The Impact of Technology Teaching in the Dental Predoctoral Curriculum on Students' Perception of Digital Dentistry

The goal was to assess dental students' perception of digital technologies after participating in a CAD/CAM exercise for scanning, designing, and manufacturing computer-aided provisional fixed dental restorations. A survey was conducted among second- (pre-D2 and post-D2), first- (D1, negative control), third-, and fourth-year dental students (D3 and D4, positive controls). Only OSU College of Dentistry students who completed the activity and completed the surveys were included. Seven questions were rated, which evaluated changes in knowledge, skill, interest, the importance of technology availability in an office, patients' perception of technology, the importance of having the technology, and the expected frequency of clinics utilizing the technology. Statistical analysis was performed with a significance level of 0.05. A total of 74 pre-D2 and 77 post-D2 questionnaires were completed. Additionally, 63 D1, 43 D3, and 39 D4 participants responded to the survey. Significant differences were found for "knowledge" and "skill" between the pre-D2 and post-D2 and pre-D2 and control groups (p < 0.001). There was a significant difference between the post-D2 participants and all the controls in terms of "interest" (p = 0.0127) and preference for in-practice technology availability (p < 0.05). There were significant results between the post-D2 participants and all the controls regarding the importance of technology availability in an office (p < 0.001) and the expected frequency of clinics utilizing the technology (p = 0.01). No significance was found for "value of technology to patients" and "the importance of having the technology". The presence of technology in practice and in educational academic environments significantly improved students' interest and perception of their knowledge and skill.

Evaluation of the effectiveness and practicality of erbium lasers for ceramic restoration removal: A retrospective clinical analysis

BACKGROUND

The purpose of this study was to assess the effectiveness and practicality of erbium lasers in the removal of ceramic restorations and appliances from natural teeth and dental implant abutments in clinical practice.

METHODS

A retrospective analysis was conducted, involving 29 clinical cases with a total of 52 abutments requiring the removal of various ceramic restorations. The analysis evaluated the clinical procedures performed, including the type and material of the prosthetic, the type of cement used, laser setting parameters, retrieval time, and retrieval success.

RESULTS

Out of the 52 abutments, 50 were successfully retrieved without causing any damage (>95%) using either an Er,Cr:YSGG laser (N = 6) or an Er:YAG laser (N = 46). In one case, a crown was partially sectioned to prevent any negative impact of laser irradiation on the adhesive strength between the post and tooth, and in another case, a fracture occurred during debonding. The restorations consisted of 13 lithium disilicate and 39 zirconia units, including six veneers, 38 single crowns, and three fixed partial dentures (FPDs). The retrieval time varied depending on the restoration type, material thickness, cement type, retention form/fitting of the abutment and restoration, ranging from 2.25 ±0.61 minutes for veneers, 6.89 ±8.07 minutes for crowns, to 25 ±10 minutes per abutment for FPDs. Removal of a zirconia crown required more time, 7.12±8.91 minutes, compared to a lithium disilicate crown, 5.86 ±2.41 minutes. The debonding time was influenced by the laser settings as well as materials and types of prosthesis.

CONCLUSIONS

Erbium lasers present a safe and effective alternative to invasive methods for removing ceramic restorations, without causing harm to the abutment or prosthesis. Laser-assisted debonding allows for recementation of the restorations during the same appointment, making it a conservative and viable option for ceramic crown retrieval in clinical settings.

The effect of crowding on the accuracy of 3-dimensional printing

INTRODUCTION

The purpose of this study was to evaluate the accuracy of 3-dimensional (3D) printed aligners compared to conventional vacuum-formed thermoplastic aligners with varying levels of dental crowding.

METHODS

Digital intraoral scans of 10 cases were assigned to their respective groups (n = 10, each, 30 total) as follows: no crowding (control), moderate crowding, and severe crowding. Digital images of these models were created in standard tessellation language (STL) file format using 3Shape software and randomly 3D printed. The STL files of each case were also sent to a dental laboratory to fabricate vacuum-formed samples, the current technology used for manufacturing aligners. The intaglio surfaces of fabricated aligners in both groups were scanned using cone beam computed tomography to create STL files, which were then compared to the original STL files of the cases using Geomagic Control X software. Absolute deviations from the original file and root mean square values were recorded. A Kruskal-Wallis test was conducted to analyze the difference in average deviation, and a t-test was repeated for the RMS measure. The significance level was set at 0.05.

RESULTS

The crowding did not affect the trueness of aligners manufactured using 3D printing or conventional vacuum-forming techniques (P = 0.79). 3D-printed aligners showed less deviation than the vacuum-formed samples (0.1125 mm vs 0.1312 mm; P <0.01). Aligners manufactured with the vacuum-forming technique had significantly higher variation than those with the 3D printing process (P = 0.04).

CONCLUSIONS

3D aligners printed directly from an STL file exhibited better precision and trueness than those fabricated using the conventional vacuum-forming technique. Since accuracy is defined as a combination of precision and trueness, it is concluded that direct printing from an STL file can be used to manufacture aligners.

Evaluation of Prosthetic Outcomes and Patient Satisfaction With 3D-Printed Implant-Supported Fixed Prosthesis

OBJECTIVES

The objectives of this study were to quantify the number and type of prosthetic complications associated with 3D-printed implant-supported fixed prostheses (3DISFP) and to evaluate patient satisfaction and oral health-related quality of life over a four-month period.

METHODS

 Fifteen edentulous patients who underwent implant therapy were included in the study. Each patient received a 3D-printed prosthesis using OnX dental resin. Prosthetic complications were documented, and data from the 14-item Oral Health Impact Profile (OHIP) questionnaire were collected at two time points: at enrollment and during a four-month recall.

RESULTS

During the four-month evaluation period, a total of nine complications were recorded, with three classified as catastrophic failures. Statistical analysis revealed statistically significant differences in OHIP scores between the preoperative and postoperative assessments (p<0.001).

CONCLUSION

Within the limitations of this study, it can be concluded that utilizing 3D-printed prostheses with OnX resin represents a viable alternative for long-term implant-supported temporaries. The patients experienced a significant improvement in their oral health-related quality of life. These results suggest that 3D printing technology, combined with the use of OnX resin, holds promise in providing satisfactory clinical outcomes and enhanced patient satisfaction. However, it is important to acknowledge the limitations of this study, and further research is warranted to validate these findings and explore the long-term performance and durability of 3D-printed implant-supported fixed prostheses. This study contributes to the growing body of evidence supporting the effectiveness of 3D printing technology in implant dentistry. The results highlight the potential of 3DISFP with OnX resin to improve oral health-related quality of life in edentulous patients. Continued advancements in 3D printing materials and techniques will likely expand the utilization of these prostheses, ultimately benefiting patients in need of implant-supported restorations.

Deep learning: A primer for dentists and dental researchers

OBJECTIVES

Despite deep learning's wide adoption in dental artificial intelligence (AI) research, researchers from other dental fields and, more so, dental professionals may find it challenging to understand and interpret deep learning studies, their employed methods, and outcomes. The objective of this primer is to explain the basic concept of deep learning. It will lay out the commonly used terms, and describe different deep learning approaches, their methods, and outcomes.

METHODS

Our research is based on the latest review studies, medical primers, as well as the state-of-the-art research on AI and deep learning, which have been gathered in the current study.

RESULTS

In this study, a basic understanding of deep learning models and various approaches to deep learning is presented. An overview of data management strategies for deep learning projects is presented, including data collection, data curation, data annotation, and data preprocessing. Additionally, we provided a step-by-step guide for completing a real-world project.

CONCLUSION

Researchers and clinicians can benefit from this study by gaining insight into deep learning. It can be used to critically appraise existing work or plan new deep learning projects.

CLINICAL SIGNIFICANCE

This study may be useful to dental researchers and professionals who are assessing and appraising deep learning studies within the field of dentistry.

Occlusive and Proliferative Properties of Different Collagen Membranes-An In Vitro Study

Different collagen barrier membranes come in various sources and crosslinking that may affect barrier function and tissue integration. This study investigated barrier function and tissue integration of the three different collagen membranes (Jason^®: porcine pericardium, GENOSS: bovine tendon, and BioMend^® Extend: cross-linked bovine tendon) with human gingival fibroblasts. The barrier function and tissue integration properties were determined under confocal microscopy. Morphological characteristics were observed using scanning electron microscopy. Our results showed that all collagen membranes allowed a small number of cells to migrate, and the difference in barrier function ability was not significant. The cross-linked characteristics did not improve barrier ability. The native collagen membrane surfaces allowed evenly scattered proliferation of HGF, while the cross-linked collagen membrane induced patchy proliferation. Statistically significant differences in cell proliferation were found between Jason and BioMend Extend membranes (p = 0.04). Scanning electron microscope showed a compact membrane surface at the top, while the bottom surfaces displayed interwoven collagen fibers, which were denser in the crosslinked collagen membranes. Within the limitations of this study, collagen membranes of different origins and physical properties can adequately prevent the invasion of unwanted cells. Native collagen membranes may provide a better surface for gingival cell attachment and proliferation.

