Endodontic and Surgical Treatment of Root Damage Caused by Orthodontic Miniscrew Placement

Dental Root Injuries Caused by Osteosynthesis Screws in Orthognathic Surgery-Comparison of Conventional Osteosynthesis and Osteosynthesis by CAD/CAM Drill Guides and Patient-Specific Implants

BACKGROUND/AIM

The primary aim was to evaluate the prevalence and localisation of dental injuries caused by osteosynthesis screws during orthognathic surgery, comparing two different CAD/CAM planning/surgical approaches through retrospective evaluation of post-operative computed tomography.

MATERIAL AND METHODS

This study considered all patients who underwent orthognathic surgery from 2010-2019. The examination for dental root injuries between conventional osteosynthesis (Maxilla conventional cohort) and osteosynthesis with patient-specific implant (Maxilla PSI cohort) was performed by evaluating the post-operative CT scans.

RESULTS

A total of 126 patients were included in the study. Among the 61 patients of the Maxilla conventional cohort, 10 dental root injuries in 8 patients (13.1%) were detected in the post-operative CT scan, representing 1.5% (n = 10/651) of the osteosynthesis screws inserted in proximity of the alveolar crest. No dental injury occurred following osteosynthesis in the 65 patients of the Maxillary PSI cohort (n = 0/773 screws) (p < 0.001). During a mean follow-up period of 13 months after primary surgery, none of the injured teeth showed evidence of periapical alterations and no endodontic treatments were necessary.

CONCLUSIONS

Maxillary positioning using CAD/CAM-fabricated drill/osteotomy guide and osteosynthesis with PSI can significantly reduce the risk for dental injury compared to the conventional procedure. However, the clinical significance of the detected dental injuries was rather minor.

Tooth Complications after Orthodontic Miniscrews Insertion

Orthodontic miniscrews (OM) are widely used in modern orthodontic clinical practice to improve skeletal anchorage and have a high safety profile. A complication at the time of OM insertion is tooth root perforation or periodontal ligament trauma. Rarely, OM injury can cause permanent damage, such as ankylosis, osteosclerosis, and loss of tooth vitality. The aim of this work was to analyze potential risks and dental complications associated with the use of OMs. A search of the PubMed, Cochrane, Web of Science, and Scopus databases was conducted without a time limit using the keywords "orthodontic mini-screw" and "dental damage", resulting in 99 studies. After screening and eligibility, including articles obtained through a citation search, 13 articles were selected. Four studies revealed accidental injuries caused by OM. Most of the damage was localized at the root level and resolved spontaneously with restorative cement formation after prompt removal of the OM, while the pain disappeared. In some cases, irreversible nerve damage, extensive lesions to the dentin-pulp complex, and refractory periapical periodontitis occurred, requiring endodontic and/or surgical treatment. The choice of insertion site was the most important element to be evaluated during the application of OMs.

Revisiting the Complications of Orthodontic Miniscrew

Miniscrew has been used widely as an effective orthodontic anchorage with reliable stationary quality, ease of insertion and removal techniques, immediate or early loading, flexibility in site insertion, less trauma, minimal patient cooperation, and lower price. Nonetheless, it is not free of complications, and they could impact not only the miniscrew success rate but also patients’ oral health. In this article, literature was searched and reviewed electronically as well as manually to evaluate the complications of orthodontic miniscrew. The selected articles are analyzed and subcategorized into complications during and after insertion, under loading, and during and after removal along with treatment if needed according to the time. In addition, the noteworthy associated factors such as the insertion and removal procedures, characteristics of both regional and local anatomic structures, and features of the miniscrew itself that play a significant role in the performance of miniscrews are also discussed based on literature evidence. Clinicians should notice these complications and their related factors to make a proper treatment plan with better outcomes.

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.

Three-dimensional comparative evaluation of customized bone-anchored vs tooth-borne maxillary protraction in patients with skeletal Class III malocclusion

INTRODUCTION

The aim of this prospective study was to assess the 3-dimensional skeletal and dental effects induced by a new maxillary protraction approach using customized miniplates for anchorage compared with a control group of traditional tooth-borne maxillary protraction.

