Design and manufacture of dental-supported surgical guide for genioplasty

Accuracy of the CAD/CAM technique compared with the conventional technique used for stand-alone genioplasty

The benefit of the computer-aided design and manufacturing (CAD/CAM) technique for stand-alone genioplasty remains uncertain and was evaluated in this study. Patients who underwent a conventional genioplasty (n = 20) or genioplasty with the CAD/CAM technique (n = 20), and for whom cephalometry and photogrammetry were performed before and 6 months after surgery, were included. Deviations from predictions of the soft tissue pogonion (Pg'), lip inferior point to aesthetic line (Li-Esth), facial convexity angle (FCA), mentolabial angle (MLA), and ratios of soft to hard tissue movements were calculated. No significant deviation was observed for Pg' in either the conventional group (3.85 ± 4.36 mm; 1.91 ± 1.11 mm) or CAD/CAM group (1.28 ± 1.16 mm; 2.81 ± 3.08 mm), for horizontal and vertical movements, respectively. However, for forward movement, deviation from the prediction of Pg´ in the CAD/CAM group was significantly lower than that in the conventional group (P = 0.015). Deviations of Li-Esth, MLA, and FCA did not differ significantly between the groups. No definite preference for the CAD/CAM technique could be established, because deviations from predictions were not significant in either of the technique groups and lay within the clinically acceptable range.

Guided versus non-guided chin repositioning: a retrospective study on accuracy

Genioplasty is a widely used surgical approach to address chin deformities by performing an osteotomy on the inferior border of the mandible to allow for comprehensive repositioning of the chin. This study aimed to compare the accuracy of freehand chin repositioning with a guided technique that employed specialised surgical guides. For this retrospective study, data from 30 adult patients who underwent orthognathic surgery to correct dentofacial deformities were analysed. All patients underwent virtual planning before surgery, with half of them treated using freehand chin repositioning and the other half using the guided technique. The surgical outcomes were measured and compared with the virtual plan to assess the positional and rotational accuracy of the techniques. In terms of translational assessment, noteworthy values that exceeded clinically acceptable limits were observed only in sagittal movement in the freehand group (0.97 mm, interquartile range (IQR) 0.73-2.29 mm). Regarding rotational accuracy, both groups exhibited an IQR that surpassed acceptable limits for pitch (3.26°, IQR 2.06-5.20 for the guided group and 2.57°, IQR 1.63-4.24° for the freehand group). The Mann-Whitney test indicated no statistical differences between the groups in any translational or rotational assessment. In conclusion, although there was no statistical difference, the guided technique proved effective in achieving clinically acceptable accuracy in all positions and almost all rotations, displaying superior results in sagittal positioning compared with the freehand technique. To fully harness the advantages of guides and to guarantee accuracy in all rotations, we recommend further research involving guides made of more rigid materials, and customised implants.

How Is a Cutting Guide With Additional Anatomical References Better in Fibular-Free Flap Mandibular Reconstruction? A Technical Strategy

BACKGROUND

Computer-assisted surgery is used to design and manufacture cutting guides in mandibular reconstructions with fibula-free flaps. To improve the outcomes of the procedure, the aim of this research was to investigate and compare the accuracy of mandibular reconstruction following the use of 2 versus 3 anatomical reference cutting guides.

METHODS

Eighteen sets of prototype bone models retrieved from an ameloblastoma patient were used for mock operations. The mandibular segmental osteotomies and fibular reconstructions were performed using 2 and 3 anatomical reference cutting guides in vivo surgeries. After reconstruction, the accuracy of the placed reference points was measured by superimposition of computed tomography images.

RESULTS

The error in cutting guides when using 2 or 3 anatomical references showed no significant difference. The fibular and condylar errors of the cutting guide between 2 and 3 anatomical references showed no significant difference in every plate type. The difference in screw hole position errors between 2 and 3 anatomical reference cutting guides was not statistically significant.

CONCLUSIONS

Two anatomical reference cutting guides are sufficient and reasonable enough for mandible resection. However, there were some limitations and errors in our study.

Exploring the distribution of visual attention in genioplasty trainees using eye-tracking technology

PURPOSE

This study aimed to investigate the visual attention of genioplasty trainees using eye-tracking technology, with the goal of providing insights for optimizing genioplasty training strategies.

METHODS

Trainees were recruited for the study, and their visual attention distribution was monitored with an eye-tracking device while they watched a genioplasty procedure video. The percentage of fixation durations dedicated to areas of interest (surgical objects, instruments manipulated by the primary surgeon, and instruments controlled by assistants) were analyzed for each phase of the procedure.

RESULTS

A total of 20 surgical trainees (8 males, 12 females; mean age, 27.8 years; range, 22-35 years) participated in the study. During the soft tissue reflection phase, trainees' percentage fixation durations on instruments controlled by the primary surgeon were higher than on surgical objects, but the difference was not significant (p > 0.05). The percentage fixation durations on instruments controlled by assistants were significantly lower than on those controlled by the primary surgeon or on surgical objects (p < 0.05). In the osteotomy, bone fixation, and suturing phases, the percentage fixation durations on surgical objects were highest, followed by instruments manipulated by the primary surgeon and those controlled by assistants, with significant differences (p < 0.05).

CONCLUSION

Surgical trainees need to invest significant cognitive effort in focusing on the instruments manipulated by the primary surgeon and the surgical objects during the soft tissue reflection phase, as well as on surgical objects during the osteotomy, fixation, and suturing phases. Emphasizing these elements during instruction can help trainees reduce their cognitive load and effectively master genioplasty techniques.

