Postoperative complications in asthmatic patients following orthognathic surgery: A two-year follow-up study

BACKGROUND

Lack of evidence exists related to the incidence of postoperative complications in asthmatic patients following orthognathic surgery. The present study aimed to assess the incidence and risk factors of postoperative complications in asthmatic patients following orthognathic surgery.

MATERIAL AND METHODS

A retrospective cohort study was conducted which consisted of two groups of patients i.e., asthmatic and systemically healthy patients, who underwent conventional orthognathic surgical procedures (Le Fort I osteotomy, bilateral sagittal split osteotomy, and genioplasty). The recorded postoperative complications in both groups of patients included infection, relapse, altered facial sensation, temporomandibular joint disorder, respiratory complications, and hemorrhage-related events. The association between baseline variables and complications for identifying the possible risk factors was assessed using bivariate analysis and a logistic regression model.

RESULTS

A total of 886 patients underwent orthognathic surgery over a period of 6-years. Following the eligibility criteria, 16 patients were recruited in the asthmatic group and 278 patients were systemically healthy. The most common complications in the asthmatic patients were altered sensation (37.5%) followed by TMJ disorder (25.0%) and relapse (18.8%). These patients were associated with an increased risk of relapse (P = 0.048) compared to healthy patients. Following adjustment of baseline variables, increased risk of relapse was still associated with asthma (odds ratio [OR]. = 4.704, P = 0.027).

CONCLUSION

Asthmatic patients suffer from a significantly higher risk of relapse and need to be closely monitored following orthognathic surgery to ensure a stable outcome. Asthma does not seem to have a significant impact on other postoperative complications.

Influence of systemic comorbidities on the complications of orthognathic surgery: A scoping review

The potential impact of systemic comorbidities has not yet been thoroughly explored in orthognathic surgery. Therefore, the following scoping review was conducted to accumulate evidence on the possible impact of systemic comorbidities on the orthognathic surgery complications. PubMed, Embase, Cochrane, and Web of Science databases were searched up to April 2022 to identify studies about patients with systemic comorbidities who underwent orthognathic surgery. A total of 12,938 articles were screened, and seven articles met the inclusion criteria. Only one study had control group, other six articles had a non-comparative study design. The current evidence suggests a high impact of rheumatic diseases and neuromuscular disorders on the surgery- and patient-related postoperative complications following orthognathic surgery. At the same instance, the findings of the review should be interpreted with caution due to a lack of substantial evidence for extrapolating the findings to a contemporary surgical practice.

Impact of orthognathic surgery on root resorption: A systematic review

OBJECTIVE

This systematic review was performed to assess the potential influence of orthognathic surgery on root resorption (RR).

MATERIAL AND METHODS

An electronic search was conducted using PubMed, Web of Science, Cochrane Central and Embase for articles published up to April 2022. Following inclusion and exclusion criteria, a total of six articles were selected that reported on RR following orthognathic surgery. Risk of bias assessment was performed according to the ROBINS-1 and ROB-2 tools.

RESULTS

The design of five studies was retrospective and one randomized clinical trial was included, with a follow-up period ranging between six months and ten years. The assessment methodologies mostly relied on two-dimensional imaging modalities where only one study used cone-beam computed tomography (CBCT) for objective quantification via linear measurements. The percentage of teeth affected by RR varied between approximately 1 and 36%, where surgically assisted rapid maxillary expansion (SARME) and Le Fort I osteotomy showed the highest percentage of RR followed by bilateral sagittal split osteotomy.

CONCLUSIONS

The present data tend to indicate that specific orthognathic procedures such as SARME and Le Fort I osteotomy may induce or reinforce RR. Yet, considering lack of evidence related to objective quantification of RR following orthodontic and/or orthognathic treatment, further CBCT-based prospective studies are required for an improved understanding of RR following different surgical procedures.

Deep convolutional neural network-based automated segmentation and classification of teeth with orthodontic brackets on cone-beam computed-tomographic images: a validation study

OBJECTIVE

Tooth segmentation and classification from cone-beam computed tomography (CBCT) is a prerequisite for diagnosis and treatment planning in the majority of digital dental workflows. However, an accurate and efficient segmentation of teeth in the presence of metal artefacts still remains a challenge. Therefore, the following study aimed to validate an automated deep convolutional neural network (CNN)-based tool for the segmentation and classification of teeth with orthodontic brackets on CBCT images.

METHODS

A total of 215 CBCT scans (1780 teeth) were retrospectively collected, consisting of pre- and post-operative images of the patients who underwent combined orthodontic and orthognathic surgical treatment. All the scans were acquired with NewTom CBCT device. A complete dentition with orthodontic brackets and high-quality images were included. The dataset were randomly divided into three subsets with random allocation of all 32 tooth classes: training set (140 CBCT scans-400 teeth), validation set (35 CBCT scans-100 teeth), and test set (pre-operative: 25, post-operative: 15 = 40 CBCT scans-1280 teeth). A multiclass CNN-based tool was developed and its performance was assessed for automated segmentation and classification of teeth with brackets by comparison with a ground truth.