METHODS

Forty-one growing patients at prepubescent stage with skeletal Class III malocclusion participated in this study. These patients were randomly split into 2 groups. In group 1 (n = 20), patients underwent maxillary protraction anchored with customized miniplates. The miniplates were individually designed and inserted using the surgical templates. In group 2 (n = 21), patients underwent tooth-borne maxillary protraction. Pretreatment and posttreatment cone-beam computed tomography scans were obtained, and 30 measurements of cone-beam computed tomography images were acquired and calculated. The changes after treatment and the comparison of the 2 groups were assessed.

RESULTS

After maxillary protraction, group 1 showed a greater forward movement of the maxilla than group 2. The maxilla length increased more in group 1 than in group 2. The rotations of the palatal and mandibular planes in group 1 were less than those in group 2. In group 1, the maxillary incisors proclined less, the mandibular incisors retroclined less, and the maxillary first molars extruded less.

CONCLUSIONS

Compared with tooth-borne maxillary protraction, customized miniplates anchored maxillary protraction produced more maxillary growth, fewer dental changes, and less maxillary and mandibular plane rotation.

Clinical effectiveness of orthodontic miniscrew implantation guided by a novel cone beam CT image-based computer aided design and computer aided manufacturing (CAD-CAM) template

Background

Although miniscrews are widely used in orthodontic treatment as temporary anchorage devices, their correct and safe placement has attracted little attention. This study aimed to introduce a novel cone beam CT (CBCT) image-based computer aided design and computer aided manufacturing (CAD-CAM) template for orthodontic miniscrew implantation and to evaluate the effectiveness of miniscrews implanted under the guidance of this template.

Methods

The CBCT scans of ten patients requiring miniscrews as anchorage were analyzed in NNT software to predetermine the insertion sites of miniscrew implants. The DICOM data of the scans, along with virtual miniscrews acquired in Solidworks software, were imported into Mimics software to construct three-dimensional (3D) images of teeth and bone and to determine the virtual position of miniscrews and 3D virtual templates were designed following consideration of the virtual implantation plans. A STL (Stereolithography) file of the virtual template was output, and the resin template was then fabricated with a stereolithographic appliance (SLA). 24 Miniscrews were then implanted guided by the template and clinical evaluation of their safety and stability, as well as their placement deviations, were made. A dental casts model and cephalometric analysis before and after orthodontic treatment were made to assess the dentomaxillofacial changes.

Results

All 24 miniscrews had no contact with adjacent roots. 18 miniscrews had a grade I safety score and six had a grade II. The miniscrews were stable at 1, 3, 6, and 9 months after implantation, although there was mild inflammation around two miniscrews. Implantation deviation of miniscrew in the crown was (1.03±0.65) and (1.26±0.72) mm in the apex, on average. Satisfactory dentomaxillofacial changes in 10 patients with these 24 miniscrews as anchorage were acquired.

Conclusions

Miniscrews could be implanted in the targeted position safely and precisely when guided by the novel templates, and remained stable during orthodontic treatment. Patients treated with these miniscrews as anchorage in orthodontic treatment acquired satisfactory dentomaxillofacial changes.

Complications reported with the use of orthodontic miniscrews: A systematic review

Objective

The aim of this systematic review was to evaluate the complications and side effects associated with the clinical use of orthodontic miniscrews by systematically reviewing the best available evidence.

Methods

A survey of articles published up to March 2020 investigating the complications associated with miniscrew insertion, in both the maxilla and mandible, was performed using 7 electronic databases. Clinical studies, case reports, and case series reporting complications associated with the use of orthodontic miniscrew implants were included. Two authors independently performed study selection, data extraction, and risk-of-bias assessment.

Results

The database survey yielded 24 articles. The risk-of-bias assessment revealed low methodological quality for the included studies. The most frequent adverse event reported was root injury with an associated periradicular lesion, vitality loss, pink discoloration of the tooth, and transitory loss of pulp sensitivity. Chronic inflammation of the soft tissue surrounding the miniscrew with mucosal overgrowth was also reported. The other adverse events reported were lesion of the buccal mucosa at the insertion site, soft-tissue necrosis, and perforation of the floor of the nasal cavity and maxillary sinus. Adverse events were also reported after miniscrew removal and included secondary bleeding, miniscrew fracture, scars, and exostosis.

Conclusions

These findings highlight the need for clinicians to preliminarily assess generic and specific insertion site complications and side effects.

