Cementum, pulp, periodontal ligament, and bone response after direct injury with orthodontic anchorage screws: a histomorphologic study in an animal model

Dental Pulp Stem Cells and Current in vivo Approaches to Study Dental Pulp Stem Cells in Pulp Injury and Regeneration

Dental pulp stem cells (DPSCs) have garnered significant interest in dental research for their unique characteristics and potential in tooth development and regeneration. While there were many studies to define their stem cell-like characteristics and osteogenic differentiation functions that are considered ideal candidates for regenerating damaged dental pulp tissue, how endogenous DPSCs respond to dental pulp injury and supply new dentin-forming cells has not been extensively investigated in vivo. Here, we review the recent progress in identity, function, and regulation of endogenous DPSCs and their clinical potential for pulp injury and regeneration. In addition, we discuss current advances in new mouse models, imaging techniques, and its practical uses and limitations in the analysis of DPSCs in pulp injury and regeneration in vivo.

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.

Factors Influencing Clinical After Effects of Post Orthognathic Surgery - An Observational Clinical Study

Background:

For maintaining the occlusion, screws to anchor bones are needed to be used in transalveolar manner to get the intermaxillary fixation in participants with no preoperative orthodontic treatment or participants with loose or broken appliances.

Aims:

The present clinical trial was hence aimed to assess the postoperative complications following orthognathic surgical repair of skeletal malocclusion.

Materials and Methods:

Forty-two participants were divided into two groups (n = 22). In Group I, predrill was done to create the holes in transalveolar position before screw insertion. For Group II, self-cutting screws were used without the drills. The radiographs were then taken to assess the associated root injuries. To evaluate the effect of different steroid doses on the pain, nerve healing, and swelling, the participants were divided into three groups (n = 14). Plate removal and associated factors were also evaluated. Collected data were statistically analyzed.

Results:

In Group where no predrill was done, no root injuries were seen. Considerably less facial edema was observed in Group II and III compared to control Group I. This difference was statistically significant with a P value of 0.2057. At 1 week, 3 months, and 6-month postoperatively in Group II and Group III, no significant difference was seen. No significant difference in the postoperative pain between the groups was seen (P = 0.85103). Neurosensory Visual Analog Score measurement revealed no significant difference between three groups at 6 months with the P value of 0.81821.

Conclusion:

The present study concludes that risk for the root injury is possessed by the screws that require predrill, whereas the self-drilling screws had no risk for root injury.

Root repair after damage due to screw insertion for orthodontic miniplate placement

Background

The aim of this investigation was to describe the healing reactions following root damage caused by placement of a miniplate anchorage system.

Material and Methods

In 4 beagle dogs, 4 titanium miniplates (2 self-tapping screws per miniplate) were placed in each maxilla, after drilling of pilot-holes. Six fixation screws were unintentionally inserted damaging the root of maxillary canines. Two weeks later, half of the miniplates were loaded with a coil spring. Two dogs were euthanized 7 weeks after placement of the miniplates, while the remaining two after 29 weeks. Histological sections were prepared, microradiographed, observed under U.V. light, then stained and analysed under ordinary light.

Results

Four screws caused direct root damage; one was damaged during the drilling process; one caused damage to the periodontal ligament only. Among these 6 screws, 2 were mobile and 4 were stable at sacrifice. Limited root damage showed some repair after 29 weeks, consisting in a thick layer of mineralized cementum including anchoring periodontal fibres. Tissue repair was not related to screw stability or loading status.

Conclusions

Limited root damage has shown potential to heal, while extensive root damage has not. Precise position of insertion of the miniplates is thus of utmost importance. Key words:Temporary anchorage devices, animal studies, root resorption.

Healing of root and surrounding periodontium after root damage with miniscrew implants: a histomorphologic study in dogs

OBJECTIVES

The main purpose of this study was to investigate the detailed healing process of the roots and surrounding periodontium [cementum, periodontal ligament (PDL), and bone] at different time points after intentional root damage with miniscrew implants (MSIs).

MATERIALS AND METHODS

After cone-beam computed tomography examination and measurement, a total of 78 premolar and molar roots from five beagle dogs were intentionally damaged by implanting miniscrews in the interradicular region. MSIs were immediately removed, and the histological morphology was observed at days 0 and 3 and at weeks 1, 2, 3, 4, 6, 8, and 12 after root injury using haematoxylin and eosin and fluorescence stainings (fluorescence staining was performed at days 28 and 56).

RESULTS

An early new attachment of PDL adhering on to the damaged root surface was found at week 2 after root injury. Tissue differentiation of newly formed bone tissue, PDL, and cementum began at week 3. Moreover, the newly formed cementum and bone were constantly forming and mineralising at weeks 4, 6, 8, and 12, and the width of PDL gradually narrowed until close to the normal width at week 12.

CONCLUSIONS

This study demonstrated the complete healing process of the roots and surrounding periodontium after root damage with MSIs in dogs when the damage was limited to the cementum or dentin.

CLINICAL RELEVANCE

The findings of this study may help provide a better understanding of the detailed healing process in roots and PDLs damaged by MSIs.