RESULTS

The CNN model took 13.7 ± 1.2 s for the segmentation and classification of all the teeth on a single CBCT image. Overall, the segmentation performance was excellent with a high intersection over union (IoU) of 0.99. Anterior teeth showed a significantly lower IoU (P < 0.05) compared to premolar and molar teeth. The dice similarity coefficient score of anterior (0.99 ± 0.02) and premolar teeth (0.99 ± 0.10) in the pre-operative group was comparable to the post-operative group. The classification of teeth to the correct 32 classes had a high recall rate (99.9%) and precision (99%).

CONCLUSIONS

The proposed CNN model outperformed other state-of-the-art algorithms in terms of accuracy and efficiency. It could act as a viable alternative for automatic segmentation and classification of teeth with brackets.

CLINICAL SIGNIFICANCE

The proposed method could simplify the existing digital workflows of orthodontics, orthognathic surgery, restorative dentistry, and dental implantology by offering an accurate and efficient automated segmentation approach to clinicians, hence further enhancing the treatment predictability and outcomes.

Long-term survival of implant-based oral rehabilitation following maxillofacial reconstruction with vascularized bone flap

Aim

The aim of the study was to assess the 5-year cumulative survival rate of implant-based dental rehabilitation following maxillofacial reconstruction with a vascularized bone flap and to investigate the potential risk factors which might influence the survival rate.

Materials and methods

A retrospective cohort study was designed. Inclusion criteria involved 18 years old or above patients with the availability of clinical and radiological data and a minimum follow-up 1 year following implant placement. The cumulative survival rate was analyzed by Kaplan–Meier curves and the influential risk factors were assessed using univariate log-rank tests and multivariable Cox-regression analysis.

Results

151 implants were assessed in 40 patients with a mean age of 56.43 ± 15.28 years at the time of implantation. The mean number of implants placed per patient was 3.8 ± 1.3 with a follow-up period of 50.0 ± 32.0 months. The cumulative survival at 1-, 2- and 5-years was 96%, 87%, and 81%. Patients with systemic diseases (HR = 3.75, 95% CI 1.65–8.52; p = 0.002), irradiated flap (HR = 2.27, 95% CI 1.00–5.17; p = 0.05) and poor oral hygiene (HR = 11.67; 95% CI 4.56–29.88; p < 0.0001) were at a significantly higher risk of implant failure.

Conclusion

The cumulative implant survival rate was highest at 1st year followed by 2nd and 5th year, indicating that the risk of implant failure increased over time. Risk indicators that seem to be detrimental to long-term survival include poor oral hygiene, irradiated flap and systemic diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-022-00413-7.

Three-dimensional quantification of the relationship between the upper first molar and maxillary sinus

Objectives

The present study aims to describe the relationship between upper first molar roots and maxillary sinus, for the first time with a truly three‐dimensional approach.

Methods

From a retrospective cone‐beam computed tomography (CBCT) sample of the upper jaw, a total of 105 upper first molars in contact with maxillary sinus from 74 patients (male 24, female 50, mean age 42) were included in the present study. Segmentation of the upper first molar and maxillary sinus in CBCT was performed utilizing a semiautomatic livewire segmentation tool in MeVisLab v.3.1. The segmentations were analyzed in 3‐matic Medical 20.0 for root volume and the contact area between upper first molar roots and maxillary sinus. Analysis of variance test was applied to detect statistically significant differences between the roots.

Results

The palatal root had the largest contact area with maxillary sinus 27.8 ± 21.4 mm² (20% of the root area) followed by the mesiobuccal 20.5 ± 17.9 mm² (17% of the root area) and distobuccal root 13.7 ± 12 mm² (14% of the root area). A significant difference in the contact area of the different roots of the upper first molar was seen.

Conclusions

This study showed that 70% of the upper first molars were in contact with the maxillary sinus. The palatal root had on average a fifth of its root surface in contact with the sinus, while for mesiobuccal this was a sixth of its root surface and distobuccal roots this was somewhat less. The true 3D relationship could help to better understand maxillary anatomy in relation to occurring pathologies and treatment planning in this area.

3D-printed porous Ti6Al4V scaffolds for long bone repair in animal models: a systematic review

BACKGROUND

Titanium and its alloys have been widely employed for bone tissue repair and implant manufacturing. The rapid development of three-dimensional (3D) printing technology has allowed fabrication of porous titanium scaffolds with controllable microstructures, which is considered to be an effective method for promoting rapid bone formation and decreasing bone absorption. The purpose of this systematic review was to evaluate the osteogenic potential of 3D-printed porous Ti6Al4V (Ti64) scaffold for repairing long bone defects in animal models and to investigate the influential factors that might affect its osteogenic capacity.