Accuracy of 3D printed scan bodies for dental implants using two additive manufacturing systems: An in vitro study

This study compared the accuracy of implant scan bodies printed using stereolithography (SLA) and digital light processing (DLP) technologies to the control (manufacturer's scan body) Scan bodies were printed using SLA (n = 10) and DLP (n = 10) methods. Ten manufacturer's scan bodies were used as control. The scan body was placed onto a simulated 3D printed cast with a single implant placed. An implant fixture mount was used as standard. The implant positions were scanned using a laboratory scanner with the fixture mounts, manufacturer's scan bodies, and the printed scan bodies. The scans of each scan body was then superimposed onto the referenced fixture mount. The 3D angulation and linear deviations were measured. The angulation and linear deviations were 1.24±0.22° and 0.20±0.05 mm; 2.63±0.82° and 0.34±0.11 mm; 1.79±0.19° and 0.32±0.03 mm; for the control, SLA, and DLP, respectively. There were statistical differences (ANOVA) among the three groups in the angular (p<0.01) or linear deviations (p<0.01). Box plotting, 95% confidence interval and F-test suggested the higher variations of precision in the SLA group compared to DLP and control groups. Scan bodies printed in-office have lower accuracy compared to the manufacturer's scan bodies. The current technology for 3D printing of implant scan bodies needs trueness and precision improvements.

Influence of Metal Guide Sleeves on the Accuracy and Precision of Dental Implant Placement Using Guided Implant Surgery: An In Vitro Study

PURPOSE

Metal sleeves are commonly used in implant guides for guided surgery. Cost and sleeve specification limit the applications. This in vitro study examined the differences in the implant position deviations produced by a digitally designed surgical guide with no metal sleeve in comparison to a conventional one with a metal sleeve.

MATERIALS AND METHODS

The experiment was conducted in two steps for each step: n = 20 casts total, 10 casts each group; Step 1 to examine one guide from each group with ten implant placements in a dental cast, and Step 2 to examine one guide to one cast. Implant placement was performed using a guided surgical protocol. Postoperative cone-beam computed tomography images were made and were superimposed onto the treatment-planning images. The implant horizontal and angulation deviations from the planned position were measured and analyzed using t-test and F-test (p = 0.05).

RESULTS

For Step 1 and 2, respectively, implant deviations for the surgical guide with sleeve were -0.3 ±0.17 mm and 0.15 ±0.23 mm mesially, 0.60 ±1.69 mm, and -1.50 ±0.99 mm buccolingual at the apex, 0.20 ±0.47 mm and -0.60 ±0.27 mm buccolingual at the cervical, and 2.73° ±4.80° and -1.49° ±2.91° in the buccolingual angulation. For Step 1 and 2, respectively, the implant deviations for the surgical guide without sleeve were -0.17 ±0.14 mm and -0.06 ±0.07 mm mesially, 0.35 ±1.04 mm and -1.619 ±1.03 mm buccolingual at the apex, 0.10 ±0.27 mm and -0.62 ±0.27 mm buccolingual at the cervical, and 1.73° ±3.66° and -1.64° ±2.26° in the buccolingual angulation. No statistically significant differences were found in any group except for mesial deviation of the Step 2 group (F-test, p < 0.001).

CONCLUSIONS

A digitally designed surgical guide with no metal sleeve demonstrates similar accuracy but higher precision compared to a surgical guide with a metal sleeve. Metal sleeves may not be required for guided surgery.

Influence of implant diameter on accuracy of static implant guided surgery: An in vitro study

STATEMENT OF PROBLEM

Static guided implant surgery may be the most accurate method of implant placement to date. However, within the same guided implant system, whether accuracy is affected when placing a larger diameter implant that requires more drills than a smaller diameter implant is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of implant diameter on the angulation and 3-dimensional (3D) deviations of posterior single implant placement using static guided surgery.

MATERIAL AND METHODS

A polyurethane dental cast was made with an edentulous site at the maxillary right first molar position. Identical implant planning for each of 3 dental implant diameters 3.3, 4.1, and 4.8 mm (Straumann BLT) were made, and surgical guides for each implant diameters were fabricated by stereolithography. Fifteen implants of each diameter (N=45) were placed in simulated casts. A scan body was placed and the cast was scanned using an intraoral scanner. The positional discrepancies of implant placement, including angulation as well as 3D implant cervical and apex area deviations, were compared with the planned position. Linear ANOVA single factor analysis (ɑ=.05) was used, and box plots were made.

RESULTS

The ranges of angulation deviations for 3.3-, 4.1-, and 4.8-mm implants were 3.6 degrees to 6.0 degrees, 3.7 degrees to 7.7 degrees, and 3.1 degrees to 6.7 degrees, respectively. The ranges of 3D implant entry deviations of 3.3-, 4.1-, and 4.8-mm implants were 0.96 to 1.4, 0.85 to 1.72, and 0.89 to 1.78 mm, respectively. The ranges of 3D implant apex of 3.3-, 4.1-, and 4.8-mm implants were 0.63 to 1.21, 0.64 to 1.48, and 0.48 to 1.27 mm, respectively. No statistically significant differences were found in any of the 3 measurements: P=.67 for deviation in angulation; P=.27 for 3D implant deviation of entry; and P=.3 for 3D implant deviation of the apex.

CONCLUSIONS

Implant diameters had no significant effect on placement deviations when a single posterior static guided surgery was used.

Erbium laser-assisted ceramic debonding: a scoping review

PURPOSE

Removal of ceramic restorations and appliances can be time consuming, invasive, and inconvenient. Erbium lasers offer an alternative noninvasive method for debonding of ceramic appliances. This paper aims to provide a comprehensive review of current literature on the effectiveness of erbium lasers for removal of ceramic restorations and appliances from natural teeth and dental implants.

METHODS

A comprehensive search of 7 databases, including Medline (Ovid), Embase, Dentistry and Oral Sciences Source (DOSS), Web of Science, Cochrane Library, and ProQuest Dissertations and Theses was performed. The inclusion and exclusion criteria were agreed prior to the literature search. Two reviewers independently screened the title and abstract. A third reviewer then broke the tie, if any. The selected articles then underwent full text review and the data was extracted.

RESULTS

The search identified 4117 unique articles published through June 10, 2021. Studies were assessed and categorized based on the type of restoration/appliance, type of abutment, type of laser, laser settings, efficacy of debonding, and pulpal temperature rise. Thirty-eight full-text articles were reviewed for inclusion. Time for ceramic debonding varies depending on the type of restorations and materials. Removal of zirconia crowns from teeth and implant abutments requires a longer period of time compared to lithium disilicate crowns. Temperature increases were reported as 5.5 degrees or less. Laser setting and laser type affect the debonding time and the increase in temperature. Examinations of debonded ceramics demonstrated no known structural damages resulting from laser applications.

CONCLUSIONS

Erbium lasers are effective noninvasive tools to remove all ceramic restorations/appliances from natural teeth and implant abutments without causing harm to abutments. Laser-assisted debonding should be considered as a viable alternative to rotary instrumentation for ceramic crowns; however, clinical studies of erbium-assisted ceramic retrieval are needed.

Insufficient Evidence to Ascertain the Long-Term Survival of PEEK Dental Prostheses: A Systematic Review of Clinical Studies

Introduction: Polyetheretherketone (PEEK) is a polymer that is used in the construction of orthopaedic and dental implants. It is also used to construct removable and fixed dental prostheses due to its superior mechanical and esthetic properties compared to conventional materials. This systematic review aims to analyse and appraise the literature concerning PEEK dental prostheses critically. Methods: The following focused question was constructed ‘Are dental prostheses made of PEEK inferior to those made of other materials in terms of clinical- and patient-reported outcomes?’. The CONSORT (Consolidated Standards of Reporting Trials) tool was used for the quality assessment of the randomised clinical trials. The STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) quality assessment tool was used to assess the quality of observational studies and the case reports were evaluated using the CARE (Case Report) guidelines. Results: A total of 12 studies were included in this review. Two case studies received an overall grade of medium and the overall quality of six studies was graded as ‘low’. All three observational studies and the only randomised controlled trial received scores of ‘medium’. Conclusion: PEEK-based dental prostheses may provide a viable and more esthetic alternative to conventional prosthodontic appliances. However, within the limitations of this study is the evidence to ascertain the long-term viability of PEEK-based dental prostheses. Future studies should focus on conducting large-scale, multicenter trials to compare the survival rate of PEEK prostheses to that of conventionally available prosthodontic appliances.

Influence of the Residual Ridge Widths and Implant Thread Designs on Implant Positioning Using Static Implant Guided Surgery

PURPOSE

Aggressive implant macrothread designs have been widely used. However, the effects of the aggressive thread design on the accuracy of static guided surgery, especially in a case of narrow residual ridge, have not been well-studied. The aim of this study was to evaluate the effects of two different implant macrothread designs and the residual ridge widths on the accuracy of tooth-supported static guided implant surgery.

