Three-Dimensional Virtual Treatment Planning: Presurgical Evaluation

Accuracy of 3D Virtual Surgical Planning Compared to the Traditional Two-Dimensional Method in Orthognathic Surgery: A Literature Review

With the innovation of three-dimensional imaging and printing techniques, computer-aided surgical planning, also known as virtual surgical planning (VSP), has revolutionized orthognathic surgery. Designing and manufacturing patient-specific surgical guides using three-dimensional printing techniques to improve surgical outcomes is now possible. This article presents an overview of VSP in orthognathic surgery and discusses the advantages and accuracy of this technique compared to traditional surgical planning (TSP). A PubMed and Google Scholar search was conducted to find relevant articles published over the past 10 years. The search revealed 2,581 articles, of which 36 full-text articles specifically addressed the topic of this study. The review concludes that VSP in orthognathic surgery provides optimal functional and aesthetic results, enhances patient satisfaction, ensures precise translation of the treatment plan, and facilitates intraoperative manipulation.

Mandible-First and Maxilla-First Sequencing in Virtual Surgical Planning for Orthognathic Surgery: Comparison of Planned and Actual Outcomes

Background: Recent studies have shown that virtual planning for orthognathic surgery is an accurate and repeatable method. It is also a fact that surgical sequence can affect the results in terms of accuracy. Various studies stated that both approaches offer comparable results when properly planned and implemented; however, further clinical studies are still needed. This study aims to evaluate the effect of virtual surgical planning (VSP) on surgical outcomes and whether it is affected by mandible-first or maxilla-first approaches. Methods: This study analyzed data from 45 patients who underwent orthognathic surgery due to dentofacial deformity. Six of these patients underwent single-jaw orthognathic surgery, and 39 underwent bimaxillary orthognathic surgery (Maxilla-first group: 21, mandible-first group: 18). The displacements of specific landmarks were assessed by comparing preoperative and postoperative conventional computed tomographies with VSP data. Results: This study showed a statistically significant relationship between the measurements made with the 2 methods (r = .944; P = .0001). The fact that the intra-class correlation coefficient value is statistically significant and relatively high and that most of the differences in the Bland-Altman chart fall between the limits of compliance indicates a correlation between the virtual plan and surgical outcomes. In addition, in vertical measurements, the absolute mean difference of the B point and the Pogonion in the Maxilla-first group were statistically significantly higher than in the Mandible-first group (P = .038, P = .011). Conclusions: Our findings corroborate the high accuracy of the VSP reported in previous studies and also demonstrate that VSP with both maxilla-first and mandible-first sequencing achieves high accuracy in the sagittal and coronal planes. Although virtual planning significantly influences accurate surgical outcomes, it is not the sole determinant. Factors like condylar positioning and fixation methods can also impact the final results.

Evaluation of the Dimensional Accuracy of Robot-Guided Laser Osteotomy in Reconstruction with Patient-Specific Implants-An Accuracy Study of Digital High-Tech Procedures

Background/Objective: With the rapid advancement in surgical technologies, new workflows for mandibular reconstruction are constantly being evaluated. Cutting guides are extensively employed for defining osteotomy planes but are prone to errors during fabrication and positioning. A virtually defined osteotomy plane and drilling holes in robotic surgery minimize potential sources of error and yield highly accurate outcomes. Methods: Ten mandibular replicas were evaluated after cutting-guided saw osteotomy and robot-guided laser osteotomy following reconstruction with patient-specific implants. The descriptive data analysis summarizes the mean, standard deviation (SD), median, minimum, maximum, and root mean square (RMS) values of the surface comparison for 3D printed models regarding trueness and precision. Results: The saw group had a median trueness RMS value of 2.0 mm (SD ± 1.7) and a precision of 1.6 mm (SD ± 1.4). The laser group had a median trueness RMS value of 1.2 mm (SD ± 1.1) and an equal precision of 1.6 mm (SD ± 1.4). These results indicate that robot-guided laser osteotomies have a comparable accuracy to cutting-guided saw osteotomies, even though there was a lack of statistical significance. Conclusions: Despite the limited sample size, this digital high-tech procedure has been shown to be potentially equivalent to the conventional osteotomy method. Robotic surgery and laser osteotomy offers enormous advantages, as they enable the seamless integration of precise virtual preoperative planning and exact execution in the human body, eliminating the need for surgical guides in the future.