METHODS

Electronic literature search was conducted in the following databases: PubMed, Web of Science, and Embase up to September 2021. The SYRCLE's tool and the modified CAMARADES list were used to assess the risk of bias and methodological quality, respectively. Due to heterogeneity of the selected studies in relation to protocol and outcomes evaluated, a meta-analysis could not be performed.

RESULTS

The initial search revealed 5858 studies. Only 46 animal studies were found to be eligible based on the inclusion criteria. Rabbit was the most commonly utilized animal model. A pore size of around 500-600 µm and porosity of 60-70% were found to be the most ideal parameters for designing the Ti64 scaffold, where both dodecahedron and diamond pores optimally promoted osteogenesis. Histological analysis of the scaffold in a rabbit model revealed that the maximum bone area fraction reached 59.3 ± 8.1% at weeks 8-10. Based on micro-CT assessment, the maximum bone volume fraction was found to be 34.0 ± 6.0% at weeks 12.

CONCLUSIONS

Ti64 scaffold might act as a promising medium for providing sufficient mechanical support and a stable environment for new bone formation in long bone defects. Trail registration The study protocol was registered in the PROSPERO database under the number CRD42020194100.

Non-antiresorptive drugs associated with the development of medication-related osteonecrosis of the jaw: a systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review was to provide evidence related to the association between non-antiresorptive medications and MRONJ.

MATERIALS AND METHODS

The following three electronic databases were screened: PubMed, EMBASE, and Web of Science from December 2020 until April 2021. Two reviewers independently performed the study selection, data extraction, and quality assessment of the included studies. The Newcastle-Ottawa Scale (NOS) was used for assessing the risk of bias. A meta-analysis was performed for assessing the relationship between MRONJ and non-antiresorptive medications.

RESULTS

The search strategy retrieved 996 articles. Following removal of duplicates, title, and abstract screening and full-text reading, 58 publications were eligible to be included in the review. A total of 867 cases of MRONJ were included (33% female, 55% male, 12% no gender reported). The mean age of the patients when MRONJ was diagnosed was 61 years (range 19-100 years) and the average time of diagnosis was 10 months following non-antiresorptive drug therapy. Patients with a history of corticosteroids (0.61, 95% CI 0.39, 0.82, p =  < 0.001) and chemotherapy (0.59, 95% CI 0.51, 0.67, p =  < 0.001) showed the highest significant effect size (ED) compared to the control group for MRONJ occurrence.

CONCLUSION

A significant association existed between MRONJ and non-antiresorptive drugs. However, considering limited evidence, findings should be interpreted with caution.

CLINICAL RELEVANCE

The non-antiresorptive drugs might allow the dentist to apply the principle of "drug holiday" following concurrence from the drug prescribing clinician.

PROSPERO REGISTRATION NUMBER

CRD42020173891.

Osseoperception following dental implant treatment: a systematic review

OBJECTIVES

Osseoperception is defined as the ability to perceive tactile sensation via mechanoreception in the peri-implant environment. The objective was to systematically review the available literature on the osseoperception phenomenon following dental implant placement and to explore potential factors which might improve the perception capacity.

MATERIAL AND METHODS

A literature search was performed using PubMed, Cochrane, Embase, and Web of Science databases up to June 2021. Both human and animal studies assessing sensory capacity or innervation following implant placement were included in this review. Two reviewers independently performed the study selection, data extraction and quality assessment of the included studies. The methodological quality of the included papers was assessed using Cochrane risk of bias for human studies and SYRCLE's risk of bias tool for animal studies.

RESULTS

The electronic search of databases yielded 1667 results. Following removal of duplicates, title and abstract screening and full-text reading, 22 publications were eligible to be included in the review. Psychophysical evidence from 14 studies indicated a lower tactile function of implants, where active and passive threshold level were found to be 5 and 50 times higher for implants compared to natural teeth, respectively. The neurophysiological evidence from 3 studies indicated cortical plasticity following dental implant placement, measured via trigeminal nerve evoked potentials and functional magnetic resonance imaging. Histological evidence from 5 studies demonstrated the presence of myelinated nerve fibres in the peri-implant tissues. Additionally, immediate implant placement and loading showed beneficial effect on peri-implant tissue (re)innervation, however, no other biological or physiological factors could be identified influencing osseoperception.

CONCLUSIONS

The reported evidence supported the existence of so-called osseoperception phenomenon for restoring the sensory feedback pathway following oral implant rehabilitation. Further studies are required to identify factors that might further assist physiological integration of the oral implants in the human body as such to approach natural oral function.

