A review on clinical use of CAD/CAM and 3D printed dentures

Three-axis load analysis of high-speed handpiece on dental training teeth and computer-aided design/computer-aided manufacturing blocks

This study aimed to evaluate and compare the mechanical properties of dental training teeth with subtractive and additive computer-aided design/computer-aided manufacturing (CAD/CAM) materials used to fabricate dental simulation models. Therefore, the three-axis load generated during cutting movements, including drilling and milling performed using a dental handpiece, was measured and compared. The samples were cut vertically downward by 1.5 mm, horizontally by 6 mm, and vertically upward at a constant speed (1 mm/s), while the rotational speed of the bur was maintained at 200,000 rotations per minute. A three-axis load cell was used to measure the X-, Y-, and Z-axis loads on the specimen. The median value of the X-, Y-, and Z-axis measurements and the resultant load during the vertical-downward, horizontal, and vertical-upward movements were compared using a one-way analysis of variance and Tukey's post hoc test. For vertical downward movement, the drilling force of the dental training teeth was lower than that of Vita Enamic® and similar to that of Lava™ Ultimate. In contrast to subtractive CAD/CAM blocks, the drilling force of the dental training teeth was higher than that of 3D-printed resin blocks. Regarding horizontal movement, the milling force of dental training teeth was lower than that of Vita Enamic®. In contrast, the milling force of Nissin was similar to that of Lava™ Ultimate, while that of Frasaco was lower. Furthermore, compared to additive CAD/CAM blocks, the milling force of the dental training teeth was higher than that of 3D-printed resin blocks. Regarding vertical upward movement, the resultant loads of dental training teeth was lower than that of Vita Enamic®. Similarly, the resultant load of Nissin was similar to that of Lava™ Ultimate, while that of Frasaco was lower. Additionally, compared to additive CAD/CAM blocks, the resultant loads of the dental training teeth were similar to those of the 3D-printed resin blocks.

The application of 3D printing in dentistry: A bibliometric analysis from 2012 to 2023

STATEMENT OF PROBLEM

Three-dimensional (3D) printing has had extensive applications across dentistry, but a comprehensive bibliometric analysis relating to the application of 3D printing in dentistry is lacking.

PURPOSE

The purpose of this study was to conduct a comprehensive bibliometric analysis of the scientific literature concerning the application of 3D printing in dentistry from 2012 to 2023.

MATERIAL AND METHODS

The literature search was conducted in the Web of Science Core Collection Database. The retrieved literature data were downloaded as plain text file in "full record and cited references" format, with software programs (VOSviewer, CiteSpace, Biblioshiny, RStudio, Carrot2, and Microsoft Excel) used for bibliometric analysis and quantitative assessment.

RESULTS

The bibliometric analysis incorporated 1911 publications. Revilla-León, Marta was the most productive author. Zurich University had the highest number of publications and citations. The United States dominated the research landscape with the highest publication volume and H-index. The Journal of Prosthetic Dentistry was the leading journal in both publication volume and citation frequency. Co-occurrence analysis of keyword and co-cited analysis of reference indicated a robust research environment, characterized by a strong focus on the pursuit of accuracy in dental restorative solutions, biocompatibility of materials, and clinical applications.

CONCLUSIONS

Research on 3D printing in the field of dentistry continues to grow. Collaborations with leading organizations and countries have been established, with Revilla-León, Marta et al playing a pivotal role. Top journals represented included the Journal of Prosthetic Dentistry and Dental Materials. Main research domain resided in prosthodontics and implantology. Hot research topics included improvements in accuracy, dental materials, and clinical applications centered on implant guide design.

Bonding Efficiency between Artificial Teeth and Denture Base in CAD/CAM and Conventional Complete Removable Dentures

A common challenge encountered with both traditional and digitally produced dentures involves the extraction of artificial teeth from the denture base. This narrative review seeks to present an updated perspective on the adherence of synthetic teeth for denture base materials, employing diverse methods. Dental technicians often employ chemical approaches and mechanical techniques (including abrasion, laser treatment, and abrasive blasting) to augment the retention of denture teeth. However, the efficacy of these treatments remains uncertain. In certain instances, specific combinations of Denture Base Resin (DBR) materials and artificial teeth exhibit improved performance in conventional heat-cured dentures following these treatments. The primary reasons for failure are attributed to material incompatibility and inadequate copolymerization. As new denture fabrication techniques and materials continue to emerge, further research is imperative to identify optimal tooth-DBR combinations. Notably, 3D-printed tooth-DBR combinations have demonstrated reduced bond strength and less favorable failure patterns, while utilizing milled and traditional combinations appears to be a more prudent choice until advancements in additive manufacturing enhance the reliability of 3D-printing methods.

Shear bond strength of ultraviolet-polymerized resin to 3D-printed denture materials: Effects of post-polymerization, surface treatments, and thermocycling

PURPOSE

The purpose of this study is to compare the shear bond strength of ultraviolet (UV)-polymerized resin to 3D-printed denture materials, both with and without post-polymerization. Moreover, the effects of surface treatment and thermocycling on shear bond strength after post-polymerization were investigated.