Virtual Reality and Augmented Reality in Plastic and Craniomaxillofacial Surgery: A Scoping Review

Virtual reality (VR) and augmented reality (AR) have evolved since their introduction to medicine in the 1990s. More powerful software, the miniaturization of hardware, and greater accessibility and affordability enabled novel applications of such virtual tools in surgical practice. This scoping review aims to conduct a comprehensive analysis of the literature by including all articles between 2018 and 2021 pertaining to VR and AR and their use by plastic and craniofacial surgeons in a clinician-as-user, patient-specific manner. From the initial 1637 articles, 10 were eligible for final review. These discussed a variety of clinical applications: perforator flaps reconstruction, mastectomy reconstruction, lymphovenous anastomosis, metopic craniosynostosis, dermal filler injection, auricular reconstruction, facial vascularized composite allotransplantation, and facial artery mapping. More than half (60%) involved VR/AR use intraoperatively with the remainder (40%) examining preoperative use. The hardware used predominantly comprised HoloLens (40%) and smartphones (40%). In total, 9/10 Studies utilized an AR platform. This review found consensus that VR/AR in plastic and craniomaxillofacial surgery has been used to enhance surgeons' knowledge of patient-specific anatomy and potentially facilitated decreased intraoperative time via preoperative planning. However, further outcome-focused research is required to better establish the usability of this technology in everyday practice.

Collaborative Control Method and Experimental Research on Robot-Assisted Craniomaxillofacial Osteotomy Based on the Force Feedback and Optical Navigation

Surgical robot has advantages in high accuracy and stability. But during the robot-assisted bone surgery, the lack of force information from surgical area and incapability of intervention from surgeons become the obstacle. The aim of the study is to introduce a collaborative control method based on the force feedback and optical navigation, which may optimally combine the excellent performance of surgical robot with clinical experiences of surgeons.

Accuracy of a surface-based fusion method when integrating digital models and the cone beam computed tomography scans with metal artifacts

The aim of this study was to evaluate the intra- and inter-observer reliability of maxillary digital dental model integration into cone-beam computed tomography (CBCT) scans to reconstruct three-dimensional (3D) skeletodental models for orthognathic patients. This retrospective study consisted of CBCT and digital maxillary dentition images of 20 Class III orthognathic patients. After two repeated fusions of digital cast images with reconstructed CBCT images by a digital engineer and an orthodontist respectively, the 3D coordinate values of the canines, first molars, and central incisors were evaluated. The intra- and inter-observer reliability of 3D positions of maxillary teeth were compared using intraclass correlation coefficients (ICCs). Intra-observer reliability of x-, y-, and z-coordinate values of maxillary teeth showed significant and excellent agreement in an engineer (0.946 ≤ ICC ≤ 1.000) and an orthodontist (0.876 ≤ ICC ≤ 1.000). The inter-observer reliability of the y- and z-coordinates of each tooth was significantly excellent or good, but that of the x-coordinates showed insignificantly poor to moderate agreement. This study showed that the integration of maxillary digital models into CBCT scans was clinically reliable. However, considering the low inter-observer reliability on the x-coordinates of dentition, clinical experience and repeated learning are needed for accurate application of digital skeletodental model in orthognathic patients.

Virtual surgical planning is a useful tool in the surgical management of mandibular condylar fractures

PURPOSE

The aim of this study is to evaluate the application value of virtual surgical planning in the management of mandibular condylar fractures and to provide a reliable reference.