A 20-year split-mouth comparative study of two screw-shaped titanium implant systems

PURPOSE

To prospectively assess marginal bone loss and implant survival with Astra Tech (Dentsply Sirona, Charlotte, NC, USA) (group A) and Brånemark (Nobel Biocare, Zurich, Switzerland) (group B) implants in a split-mouth study conducted over a 20-year follow-up period.

MATERIALS AND METHODS

A total of 95 implants (n = 50, group A and n = 45, group B) were randomly placed in the left or right side of the maxilla or mandible in 18 patients. Clinical and radiographic examinations were performed, and results were reported at 5, 10, 15 and 20 years after insertion of the prosthesis.

RESULTS

Ten patients were followed up for 20 years (n = 26 implants, group A and n = 25 implants, group B). No implant loss or prosthetic failures were observed. After 20 years of follow-up, no significant differences in marginal bone loss were found between both implant groups (P = 0.25). The proportion of marginal bone loss ≥ 0.5 mm was not significantly different between implant types (P > 0.05), and no statistically significant relationships were found between marginal bone loss and time (P ≥ 0.05). More specifically, there was no significant difference in marginal bone level between year 20 and baseline in group A (P = 0.70), whereas a difference of 0.5 to 1.0 mm was found in group B (P = 0.15).

CONCLUSIONS

After 20 years of follow-up, marginal bone loss around screw-shaped titanium implants was clinically insignificant. Furthermore, no significant differences in survival and marginal bone loss were found between group A and B implants over the follow-up period.

Integration of imaging modalities in digital dental workflows - possibilities, limitations, and potential future developments

The digital workflow process follows different steps for all dental specialties. However, the main ingredient for the diagnosis, treatment planning and follow-up workflow recipes is the imaging chain. The steps in the imaging chain usually include all or at least some of the following modalities: cone-beam computed tomographic data acquisition, segmentation of the cone-beam computed tomography image, intraoral scanning, facial three-dimensional soft tissue capture and superimposition of all the images for the creation of a virtual augmented model. As a relevant clinical problem, the accumulation of error at each step of the chain might negatively influence the final outcome. For an efficient digital workflow, it is important to be aware of the existing challenges within the imaging chain. Furthermore, artificial intelligence-based strategies need to be integrated in the future to make the workflow more simplified, accurate and efficient.

Long-term dental stability after orthognathic surgery: a systematic review

BACKGROUND

Long-term dental stability is one of the main objectives following combined orthodontic and orthognathic surgical treatment. It is influenced by multiple factors such as surgical, patient-related, and orthodontic aspects. While recent reviews mainly focus on short-term dental changes (0.5-2 years), longer follow-up dental stability remains hardly reviewed.

OBJECTIVES

The aim of this study was to evaluate long-term stability of dental and dentolabial changes following combined orthodontic and orthognathic surgical treatment with a minimum follow-up period of 5 years.

SEARCH METHODS

A systematic search was conducted up to December 2019 using Pubmed, Embase, Web of Science, and Cochrane Central.

SELECTION CRITERIA

Randomized controlled trials (RCTs), prospective and retrospective cohort studies, and case series with a minimum of 10 patients, which reported long-term dental stability following combined orthodontic and orthognathic treatment, were included.

DATA COLLECTION AND ANALYSIS

Long-term changes were assessed for overjet, overbite, maxillary, and mandibular incisors' position and relationship of lip position to maxillary and mandibular incisors. Risk of bias was assessed according to the Cochrane Handbook.

RESULTS

Following the screening of 3178 articles, 11 studies were included (2 RCT, 9 retrospective) with a postoperative follow-up period ranging from 5 to 15 years. A decrease in overjet was observed for patients with skeletal class III malocclusion, whereas overjet increased in class II patients at long-term follow-up. Overbite increased in class II patients, whereas class III showed variable results. The lower incisor position was more stable vertically than horizontally; the latter showing more outcome variability. Dentolabial changes corresponded to the normal ageing process and results were not clinically significant after long-term follow-up.

CONCLUSION

Current evidence suggests variability of dental and dentolabial stability in both skeletal class II and III patients. Further prospective studies are required to develop guidelines for long-term follow-up assessment using computer tomography or cone-beam computed tomography imaging, before final conclusions can be drawn.

REGISTRATION

The protocol for this systematic review (CRD42020133844) was registered in the International Prospective Register of Systematic Reviews (PROSPERO).

Three-dimensional facial hard tissue symmetry in a healthy Caucasian population group: a systematic review

OBJECTIVE

The aim of this study was to quantify the symmetry of the facial hard tissue structures using three-dimensional radiographic imaging modalities in a normal Caucasian population group.

MATERIALS AND METHODS

Electronic literature search was conducted in the following databases: PubMed, Embase, Web of Science, and Cochrane Library up to February 2021. The studies assessing symmetry of facial bones using computed tomography (CT) and cone beam CT were included.