MATERIALS AND METHODS

Forty implant fixtures with two different macrodesigns: a conventional thread design bone level tapered (BLT), and an aggressive thread design bone level tapered (BLX) were placed in 40 simulated polyurethane models with narrow and wide residual ridges. The placed implant positions were compared with the planned implant position and angulational deviation, as well as three-dimensional (3D) deviations at the entry and apex of the implant were measured. One-way ANOVA with Tukey's multiple comparisons (ɑ = 0.05) were used to determine level of significance between the mean and variance deviation values. 95% confidence intervals and box plots were used to demonstrate the means and ranges of precision.

RESULTS

In terms of angulational deviation, there was no statistically significant difference in the mean deviations for both types of implants, p = 1.55 and p = 0.84 for wide and narrow ridge groups, respectively. However, the range of deviation was much larger in the narrow ridge of the BLX group compared to the BLT group. In both narrow ridge and wide ridge, the BLX group had lower mean 3D deviation values at both the entry and the apex with statistically significant differences for both entry point of the wide ridge (p = 0.027) and narrow ridge (p = 0.022) as well as at the apex of the wide ridge (p = 0.006) but not the apex of the narrow ridge (p = 0.142).

CONCLUSION

The aggressive larger thread design of dental implants may influence the accuracy of implant placement more than the ridge dimension.

In Vitro Study of Laser-Assisted Prefabricated Ceramic Crown Debonding as Compared to Traditional Rotary Instrument Removal

This study compared the laser and rotary removals of prefabricated zirconia crowns in primary anterior and permanent posterior teeth. Sixty-two extracted teeth were prepared for prefabricated zirconia crowns cemented with resin-modified glass-ionomer cement. Specimens underwent crown removals by a rotary handpiece, or erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser. Pulpal temperatures, removal times, and scanning electron microscopy (SEM) examinations were compared. The average crown removal time for rotary and laser methods was 80.9 ± 19.36 s and 353.3 ± 110.6 s, respectively, for anterior primary teeth; and 114.2 ± 32.1 s and 288.5 ± 76.1 s, respectively, for posterior teeth (p < 0.001). The maximum temperature for the rotary and laser groups was 22.2 ± 8.5 °C and 27.7 ± 1.6 °C for anterior teeth, respectively (p < 0.001); and 21.8 ± 0.77 °C and 25.8 ± 0.85 °C for the posterior teeth, respectively (p < 0.001). More open dentinal tubules appeared in the rotary than the laser group. The rotary handpiece removal method may be more efficient than the laser with lower pulpal temperature changes. However, the laser method does not create noticeable tooth or crown structural damage compared to the rotary method.

Comparison of 3-dimensional printing technologies on the precision, trueness, and accuracy of printed retainers

INTRODUCTION

This study aimed to evaluate the differences in the precision, trueness, and accuracy of 3-dimensional (3D) printed clear orthodontic retainers fabricated using printer systems with different printing technologies.

METHODS

Retainers (n = 15) were 3D printed using 4 different printers: stereolithography (SLA), digital light processing (DLP), continuous DLP, and polyjet photopolymer (PPP) printers. Printed retainers were transformed into a digital image through a cone-beam computed tomography scan and compared with the original image using 3D superimposition analysis software. At previously chosen landmarks (R6, L6, R3, L3, R1, and L1), intaglio surfaces of the retainers were compared to that of the reference model. The intercanine and the intermolar width measurements were also assessed. A discrepancy of up to 0.25 mm between the printed retainer and the reference retainer intaglio surfaces indicated accuracy and clinical acceptability. Precision and trueness were also determined. Root mean square and percent of points within the tolerance level were calculated for precision and trueness for each retainer. Statistical significance was set at P <0.05.

RESULTS

Interrater correlation coefficient indicated good agreement. Statistically significant differences were found between printer types among the 6 landmarks and the arch width measurements. When evaluating tolerance level and root mean square, statistically significant differences in median precision and trueness among each printer type were found.

CONCLUSION

Retainers fabricated by SLA, DLP, continuous DLP, and PPP technologies were shown to be clinically acceptable and accurate compared to the standard reference file. Based on both high precision and trueness, SLA and PPP printers yielded the most accurate retainers.

Effect of print angulation on the accuracy and precision of 3D-printed orthodontic retainers

INTRODUCTION

The study aimed to (1) compare the accuracy and precision of 3-dimensional (3D) printed retainers at various angulations and (2) evaluate the effect of angulation on printing time and the amount of resin consumed.

METHODS

Using a stereolithography 3D printer, 60 clear retainers were printed at 5 angulations (n = 12, each): 15°, 30°, 45°, 60°, and 90°. Samples for each group were randomly printed in a batch of 6 retainers at all print angulations as print 1 and print 2 cycles. Digital images of the original and printed samples were superimposed. Discrepancies on 8 landmarks were measured by 2 independent examiners, and 0.25 mm was set as the clinically acceptable threshold to determine the accuracy of the retainers.

RESULTS

Deviations ranged from 0.074 mm to 0.225 mm from the reference retainer at the cusp tips and incisal edges at all angulations, falling within the threshold of clinical acceptance. However, smooth surface measurements with deviations up to 0.480 mm were deemed clinically not acceptable. Three-dimensional printing at 15° was estimated to be the most time-efficient, whereas 3D printing at 45° was shown to be the most cost-effective setting.

CONCLUSIONS

Three-dimensional printed retainers, using a stereolithography printer, were found to be accurate within 0.25 mm at all print angulations at the cusp tips and incisal edges compared with the digital reference file. Smooth facial surfaces did not meet clinical acceptability. Print angulations were shown to affect the cost and amount of resin used.

Effectiveness of CAD/CAM technology: A self-assessment tool for preclinical waxing exercise

INTRODUCTION

This study assessed the utility of CAD/CAM technology as a self-assessment tool for preclinical waxing compared to traditional student self-assessment to evaluate preclinical work.

MATERIAL AND METHODS

Thirty-seven students completed the wax-up of the maxillary left central incisor with the goal of recreating original anatomy and completed a traditional self-assessment. The original, unreduced cast and waxings were scanned with an intraoral scanner (E4D, Planmeca). Using CAD/CAM software (Compare, Planmeca), each waxing was superimposed over the original. Tolerance (250 µm) was set to illustrate under- and over-contoured areas, enabling visualisation of the waxing compared to original in three dimensions. Students then completed another self-assessment and an exit survey.

RESULTS

Twenty-four per cent of self-assessment responses changed after using Compare Software. 20% changed from satisfactory to unsatisfactory. Four per cent changed from unsatisfactory to satisfactory. Greatest change in response occurred in the Incisal Edge (49%) rubric category. Interproximal Contact Area (3%) demonstrated least change in response. Seventy per cent strongly agreed that Compare Software enabled more effective assessment of Lingual Contour. Eight per cent strongly disagreed that Compare Software enabled more effective assessment of finishing.

DISCUSSION

CAD/CAM software can improve student's critical self-assessment. Different rubric categories demonstrated differing rates of response change, indicating more critical of certain aspects of the waxing. Majority strongly agreed that the software enabled more effective self-assessment.

CONCLUSION

CAD/CAM technology enhances student's learning in dental wax-up through improving self-assessment. This technology may improve teacher-student communication, reduce one-on-one teaching time and allow higher student-teacher ratio.

Salivary biomarkers associated with obstructive sleep apnea: a systematic review

Introduction: This study aimed to define and characterize current literature describing salivary biomarker changes with the goal of improving diagnosis and treatment outcomes for sleep apnea.Area Covered: A search of six databases yielded 401 peer-reviewed articles published through October 2019 corresponded to 221 unique references following deduplication. Twenty studies were selected. The sample size ranged from 17 to 99. The samples were mostly whole saliva and selected glandular areas.Expert Opinion: Most targeted studies focused on the level of salivary cortisol and ɑ-amylase. One study used RNA transcriptome analysis of 96 genes. Only two explored novel targets using mass spectrometry. ɑ-amylase, myeloperoxidase, and IL-6 were among those biomarkers found associated with OSA. Cytokeratin, CystatinB, calgranulin A, and alpha-2-HS-glycoprotein are upregulated in OSA patients based on non-targeting mass spectrometry. Salivary cortisol and ɑ-amylase and others appeared to be associated with severity of OSA and OSA treatment. There were inconsistencies in saliva collection and processing protocols. More studies are needed in exploring novel biomarkers to examine if these biomarkers are capable of diagnosing and monitoring OSA through proteomics or transcriptomics. Salivary biomarkers have a potential to be a noninvasive measure for the disease diagnosis and treatment outcome monitoring for sleep apnea.