3D designed in-house positioning and cutting guide system for genioplasty surgery. Technical note and case report

Advances in 3D printing technology have the potential to significantly improve the workflow of maxillofacial surgical planning. In-house fabricated custom positioning and cutting guides allow for intraoperative reproduction of pre-planned osteotomy cuts, which can result in greater surgical accuracy and patient safety while maintaining an acceptable cost-effectiveness ratio. The design and creation of the customized surgical guides is performed in our hospital fab lab, which allows time savings, from an average of 10 days to just 24 hours, and a cost reduction of more than 90%. The process begins with the import of the pre-surgical facial CT scan into 3D software that allows to perform the surgical cuts virtually and the manipulation of the segments. Once the virtual planning of the surgery has been performed, the next step is the creation of the cutting and positioning guides. The final step is the printing of the guides in surgical resin and their sterilization. In addition, post-surgical models can be 3D printed to pre-mold the plates on them, which saves surgical time. The mentoplasty surgery is a simple example of how 3D surgery can be applied to maxillofacial surgery in an efficient way obtaining all the advantages of customized surgery with a limited investment in time and resources. Key words:3Dsurgery, customized, personalized medicine, genioplasty, surgical guides, in house.

Application of digital guide plate with drill-hole sharing technique in the mandible reconstruction

Background/purpose

With the development of computer-assisted surgery, digital guide plate was widely used in vascularized bone flap grafts for mandibular reconstruction. The purpose of this study was to design and manufacture a digital guide plate with drill-hole sharing for mandibular reconstruction and assess for surgical accuracy.

Materials and methods

17 patients that required mandibular reconstruction using fibula free flap or iliac crest free flap were included in the study. The computed tomography (CT) data of the patient's mandible and pelvis or fibula were acquired preoperatively. A surgical simulation was then performed using computer-aided surgical simulation (CASS) technology based on above date, which allowed the design of two cutting guide and a repositioning guide for mandibular reconstruction. After surgery, the accuracy of reconstruction was evaluated by superimposing the postoperative image onto the preoperative image of mandible, recording the linear and angular deviation of landmarks, measuring the differences between the planned and actual outcomes.

Results

The osteotomy and repositioning of fibula or iliac crest segments were successfully performed as planned using surgical guides. The digital guide plate with drill-hole sharing showed excellent accuracy, When the iliac crest or the fibula free flap were used for mandibular reconstruction, the largest mean differences between the preoperative and postoperative were 1.11 mm and 2.8° or 1.3 mm and 3.87°.

Conclusion

The digital guide plate with drill-hole sharing designed preoperatively provides a reliable method of for the mandibular reconstruction. This can assist surgeons in accurately performing osteotomy and repositioning fibula or iliac crest segments during the mandibular reconstruction.

Free-Hand versus Surgical Guide Implant Placement

One of the most key areas of dentistry is dental implant surgery. The use of digital equipment and software in dentistry has developed considerably in recent years compared to other fields of medicine. Since examining the advantages and disadvantages of each approach, along with case studies, can help physicians make informed decisions, this review study aims to raise the awareness of dentists to make easier decisions about using guided or free-hand surgery. When planning for a dental implant, one of the most challenging questions that doctors face is which method to use (guided surgery or free-hand). Choosing the right method, such as other clinical considerations, will depend on the individual circumstances of each patient and the preference of the treating physician. Free-hand surgery is a cost-effective method in which the flap is reflected, and, according to the doctor's diagnostic information, an implant is placed, which in many cases is a useful method. Guided surgery has the highest level of accuracy and control, in which osteotomy is designed and printed through a digital surgery guide, and depending on the complexity of the case and the patient's anatomy, it has a higher level of value than free surgery. The surgical guide helps the surgeon make the implant surgery more accurate, safer, simpler, at a lower cost, and in less time. In fact, there are patterns that convey information about the position of the tooth to the dentist before the implant is placed.

Application of digital guide plate based on drill-hole sharing in oral and maxillofacial surgery

OBJECTIVES

This study aimed to investigate the application of digital guide plate based on the drill-hole sharing concept in orthognathic surgery and mandibular reconstruction.

METHODS

Sixteen patients with maxillofacial deformity requiring orthognathic surgery and 10 patients requiring mandibular reconstruction were selected as the research objects. Patients with maxillofacial deformity were scanned by computed tomography (CT), gypsum mold of the maxilla and mandibular arch were scanned using a laser surface scanner, and the fibula or iliac bone of the patients who needed mandibular reconstruction were scanned by CT to create a 3D model. The osteotomy and repositioning guides based on the drill-hole sharing concept were manufactured by digital technology. The guide plate was used to guide osteotomy and reposition the bone segment. Postoperative CT scan was performed. The displacement error of the bone segment was compared between the preoperative virtual surgery and the actual surgery to evaluate the accuracy of the guide plate, by measuring the distance between the landmarks and three reference planes and the distance between the two landmarks.

RESULTS

The wounds healed well in all patients, and no serious complications were observed. The maximum mean values of LeFort Ⅰ osteotomy, genioplasty, fibular reconstruction, and iliac reconstruction were 0.84, 0.64, 1.27, and 1.18 mm, respectively; these values were acceptable by clinical standards.

CONCLUSIONS

The digital guide plate based on the drill-hole sharing concept has high accuracy and clinical application value in orthognathic surgery and mandibular reconstruction.