RESULTS

The initial search revealed 8811 studies. Full-text analysis was performed on 33 studies. Only 10 studies were found eligible based on the inclusion criteria. The qualitative analysis revealed that a significant variability existed in relation to the methodologies applied for symmetry quantification.

CONCLUSION

The current review suggested that the overall relative symmetry of the normal Caucasian population group varied depending on the skeletal structure being assessed; however, majority of the observations showed a symmetry within the range of 1 mm without any significant difference between left and right sides.

CLINICAL RELEVANCE

The quantification of facial hard tissue structure symmetry is vital for the diagnosis and treatment planning of orthodontic and/or maxillofacial surgical procedures. Prospero registration number CRD42020169908.

Adherence to Computer-Assisted Surgical Planning in 136 Maxillofacial Reconstructions

Objective

To investigate the adherence to initially planned maxillofacial reconstructions using computer-assisted surgery (CAS) and to identify the influential factors affecting its compliance for maxillofacial reconstruction.

Patients and Methods

A retrospective analysis of 136 computer-assisted maxillofacial reconstructive surgeries was conducted from January 2014 to June 2020. The categorical parameters involved age, gender, disease etiology, disease site, defect size, bone flap segments, and flap type. Apart from descriptive data reporting, categorical data were related by applying the Fisher-exact test, and a p-value below 5% was considered statistically significant (P < 0.05).

Results

The main reasons for partial or non-adherence included unfitness, patient health condition, and other subjective reasons. Out of the total patient population, 118 patients who underwent mandibular reconstruction showed higher CAS compliance (83.9%) compared to the 18 midface reconstruction (72.2%) without any statistically significant difference (p = 0.361). Based on the size of the defect, a significantly higher CAS compliance (p = 0.031) was observed with a minor defect (80.6%) compared to the large-sized ones (74.1%). The bone flaps with two or more segments were significantly (p = 0.003) prone to observe a partial (15.4%) or complete (12.8%) discard of the planned CAS compared to the bone flaps with less than two segments. The malignant tumors showed the lowest CAS compliance when compared to other disorders without any significant difference (p = 0.1).

Conclusion

The maxillofacial reconstructive surgical procedures offered optimal compliance to the initially planned CAS. However, large-sized defects and multiple bone flap segments demonstrated a higher risk of partial or complete abandonment of the CAS.

Impact of the blooming artefact on dental implant dimensions in 13 cone-beam computed tomography devices

BACKGROUND

The purpose of this study was to objectively assess dimensional alteration (blooming artefact) on dental implant using 13 cone-beam computed tomography (CBCT) devices adjusted to device-specific scanning protocols and to assess whether subjective adjustment of brightness and contrast (B&C) could alter its visualization.

METHODS

An anthropomorphic phantom containing a dental implant was scanned in 13 CBCT devices adjusted to three scanning protocols: medium-FOV standard resolution, small-FOV standard resolution, and small-FOV high resolution. The diameter of the implant was measured at five levels, averaged, and compared with those from a reference standard industrial CT image. B&C adjustments were performed and measurements were repeated. The intraclass correlation coefficient assessed the reliability of the measurements and general linear mixed models were applied for multiples comparisons at a 95% confidence interval.

RESULTS

Implant diameter obtained from small-FOV high-resolution protocols in most CBCT devices was not significantly different when compared to that from the reference (p > 0.05). For standard protocols, significant dimensional alteration of the implant ranging from 23 to 34% (0.67 to 1.02 mm) was observed in 9 CBCT devices for small-FOV scanning (p < 0.05), and in 8 CBCT devices for medium-FOV scanning, implant dimensional alteration ranged significantly from 21 to 35% (0.62 to 1.04 mm). After B&C adjustments, dimensional alteration was reduced for several of the CBCT devices tested (p < 0.05).

CONCLUSIONS

The visualization of the implant dimensional alteration differed between CBCT devices and scanning protocols with an increase in diameter ranging from 0.27 to 1.04 mm. For most CBCT devices, B&C adjustments allowed to reduce visualization of implant blooming.

Accuracy of desktop versus professional 3D printers for maxillofacial model production. A systematic review and meta-analysis

OBJECTIVES

The present review systematically analyzed the accuracy of three-dimensional (3D) maxillofacial skeletal models generated from desktop and professional 3D printers.

DATA/SOURCES

Electronic literature search was conducted in the following databases: PubMed, Embase, Web of Science and Cochrane Library up to September 2020. Two reviewers independently performed the study selection, data extraction and quality assessment of the included studies. Risk of bias was assessed using the Joanna Briggs Critical Appraisal Checklist for Diagnostic Test Accuracy.

