Recent advances in additive manufacturing of patient-specific devices for dental and maxillofacial rehabilitation

OBJECTIVES

Customization and the production of patient-specific devices, tailoring the unique anatomy of each patient's jaw and facial structures, are the new frontiers in dentistry and maxillofacial surgery. As a technological advancement, additive manufacturing has been applied to produce customized objects based on 3D computerized models. Therefore, this paper presents advances in additive manufacturing strategies for patient-specific devices in diverse dental specialties.

METHODS

This paper overviews current 3D printing techniques to fabricate dental and maxillofacial devices. Then, the most recent literature (2018-2023) available in scientific databases reporting advances in 3D-printed patient-specific devices for dental and maxillofacial applications is critically discussed, focusing on the major outcomes, material-related details, and potential clinical advantages.

RESULTS

The recent application of 3D-printed customized devices in oral prosthodontics, implantology and maxillofacial surgery, periodontics, orthodontics, and endodontics are presented. Moreover, the potential application of 4D printing as an advanced manufacturing technology and the challenges and future perspectives for additive manufacturing in the dental and maxillofacial area are reported.

SIGNIFICANCE

Additive manufacturing techniques have been designed to benefit several areas of dentistry, and the technologies, materials, and devices continue to be optimized. Image-based and accurately printed patient-specific devices to replace, repair, and regenerate dental and maxillofacial structures hold significant potential to maximize the standard of care in dentistry.

Classifying Maxillary Sinuses of Polish Patients for Sinus Lift: A Pilot Study

To date, there is no systematic anatomical classification available that could help clinicians in choosing between the lateral and palatal approach in sinus lift procedures. The aim was to provide a simple-to-use and memorable classification of the maxillary sinus concerning the thickness of lateral and palatal walls to facilitate the most adequate choice for the window location during direct sinus floor elevation. Cone beam computed tomography scans were consecutively obtained for 200 maxillary sinuses of patients needing dental implant placement with potential maxillary sinus augmentation. The thickness and height of the alveolar bone of the lateral and palatal walls of the maxillary sinuses were assessed. Four variants were distinguished. Class 0: an adequate sub-sinus residual bone height; without the need for sinus floor augmentation. Classes 1-3 had a reduced sub-sinus residual bone height. Class 1: a thinner lateral than palatal sinus wall. Class 2 (the most frequent; 49%): the comparable thickness of both walls in which either lateral, palatal, or crestal window osteotomies can be applied. Class 3 (the least frequent; 3%): a thinner palatal sinus wall in comparison to the lateral wall. The presented anatomical classification simplifies the decision-making process of choosing the most adequate window location and osteotomy technique.

Polymorphism in epigenetic regulating genes in relation to periodontitis, number of teeth, and levels of high-sensitivity C-reactive protein and glycated hemoglobin: The Tromsø Study 2015-2016

BACKGROUND

The aim of this study was to investigate the association between periodontitis and four single nucleotide polymorphisms (SNPs) in genes involved in epigenetic regulation of DNA, and between these same SNPs and tooth loss, high-sensitivity C-reactive protein (hs-CRP), and glycated hemoglobin (HbA1c) levels.

METHODS

We included participants with periodontal examination (n = 3633, aged: 40-93 years) from the Tromsø Study seventh survey (2015-2016), Norway. Periodontitis was defined according to the 2017 AAP/EFP classification system as no periodontitis, grades A, B, or C. Salivary DNA was extracted and genotyping was performed to investigate four SNPs (rs2288349, rs35474715, rs34023346, and rs10010325) in the sequence of the genes DNMT1, IDH2, TET1, and TET2. Association between SNPs and periodontitis was analyzed by logistic regression adjusted for age, sex, and smoking. Subgroup analyses on participants aged 40-49 years were performed.

RESULTS

In participants aged 40-49 years, homozygous carriage of minor A-allele of rs2288349 (DNMT1) was associated with decreased susceptibility to periodontitis (grade A: odds ratio [OR] 0.55; p = 0.014: grade B/C OR 0.48; p = 0.004). The minor A-allele of rs10010325 (TET2) was associated with increased susceptibility to periodontitis (grade A OR 1.69; p = 0.035: grade B/C OR 1.90; p = 0.014). In the entire sample, homozygous carriage of the G-allele of rs35474715 (IDH2) was associated with having ≤24 teeth (OR 1.31; p = 0.018). Homozygous carriage of the A-allele of TET2 was associated with hs-CRP≥3 mg/L (OR 1.37; p = 0.025) and HbA1c≥6.5% (OR 1.62; p = 0.028).