Implant site preparation application of injectable platelet-rich fibrin for vertical and horizontal bone regeneration: A clinical report

Guided bone regeneration (GBR) using a combined injectable platelet-rich fibrin (i-PRF), leukocyte- and platelet-rich fibrin (L-PRF) and biocompatible bone substitute materials, is a convenient and effective method to augment a combined vertical and horizontal bone defect. This approach can create sufficient bone quality and quantity for implant surgical sites. A 55-year-old Asian woman presented with a severe bone defect in posterior mandible. The edentulous mandibular alveolar ridge was severely resorbed vertically and horizontally.  A GBR procedure using i-PRF and L-PRF combined with particulate bone graft was performed. Postoperative cone beam computed tomography scans, 8 months after the augmentation, revealed a large regeneration of the alveolar bone sufficient for implant placement. A combination i-PRF/L-PRF and particulate bone graft may provide biologically active molecules as well as a scaffold for osteogenesis. This treatment protocol may be a viable option for a large bone defect required augmentation prior to implant placement.

Monolithic Zirconia Partial Coverage Restorations: An In Vitro Mastication Simulation Study

PURPOSE

To evaluate the survival rate (fatigue resistance), bonding efficiency and marginal integrity of monolithic zirconia partial and full coverage single restorations adhesively bonded to the tooth structure using air-particle abrasion, a primer with 10-methacryloyloxydecyl dihydrogen phosphate and a composite-resin cement (APC) protocol.

MATERIALS AND METHODS

Extracted human premolars (N = 32) were randomly divided into four groups of eight specimens each. Premolars were prepared for the following restorations: full crown (group 1, control), mesial-occlusal-distal-facial onlay (MODF, group 2) preserving 2 mm facio-lingual functional cusp width, mesial-occlusal-distal-lingual onlay (MODL, group 3) preserving 2 mm facio-lingual nonfunctional cusp width, mesial-occlusal-distal-buccal-lingual onlay (MODBL, group 4), overlay preparation. All restorations were milled from monolithic 3 mol% yttria (3Y) zirconia blocks (ZirCad, A1 LT, Ivoclar Vivadent) with CAD/CAM software presets at minimum occlusal and axial thicknesses of 1 mm. The intaglio surface of the restorations was air-particle abraded (50 µm Al₂ O₃ , 2-Bar pressure, 15 s, 10 mm distance) and primed. An adhesive cement system was used to bond the restorations. Each group was subjected to thermomechanical loading for 1.2 million cycles (force = 70 N, 1.4 Hz) with simultaneous thermocycling (5-55°C, 30 s dwell time) using a mastication simulator. All specimens were examined under scanning electron microscope (SEM) analysis (30, 100, and 150×) to evaluate cracks and marginal defects. Fracture of restoration and/or fracture within tooth structure, and debonding were considered modes of failure.

RESULTS

One specimen from group 2 debonded at 632,000 cycles. None of the specimens failed due to fracture. SEM analysis at 30× indicated marginal integrity issue of the remaining seven intact specimens of group 2 in the area of antagonist contact. No specimens from group 1, 3, and 4 demonstrated marginal integrity issue at 30×. None of the specimens demonstrated any microcrack at 100× and150×.

CONCLUSIONS

Due to its fatigue resistance, 3Y-zirconia is a viable option for partial and full coverage single restorations. Following a strict bonding protocol, zirconia demonstrated durable adhesion to the tooth structure. Occlusal contact on restoration margins should be avoided.

Fracture Load of Different Zirconia Types: A Mastication Simulation Study

PURPOSE

To assess the effect of yttria mol% concentration and material thickness on the biaxial fracture load (N) of zirconia with and without mastication simulation.

MATERIALS AND METHODS

Disk-shaped specimens (N = 120) of 3 mol% yttria-partially stabilized zirconia, 3Y-PSZ (Katana High Translucent, Kuraray Noritake), 4 mol% yttria-partially stabilized zirconia, 4Y-PSZ (Katana Super Translucent Multi Layered) and 5 mol% Yttria-partially stabilized zirconia, 5Y-PSZ (Katana Ultra Translucent Multi Layered) were prepared to thicknesses of 0.7 and 1.2 mm. For each thickness, the biaxial fracture load (N) was measured with and without mastication simulation with 1.2 million cycles at a 110-N load and simultaneous thermal cycling at 5°C to 55°C. The data were analyzed by three-way Analysis of Variance (α = 0.05) and Tukey-Kramer adjusted multiple comparison test.

RESULTS

Yttria mol% concentration and material thickness had a statistically significant effect on the mean biaxial fracture load (F = 388.16, p < 0.001 and F = 714.33, p < 0.001 respectively). The mean biaxial fracture load ranged from the highest to the lowest; 3Y-PSZ, 4Y-PSZ, and 5Y-PSZ (p = 0.012). The mean biaxial fracture load of the 1.2 mm thickness groups was significantly higher than 0.7 mm thickness at any given condition (p = 0.002). Not all specimens survived the mastication simulation protocol. Fifty percent of the 0.7-mm-thick 4Y-PSZ specimens, 70% of the 0.7-mm-thick 5Y-PSZ specimens and 20% of 1.2-mm-thick 5Y-PSZ specimens fractured during mastication simulation. Mastication simulation had no statistically significant effect on the biaxial fracture load (F = 1.24, p = 0.239) of the survived specimens.

CONCLUSIONS

Lowering yttria mol% concentration and increasing material thickness significantly increases the fracture load of zirconia. At 0.7 mm thickness, only 3Y-PSZ survived masticatory simulation. A minimum material thickness of 1.2 mm is required for 4Y-PSZ or 5Y-PSZ.

Effects of two Postprocessing Methods onto Surface Dimension of in-Office Fabricated Stereolithographic Implant Surgical Guides

PURPOSE

To evaluate the effects of two postprocessing methods in terms of the overall, intaglio, and cameo surface dimensions of in-office stereolithographic fabricated implant surgical guides.

MATERIALS AND METHODS

Twenty identical implant surgical guides were fabricated using a stereolithographic printer. Ten guides were postprocessed using an automated method. The other ten guides were postprocessed using a series of hand washing in combination with ultrasonics. Each guide was then scanned using cone-beam computed tomography to produce a set of digital imaging and communications in medicine (DICOM) files which were converted into standard tessellation language (STL) files. The STL file was then superimposed onto the original STL design file using the best fit alignment. The average positive and negative surface discrepancy differences in terms of means and variances were analyzed using t-test (α = 0.05).

RESULTS

For the alternative group, the average positive and negative overall, intaglio, and cameo surface discrepancies were 77.38 ± 10.68 µm and -67.74 ± 6.55 µm; 78.83 ± 8.65 µm and -68.16 ± 5.26 µm; and 70.5 ± 8.48 µm -64.84 ± 5.55 µm, respectively. For the automated group, the average positive and negative overall, intaglio, and cameo surface discrepancies were 51.88 ± 4.38 µm and -170.7 ± 11.49 µm; 64.3 ± 4.44 µm and -89.45 ± 6.25 µm; and 83.59 ± 4.81 µm and -144.26 ± 13.19 µm, respectively. There was a statistical difference between the means of the two methods for the overall, intaglio, and cameo positive and negative discrepancies (p < 0.001).

CONCLUSIONS

For a single implant tooth-supported implant guide, using hand washing with ultrasonics appeared to be consistently better than the automated method. The manual method presented with more positive discrepancies, while the automated method presented with more negative discrepancies.

Accuracy of Implant Placement Position Using Nondental Open-Source Software: An In Vitro Study

PURPOSE

To evaluate the accuracy of implant placement position using two different dental implant planning software.

MATERIALS AND METHODS

A set of Digital Imaging and Communications in Medicine (DICOM) files from a cone beam computed tomography of a patient missing maxillary right first premolar was used. Implant planning was done using two open-source programs: A nondental 3D Slicer/Blender (3DSB) software and a commercial dental implant treatment planning program: Blue Sky Plan 4 (BSP4). An intraoral scan of the same patient was used to create a standard tessellation language (STL) file of the maxillary arch and later printed into 20 identical casts. Ten surgical guides were printed for each group as well. A dental implant (3.8 mm × 12 mm, Biohorizons) was placed into each cast using fully guided surgical protocol. The horizontal displacements at the implant cervical platform and at the implant apex as well as the angulation displacements were measured using digital scanning of the implant scan bodies and were analyzed using a 3D compare software. Statistical analyses were conducted (⍺ = 0.05) using t-test and F-test to examine differences in trueness and precision, respectively.

RESULTS

The average horizontal deviations for the platform and the apex, respectively, were 0.33 ± 0.12 mm and 0.76 ± 0.30 mm for 3DSB and 0.44 ± 0.21 mm and 0.98 ± 0.48 mm for BSP4. The average angulation deviations for 3DSB and BSB4 were 2.34 ± 0.93° and 3.07 ± 1.57°, respectively. There were no statistical differences in the means (t-test) of the platform, apex, and angulation deviations (p = 0.16, p = 0.19, and p = 0.18, respectively). There were statistical differences in the variances (F test) of the platform (p = 0.043) and angulation (p = 0.049) deviations but not the apex (p = 0.059) deviations.