STUDY SELECTION/RESULTS

The search strategy retrieved 5680 articles. Following removal of duplicates, title and abstract screening and full-text reading, 20 publications were eligible to be included in the review which focused towards the accuracy of skeletal models generated from either desktop or professional printer. Both types of printers were defined based on their cost, size and layer thickness, where desktop printers cost between $1500-$7000, have a build size of 10×10×10 inches or less and a minimum layer thickness of 100 µm. Whereas, the professional printers cost was between $20,000- $200,000 with a build size of 12×12×12 inches or more and a layer thickness of as less as 3 µm. The risk of bias was found to be low to moderate. Meta-analysis results indicated no significant absolute mean difference (AMD) (p = 0.9487) between desktop (0.12 mm, 95% CI: 0.00-0.27 mm) and professional printers (0.10 mm, 95% CI: 0.04-0.16 mm). Amongst the printing technology, material jetting (0.09 mm, 95% CI: 0.00-0.17 mm) and selective laser sintering (0.09 mm, 95% CI: 0.00-0.26 mm) offered the lowest AMD and the highest difference was observed with the fused deposition modeling (0.22 mm, 95% CI: 0.00-0.53 mm).

CONCLUSIONS

The maxillofacial skeletal models generated from desktop printers offered comparable accuracy to that acquired with professional printers.

CLINICAL SIGNIFICANCE

The desktop 3D printers may be a viable option to print maxillofacial skeletal models for surgical planning, simulation, guide manufacturing and education purposes.

Automatic segmentation of the pharyngeal airway space with convolutional neural network

OBJECTIVES

This study proposed and investigated the performance of a deep learning based three-dimensional (3D) convolutional neural network (CNN) model for automatic segmentation of the pharyngeal airway space (PAS).

METHODS

A dataset of 103 computed tomography (CT) and cone-beam CT (CBCT) scans was acquired from an orthognathic surgery patients database. The acquisition devices consisted of 1 CT (128-slice multi-slice spiral CT, Siemens Somatom Definition Flash, Siemens AG, Erlangen, Germany) and 2 CBCT devices (Promax 3D Max, Planmeca, Helsinki, Finland and Newtom VGi evo, Cefla, Imola, Italy) with different scanning parameters. A 3D CNN-based model (3D U-Net) was built for automatic segmentation of the PAS. The complete CT/CBCT dataset was split into three sets, training set (n = 48) for training the model based on the ground-truth observer-based manual segmentation, test set (n = 25) for getting the final performance of the model and validation set (n = 30) for evaluating the model's performance versus observer-based segmentation.

RESULTS

The CNN model was able to identify the segmented region with optimal precision (0.97±0.01) and recall (0.96±0.03). The maximal difference between the automatic segmentation and ground truth based on 95% hausdorff distance score was 0.98±0.74mm. The dice score of 0.97±0.02 confirmed the high similarity of the segmented region to the ground truth. The Intersection over union (IoU) metric was also found to be high (0.93±0.03). Based on the acquisition devices, Newtom VGi evo CBCT showed improved performance compared to the Promax 3D Max and CT device.

CONCLUSION

The proposed 3D U-Net model offered an accurate and time-efficient method for the segmentation of PAS from CT/CBCT images.

CLINICAL SIGNIFICANCE

The proposed method can allow clinicians to accurately and efficiently diagnose, plan treatment and follow-up patients with dento-skeletal deformities and obstructive sleep apnea which might influence the upper airway space, thereby further improving patient care.

Computer-assisted versus traditional freehand technique for mandibular reconstruction with free vascularized fibular flap: A matched-pair study

OBJECTIVES

This study aimed to perform a surgery-related and patient-related outcome analysis of a case-matched series of patients treated with computer-assisted surgery (CAS) and traditional freehand surgery.

METHODS

A total of 153 patients who underwent mandibular reconstruction by VFF were included from Jan 1999 to Dec 2019. The mandibular resection and reconstruction were performed by four experienced oral and maxillofacial surgeons. Reasons for reconstruction were oncologic, osteoradionecrosis, trauma, and osteoporosis. All the patients were followed up postoperatively for at least 1 year. Eighteen pairs were formed with the matched cohort consisting of a total of 36 patients who underwent primary mandibular reconstruction without additional combined flaps. The surgery-related and patient-related continuous and categorical parameters were assessed in both groups.

RESULTS

The average operation time and bleeding volume in the CAS group were less than those in the non-CAS group. Additionally, both hospitalization and ICU days were lower in the CAS group without any significant difference. The only significant finding related to surgical parameters was observed for the ischemia time, which was lower in the CAS group.

CONCLUSIONS

Computer-assisted surgery indicated improved efficiency considering reduced ischemia time, operation time, and length of hospital stay with lower early complications than that of conventional surgical procedures. It can thus be considered as an optimized alternative to the freehand approach.

