Virtual Surgical Planning and Three-Dimensional Printing to Aid the Anatomical Reduction of an Old Malunited Fracture of the Mandible.

ABSTRACT: Mandible fracture is a common injury in maxillofacial surgery. It causes not only maxillofacial dysfunction but also facial deformities. Malunited fractures of the mandible have been a vast challenge in clinical treatment due to the misalignment of the broken ends and the occurrence of occlusal disorders. This case report describes using virtual surgical planning and three-dimensional printing to treat a patient with malunited fracture of the mandible. Failing to perform mandibular surgery due to severe brain trauma after the car accident, the patient got malunited healing of mandible. The authors applied virtual surgical planning to perform preoperative analysis and surgical design on this patient, three-dimensional printing to fabricate occlusal plate, and models of the preoperative and postoperative mandible to guide the operation. Finally, the authors achieved the reduction and reconstruction of the mandible with satisfactory clinical results.

Evaluation of Bone Height and Bone Mineral Density Using Cone Beam Computed Tomography After Secondary Bone Graft in Alveolar Cleft.

The purpose of this study was to assess the optimal timing of subsequent dental implant placement and orthodontics after alveolar bone grafting (ABG) in patients with unilateral complete clefts of the alveolar process. Iliac bone graft surgery was performed on 60 patients. Bone mineral density (BMD) and height of the ABG areas were assessed using cone beam computed tomography at 3 and 6 months postoperatively. The heights of the labial and palatal bone graft areas were classified using the modified Bergland classification. The study found that there was no change in BMD between 3 months (mean ±â€ŠSD: 406.51 ±â€Š71.28 Hounsfield units [HU]) and 6 months (409.53 ±â€Š46.37 HU; P = 0.381). Significant changes in the distribution of bone height classifications were observed in the labial and palatal sides of the ABG between 3 and 6 months (P = 0.025 for labial bone height, P = 0.008 for palatal bone height). These results indicate that the alveolar density remained stable between 3 and 6 months, whereas bone height level declined during that period after ABG, the latter indicating bone graft absorption over time. It is, therefore, suggested that subsequent orthodontic or dental implants be placed 3 months after ABG rather than at 6 months or later.

Periodontal health and oral hygiene of children with orofacial clefts in Eastern China.

To comparatively assess the periodontal condition and oral hygiene of children and adolescents at different ages presenting with different types of orofacial clefts (OFCs). A total of 1608 patients aged 6-18 years who had not previously undergone periodontal treatment were enrolled in this study. Participants were categorized into two age groups: 6-12 years (Group I) and 13-18 years (Group II). Participants in both age groups were further classified into one of the three OFC-type subgroups: cleft lip only (without or with alveolar cleft), cleft lip and cleft palate, and cleft palate only. Periodontal health was determined by evaluating plaque formation and gingival status with reference to the Silness and Loe plaque index (PI), Loe gingival index (GI), and community periodontal index (CPI). Periodontal health and oral hygiene were not significantly different between Groups I and II for cleft type (p > 0.05). A significant difference was not observed in PI for cleft type among the groups (p > 0.05). In Group II, GI and CPI were significantly higher than in Group I (p < 0.05). According to our results, cleft type does not influence periodontal health of children and adolescents with OFCs. Age, however, influences periodontal diseases' prevalence and severity.

CA1 Modulates the Osteogenic Differentiation of Dental Follicle Stem Cells by Activating the BMP Signaling Pathway In Vitro.