METHODS

Cylindrical 3D-printed denture bases and teeth specimens were prepared. The specimens are subjected to two tests. For Test 1, the specimens were bonded without any surface treatment or thermal stress for comparison with and without post-polymerization. In Test 2, specimens underwent five surface treatments: untreated (CON), ethyl acetate (EA), airborne particle abrasion (APA) with 50 μm (50-APA) and 110 μm alumina (110-APA), and tribochemical silica coating (TSC). A UV-polymerized resin was used for bonding. Half of the Test 2 specimens were thermocycled for 10,000 cycles. Shear bond strength was measured and analyzed using Kruskal-Wallis and Steel-Dwass tests (n = 8).

RESULTS

In Test 1, post-polymerization significantly reduced shear bond strength of both 3D-printed denture materials (P < 0.05). No notable difference was observed between the denture teeth and the bases (P > 0.05). In Test 2, before thermocycling, the CON and EA groups exhibited low bond strengths, while the 50-APA, 110-APA, and TSC groups exhibited higher bond strengths. Thermocycling did not reduce bond strength in the latter groups, but significantly reduced bond strength in the EA group (P < 0.001).

CONCLUSIONS

Post-polymerization can significantly reduce the shear bond strength of 3D-printed denture materials. Surface treatments, particularly APA and TSC, maintained bond strength even after thermocycling.

Effect of a novel mesh design and the sandblasting technique on the bond strength of computer-designed and three-dimension laser printed resin bonded bridges: an in vitro study

Resin-bonded bridges (RBBs) are a minimally invasive and aesthetically pleasing treatment modality. However, their frequent failure has posed challenges for both dental professionals and patients. This necessitates the exploration of innovative strategies to enhance the longevity of RBBs. This study aimed to assess the bond strength of a mesh bridge fabricated using computer-aided design and three-dimensional (3D) printing technology in comparison to the traditional aluminum oxide sandblasting method. A total of 48 lower incisors were embedded in acrylic bases according to a standardized computer-generated model to receive 24 metal RBBs. The two groups underwent distinct metal surface treatments: the 3D mesh novel design and sandblasting with aluminum oxide particles sized at 250.00 µm. The bond strength of the bridges was evaluated, and statistical analysis was performed using the independent samples t-test with a significance level set at α = 0.05. The findings revealed a significant difference between the two methods (p < 0.001). The 3D mesh design exhibited a mean bond strength of 387.89 ± 24.15 N, while the sandblasting technique yielded a mean value of 161.46 ± 31.25 N. In summary, the 3D mesh design substantially enhanced the bond strength of RBBs compared to the traditional sandblasting technique.

Dry Mouth Dilemma: A Comprehensive Review of Xerostomia in Complete Denture Wearers

Xerostomia, commonly known as dry mouth, presents a significant challenge for individuals wearing complete dentures, affecting their oral health and quality of life. This review explores the relationship between saliva and complete dentures, highlighting the varied management strategies for xerostomia. Saliva plays a critical role in denture retention, lubrication, and oral environment buffering. Complete denture wearers often experience reduced salivary flow, aggravating symptoms of xerostomia. Various management approaches are discussed, including general measures such as hydration and salivary stimulation techniques which aim to boost saliva production naturally. The use of salivary substitutes provides artificial lubrication and moisture to alleviate dry mouth discomfort. Oral lubricating devices, such as sprays, gels, and lozenges, offer relief by mimicking saliva's lubricating properties, thereby improving denture stability and comfort. This review addresses the etiology of xerostomia in complete denture wearers and explores preventive measures to reduce its impact. A comprehensive approach has been discussed for the management of xerostomia which will help to improve the oral health and well-being of complete denture wearers experiencing dry mouth.

Adhesion of Candida Albicans to digital versus conventional acrylic resins: a systematic review and meta-analysis

BACKGROUND

The present systematic review and meta-analysis investigated the available evidence about the adherence of Candida Albicans to the digitally-fabricated acrylic resins (both milled and 3D-printed) compared to the conventional heat-polymerized acrylic resins.

METHODS

This study followed the guidelines of the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA). A comprehensive search of online databases/search tools (Web of Science, Scopus, PubMed, Ovid, and Google Scholar) was conducted for all relevant studies published up until May 29, 2023. Only in-vitro studies comparing the adherence of Candida albicans to the digital and conventional acrylic resins were included. The quantitative analyses were performed using RevMan v5.3 software.