CONCLUSIONS

The combination of nondental open-source software, 3D Slicer/Blender can be used to plan implant guided surgery with an accuracy similar to commercial dental software with slightly higher precision. Open-source nondental software can be considered as an alternative in dental implant treatment planning and guided surgery.

Exploring the use of pulsed erbium lasers to retrieve a zirconia crown from a zirconia implant abutment

Background

Removal of cement-retained implant fixed restorations when needed, can be challenging. Conventional methods of crown removal are time consuming and costly for patients and practitioners. This research explored the use of two different types of pulsed erbium lasers as a non-invasive tool to retrieve cemented zirconia crowns from zirconia implant abutments.

Materials and methods

Twenty identical zirconia crowns were cemented onto 20 identical zirconia prefabricated abutments using self-adhesive resin cement. The specimens were divided into two groups for laser assisted crown removal; G1 for erbium-doped yttrium aluminum garnet laser (Er:YAG), and G2 for erbium, chromium-doped yttrium, scandium, gallium and garnet (Er,Cr:YSGG). For the G1, after the first crown removal, the specimens were re-cemented and removed again using the Er:YAG laser. Times needed to remove the crowns were recorded and analyzed using ANOVA (α = 0.05). The surfaces of the crown and the abutment were further examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses.

Results

The average times of zirconia crown removal from zirconia abutments were 5 min 20 sec and 5 min 15 sec for the Er:YAG laser of first and second experiments (G1), and 5 min 55 sec for the Er,Cr:YSGG laser experiment (G2). No statistical differences were observed among the groups. SEM and EDS examinations of the materials showed no visual surface damaging or material alteration from the two pulsed erbium lasers.

Conclusions

Both types of pulsed erbium lasers can be viable alternatives for retrieving a zirconia crown from a zirconia implant abutment. Despite operating at different wavelengths, the Er:YAG and Er,Cr:YSGG lasers, perform similarly in removing a zirconia crown from a zirconia implant abutment with similar parameters. There are no visual and elemental composition damages as a result of irradiation with pulsed erbium lasers.

Creating a digital duplicate denture file using a desktop scanner and an open-source software program: A dental technique

This article describes a digital technique for obtaining a standard tessellation language (STL) file of a complete denture using a desktop scanner and an open-source software program. Accurate recording of the surface details of the denture in 3D was performed using a desktop scanner. The generated STL file from this technique represents a digital duplicate of the scanned denture. This file can be used for surgical implant placement planning, fabricating a duplicate denture, and storing the scanned denture as a digital file for future use.

Finite element analysis of a one-piece zirconia implant in anterior single tooth implant applications

This study evaluated the von Mises stress (MPa) and equivalent strain occurring around monolithic yttria-zirconia (Zir) implant using three clinically simulated finite element analysis (FEA) models for a missing maxillary central incisor. Two unidentified patients' cone-beam computed tomography (CBCT) datasets with and without right maxillary central incisor were used to create the FEA models. Three different FEA models were made with bone structures that represent a healed socket (HS), reduced bone width edentulous site (RB), and immediate extraction socket with graft (EG). A one-piece abutment-implant fixture mimicking Straumann Standard Plus tissue level RN 4.1 X 11.8mm, for titanium alloy (Ti) and Zir were modeled. 178 N oblique load and 200 N vertical load were used to simulate occlusal loading. Von Mises stress and equivalent strain values for around each implant model were measured. Within the HS and RB models the labial-cervical region in the cortical bone exhibited highest stress, with Zir having statistically significant lower stress-strain means than Ti in both labial and palatal aspects. For the EG model the labial-cervical area had no statistically significant difference between Ti and Zir; however, Zir performed better than Ti against the graft. FEA models suggest that Ti, a more elastic material than Zir, contributes to the transduction of more overall forces to the socket compared to Zir. Thus, compared to Ti implants, Zir implants may be less prone to peri-implant bone overloading and subsequent bone loss in high stress areas especially in the labial-cervical region of the cortical bone. Zir implants respond to occlusal loading differently than Ti implants. Zir implants may be more favorable in non-grafted edentulous or immediate extraction with grafting.

Intaglio Surface Dimension and Guide Tube Deviations of Implant Surgical Guides Influenced by Printing Layer Thickness and Angulation Setting

PURPOSE

To measure overall intaglio dimensional and tube deviations of implant guides printed at 50 and 100 µm layer thickness at 0°, 45°, and 90° angulation using a stereolithographic (SLA) printer.

MATERIALS AND METHODS

A surgical implant guide design from a subject missing a maxillary right central incisor, used as the original standard tessellation language (STL) were stereolithographically fabricated at each thickness and angulation, 50 and 100 µm layer thickness at 0°, 45°, and 90° angulation (n = 10 each group). The guide was then scanned using cone beam computed tomography. The digital imaging and communications in medicine (DICOM) scanned files were then converted to an STL format. The overall dimensional deviations of the intaglio surface and the positioning of the implant guide tube were then superimposed onto the original designed STL file using best-fitting alignment. A t-test and an F-test as well as ANOVA followed by a post hoc t-test were used to determine statistical significant differences (α = 0.05) for the intaglio surface and guide tube deviation, respectively.

RESULTS

The overall intaglio surface discrepancies (µm) printed at 0°, 45°, and 90° were 55.07 ± 1.36, 52.39 ± 2.09, and 61.02 ± 15.96 for 50 µm layer; and 98.38 ± 10.55, 84.47 ± 10.61, and 90.26 ± 5 for 100 µm layer with statistically significant differences for both t-test and F-test, p < 0.001. The maximal guide tube linear deviations (µm) printed at 0°, 45°, and 90° were 10.78 ± 3.84, 8.16 ± 3.68, and 12.57 ± 5.39 for 50 µm layer (ANOVA, p = 0.096); and 10.95 ± 5.23, 16.79 ± 4.97, and 22.63 ± 2.81 for 100 µm layer (ANOVA, p < 0.001). The maximal guide tube angular deviations (°) printed at 0°, 45°, and 90° were 1.29 ± 0.30, 0.64 ± 0.13, and 0.56 ± 0.21 for 50 µm layer (ANOVA, p < 0.001); and 1.57 ± 0.29, 0.86 ± 0.14, and 1.02 ± 0.31 for 100 µm layer (ANOVA, p = 0.034). There was a statistical difference in the deviations between 50 and 100 µm layer printing in all printed angulations except at 0° (t-test, p = 0.05, p = 0.03, and p = 0.001 for 0°, 45°, and 90°) and linear deviations (t-test, p < 0.001, p = 0.009, and p = 0.001 for 0°, 45°, and 90°).

CONCLUSION

Printing at 50 µm layer reduces dimensional intaglio deviations in general and reduces tube angular deviations with different angulations of printing. However, the deviations were only ∼60 to 100 µm for the intaglio dimension deviations; and ∼0.04 to 0.26 mm and ∼0.25° to ∼2° for tube deviations.

Salivary protein biomarkers associated with orthodontic tooth movement: A systematic review

OBJECTIVE

Saliva can provide a non-invasive approach to indicate changes in the oral and systemic conditions. Salivary proteomics allows the discovery of new protein biomarkers associated with certain conditions. The effectiveness and physiological effects of orthodontic tooth movement in theory can be measured using salivary protein biomarkers.

SETTING AND SAMPLE POPULATION

This study applied a systematic review to analyse current literature to define and summarize salivary biomarkers associated with orthodontic tooth movement identified by mass spectrometry proteomics and other protein detection techniques.

MATERIALS AND METHODS

Peer-reviewed articles published through the 15th of November 2018 via the PubMed, EMBASE, Web of Science and Dentistry & Oral Sciences databases were reviewed. Only studies analysing protein biomarkers in saliva samples collected from human subjects associated with orthodontic treatments were included.

RESULTS

Out of 482 articles, 7 studies were selected. Sample size ranged from 3 to 72 subjects. Minor variations of unstimulated whole saliva sample collection protocol were noted. Mass spectrometry proteomics and ELISA represented the majority of biomarker discovery and targeting, respectively. Twenty biomarkers were identified or chosen as target biomarkers.

CONCLUSION

Salivary proteins may be used to indicate effectiveness of orthodontic treatment and orthognathic treatment as well as adverse treatment consequence, such as root resorption.

Exploring training dental implant placement using computer-guided implant navigation system for predoctoral students: A pilot study

INTRODUCTION

Recent computer-guided dynamic navigation systems promise a novel training approach for implant surgery. This study aimed to examine learning progress in placement of dental implants among dental students using dynamic navigation on a simulation model.

MATERIALS AND METHODS

Senior students with no implant placement experience were randomly assigned five implant placement attempts involving either three maxillary or four mandibular implants distributed in the anterior/posterior, and left/right segments. Implant placement was planned using a Navident Dynamic Guidance system. Surgical time was recorded. Horizontal, vertical and angulation discrepancies between the planned and placed implant positions were measured using superimposed CBCT scans. Data were analysed with repeated measures regression with Tukey's adjusted pairwise comparisons (α = 0.05).