METHODS

This was a prospective randomized controlled study and recruited 50 patients requiring surgical treatment for their mandibular condylar fractures. The inclusion criteria were patients (1) diagnosed with a condylar fracture by two clinically experienced doctors and required surgical treatment; (2) have given consent for the surgical treatment; and (3) had no contraindications to the surgery. Patients were excluded from this study if: (1) they were diagnosed with a non-dislocated or only slightly dislocated condylar fracture; (2) the comminuted condylar fracture was too severe to be treated with internal reduction and fixation; or (3) patients could not complete follow-up for 3 months. There were 33 male and 17 female patients with 33 unilateral condylar fractures and 17 bilateral condylar fractures included. The 50 patients were randomly (random number) divided into control group (25 patients with 35 sides of condylar fractures) and experimental group (25 patients with 32 sides of condylar fractures). Virtual surgical planning was used in the experimental group, but only clinical experience was used in the control group. The patients were followed up for 1, 3, 6 and 12 months after operation. Variables including the rate of perfect reduction by radiological analysis, the average distance of deviation between preoperative and postoperative CT measurements using Geomagic software and postoperative clinical examinations (e.g., mouth opening, occlusion) were investigated for outcome measurement. SPSS 19 was adopted for data analysis.

RESULTS

The average operation time was 180.60 min in the experimental group and 223.2 min in the control group. One week postoperatively, CT images showed that the anatomic reduction rate was 90.63% (29/32) in the experimental group and 68.57% (24/35) in the control group, revealing significant difference (X² = 4.919, p = 0.027). Geomagic comparative analysis revealed that the average distance of deviation was also much smaller in the experimental group than that in the control group (0.639 mm vs. 0.995 mm; t = 3.824, p < 0.001).

CONCLUSION

These findings suggest that virtual surgical planning can assist surgeons in surgical procedures, reduce operative time, and improve the anatomic reduction rate & accuracy, and thus of value in the diagnosis and treatment of condylar fractures.

Current Understanding of Hearing Loss in Sporadic Vestibular Schwannomas: A Systematic Review

Objective

Hearing loss is the most common initial symptom in patients with sporadic vestibular schwannomas (SVS). Hearing preservation is an important goal of both conservative and surgical therapy. However, the mechanism of SVS-associated hearing loss remains unclear. Thus, we performed this systematic review to summarize the current understanding of hearing loss in the SVS and distill a testable hypothesis to further illuminate its underlying mechanism.

Methods

A systematic review querying four databases (PubMed, Medline, Embase, and Web of Science) was performed to identify studies evaluating hearing loss in patients with SVS and exploring the potential mechanisms of hearing impairment.

Results

A total of 50 articles were eligible and included in this review. After analysis, the retrieved studies could be categorized into four types: (1) 29 studies explore the relationship between hearing loss and the growth pattern of the tumor (e.g., tumor size/volume, growth rate, tumor location, etc.); (2) ten studies investigate the potential role of cochlear dysfunction in hearing deterioration, including structural abnormality, protein elevation in perilymph, and cochlear malfunctioning; (3) two studies looked into SVS-induced impairment of auditory pathway and cortex; (4) in the rest nine studies, researchers explored the molecular mechanism underlying hearing loss in SVS, which involves molecular and genetic alterations, inflammatory response, growth factors, and other tumor-associated secretions.

Conclusions

Multiple factors may contribute to the hearing impairment in SVS, including the growth pattern of tumor, cochlear dysfunction, impairment of auditory pathway and cortex, genetic and molecular changes. However, our current understanding is still limited, and future studies are needed to explore this multifactorial hypothesis and dig deeper into its underlying mechanism.