CONCLUSIONS

In this Norwegian population, there were associations between polymorphism in genes related to DNA methylation and periodontitis, tooth loss, low-grade inflammation, and hyperglycemia.

The Role of Titanium Particles and Ions in the Pathogenesis of Peri-Implantitis

Titanium (Ti) particles and ions have been investigated in recent years as important factors in the pathogenesis of peri-implantitis. However, their role in the pathogenesis is yet to be fully understood. A review of pertinent literature was performed in various databases to determine the current position of Ti particles and ions role in the pathogenesis of peri-implantitis. There are several in vitro, preclinical and clinical published studies that have addressed the role of Ti particles and ions in the pathogenesis of peri-implantitis. These studies explored the effect of Ti particles and ions in the pathogenesis of peri-implantitis with respect to foreign body reaction, cellular response, epigenetic mechanisms, namely DNA methylation, and the oral microbiome. Studies have shown that the release of Ti particles/ions during implant insertion, early healing stages, late healing stages, and treatments during peri-implantitis might contribute to peri-implantitis through different mechanisms, such as foreign body reaction, cellular response, DNA methylation, and shaping the oral microbiome by increasing dysbiosis. However, further studies are needed to elucidate the complex interactions between all these mechanisms and Ti particles/ions in the pathogenesis and progression of peri-implantitis.

Understanding the role of endotoxin tolerance in chronic inflammatory conditions and periodontal disease

OBJECTIVE

This review aims to present the current understanding of endotoxin tolerance (ET) in chronic inflammatory diseases and explores the potential connection with periodontitis.

SUMMARY

Subsequent exposure to lipopolysaccharides (LPS) triggers ET, a phenomenon regulated by different mechanisms and pathways, including toll-like receptors (TLRs), nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB), apoptosis of immune cells, epigenetics, and microRNAs (miRNAs). These mechanisms interconnect ET with chronic inflammatory diseases that include periodontitis. While the direct correlation between ET and periodontal destruction has not been fully elucidated, emerging reports point towards the potential tolerization of human periodontal ligament cells (hPDLCs) and gingival tissues with a significant reduction of TLR levels.

CONCLUSIONS

There is a potential link between ET and periodontal diseases. Future studies should explore the crucial role of ET in the pathogenesis of periodontal diseases as evidence of a tolerized oral mucosa may represent an intrinsic mechanism capable of regulating the oral immune response. A clear understanding of this host immune regulatory mechanism might lead to effective and more predictable therapeutic strategies to treat chronic inflammatory diseases and periodontitis. This article is protected by copyright. All rights reserved.

Aesthetic outcomes of non-functional immediately restored single post-extraction implants with and without connective tissue graft: A multicentre randomized controlled trial

OBJECTIVES

To compare the 1-year aesthetic results of flapless single implants, placed in fresh extraction sockets with bone replacement and immediate provisional restoration with or without a connective tissue graft (CTG).

MATERIAL AND METHODS

The present study proposes a partially blinded multicentre parallel randomized controlled trial, where computer-generated tables were used for central randomization to allocate treatments. A total of 59 of the 60 patients screened by eight private practices in Northern Italy fulfilled the inclusion criteria. Immediate implants were placed in a fresh extraction socket with a non-functional immediate provisional restoration with (Test group) or without (Control group) a CTG. The primary outcome variable was the implant Crown Aesthetic Index (ICAI) at the 1-year follow-up.

RESULTS

ICAI for the 59 randomized patients (Test group = 31, Control group = 28) at the 1-year follow-up was 4.69 (95% CI = 3.16-6.22) for the Test group and 3.45 (95% CI = 1.83-5.08) for the Control group, without statistically significant difference between the two groups (p = .086). One implant failure was recorded in each group, resulting in an implant survival rate of 96.8% [95% CI = 83.3-99.9] for the Test group and 96.4% [95% CI = 81.7-99.9] for the Control group. Other secondary outcome variables and complication rates were comparable across the two groups.

CONCLUSIONS

Within the limitations of the present clinical trial, the results suggested that the adjunct use of CTG is not mandatory to achieve successful aesthetic outcomes for a well-planned immediate implant placement with immediate non-functional provisional restoration in a fresh extraction socket.