RESULTS

Fourteen students participated, with a mean age of 26.1 years and equal males and females. Mean time for implant placement was associated with attempt number (P < 0.001), implant site (P = 0.010) and marginally related to gender (P = 0.061). Students had a significant reduction in time from their first attempt to their second (10.6 vs 7.6 minutes; adjusted P < 0.001) then plateaued. Overall 3D angulation (P < 0.001) and 2D vertical apex deviation (P = 0.014) improved with each attempt, but changes in lateral 2D (P = 0.513) and overall 3D apex deviations (P = 0.784) were not statistically significant. Implant sites were associated with lateral 2D, 2D vertical and overall 3D apex deviation (P < 0.001).

DISCUSSION

Males were marginally faster than females, had slightly lower overall 3D angulation, and reported higher proficiency with video games. Novice operators improved significantly in speed and angulation deviation within the first three attempts of placing implants using dynamic navigation.

CONCLUSION

Computer-aided dynamic implant navigation systems can improve implant surgical training in novice population.

Retrieval of Glass Fiber Post Using Er:YAG Laser and Conventional Endodontic Ultrasonic Method: An In Vitro Study

PURPOSE

To compare the times and temperatures used to remove a glass fiber post from an endodontically treated tooth using erbium-doped yttrium aluminum garnet (Er:YAG) compared to conventional endodontic ultrasonic method.

MATERIALS AND METHODS

Thirty-four single-root human extracted teeth were endodontically treated ex vivo. The post space was prepared to 7 mm in depth and a 11.4 mm glass fiber post was cemented using composite resin cement. Specimens were kept in 100% humidity for 24 hours and then randomly assigned to Er:YAG laser or ultrasonic methods for post removal. The removal time was recorded. Specimens with a fractured post during the removal process were excluded. The temperature on the external surface of the root was measured at the coronal, middle, and apical third portions during the laser or ultrasonic applications from 1 to 10 minutes. Data were analyzed using one-tailed t-test and paired t-test (ɑ = 0.01) for the post removal time and temperature difference, respectively. The specimen surfaces were examined using scanning electron microscopy (SEM).

RESULTS

Fifteen specimens were tested in each group. Four specimens were fractured, 2 in the laser and 1 in ultrasonic group. One post was excluded because of laser tip damage. The average removal time were 98 ± 46.1 seconds for Er:YAG laser and 538 ± 215.6 seconds or ultrasonic groups with significant difference between the groups (p < 0.001). The temperature (°C) ranges measured from 1 to 10 minutes were [24.2°, 27.3°] for laser and [33.0°, 38.0°] for ultrasonic in the cervical area, [22.1°,24.6°] for laser and [31.0°, 34.6°] for ultrasonic in the middle area, and [24.4°, 27.7°] for laser and [30.3°, 34.1°] for ultrasonic in the apical area. There were significant differences between temperatures for each treatment (p < 0.001). SEM examination showed no visible damage caused by treatment with Er:YAG laser.

CONCLUSIONS

Er:YAG laser can remove posts up to 5 times faster than ultrasonic removal method. The laser causes lower temperature increase at the root surface compared to the ultrasonic removal. Er:YAG may be considered as a viable alternative to sonication for post removal.

Accuracy and precision of 3D-printed implant surgical guides with different implant systems: An in vitro study

STATEMENT OF PROBLEM

Implant guided surgery systems promise implant placement accuracy and precision beyond straightforward nonguided surgery. Recently introduced in-office stereolithography systems allow clinicians to produce implant surgical guides themselves. However, different implant designs and osteotomy preparation protocols may produce accuracy and precision differences among the different implant systems.

PURPOSE

The purpose of this in vitro study was to measure the accuracy and precision of 3 implant systems, Tapered Internal implant system (BioHorizons) (BH), NobelReplace Conical (Nobel Biocare) (NB), and Tapered Screw-Vent (Zimmer Biomet) (ZB) when in-office fabricated surgical guides were used.

MATERIAL AND METHODS

A cone beam computed tomography (CBCT) data set of an unidentified patient missing a maxillary right central incisor and intraoral scans of the same patient were used as a model. A software program (3Shape Implant Studio) was used to plan the implant treatment with the 3 implant systems. Three implant surgical guides were fabricated by using a 3D printer (Form 2), and 30 casts were printed. A total of 10 implants for each system were placed in the dental casts by using the manufacturer's recommended guided surgery protocols. After implant placement, postoperative CBCT images were made. The CBCT cast and implant images were superimposed onto the treatment-planning image. The implant positions, mesiodistal, labiopalatal, and vertical, as well as implant angulations were measured in the labiolingual and mesiodistal planes. The displacements from the planning in each dimension were recorded. ANOVA with the Tukey adjusted post hoc pairwise comparisons were used to examine the accuracy and precision of the 3 implant systems (α=.05).

RESULTS

The overall implant displacements were -0.02 ±0.13 mm mesially (M), 0.07 ±0.14 mm distally (D), 0.43 ±0.57 mm labially (L), and 1.26 ±0.80 mm palatally (P); 1.20 ±3.01 mm vertically in the mesiodistal dimension (VMD); 0.69 ±2.03 mm vertically in the labiopalatal dimension (VLP); 1.69 ±1.02 degrees in mesiodistal angulation (AMD); and 1.56 ±0.92 degrees in labiopalatal angulation (ALP). Statistically significant differences (ANOVA) were found in M (P=.026), P (P=.001), VMD (P=.009), AMD (P=.001), and ALP (P=.001). ZB showed the most displacements in the M and vertical dimensions and the least displacements in the P angulation (P<.05), suggesting statistically significant differences among the M, VMD, VLP, AMD, and ALP. NB had the most M variation. ZB had the least P deviation. NB had the fewest vertical dimension variations but the most angulation variations.

CONCLUSIONS

Dimensional and angulation displacements of guided implant systems by in-office 3D-printed fabrication were within clinically acceptable limits: <0.1 mm in M-D, 0.5 to 1 mm in L-P, and 1 to 2 degrees in angulation. However, the vertical displacement can be as much as 2 to 3 mm. Different implant guided surgery systems have strengths and weaknesses as revealed in the dimensional and angulation implant displacements.

In Vitro Examination of the Use of Er:YAG Laser to Retrieve Lithium Disilicate Crowns from Titanium Implant Abutments

PURPOSE

Removal of cement-retained implant crowns can be difficult and often requires sectioning of the prosthesis by rotary instruments. This study aimed to measure how much time is required in crown removal and the temperature changes when erbium-doped yttrium aluminum garnet (Er:YAG) laser was used to retrieve lithium disilicate crowns from titanium implant abutments luted with composite resin (CR) cement and resin-modified glass ionomer (RMGI).

MATERIALS AND METHODS

Forty identical lithium disilicate crowns were fabricated for prefabricated titanium abutments. CR and RMGI cements were used to lute the crowns, 20 specimens for each cement. Specimens were kept in 100% humidity for 48 hours. Er:YAG laser was then used to facilitate the crown retrieval. The retrieval time was recorded. The temperature changes at the abutment level for each type of cement were recorded during irradiation of 10 specimens for each type of cement from 1 to 10 minutes. Data were analyzed using t-test (ɑ = 0.01) and paired t-test (ɑ = 0.05). The surfaces of the crown and the abutment were further examined using scanning electron microscopy (SEM).

RESULTS

The average times of crown removal from titanium abutments were 196.5 seconds for CR and 97.5 seconds for RMGI groups with statistical significance (p < 0.001). The temperatures measured from 1 to 10 minutes of irradiation ranged from 18° to 20.8° for CR and 18° to 23° for RMGI at the abutment surface, and 22.1° to 24.6° for CR and 22° to 24.8° for RMGI at the crown surface. No statistical differences were observed between temperature changes at the abutment or the crown for each cement (p = 0.63); however, there was a statistically significant difference between the temperatures at the abutment and crown for both cements (p < 0.001). SEM examination showed no visible damage caused by treatment with Er:YAG laser.

CONCLUSIONS

It is faster to remove lithium disilicate crowns from titanium implant abutments when luted with RMGI compared to CR cement. The temperature rise was higher in the crown compared to the abutment. The type of cement had no effects on temperature changes. Heat generated from Er:YAG irradiation does not appear to be high enough to have any adverse effect on implant osseointegration.