RESULTS

Fourteen studies were included, 11 of which were meta-analyzed based on Colony Forming Unit (CFU) and Optical Density (OD) outcome measures. The pooled data revealed significantly lower candida colonization on the milled digitally-fabricated compared to the heat-polymerized conventionally-fabricated acrylic resin materials (MD = - 0.36; 95%CI = - 0.69, - 0.03; P = 0.03 and MD = - 0.04; 95%CI = - 0.06, - 0.01; P = 0.0008; as measured by CFU and OD respectively). However, no differences were found in the adhesion of Candida albicans between the 3D-printed digitally-fabricated compared to the heat-polymerized conventionally-fabricated acrylic resin materials (CFU: P = 0.11, and OD: P = 0.20).

CONCLUSION

The available evidence suggests that candida is less likely to adhere to the milled digitally-fabricated acrylic resins compared to the conventional ones.

A combined 3D printed metal and resin digital denture: 5-year follow-up data and a creative design concept

Many denture frameworks are currently manufactured using metal 3-dimensional (3D) printing technology. However, this advanced technology is still limited to conventional denture designs. A metal 3D printing-based denture design concept was developed and is presented based on a nonwear occlusal surface, a nonfracture denture base, and a novel connection between metal and resin.

The prevalence of denture loss within community residential settings

Introduction Denture loss prevalence in community settings is unknown and results in deteriorating residents' systemic and psychosocial wellbeing.Materials and methods An electronic survey was distributed nationally through professional networks to community residential settings.Results Of the 156 responses from community residential settings, 69% of settings experienced at least one denture lost in the last two years. Sixty percent of responders reported no dentures were labelled, only 64% had received training about how to care for dentures and 86% felt they would benefit from further training on mouth care. In addition, 68% of staff found arranging dental care for their residents challenging.Discussion Extrapolated data suggest that at least 10,205 dentures are lost annually in community residential settings and are never found, costing the NHS Business Service Authority more than £3 million. A high prevalence of denture loss in community residential settings is likely due to residents with multiple comorbidities and frailty. Remaking dentures poses financial, logistical, and patient challenges, which may result in patients being unable to wear a remade denture.Conclusion The prevalence of denture loss within community residential settings needs to be understood to encourage targeted interventions, inform stakeholders, and encourage workflows that will improve service delivery and patients' oral health-related quality of life.

Digitally versus conventionally fabricated complete dentures: A systematic review on cost-efficiency analysis and patient-reported outcome measures (PROMs)

STATEMENT OF PROBLEM

Reports on digitally fabricated complete dentures are increasing. However, comprehensive evidence-based research on their cost-efficiency and patient-reported outcome measures (PROMs) is lacking.

PURPOSE

The purpose of this systematic review was to compare the cost-effectiveness and PROMs between digitally and conventionally fabricated complete dentures.

MATERIAL AND METHODS

An electronic search of publications from 2011 to mid-2023 was established using PubMed/Medline, EBSCOhost, and Google Scholar. Retrospective, prospective, randomized controlled, and randomized crossover clinical studies on at least 10 participants were included. A total of 540 articles were identified and assessed at the title, abstract, and full article level, resulting in the inclusion of 14 articles. Data on cost, number of visits, patient satisfaction, and oral health-related quality of life were examined and reported.

RESULTS

The systematic review included 572 digitally fabricated complete dentures and 939 conventionally fabricated complete dentures inserted in 1300 patients. Digitally fabricated complete dentures require less clinical time with a lower total cost, despite higher material costs compared with the conventional fabrication technique. Digitally and conventionally fabricated complete dentures were found to have significant effects on mastication efficiency, comfort, retention, stability, ease of cleaning, phonetics, and overall patient satisfaction, as well as social disability, functional limitation, psychological discomfort, physical pain, and handicap.

CONCLUSIONS

Digitally fabricated complete dentures are more cost-effective than conventionally fabricated dentures. There are various impacts of conventionally and digitally fabricated complete dentures on PROMs, and they are not better than one another.

Adhesion of Conventional, 3D-Printed and Milled Artificial Teeth to Resin Substrates for Complete Dentures: A Narrative Review

BACKGROUND

One type of failure in complete or partial dentures is the detachment of resin teeth from denture base resin (DBR). This common complication is also observed in the new generation of digitally fabricated dentures. The purpose of this review was to provide an update on the adhesion of artificial teeth to denture resin substrates fabricated by conventional and digital methods.

METHODS

A search strategy was applied to retrieve relevant studies in PubMed and Scopus.

RESULTS

Chemical (monomers, ethyl acetone, conditioning liquids, adhesive agents, etc.) and mechanical (grinding, laser, sandblasting, etc.) treatments are commonly used by technicians to improve denture teeth retention with controversial benefits. Better performance in conventional dentures is realized for certain combinations of DBR materials and denture teeth after mechanical or chemical treatment.

CONCLUSIONS

The incompatibility of certain materials and lack of copolymerization are the main reasons for failure. Due to the emerging field of new techniques for denture fabrication, different materials have been developed, and further research is needed to elaborate the best combination of teeth and DBRs. Lower bond strength and suboptimal failure modes have been related to 3D-printed combinations of teeth and DBRs, while milled and conventional combinations seem to be a safer choice until further improvements in printing technologies are developed.