Epigenetic changes of osteoblasts in response to titanium surface characteristics

We aimed to investigate the influence of titanium surface characteristics on epigenetic mechanisms and DNA damage/repair pathways. Osteoblast-like cells (MG63) were incubated on glass, smooth titanium, and minimally rough titanium discs, respectively, for 0, 1, 6, and 24 hr. The presence of double-stranded DNA damage (γH2AX), DNA repair (Chk2), and epigenetic markers (AcH3 & DNMT1) were investigated using immunofluorescence. There were no Chk2-positive cells on the minimally rough titanium surfaces at all-time points, in comparison to glass and smooth titanium. Total γH2AX-positive cells on minimally rough titanium gradually decreased as incubation time increased, on the contrary to smooth titanium. Minimally rough titanium surfaces induced cytoplasmic staining of DNMT1 up to 99% at 24 hr. For epigenetic markers related to the DNA damage/repair pathway, minimally rough titanium surfaces showed the lower percentage of AcH3-positive cells compared to glass and smooth titanium surface. The findings in the current study show that titanium surface characteristics indeed influence DNA damage and the DNA repair pathway, including epigenetic factors.

Shared decision-making (SDM) in dentistry: A concise narrative review

OBJECTIVE

The aim of this review was to evaluate the implementation of shared decision-making (SDM) in dentistry and the roles of informed consent and patient decision-making aids (PDAs) as part of this process.

MATERIALS AND METHODS

A review of pertinent literature was performed using PubMed and MEDLINE to determine the current position of the application of SDM in dentistry and the influence of informed consent and PDAs on this process.

RESULTS

Limited number of published studies on the implementation of SDM in dental practice is available. These studies demonstrated that SDM is influenced by many factors. Informed consent intertwines with the SDM process and begins with providing high quality information to patients and employing PDAs. PDAs have been developed for some dental fields to facilitate the SDM process.

CONCLUSIONS

SDM is applied in dentistry and is influenced by many factors. Informed consent is an important part of this process. PDAs in more dental fields need to be further developed, in order to ensure a satisfactory integration of patients in the SDM process.

Comparison of two soft tissue substitutes for the treatment of gingival recession defects: an animal histological study

Objectives:

This study aimed to compare two different soft tissue replacement grafts in their ability to treat gingival recession defects and successfully integrate with the surrounding tissues.

Methodology:

Nine beagle dogs were included and followed up to 10 weeks. Sites for intervention were allocated to one of the grafting materials investigated. Treatment consisted of coronally advanced flap combined with one of the two soft tissue substitutes on a previous surgically created defect. Materials employed were porcine-derived acellular dermal matrix (ADM) [Novomatrix^™ (Test)] and collagen-based matrix (CBM) [Mucograft^® (Control)]. Animals were sacrificed at 2, 6, and 10 weeks postoperatively and compared using descriptive histology and histomorphometric outcomes.

Results:

Macroscopic findings were similar between test and control groups at all intervals. After 10 weeks, both groups demonstrated successful incorporation of the grafting materials without signs of rejection and with comparable tissue integration. The histomorphometric data were similar between groups at 2 weeks; however, the test group provided greater root coverage and increase in tissue thickness than the control at 6- and 10-weeks post surgically.

Conclusions:

Both porcine-derived ADM and CBM revealed similar histological outcomes with successful integration and absence of adverse events. Test group provided superior outcomes regarding root coverage and increase in tissue thickness.

Gene Delivery Therapeutics in the Treatment of Periodontitis and Peri-Implantitis: A State of the Art Review

BACKGROUND

Periodontal disease is a chronic inflammatory condition that affects supporting tissues around teeth, resulting in periodontal tissue breakdown. If left untreated, periodontal disease could have serious consequences; this condition is in fact considered as the primary cause of tooth loss. Being highly prevalent among adults, periodontal disease treatment is receiving increased attention from researchers and clinicians. When this condition occurs around dental implants, the disease is termed peri-implantitis. Periodontal regeneration aims at restoring the destroyed attachment apparatus, in order to improve tooth stability and thus reduce disease progression and subsequent periodontal tissue breakdown. Although many biomaterials have been developed to promote periodontal regeneration, they still have their own set of disadvantages. As a result, regenerative medicine has been employed in the periodontal field, not only to overcome the drawbacks of the conventional biomaterials but also to ensure more predictable regenerative outcomes with minimal complications. Regenerative medicine is considered a part of the research field called tissue engineering/regenerative medicine (TE/RM), a translational field combining cell therapy, biomaterial, biomedical engineering and genetics all with the aim to replace and restore tissues or organs to their normal function using in vitro models for in vivo regeneration. In a tissue, cells are responding to different micro-environmental cues and signaling molecules, these biological factors influence cell differentiation, migration and cell responses. A central part of TE/RM therapy is introducing drugs, genetic materials or proteins to induce specific cellular responses in the cells at the site of tissue repair in order to enhance and improve tissue regeneration. In this review, we present the state of art of gene therapy in the applications of periodontal tissue and peri-implant regeneration.