Influence of Fractionation Methods on Physical and Biological Properties of Injectable Platelet-Rich Fibrin: An Exploratory Study

Injectable platelet-rich fibrin (i-PRF) has been used as an autografting material to enhance bone regeneration through intrinsic growth factors. However, fractionation protocols used to prepare i-PRF can be varied and the effects of different fractionation protocols are not known. In this study, we investigated the influence of different fractions of i-PRF on the physical and biological properties derived from variations in i-PRF fractionation preparation. The i-PRF samples, obtained from the blood samples of 10 donors, were used to harvest i-PRF and were fractioned into two types. The yellow i-PRF fractionation was harvested from the upper yellow zone, while the red i-PRF fractionation was collected from both the yellow and red zone of the buffy coat. The viscoelastic property measurements, including the clot formation time, α-angle, and maximum clot firmness, were performed by rotational thromboelastometry. The fibrin network was examined using a scanning electron microscope. Furthermore, the concentration of growth factors released, including VEGF, TGF-β1, and PDGF, were quantified using ELISA. A paired t-test with a 95% confidence interval was used. All three viscoelastic properties were statistically significantly higher in the yellow i-PRF compared to the red i-PRF. The scanning electron microscope reviewed more cellular components in the red i-PRF compared to the yellow i-PRF. In addition, the fibrin network of the yellow i-PRF showed a higher density than that in the red i-PRF. There was no statistically significant difference between the concentration of VEGF and TGF-β1. However, at Day 7 and Day 14 PDGF concentrations were statistically significantly higher in the red i-PRF compared to the yellow group. In conclusion, these results showed that the red i-PRF provided better biological properties through the release of growth factors. On the other hand, the yellow i-PRF had greater viscoelastic physical properties. Further investigations into the appropriate i-PRF fractionation for certain surgical procedures are therefore necessary to clarify the suitability for each fraction for different types of regenerative therapy.

Comparing Initial Wound Healing and Osteogenesis of Porous Tantalum Trabecular Metal and Titanium Alloy Materials

Porous tantalum trabecular metal (PTTM) has long been used in orthopedics to enhance neovascularization, wound healing, and osteogenesis; recently, it has been incorporated into titanium alloy dental implants. However, little is known about the biological responses to PTTM in the human oral cavity. We have hypothesized that, compared with conventional titanium alloy, PTTM has a greater expression of genes specific to neovascularization, wound healing, and osteogenesis during the initial healing period. Twelve subjects requiring at least 4 implants in the mandible were enrolled. Four 3 × 5mm devices, including 2 titanium alloy tapered screws and 2 PTTM cylinders, were placed in the edentulous mandibular areas using a split-mouth design. One device in each group was trephined for analysis at 2 and 4 weeks after placement. RNA microarray analysis and ingenuity pathway analysis were used to analyze osteogenesis gene expression and relevant signaling pathways. Compared to titanium alloy, PTTM samples exhibited significantly higher expressions of genes specific to cell neovascularization, wound healing, and osteogenesis. Several genes-including bone morphogenic proteins, collagens, and growth factors-were upregulated in the PTTM group compared to the titanium alloy control. PTTM materials may enhance the initial healing of dental implants by modifying gene expression profiles.

Differential Mucosal Gene Expression Patterns in Candida-Associated, Chronic Oral Denture Stomatitis

PURPOSE

Denture stomatitis is a common condition manifested by inflammation of the oral mucous membrane beneath a denture. The objective of this study was to compare the transcriptome of human palatal mucosa with chronic oral stomatitis-associated Candida albicans infection to that of healthy oral mucosa.

MATERIALS AND METHODS

Oral palatal biopsies were obtained from 17 healthy and 15 C. albicans-infected stomatitis subjects for whole transcriptome analyses. The presence of C. albicans was confirmed by cytology and cultivable methods. The clinical severity of the stomatitis was evaluated by the Newton Classification (Class II or III). For transcriptome analyses a false discovery rate (FDR) of <0.05 was used, and the effects of age, race, and gender were evaluated by principle component analysis (PCA). Specific differentially expressed genes identified by mRNA array data were confirmed by measurements of salivary protein expression using multiplex analyses.

RESULTS

Microarray analysis of mRNA expression indicated that in C. albicans stomatitis there were 3034 genes-in-play that were differentially expressed and met the FDR < 0.05 criteria. Two hundred thirty five (235) genes were up-regulated >2-fold, and 71 genes were down-regulated >2-fold. Five of the 6 most significant gene ontology pathways involve inflammation and activation of the immune response with CD28 and CTLA signaling of T cells. There was strong up-regulation of TLR2, CD14, MYD88, IKKA, and NFKB as the dominant toll-like receptor-signaling pathway. The expression of several extracellularly expressed inflammatory protein genes was up-regulated in candidiasis, and 2 were confirmed as up-regulated within the saliva using protein multiplexing analyses.

CONCLUSIONS

Neutrophil recruitment and activation, epithelial suppression, and T-cell activation appear as major pathways in chronic oral candidiasis. Tissue up-regulation of TLR2 pathways, as well as potential C. albicans binding proteins, was observed, whereas keratin and adhesion molecule synthesis were down-regulated. Several candidate biomarkers to potentially identify the presence of oral candidiasis were differentially expressed in tissues and saliva.

Trephination-based, guided surgical implant placement: A clinical study

STATEMENT OF PROBLEM

Conventional guided implant surgery promises clinical success through implant placement accuracy; however, it requires multiple drills along with surgical sleeves and sleeve adapters for the horizontal and vertical control of osteotomy drills. This results in cumbersome surgery, problems with patients having limited mouth opening, and restriction to specific drill or implant manufacturers. A protocol for using trephination drills to simplify guided surgery and accommodate multiple implant systems is introduced.

PURPOSE

The purpose of this clinical study was to evaluate the accuracy of implant placement using this novel guided trephine drill protocol with and without a surgical sleeve.

MATERIAL AND METHODS

Intraoral scanning and preoperative cone beam computed tomography (CBCT) scans were used for implant treatment planning. Surgical guides were fabricated using stereolithography. Implant surgery was performed using the guided trephination protocol with and without a surgical sleeve. Postoperative CBCT scans were used to measure the implant placement deviations rather than the implant planning position. Surgical placement time and patient satisfaction were also documented. One-tailed t test and F-test (P=.01) were used to determine statistical significance.

RESULTS

Thirty-five implants in 17 participants were included in this study. With a surgical sleeve, implant positional deviations were 0.51 ±0.13 mm vertically, 0.32 ±0.10 mm facially, 0.11 ±0.11 mm lingually, and 0.38 ±0.13 mm mesially. Without a surgical sleeve, implant positional deviations were 0.58 ±0.27 mm vertically, 0.3 ±0.14 mm facially, 0.39 ±0.16 mm lingually, and 0.41 ±0.12 mm mesially. No statistically significant difference was found between the 2 protocols (P>.01), except that the sleeve group had greater vertical control precision (F-test, P=.006), reduced placement time, and the time variation was reduced (t test, P=.003; F-test, P<.001).

CONCLUSIONS

This trephination-based, guided implant surgery protocol produces accurate surgical guides that permit guided surgery in limited vertical access and with the same guided surgery protocol for multiple implant systems. Guided sleeves, although not always necessary, improve depth control and reduce surgical time in implant placement.

Transcriptomic profiling of tantalum metal implant osseointegration in osteopenic patients

OBJECTIVES

The long-term success of dental implants is established by literature. Although clinically well defined, the complex genetic pathways underlying osseointegration have not yet been fully elucidated. Furthermore, patients with osteopenia/osteoporosis are considered to present as higher risk for implant failure. Porous tantalum trabecular metal (PTTM), an open-cell porous biomaterial, is suggested to present enhanced biocompatibility and osteoconductivity. The goal of this study was to evaluate the expression patterns of a panel of genes closely associated with osteogenesis and wound healing in osteopenic patients receiving either traditional titanium (Ti) or PTTM cylinders to assess the pathway of genes activation in the early phases of osseointegration.

MATERIAL AND METHODS

Implant cylinders made of Ti and PTTM were placed in osteopenic volunteers. At 2- and 4 weeks of healing, one Ti and one PTTM cylinder were removed from each subject for RT-PCR analysis using osteogenesis PCR array.

RESULTS

Compared to Ti, PTTM-associated bone displayed upregulation of bone matrix proteins, BMP/TGF tisuperfamily, soluble ligand and integrin receptors, growth factors, and collagen genes at one or both time points. Histologically, PTTM implants displayed more robust osteogenesis deposition and maturity when compared to Ti implants from the same patient.

CONCLUSIONS

Our results indicate that PTTM properties could induce an earlier activation of genes associated with osteogenesis in osteopenic patients suggesting that PTTM implants may attenuate the relative risk of placing dental implants in this population.

Retrospective analysis of porous tantalum trabecular metal-enhanced titanium dental implants

STATEMENT OF PROBLEM

The design of porous tantalum trabecular metal-enhanced titanium (TM) dental implants promises improved osseointegration, especially when grafting materials such as demineralized bone matrix are used; however, studies are lacking.

PURPOSE

The purpose of this retrospective study was to compare TM implants with conventional titanium alloy (Ti) implants with and without demineralized bone matrix in terms of peri-implant bone remodeling in the first year after implant loading.