BACKGROUND: Carbonic anhydrase 1 (CA1) has been found to be involved in osteogenesis and osteoclast in various human diseases, but the molecular mechanisms are not completely understood. In this study, we aim to use siRNA and lentivirus to reduce or increase the expression of CA1 in Dental follicle stem cells (DFSCs), in order to further elucidate the role and mechanism of CA1 in osteogenesis, and provide better osteogenic growth factors and stem cell selection for the application of bone tissue engineering in alveolar bone fracture transplantation. METHODS: The study used RNA interference and lentiviral vectors to manipulate the expression of the CA1 gene in DFSCs during in vitro osteogenic induction. The expression of osteogenic marker genes was evaluated and changes in CA1, alkaline phosphatase (ALP), Runt-related transcription factor 2 (RUNX2), and Bone morphogenetic proteins (BMP2) were measured using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting (WB). The osteogenic effect was assessed through Alizarin Red staining. RESULTS: The mRNA and protein expression levels of CA1, ALP, RUNX2, and BMP2 decreased distinctly in the si-CA1 group than other groups (p < 0.05). In the Lentivirus-CA1 (LV-CA1) group, the mRNA and protein expressions of CA1, ALP, RUNX2, and BMP2 were amplified to varying degrees than other groups (p < 0.05). Apart from CA1, BMP2 (43.01%) and ALP (36.69%) showed significant upregulation (p < 0.05). Alizarin red staining indicated that the LV-CA1 group produced more calcified nodules than other groups, with a higher optical density (p < 0.05), and the osteogenic effect was superior. CONCLUSIONS: CA1 can impact osteogenic differentiation via BMP related signaling pathways, positioning itself upstream in osteogenic signaling pathways, and closely linked to osteoblast calcification and ossification processes.

Comparative study of stress characteristics around the adjacent teeth tissues during insertion of mini-screws with different insertion angles: A three-dimensional finite element study.

With a limited alveolar bone position, there is a high risk that mini-screws (MS) implants could cause damage to the adjacent teeth. To reduce this damage, the position and tilt angle of the MS must be optimized. The aim of this study was to assess the effect of MS implantation angle on the stress exerted on adjacent periodontal membrane and roots. A three-dimensional finite element model containing dentition, periodontal ligament, jaw and MS were established based on the CBCT images and MS scanning data. The MS was first inserted perpendicular to the surface of the bone at specific locations and then tilted at an angle of 10° and 20° to the mesial and distal teeth, respectively. The stress distribution in the periodontal tissue of the adjacent teeth was analyzed after MS implantation at different angles.The stress on the adjacent tooth root and periodontal ligament was most uniformly distributed when the MS was inserted vertically. It changed 9.4-97.7% when the axis of MS was tilted at 10-degree and 20-degree angles from the point of vertical insertion. The stresses experienced by the periodontal ligament and the root are similar. When the horizontal angle of the MS insertion was changed, the MS was closer to the adjacent tooth, resulting in greater stress near the PDL and root. It was recommended to insert the MS vertically into the alveolar bone surface to avoid root damage due to excessive stress.

Effect of a digital guide on the positional accuracy of intermaxillary fixation screw implantation in orthognathic surgery.

BACKGROUND: Intermaxillary fixation screw (IMFS) implantation is a common procedure in orthognathic surgery (OGS) performed to the temporary maxillary-mandibular fixation and stable bite relationships. The study aims to assess the accuracy of IMFS implantation with a digital guide to reduce the occurrence of root damage. METHODS: This prospective study involved 40 patients undergoing OGS at the Affiliated Hospital of Qingdao University from August 2017 to May 2021. The patients were randomly divided into two groups according to whether the IMFS implantation was with or without digital guide (20 patients in the experimental group and 20 controls). The digital guides used in the experimental group were designed according to a virtual implantation plan and printed using stereolithography. In the control group, IMFSs were directly implanted by a surgeon based on clinical experience. Postoperatively, cone-beam computed tomography was performed to compare root proximity of IMFSs between the two groups and verify the accuracy of IMFS placement. RESULTS: In the experimental group, there was no case of root damage, the incidence of the periodontal ligament (PDL) injured was 22.1%, and 77.9% IMFSs were placed without contacting adjacent anatomic structures. In the control group, the incidence of root damage had been up to 20.8%, 31.7% IMFSs injured the PDL, and only 47.5% IMFSs were placed between the roots (P < 0.001). CONCLUSION: IMFSs can be placed more accurately with surgical guides, reducing the incidence of root and PDL damages.