Error Analysis of Robot-Assisted Orthognathic Surgery

OBJECTIVE

Orthognathic surgery is an effective method to correct the dentomaxillofacial deformities. The aim of the study is to introduce the robot-assisted orthognathic surgery and demonstrate the accuracy and feasibility of robot-assisted osteotomy in transferring the preoperative virtual surgical planning (VSP) into the intraoperative phase.

METHODS

The CMF robot system, a craniomaxillofacial surgical robot system was developed, consisted of a robotic arm with 6 degrees of freedom, a self-developed end-effector, and an optical localizer. The individualized end-effector was installed with reciprocating saw so that it could perform osteotomy. The study included control and experimental groups. In control group, under the guidance of navigation system, surgeon performed the osteotomies on 3 skull models. In experimental group, according to the preoperative VSP, the robot completed the osteotomies on 3 skull models automatically with assistance of navigation. Statistical analysis was carried out to evaluate the accuracy and feasibility of robot-assisted orthognathic surgery and compare the errors between robot-assisted automatic osteotomy and navigation-assisted manual osteotomy.

RESULTS

All the osteotomies were successfully completed. The overall osteotomy error was 1.07 ± 0.19 mm in the control group, and 1.12 ± 0.20 mm in the experimental group. No significant difference in osteotomy errors was found in the robot-assisted osteotomy groups (P = 0.353). There was consistence of errors between robot-assisted automatic osteotomy and navigation-assisted manual osteotomy.

CONCLUSION

In robot-assisted orthognathic surgery, the robot can complete an osteotomy according to the preoperative VSP and transfer a preoperative VSP into the actual surgical operation with good accuracy and feasibility.

Analysis of facial features and prediction of lip position in skeletal class III malocclusion adult patients undergoing surgical-orthodontic treatment

OBJECTIVES

This study presents a retrospective study aimed to analyze the facial features at each stage of surgical-orthodontic treatment for skeletal class III malocclusion, and predict the changes in the lips after treatment.

MATERIALS AND METHODS

There were 49 skeletal class III malocclusion patients treated with bimaxillary surgery and orthodontic treatment enrolled in this study. Lateral cephalograms were obtained before treatment (T0), 1 month before surgery (T1), 1 month after surgery (T2), and after debonding (T3) for cephalometric measurements. After the measurement of the required variables, paired t-test, Pearson's correlation analysis, and multiple linear regression were performed using SPSS 19.0.

RESULTS

The main factors associated with changes in the upper lip included ΔUIE-V, ΔA-V, ΔU1A-V, and ΔL1A-V, and those associated with changes in the lower lip included ΔLIE-V, ΔL1A-V, ΔB-V, ΔPog-V, and Δfacial angle. The predicted regression equation for the horizontal change in the upper lip was represented as ΔUL-vertical reference line (VRL) = 9.430 + 0.779 (ΔUIE-VRL) - 0.542(VULT) (P < 0.05) with a mean error of 1.04 mm; the corresponding equation for the lower lip was ΔLL-VRL = -1.670 + 0.530 (ΔB-VRL) + 0.360 (Ls-E) + 0.393 (ΔLIE-VRL) (P < 0.05), with a mean error of 1.51 mm.

CONCLUSIONS

This study explored the relationship between orthognathic surgery and changes in the lips and obtained the predictive equations of lip position after treatment by using multiple linear regression, which likely offers a reference for prediction of soft tissue changes before surgical-orthodontic treatment in patients with skeletal class III malocclusion.

CLINICAL RELEVANCE

The findings can help dentists to rapidly predict the lip changes after surgical-orthodontic treatment in patients with skeletal class III malocclusion. The study has been registered with the Chinese Clinical Trial Registration (No: ChiCTR1800017694).