Failure load and stress analysis of orthodontic miniscrews with different transmucosal collar diameter

Miniscrews have been introduced in orthodontics as temporary anchorage devices (TADs), in order to move the correct teeth and avoid other elements to slide toward a wrong direction. Moreover the ease of use of TADs encouraged clinicians to use miniscrews also for non-conventional purposes, as fixation in mandibular fracture, mini-implant supported temporary pontics, miniscrew-assisted rapid palatal expanders and distalizers. These applications develop higher forces, so TAD fracture can be an unwanted complication. Some authors analyzed torsional loads but no studies measured forces required to bend the screws and ultimate flexural strength. Accordingly, in the present report, Ti-6Al-4V TADs were mechanically evaluated. Seven different diameters of screws were tested: 1.3 mm (Aarhus Screw, Medicon), 1.5 mm (Spider Screw, HDC), 1.6 mm (Aarhus Screw, Medicon), 1.7 mm (Ortho Easy, Forestadent), 1.8 mm (Ortho Implant, 3 M), 1.9 mm (Spider Screw, HDC) and 2.0 mm (Storm, Kristal). The forces to bend the titanium TADs were measured at 0.1 mm, 0.2 mm magnitude of deflections and at maximum load (as peak before screw fracture) in air with a universal testing machine. Statistical analyses were performed. Both at 0.1 mm and at 0.2 mm deflections and at maximum load, the significantly highest forces were reported with 1.7, 1.8, 1.9, and 2.0 mm TADs. The lowest values were reported with 1.6, 1.5, and 1.3 mm mini-implants. No significant differences were reported between 1.6 mm and 1.7 mm screws. It was found that load values in N versus stress in MPa were not fully comparable when screws with small and larger diameter were compared. Therefore, when placing a miniscrew for applications that need maximum shear bending resistance, these results would be considered in order to reduce risk of unwanted fracture.

Incidence of pulp sensibility loss of anterior teeth after paramedian insertion of orthodontic mini-implants in the anterior maxilla

BACKGROUND

The aim of this retrospective investigation was to evaluate the incidence of loss to pulp sensibility testing (PST) of maxillary front teeth after paramedian (3 to 5 mm away from the suture) orthodontic mini-implant (OMI) insertion in the anterior palate.

METHODS

A total of 284 patients (102 males, 182 females; mean age was 14.4 years (±8.8) years at time of OMI-Insertion) with a total of 568 OMIs (1.7 mm diameter, length 8 mm) were retrospectively investigated. A binomial regression analysis was performed to explore covariates, such as age, gender, inclination of upper central incisors, dentition status and insertion position of OMIs that could have contributed to loss of sensibility. Statistical significance was set at p < 0.05.

RESULTS

Loss of response to PST was encountered during retention in 3 out of 284 patients and the respective OMIs had been placed at height of the second rugae (R-2). Affected teeth were a right canine, a left lateral and a left central incisor. Subsequent root canal treatment was successful. Results of the binomial regression analysis revealed that the covariate insertion position (R-2) of OMIs (p = 0.008) had statistically significant influence on loss of response to PST.

CONCLUSIONS

(1) Although there was no radiographic evidence for direct root injury, the proximity of the implants to the anterior teeth was nevertheless statistically related to loss of PST. (2) In all cases of PST loss OMIs were inserted at the second rugae. Therefore OMIs should be placed either more posteriorly, at the third rugae or in the median plane. (3). Loss of PST was not increased for patients with palatal OMI (0.18%) compared to samples without OMI (0.25%).

Miniscrew implant fracture and effects of such retained tip on dentin-pulp complex: a histological report

Miniscrew implants provide an excellent orthodontic anchorage. Besides the clinical benefits, miniscrew implants cause minor discomforts and in certain instances poses problematic complications. Damage to the adjacent tooth structure is the most feared complication of miniscrew implant placement, while fracture of miniscrew implants is the rarest. Miniscrew fracture could occur either during its placement or during its removal. An unusual case report is presented of a miniscrew implant tip fracture following root contact while attempting to remove it. This report highlights the effect of such miniscrew implant fracture on the dentin-pulp complex. The present case is probably the first to give direct histological evidence in humans that a miniscrew fracture or a retained miniscrew implant tip along the dentin/cementum without obvious miniscrew implant penetration could elicit pulp changes. Therefore this case report emphasizes the fact that prior to placing miniscrew implant, clinicians should have acquired proper training and adequate skills in terms of MSI placement and management of fractured MSI.