PURPOSE

We aim herein to review the currently available methods for gene therapy, which include the utilization of viral/non-viral vectors and how they might serve as therapeutic potentials in regenerative medicine for periodontal and peri-implant tissues.

Minimizing Patient Morbidity Following Palatal Gingival Harvesting: A Randomized Controlled Clinical Study

This clinical study was conducted to evaluate the impact of different hemostatic treatments following palatal gingival harvesting on patient discomfort. Fifty patients who needed a mucogingival surgery requiring gingival graft harvesting were enrolled and randomly assigned to one of five groups: (1) a control group in which only sutures were applied; (2) a cyanoacrylate group; (3) a periodontal dressing material group; (4) a hemostatic gelatin sponge group; and (5) a group in which the gelatin sponge and cyanoacrylate were combined. In the 2 weeks following the procedures, perception of pain, healing, consumption of drugs, and willingness to repeat the procedure were recorded through visual analog scale (VAS) by patients. Over the 2 weeks, lower pain (VAS) was found in all test groups compared to the control group (P < .01, value for time-group interaction). Notably, the gelatin sponge combined with cyanoacrylate group had very low pain (VAS ≤ 0.5 points) throughout the 14 days. The lowest healing scores at day 10 were associated with the control group (6.8 VAS points) in contrast to the four test groups (8.2 to 9.0 VAS points, P = .0001). Pain was inversely correlated with age (P < .05). Pain also depended on the apicocoronal dimension of the graft: the higher the graft, the more pain was experienced by the participants (0.4 VAS points per 1 mm, P < .05). Within the limitations of this study, palatal coverage appears to result in better outcomes when compared to suture alone. In particular, a double-layered protection of the palatal wound with a gelatin sponge combined with cyanoacrylate appeared to be the best option in reducing pain and postoperative discomfort.

Decontamination of Customized Laser-Microtextured Titanium Abutments: A Comparative in Vitro Study of Different Cleaning Procedures

The aim of this study was to evaluate different cleaning procedures for customized laser-microtextured titanium abutments. A total of 20 customized laser-microtextured abutments were randomized into four groups: no cleaning (control group), ultrasonic treatments + autoclave cycle (group 1), ultrasonic treatments + argon plasma (group 2), and only argon plasma (group 3). Surface contaminants were assessed through scanning electron microscopy and energy-dispersive x-ray spectroscopy microanalysis. In the control group, 99.96% of the abutment surfaces were contaminated with organic and inorganic pollutants. Group 3 showed the second highest contamination percentage, with almost 23% of the analyzed surfaces polluted. Samples in groups 1 and 2 were almost clean, with negligible traces of microparticles (0.009% and 0.047% of the surfaces were contaminated, respectively). These results were statistically significant for differences between control and test groups, and between groups 1 and 2 in comparison to 3 (P < .001). Abutment decontamination with argon plasma alone might not be as effective on laser-microtextured surfaces as other cleaning protocols.

Failed Blade Implant After 25 Years in Function: Case Description and Histologic Analysis

This report describes a failed blade implant after 25 years in function in the left maxilla and the results of histologic analysis of peri-implant tissues. The blade was retrieved, and histologic findings revealed that it was not osseointegrated despite being successfully in function for so many years. The long-term function of blade implants without osseointegration can be attributed to biotolerance exhibited by the implant rather than actual osseointegration.

The association between periodontal disease and metabolic syndrome among outpatients with diabetes in Jordan

Background

To date, conflicting results have been reported about the association between metabolic syndrome (MetS) and periodonttitis.