First-in-man application of a cold ablation robot guided laser osteotome in midface osteotomies

The aim of the study was to assess the clinical applicability of robot guided laser osteotomy for clinical application. This is the initial report on 14 consecutive patients requiring an orthognathic procedure with a midface osteotomy (no restrictions made on the surgical indication itself) who have undergone surgery by means of the Cold Ablation Laser Osteotome CARLO® (AOT Advanced Osteotomy Tools, Basle, Switzerland), which is an integrated system, functionally comprising: an Er:YAG laser source, intended to perform osteotomies using cold laser ablation, a robot arm that controls the position of the laser source, an optical tracking device that provides a continuous and accurate measurement of the position of the laser source and of reference elements attached to instruments or bones, a navigation system (software) that is able to read preoperatively defined planned osteotomies, and - under the control of a surgeon - performs the planned osteotomies. Safety was assessed by unimpaired postoperative healing and the absence of device related injuries; performance was assessed as ability to cut the maxilla along the preoperatively planned cutting path with a rage of accuracy of 2mm. Cold ablation robot-guided laser osteotomy could successfully be performed in 14 consecutive patients. No intraoperative complications or technical failure occurred. All osteotomies were within an average deviation of 0.80 mm (±0.26 mm) of the virtually preplanned location. The registration procedure to set up the robot at the beginning of the operation required a mean time of 4.6 min (±5.3min). In this report we describe the effective and successful routine use of Cold ablation robot-guided laser osteotomy in an actual clinical setting. It is a promising technical innovation that has the potential to set new standards for accuracy and safety in orthognathic surgery.

Stannous Fluoride Preventive Effect on Enamel Erosion: An In Vitro Study

The aim of this in vitro study was to evaluate the effects of a single dose application of two daily toothpastes on enamel exposed to acid attack. The research was conducted on human molars enamel fragments (n = 72). The two different toothpastes active ingredients were sodium fluoride (NaF) and stannous fluoride (SnF₂). They were compared in protecting the surface of the enamel exposed to three acids: citric acid, lactic acid and hydrochloric acid. A spectrophotometer was used to measure the calcium ions and phosphate released in the solutions by the enamel specimens. Afterward, ionic concentrations were analyzed through the t-Student test, in order to estimate the significance level (p < 0.05) of the solubility differences obtained between the treatment and control groups. Finally, sample surfaces were analyzed with scanning electron microscopy and X-ray energy dispersive spectroscopy (SEM/EDX). The two analyzed toothpastes did not reveal any statistically significant variation in the release of calcium and phosphate (p > 0.05). Nevertheless, acid-resistant deposits were detected in samples treated with stannous fluoride and exposed to lactic acid, though the presence of tin ion deposits on samples treated with stannous fluoride was not shown. A single dose of a fluoride-based toothpaste before different acids attack, in simulated oral cavity conditions, did not show a significant preventive effect.

Efficacy of Operculectomy in the Treatment of 145 Cases with Unerupted Second Molars: A Retrospective Case-Control Study

The aim of this study is to assess whether operculectomy in patients with retained second molars eases spontaneous tooth eruption in respect to untreated controls. Two hundred and twenty-two patients with delayed eruption of at least one second molar were selected from the archives of the Department of Orthodontics, Milan, Italy. Eighty-eight patients, 40 males and 48 females (mean age 14.8 ± 1.3 years), met the inclusion criteria. Records were then divided into case and control groups. The case group consisted of patients that underwent removal of the overlaying mucosa over second molars (i.e., operculectomy) and the control group consisted of subjects who retained their operculum over an unerupted second molar and were followed for one year without performing any treatment. A total of 145 impacted second molars were considered (75 cases, 70 controls). A risk ratio with 95% confidence interval was used to compare the prevalence of eruption in the two groups. Spontaneous eruption occurred in 93.3% of cases in the operculectomy group (70/75), while in the control group, 10% teeth erupted spontaneously (7/70). Spontaneous eruption in the upper arch occurred in 95.2% of cases among treated patients (40 out of 42), while in the lower arch, spontaneous eruption occurred in 90.9% of cases (30 out of 33). Spontaneous eruption of the upper second molars in the control group occurred in 8.5% of cases (3 out of 35), while in the lower arch, it occurred in 8.5% (3 out of 35). Operculectomy can ease the spontaneous eruption of retained second molars and reduce the chances of inclusion.