Three-dimensional evaluation of distal and proximal segment skeletal relapse following isolated mandibular advancement surgery in 100 consecutive patients: A one-year follow-up study

The aim of this study was to perform a three-dimensional evaluation of the skeletal relapse of the proximal and distal mandibular segments following isolated bilateral sagittal split osteotomy advancement surgery. One hundred consecutive patients (mean age 25.8±11.7 years), comprising 65 female patients (mean age 26.4±12.1 years) and 35 male patients (mean age 24.6±11.0 years) requiring mandibular advancement without genioplasty, were enrolled prospectively in the study. Cone beam computed tomography scans were acquired for each patient at three time-points: preoperatively, immediately (1-6 weeks) after surgery, and 1 year after surgery. A validated tool was utilized to assess the surgical movement and relapse. Based on percentage, the majority of the distal and proximal translational and rotational movements relapsed within the range of ≤2mm and ≤2°. The distal segment revealed a significant relapse in a posterior, inferior, and clockwise pitch direction. Both left and right proximal segments showed a significant translational relapse in the medial, posterior, and superior direction. Amongst the rotational parameters, proximal segments relapsed significantly in clockwise pitch, clockwise roll, and counterclockwise yaw direction. Overall, both distal and proximal bone segments showed a clinically acceptable translational and rotational stability. The proximal segments torqued towards their original position with a reduction of flaring.

Donor- and recipient-site morbidity of vascularized fibular and iliac flaps for mandibular reconstruction: A systematic review and meta-analysis

The aim of this article is to evaluate the early and late morbidities of the donor- and recipient-site in patients undergoing mandibular reconstruction using either vascularized fibular flap (VFF) or vascularized iliac flap (VIF). Electronic databases, including PubMed, Web of Science, Cochrane Central and Embase, were explored for literature published until October 2020. A total of twenty-four articles reporting complications following mandibular reconstruction surgery with follow-up periods ranging from six to 63 months were selected based on the exclusion criteria. For each research, the JBI Critical Assessment Tool and the ROBINS-I Tool were used to analyze the methodological quality and the risk of bias. A single-arm meta-analysis was performed to have a synthesized analysis of the donor- and recipient-site early and late morbidities. Results showed that the early morbidities in VFF group ranged from 3% to 12%, and the late morbidities in VFF group ranged from 5% to 67%. In VIF group, the early morbidities ranged from 3% to 16%, and the donor-site late morbidities ranged from 6% to 43%. Complications with the top three morbidities in the VFF group were: chronic sensory disturbances at the donor-site (67%), malocclusion (22%) and chronic lower limb weakness (20%); and in the VIF group were: chronic sensory disturbances at the donor-site (43%), chronic pain at the donor-site (26%), chronic gait disturbance (20%). Further controlled clinical trials are needed to assess the long-term outcome of VFF or VIF grafting.

Three-dimensional design of a geometric model for an ocular prosthesis in ex vivo anophthalmic socket models

PURPOSE

Fitting a customized ocular prosthesis for anophthalmic patients entails an artisanal labour-exhausting process and is standardly based on impression moulding of the socket, which may be anatomically inaccurate. The objective of the study was to design an impression-free socket mould with three-dimensional (3D) technology.

METHODS

The ex vivo anophthalmic socket models included one silicone, one fresh pig cadaver head and three fresh-frozen human cadaver heads. After intra-socket application with iodine substance, five observers obtained eighteen low-dose cone beam computed tomography (CBCT) scans and one observer one high-dose CBCT scan of each model. The observers designed non-impression 3D moulds of the socket with 3D software. For the human cadaver sockets 3D geometric models of the ocular prosthesis were rendered from the 3D mould of the socket and the mirrored cornea of the contralateral eye.

RESULTS

The posterior surface of the 3D mould was highly accurate, with a mean absolute deviation of 0.28 mm, 0.53 mm, 0.37 mm and mean upper deviation of 0.53 mm, 0.86 mm, 1.17 mm, respectively, for the phantom, pig and human model. The intra- and interobserver repeatability and reproducibility of the 3D moulds and designs was good (<0.35 mm). The largest variation in the 3D geometric model was found at the junction of the 3D mould and mirrored cornea.

CONCLUSION

3D design of an impression-free geometric model for an ocular prosthesis with low-dose CBCT is highly accurate in ex vivo anophthalmic socket models. This novel method is a critical step towards the manufacturing of 3D printed ocular prostheses and requires validation in anophthalmic patients.

Effect of platelet-rich and platelet-poor plasma on 3D bone-to-implant contact: a preclinical micro-CT study

BACKGROUND

Bone-to-implant contact ratio (BIC%) plays a critical role in secondary stability of osseointegrated dental implants. The aim of this study was to identify the correlation of 2D/3D micro-CT images with histology as a gold standard for evaluating BIC% and to investigate the influence of the platelet-rich plasma (PRP) and platelet-poor plasma (PPP) on 3D BIC% following delayed implant placement with delayed loading (DIP+DL).

