising.

Wear measurement of dental tissues and materials in clinical studies: A systematic review

OBJECTIVES

This study aims to systematically review the different methods used for wear measurement of dental tissues and materials in clinical studies, their relevance and reliability in terms of accuracy and precision, and the performance of the different steps of the workflow taken independently.

METHODS

An exhaustive search of clinical studies related to wear of dental tissues and materials reporting a quantitative measurement method was conducted. MedLine, Embase, Scopus, Cochrane Library and Web of Science databases were used. Prospective studies, pilot studies and case series (>10 patients), as long as they contained a description of wear measurement methodology. Only studies published after 1995 were considered.

RESULTS

After duplicates' removal, 495 studies were identified, and 41 remained for quantitative analysis. Thirty-four described wear-measurement protocols, using digital profilometry and superimposition, whereas 7 used alternative protocols. A specific form was designed to analyze the risk of bias. The methods were described in terms of material analyzed; study design; device used for surface acquisition; matching software details and settings; type of analysis (vertical height-loss measurement vs volume loss measurement); type of area investigated (entire occlusal area or selective areas); and results.

SINIFICANCE

There is a need of standardization of clinical wear measurement. Current methods exhibit accuracy, which is not sufficient to monitor wear of restorative materials and tooth tissues. Their performance could be improved, notably limiting the use of replicas, using standardized calibration procedures and positive controls, optimizing the settings of scanners and matching softwares, and taking into account unusable data.

Efficacy of bone substitute material in preserving volume when placing a maxillary immediate complete denture: study protocol for the PANORAMIX randomized controlled trial

BACKGROUND

Bone preservation is an essential issue in the context of last teeth extraction and complete edentulism. The intended treatment, whether a complete denture or an implant placement, is facilitated with a voluminous residual ridge. Bone resorption after multiple extractions has not been as well studied as the bone resorption that occurs after the extraction of a single tooth. Recent advances in bone substitute materials have revived this issue. The purpose of this study is to evaluate the interest in using bone substitute material to fill the socket after last teeth extraction in a maxillary immediate complete denture procedure compared with the conventional protocol without socket filling.

METHODS/DESIGN

A randomized, controlled, clinical trial was designed. The 34 participants eligible for maxillary immediate complete denture were divided into two groups. Complete dentures were prepared despite persistence of the last anterior teeth. The control group received a conventional treatment including denture placement immediately after extractions. In the experimental group, in addition to the immediate denture placement, a xenograft bone-substitute material (Bio-Oss Collagen®) was placed in the fresh sockets. The primary outcome of the study is to compare mean bone ridge height loss 1 year after maxillary immediate complete denture placement, with or without bone-substitute material, in incisor and canine sockets. The secondary outcomes are to compare the average bone ridge height and width loss for each extraction site. An original quantitative evaluation method using cone beam computed tomography was designed for reproducible measurements, with a radio-opaque denture duplicate. Two independent operators perform the radiologic measurements.

DISCUSSION

The immediate complete denture technique limits bone resorption in multiple extraction situations and thus allows better denture retention and better options for implant placement. To compare the benefit of using any bone socket-filling material, we proposed a quantitative evaluation protocol of resorption in the specific case of the last anterior maxillary teeth extraction with immediate denture placement.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02120053 . Registered on 18 April 2014.

Zirconia dental implants degradation by confocal Raman microspectroscopy: analytical simulation and experiments

Subsurface hydrothermal degradation of yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) is presented. Evaluation of low temperature degradation (LTD) phase transformation induced by aging in 3Y-TZP is experimentally studied by Raman confocal microspectroscopy. A non-linear distribution of monoclinic volume fraction is determined in depth by using different pinhole sizes. A theoretical simulation is proposed based on the convolution of the excitation intensity profile and the Beer-Lambert law (optical properties of zirconia) to compare between experiment and theory. The calculated theoretical degradation curves matche closely to the experimental ones. Surface transformation (V0) and transformation factor in depth (T) are obtained by comparing simulation and experience for each sample with nondestructive optical sectioning.

Radiographic and surgical guide fabrication for implant-retained mandibular overdenture

A simple technique is presented to make a multipurpose duplicate of the patient's complete denture to plan and fabricate a mandibular implant-retained overdenture. This duplicate serves 3 different functions. It can be used as a radiographic guide, surgical template, and custom tray adapted to the patient's occlusion. Advantages of the technique described are twofold: it is cost effective and makes use of equipment and materials commonly found in dental practices. The use of a single guide allows the clinician to refer to the recorded prosthetic data at each step of implant treatment.