Correlation between Dental Vestibular-Palatal Inclination and Alveolar Bone Remodeling after Orthodontic Treatment: A CBCT Analysis

The aim of this study was to evaluate the correlation between dental vestibular-palatal inclination changes and the cortical bone remodeling after fixed orthodontic treatment using cone beam computed tomography (CBCT). Twenty-two patients with Angle Class I malocclusion, permanent dentition, and mild to moderate dental crowding were included in the present three-dimensional (3D) analysis. Bone dimensions were evaluated by CBCT scans obtained before and after orthodontic treatment, whereas the torque values were calculated by means of digital models using the 3D VistaDent software. A paired t-test was used to compare the changes between the pretreatment and post-treatment measurements. The correlations between variables were analyzed with linear regression analysis. A significant correlation between torque variations and bone thickness changes was observed for the apical buccal level of the anterior side (P < 0.05). Limited and not significant alveolar bone resorption for the apical thickness of anterior teeth occurred at ± 5 degrees of torque variation, while for tooth inclination exceeding +5 or -5 degrees, the bone remodeling was more evident. The present study demonstrated that anterior region was the most affected area by bone remodeling and that torque variation was highly related to apical bone thickness adaptation for maxillary and mandibular incisors and maxillary canines.

Comparison of a tridimensional cephalometric analysis performed on 3T-MRI compared with CBCT: a pilot study in adults

OBJECTIVE

Since the introduction of cone-beam computed tomography (CBCT) in dentistry, this technology has enabled distortion-free three-dimensional cephalometric analysis for orthodontic and orthognathic surgery diagnosis. However, CBCT is associated with significantly higher radiation exposure than traditional routine bidimensional examinations for orthodontic diagnosis, although low-dose protocols have markedly reduced radiation exposure over time. The objective of this preliminary feasibility study is to compare the accuracy and diagnostic capabilities of an already-validated three-dimensional cephalometric analysis on CBCT to those of an analysis on 3-T magnetic resonance imaging (3T-MRI) to assess whether the latter can deliver a comparable quality of information while avoiding radiation exposure.

MATERIALS AND METHODS

In order to test the feasibility of three-dimensional cephalometry on 3T-MRI, 18 subjects (4 male; 14 female) with mean age 37.8 ± SD 10.2, who had undergone both maxillofacial CBCT and maxillofacial 3T-MRI for various purposes within 1 month, were selected from the archive of the Department of Dentistry and Maxillofacial Surgery of Fondazione Ospedale Policlinico Maggiore, IRCCS, Milano, Italy. A three-dimensional cephalometric analysis composed of ten midsagittal and four bilateral landmarks and 24 measurements (11 angular, 13 linear) was performed on both scans using Mimics Research® v. 17.0 (NV, Technologielaan 15, 3001 Leuven, Belgium). Cephalometric analysis was performed twice by two independent orthodontists for each scan, and each orthodontist repeated the measurements 3 weeks later. Statistical analysis was performed with SPSS® 20.00 for Windows (IBM® Corporation, Sommers, NY, USA). A Bland-Altman test for each cephalometric value was performed to assess the agreement between the procedures. The intraclass correlation coefficient (ICC) was used to assess interobserver and intraobserver reliability. The coefficient of variation was used to evaluate precision.

RESULTS

Both procedures showed good reliability, with mean intraobserver ICCs of 0.977/0.971 for CBCT and 0.881/0.912 for MRI. The average interobserver ICCs were 0.965 for CBCT and 0.833 for MRI. A Bland-Altman analysis for the cephalometric tracing revealed a similar range of agreement between the two modalities; the bias range (mean ± SD) was - 0.25-0.66 mm (0.174 ± 0.31) for distances and - 0.41-0.54° (0.12 ± 0.33) for angles.