MATERIAL AND METHODS

A chart review was used for all patients receiving Tapered Screw-Vent Ti and TM implants. Implants were placed and restored by a single provider between 2011 and 2015. Peri-implant bone remodeling was compared by using a paired t test (α=.05).

RESULTS

A total of 82 patients received 205 implants, 44 TM and 161 Ti implants (control). No implants failed in the TM group (survival rate of 100%), and 3 implants in total, 1 immediate, failed in the Ti groups (survival rate of 98.1%). TM implants exhibited a 0.28-mm bone gain on average, whereas the control group demonstrated 0.20 mm of marginal bone loss after the first year of implant loading. Multivariate logistic regression analysis demonstrated that the odds of having bone loss was 64% less (odds ratio: 0.36; 95% confidence interval: 0.14-0.94) in the TM group than in the Ti group after controlling for bone grafting, implant location, immediate placement, bone type, and pretreatment bone level.

CONCLUSIONS

TM implants exhibited less peri-implant bone loss than the control Ti implants.

GWAS for Interleukin-1β levels in gingival crevicular fluid identifies IL37 variants in periodontal inflammation

There is no agnostic GWAS evidence for the genetic control of IL-1β expression in periodontal disease. Here we report a GWAS for "high" gingival crevicular fluid IL-1β expression among 4910 European-American adults and identify association signals in the IL37 locus. rs3811046 at this locus (p = 3.3 × 10-22) is associated with severe chronic periodontitis (OR = 1.50; 95% CI = 1.12-2.00), 10-year incident tooth loss (≥3 teeth: RR = 1.33; 95% CI = 1.09-1.62) and aggressive periodontitis (OR = 1.12; 95% CI = 1.01-1.26) in an independent sample of 4927 German/Dutch adults. The minor allele at rs3811046 is associated with increased expression of IL-1β in periodontal tissue. In RAW macrophages, PBMCs and transgenic mice, the IL37 variant increases expression of IL-1β and IL-6, inducing more severe periodontal disease, while IL-37 protein production is impaired and shows reduced cleavage by caspase-1. A second variant in the IL37 locus (rs2708943, p = 4.2 × 10-7) associates with attenuated IL37 mRNA expression. Overall, we demonstrate that IL37 variants modulate the inflammatory cascade in periodontal disease.

Computer-guided implant removal: A clinical report

Occasionally, osseointegrated dental implants must be removed because of complications such as malpositioning or screw fracture. This is most often accomplished with a surgical handpiece and trephine. However, a flap is often required to access and visualize the implants. This paper presents a treatment in which computer planning and a 3-dimensional-printed, custom fabricated, surgical guide was used to assist in implant removal. This technique simplified the procedure, allowed conservative removal of peri-implant bone, and permitted subsequent immediate implant replacement.

Common Polymorphisms in IFI16 and AIM2 Genes Are Associated With Periodontal Disease

BACKGROUND

The single nucleotide polymorphism (SNP) context of a previously identified periodontitis-associated locus is investigated, and its association with microbial, biologic, and periodontal disease clinical parameters is examined.

METHODS

A 200-kb spanning region of 1q12 previously highlighted in a genome-wide association scan among 4,766 European American individuals (SNP rs1633266) was annotated. Two haplotype blocks were selected. Association of these polymorphisms with data on microbial plaque composition, gingival crevicular fluid (GCF)-interleukin (IL)-1β levels, and clinical parameters of periodontal disease were examined. Descriptive analysis of IFI16 and AIM2 protein expression in gingival tissues from healthy individuals (n = 2) and individuals with chronic periodontitis (n = 2) was done via immunohistochemistry.

RESULTS

The highlighted locus is a 100-kb region containing the interferon γ-inducible protein 16 (IFI16) and absent in melanoma 2 (AIM2) genes. Two haplotype blocks, rs6940 and rs1057028, were significantly associated with increased extent bleeding on probing and levels of microorganisms Porphyromonas gingivalis, Tannerella forsythia, and Campylobacter rectus (P ≤0.05). Haplotype block rs1057028 was also significantly associated with pathogens Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans, increased GCF-IL-1β levels, and extent of probing depth ≥4 mm (P ≤0.05). Prevalence of severe periodontitis (biofilm-gingival interface P3 classification) was positively associated with haplotype block rs1057028. Similar trends were observed for haplotype block rs1057028. IFI16 and AIM2 protein expression was observed in multiple cell types of gingival tissues, including inflammatory cells.

CONCLUSION

This study found IFI16 and AIM2 SNPs associated with higher levels of periodontal microorganisms and an increased percentage of periodontal disease clinical parameters, suggesting the need for functional studies and additional fine-mapping of variants in the 1q12-locus.

Dental and orofacial mesenchymal stem cells in craniofacial regeneration: The prosthodontist's point of view

Of the available regenerative treatment options, craniofacial tissue regeneration using mesenchymal stem cells (MSCs) shows promise. The ability of stem cells to produce multiple specialized cell types along with their extensive distribution in many adult tissues have made them an attractive target for applications in tissue engineering. MSCs reside in a wide spectrum of postnatal tissue types and have been successfully isolated from orofacial tissues. These dental- or orofacial-derived MSCs possess self-renewal and multilineage differentiation capacities. The craniofacial system is composed of complex hard and soft tissues derived from sophisticated processes starting with embryonic development. Because of the complexity of the craniofacial tissues, the application of stem cells presents challenges in terms of the size, shape, and form of the engineered structures, the specialized final developed cells, and the modulation of timely blood supply while limiting inflammatory and immunological responses. The cell delivery vehicle has an important role in the in vivo performance of stem cells and could dictate the success of the regenerative therapy. Among the available hydrogel biomaterials for cell encapsulation, alginate-based hydrogels have shown promising results in biomedical applications. Alginate scaffolds encapsulating MSCs can provide a suitable microenvironment for cell viability and differentiation for tissue regeneration applications. This review aims to summarize current applications of dental-derived stem cell therapy and highlight the use of alginate-based hydrogels for applications in craniofacial tissue engineering.

In-office fabrication of dental implant surgical guides using desktop stereolithographic printing and implant treatment planning software: A clinical report

Guided surgery is accepted as the most accurate way to place an implant and predictably relate the implant to its definitive prosthesis, although few clinicians use it. However, recent developments in high-quality desktop 3-dimensional stereolithographic printers have led to the in-office fabrication of stereolithographic surgical guides at reduced cost. This clinical report demonstrates a protocol for using a cost-effective, in-office rapid prototyping technique to fabricate a surgical guide for dental implant placement.

Exploring Effectiveness of Computer-Aided Planning in Implant Positioning for a Single Immediate Implant Placement

The value of computer-aided implant planning using cone-beam computerized tomography (CBCT) for single immediate implants was explored. Eighteen patients requiring extraction of a tooth followed by a single immediate implant were enrolled. Small volume preoperative CBCT scans were used to plan the position of the implant. A taper screwed–type implant was immediately placed into a fresh socket using only the final 1 or 2 drills for osteotomy. Postoperative CBCTs were used for the analysis of actual implant placement positioning. Measurements of the planned and the actual implant position were made with respect to their position relative to the adjacent teeth. Mesio-distal displacements and the facial-lingual deviation of the implant from the planned position were determined. Changes in the angulation of the planned and actual implant position in relation to the clinical crown were also measured. To statistically summarize the results, box plots and 95% CIs for means of paired differences were used. The analysis showed no statistical difference between the planned position and final implant placement position in any measurement. The CBCT scans coupled with the computer-aided implant planning program along with a final 1-to-2 drill protocol may improve the accuracy of single immediate implant placement for taper screwed–type implants.

Role of salivary and candidal proteins in denture stomatitis: an exploratory proteomic analysis

Denture stomatitis, inflammation and redness beneath a denture, affects nearly half of all denture wearers. Candidal organisms, the presence of a denture, saliva, and host immunity are the key etiological factors for the condition. The role of salivary proteins in denture stomatitis is not clear. In this study 30 edentulous subjects wearing a maxillary complete denture were recruited. Unstimulated whole saliva from each subject was collected and pooled into two groups (n = 15 each), healthy and stomatitis (Newton classification II and III). Label-free multidimensional liquid chromatography/tandem mass spectrometry (2D-LC-MS/MS) proteomics on two mass spectrometry platforms were used to determine peptide mass differences between control and stomatitis groups. Cluster analysis and principal component analysis were used to determine the differential expression among the groups. The two proteomic platforms identified 97 and 176 proteins (ANOVA; p < 0.01) differentially expressed among the healthy, type 2 and 3 stomatitis groups. Three proteins including carbonic anhydrase 6, cystatin C, and cystatin SN were found to be the same as previous study. Salivary proteomic profiles of patients with denture stomatitis were found to be uniquely different from controls. Analysis of protein components suggests that certain salivary proteins may predispose some patients to denture stomatitis while others are believed to be involved in the reaction to fungal infection. Analysis of candidal proteins suggests that multiple species of candidal organisms play a role in denture stomatitis.