Methods

Two hundred and eighty patients with type 2 diabetes were recruited from outpatients visiting diabetes clinics in Islamic Hospital, Amman-Jordan. The oral hygiene and the periodontal status of all teeth, excluding third molars, were assessed using the plaque index of Silness and Löe, the gingival index of Löe and Silness, probing pocket depth (PPD), and clinical attachment level (CAL). Data were analyzed using the general linear model multivariate procedure with average PPD, average CAL, percent of teeth with CAL ≥3 mm, and percent of teeth with PPD ≥3 mm as outcome variables and diabetes, MetS and its individual components as predictors.

Results

Overall, 83.2 % of patients with diabetes had MetS. In the multivariate analysis, patients with MetS had a significantly more severe periodontitis, as measured by average PPD and average CAL (P < 0.005). The extent of periodontitis, as measured by the percent of teeth with CAL ≥3 mm and the percent of teeth with PPD ≥3 mm, was also significantly greater among patients with MetS (P < 0.005). As the number of metabolic components additional to diabetes increased, the odds of having periodontitis increased, and the odds were greatest when all the components additional to diabetes were present (OR = 10.77, 95 % CI: 2.23 -51.95).

Conclusion

Patients with MetS displayed more severe and extensive periodontitis. Having other MetS components additional to diabetes increased the odds of having periodontitis.

Periodontal health awareness among gynecologists in Riyadh, Saudi Arabia

Objective:

To determine the knowledge of periodontal disease and pregnancy outcomes among the gynecologists practicing in Riyadh, Saudi Arabia.

Materials and Methods:

A cross-sectional survey of 200 randomly chosen gynecologists from Riyadh was carried out by using a structured, self-administered, closed-ended questionnaire. Knowledge of periodontal disease and possible ways of prevention; knowledge of periodontal disease and pregnancy outcomes; and oral self-care attitudes among gynecologists were assessed.

Results:

One-quarter of the gynecologists knew the meaning of dental plaque. Almost 57.5% believed that the frequency of toothbrushing should be increased during pregnancy. Eighty percent of gynecologists were aware of the serious effects of smoking on the pregnant woman and her child. Less than half (44.5%) believed that there is a relationship between gum disease and premature labor. Gynecologists working in the government sector were significantly more aware about the causes of inflamed gum in pregnancy, gum disease and its prevention, and negative effects of smoking on pregnancy. A significantly higher percentage of male and senior gynecologists aged between 50 and 54 years answered that gum disease would lead to the delivery of a preterm or low-birth-weight infant.

Conclusion:

Gynecologists considered in the present study showed an acceptable level of knowledge and awareness toward periodontal health and the association between periodontal disease and adverse pregnancy outcomes.

Pre-augmentation soft tissue expansion: an overview

OBJECTIVES

The aim of this study was to explore the development of soft tissue expanders, their different types and their potential applications prior to bone augmentation and implant placement.

MATERIAL AND METHODS

A review of pertinent literature was performed using PubMed to comprehend the dynamics of soft tissue expanders and determine the current position of their pre-augmentation applications.

RESULTS

There is promising, albeit preliminary information regarding the benefits of pre-augmentation soft tissue expansion. Findings cannot be generalised due to relatively small sample size.

CONCLUSIONS

Further clinical trials with larger sample sizes and long-term follow-up are needed before soft tissue expanders can be confidently applied in everyday clinical practice.

Knowledge, attitude and practices of gynecologists regarding the prevention of oral diseases in Riyadh city, Saudi Arabia

AIM

To assess the knowledge, attitude and practices of gynecologists regarding the prevention of oral diseases in Riyadh city, Saudi Arabia.

METHODS

A structured, self administered, close-ended questionnaire was distributed among the randomly chosen sample of 200 gynecologists and their responses were recorded and analyzed.

RESULTS

Nearly half of the respondents knew all the main risk factors of dental caries, gingivitis and malocclusion. An overall mean scores of 16.49 ± 5.63, 6.62 ± 1.59 and 7.13 ± 2.82, were observed for knowledge of risk factors, attitude and practices towards prevention of oral diseases respectively. Gynecologists working in the private hospitals showed signifi cantly higher mean attitude and practice scores towards prevention of oral diseases. A linear positive correlation between knowledge and attitude (r=0.11, p=0.11), knowledge and practice (r=0.07, p=0.26), instead a negative correlation between attitude and practice (r=-0.04, p=0.53) was found by a Spearman's test.

CONCLUSION

Gynecologists considered in the present study showed inadequate oral health knowledge, attitude and practices towards prevention of oral diseases. However, gynecologists expressed their need for further information regarding the prevention of oral diseases.