CONCLUSIONS

Within the main limitation of this pilot study, that is, the small sample, it is possible to state that cephalometric measurements on 3T-MRI seem to possess adequate reliability and repeatability and that they show satisfying agreement with values measured on CBCTs. An MRI examination does not expose patients to ionizing radiation and could provide an alternative to CBCT for three-dimensional cephalometrics in the future.

Digital dentistry: The new state of the art - Is it disruptive or destructive?

OBJECTIVE

Summarizing the new state of the art of digital dentistry, opens exploration of the type and extent of innovations and technological advances that have impacted - and improved - dentistry. The objective is to describe advances and innovations, the breadth of their impact, disruptions and advantages they produce, and opportunities created for material scientists.

METHODS

On-line data bases, web searches, and discussions with industry experts, clinicians, and dental researchers informed the content. Emphasis for inclusion was on most recent publications along with innovations presented at trade shows, in press releases, and discovered through discussions leading to web searches for new products.

RESULTS

Digital dentistry has caused disruption on many fronts, bringing new techniques, systems, and interactions that have improved dentistry. Innovation has spurred opportunities for material scientists' future research.

SIGNIFICANCE

With disruptions intrinsic in digital dentistry's new state of the art, patient experience has improved. More restoration options are available delivering longer lifetimes, and better esthetics. Fresh approaches are bringing greater efficiency and accuracy, capitalizing on the interest, capabilities, and skills of those involved. New ways for effective and efficient inter-professional and clinician-patient interactions have evolved. Data can be more efficiently mined for forensic and epidemiological uses. Students have fresh ways of learning. New, often unexpected, partnerships have formed bringing further disruption - and novel advantages. Yes, digital dentistry has been disruptive, but the abundance of positive outcomes argues strongly that it has not been destructive.

Current state of the art in the use of augmented reality in dentistry: a systematic review of the literature

Background

The aim of the present systematic review was to screen the literature and to describe current applications of augmented reality.

Materials and methods

The protocol design was structured according to PRISMA-P guidelines and registered in PROSPERO. A review of the following databases was carried out: Medline, Ovid, Embase, Cochrane Library, Google Scholar and the Gray literature. Data was extracted, summarized and collected for qualitative analysis and evaluated for individual risk of bias (R.O.B.) assessment, by two independent examiners. Collected data included: year of publishing, journal with reviewing system and impact factor, study design, sample size, target of the study, hardware(s) and software(s) used or custom developed, primary outcomes, field of interest and quantification of the displacement error and timing measurements, when available. Qualitative evidence synthesis refers to SPIDER.

Results

From a primary research of 17,652 articles, 33 were considered in the review for qualitative synthesis. 16 among selected articles were eligible for quantitative synthesis of heterogenous data, 12 out of 13 judged the precision at least as acceptable, while 3 out of 6 described an increase in operation timing of about 1 h. 60% (n = 20) of selected studies refers to a camera-display augmented reality system while 21% (n = 7) refers to a head-mounted system. The software proposed in the articles were self-developed by 7 authors while the majority proposed commercially available ones. The applications proposed for augmented reality are: Oral and maxillo-facial surgery (OMS) in 21 studies, restorative dentistry in 5 studies, educational purposes in 4 studies and orthodontics in 1 study. The majority of the studies were carried on phantoms (51%) and those on patients were 11 (33%).

Conclusions

On the base of literature the current development is still insufficient for full validation process, however independent sources of customized software for augmented reality seems promising to help routinely procedures, complicate or specific interventions, education and learning. Oral and maxillofacial area is predominant, the results in precision are promising, while timing is still very controversial since some authors describe longer preparation time when using augmented reality up to 60 min while others describe a reduced operating time of 50/100%.

Trial registration

The following systematic review was registered in PROSPERO with RN: CRD42019120058.