METHODS

Nine beagle dogs were recruited. Following bilateral extraction of mandibular 3rd premolar, 4th premolar, and 1st molar, 54 screw-type titanium implants were inserted and randomly divided into one control and two test groups based on a split-mouth design. The control group involved DIP+DL (n = 18) and both test groups included DIP+DL with local application of PRP (n = 18) and PPP (n = 18). A BIC analysis was performed utilizing 2D histomorphometry and 2D/3D micro-CT. Following identification of correlation between histology and 2D/3D micro-CT images, a 3D micro-CT assessment of the 3D BIC% at three follow-up time-points (1, 3, and 6 months) was carried out for observing the influence of PRP and PPP on BIC.

RESULTS

The 2D micro-CT BIC% values revealed a strong positive correlation with histology (r = 0.98, p < 0.001) and a moderate correlation existed with 3D micro-CT (r = 0. 67, p = 0.005). BIC levels at 1 month and combined influence of PPP and PRP irrespective of time-points revealed significantly higher 3D BIC% compared to the control. However, a reduction in 3D BIC% was observed at the 3rd and 6th month. No significant difference was observed between both PRP and PPP.

CONCLUSIONS

Both 2D and 3D micro-CT demonstrated a potential to be utilized as a complimentary method for assessing BIC compared to the histological gold standard. Overall, both PRP and PPP significantly facilitated bone healing and osseointegration with a higher 3D BIC at follow-up. However, their influence was reduced as the observation period was increased.

Diagnostic accuracy of CBCT versus intraoral imaging for assessment of peri-implant bone defects

Background

Early detection of marginal bone loss is vital for treatment planning and prognosis of teeth and implant. This study was conducted to assess diagnostic accuracy of CBCT compared to intra-oral (IO) radiography for detection, classification, and measurement of peri-implant bone defects in an animal model.

Methods

Fifty-four mandible blocks with implants were harvested from nine male health adult beagle dogs with acquisition of IO, CBCT and micro-CT images from all samples. Peri-implant bone defects from 16 samples were diagnosed using micro-CT and classified into 3 defect categories: dehiscence (n = 5), infrabony defect (n = 3) and crater-like defect (n = 8). Following training and calibration of the observers, they asked to detect location (mesial, distal, buccal, lingual) and shape of the defect (dehiscence, horizontal defect, vertical defect, carter-like defect) utilizing both IO and CBCT images. Both observers assessed defect depth and width on IO, CBCT and micro-CT images at each side of peri-implant bone defect via CT-analyzer software. Data were analyzed using SPSS software and a p value of < 0.05 was considered as statistically significant.

Results

Overall, there was a high diagnostic accuracy for detection of bone defects with CBCT images (sensitivity: 100%/100%), while IO images showed a reduction in accuracy (sensitivity: 69%/63%). Similarly, diagnostic accuracy for defect classification was significantly higher for CBCT, whereas IO images were unable to correctly identify vestibular dehiscence, with incorrect assessment of half of the infrabony defects. For accuracy of measuring defect depth and width, a higher correlation was observed between CBCT and gold standard micro-CT (r = 0.91, 95% CI 0.86–0.94), whereas a lower correlation was seen for IO images (r = 0.82, 95% CI 0.67–0.91).

Conclusions

The diagnostic accuracy and reliability of CBCT was found to be superior to IO imaging for the detection, classification, and measurement of peri-implant bone defects. The application of CBCT adds substantial information related to the peri-implant bone defect diagnosis and decision-making which cannot be achieved with conventional IO imaging.

Long-term stability of isolated advancement genioplasty, and influence of associated risk factors: A systematic review

The aim of this review was to investigate the skeletal and soft tissue stability of isolated advancement genioplasty after more than 1 year, and to observe the influence of associated risk factors. A literature search was performed on PubMed, Web of Science, Embase, ScienceDirect, and Cochrane. Only studies with at least 10 patients who underwent an isolated advancement genioplasty, and with a follow-up period of at least 1 year, were included. Of the 2224 records initially identified, eight articles met the eligibility criteria. The mean age of the total study population was 23 years and ranged from 19.1 to 26.5 years in the individual studies. The average surgical advancement at pogonion was 8.2 mm and ranged from 6.2 to 11.7 mm in the individual studies. After 1 year, the horizontal hard tissue relapse at the level of pogonion varied from 0.1 to 2.1 mm. In two studies, this was reported as statistically significant. Regarding the soft tissue, the horizontal relapse varied from 0.3 to 2.9 mm, which was also considered statistically significant in two studies. Isolated advancement genioplasty was found to be a predictable and stable orthognathic procedure in the sagittal plane at both soft and hard tissue levels. The amount of relapse was not associated with the fixation method or with the amount of surgical advancement.