Effects of Low-Level Laser Therapy in Orthodontic Patients on Immediate Inflammatory Response After Mini-Implants Insertion: A Preliminary Report

BACKGROUND

The primary stability of a mini-implant is crucial to treatment sequence since most orthodontic mini-implant failures occur at an early stage. Irritation or inflammation of peri-implant tissues has been related to decreasing mini-implant success.

PURPOSE

This study evaluates the effect of low-level laser therapy on initial inflammation after orthodontic mini-implants installation.

METHODS

Ten volunteers received two mini-implants (1.3 mm diameter, 7 mm length). One mini-implant was inserted on each side of the maxilla following manufacturer recommendation. On the right side, low-level laser therapy (LLLT) was applied (diode laser 660 nm, 40 mW, 1 min, 2.4 J of total energy). Peri-implant crevicular fluid (PGF) was obtained after 24 h (T1), 48 h (T2), and 72 h (T3) to identify levels of interleukin (IL)-6 and IL-8 around mini-implants and around upper first premolars.

RESULTS

An increase in interleukin levels was observed for both groups, compared to upper first premolar. PGF around nonirradiated mini-implants showed higher levels of IL-8. Levels of IL-6 24 h after mini-implant insertion were higher for laser group.

CONCLUSIONS

LLLT modulates the initial inflammation after the insertion of mini-implant, possibly increasing the mini-implant success prognostic and decreasing patient discomfort.

[Vitality loss: influence of orthodontic process]

Vitality loss is an unusual event that can occur before, during or after an orthodontic treatment. It can lead to loss of sensitivity, color change or necrosis of the pulp tissue. Before starting the orthodontic treatment, we have to identify the tooth's risk (injured tooth, included occlusal trauma...). Knowing that, if an endodontic treatment has to be done, it is better to do it before starting orthodontic forces. Lamps do not provide problems except high intensity halogen ones. RPE on children, Le Fort I and mandibular osteotomies, corticotomies, genioplasties are responsible of a transitory ischemia without reaching a pathogen level. Mini-screws or mini-plates may be iatrogenic, if they impact the root. The repair options depend on the delay before removing the miniscrew and the nature of injured tissue.

Dental extrusion with orthodontic miniscrew anchorage: a case report describing a modified method

In recent years, the skeletal anchorage through miniscrews has expanded the treatment options in orthodontics (Yamaguchi et al., 2012). We hereby present a modified method for tooth extrusion for cases where crown-lengthening surgery is contraindicated for aesthetic reasons. This modified method uses three orthodontic appliances: a mini-implant, an orthodontic wire, and a bracket. The aim of this case report was to increase the length of the clinical crown of a fractured tooth (tooth 23) by means of an orthodontic extrusion with the modified method of Roth and Diedrich.

Surgical complications after implant placement

Placement of dental implants in the maxillofacial region is routine and considered safe. However, as with any surgical procedure, complications occur. Many issues that arise at surgery can be traced to the preoperative evaluation of the patient and assessment of the underlying anatomy. In this article, the authors review some common and uncommon complications that can occur during and shortly after implant placement. The emphasis of each section is on the management and prevention of complications that may occur during implant placement.

Unconventional Implant Placement Part III: Implant Placement Encroaching upon Residual Roots - A Report of Six Cases

BACKGROUND

When a residual root is found in the way of a planned implant placement, invasive surgery is usually performed in order to remove it. Consequently, implant therapy is rendered more complex and lengthy.

PURPOSE

We present 6 cases treated according to an unconventional protocol in which invasive surgery was avoided by allowing the implants to encroach upon the residual roots in order to permit a prosthetically driven surgery.

MATERIALS AND METHODS

Six patients were treated with 7 implants placed through a residual root (4 in the mandible and 3 in the maxilla). The residual roots had to be clinically and radiographically asymptomatic and covered by bone or healthy gingiva. The radiographic follow-up ranged from 20 months to 9 years.

RESULTS

Healing was uneventful. Implants were clinically stable, and radiographic examination did not show any unusual feature at the root-implant interface.

CONCLUSION

Several types of new implant-tissue interfaces were created in addition to the classical implant-bone interface, but this did not seem to jeopardize implant integration. Reports of more cases with a longer follow-up are needed before this protocol can be endorsed for routine application. Nonetheless, if confirmed as acceptable, this protocol might open intriguing possibilities; it might also lead to revision of one of the leading concepts in dental implantology.

A study of interleukin 1β levels in peri-miniscrew crevicular fluid (PMCF)

Background

This study provides a vital insight in assessing the clinical and biochemical changes in interleukin (IL)-1β levels in peri-miniscrew crevicular fluid (PMCF) during the course of orthodontic tooth movement.

Methods

The study comprised the analysis of IL-1β in peri-miniscrew crevicular fluid obtained from crevices around the miniscrews inserted in 11 patients (eight females and three males, mean age 17.3 ± 4.64 years) with all first premolar extraction and maximum anchorage requirement using miniscrew-supported anchorage. Miniscrews were loaded at 3 weeks after placement by 200-g nitinol closed coil springs of 9-mm length for en masse retraction. Peri-miniscrew crevicular fluid was collected at miniscrew placement (T1), at 3 weeks (T2/baseline) and on loading at 0 (T3) and 1 day (T4), 21 (T5), 72 (T6), 120 (T7), 180 (T8) and 300 (T9) days. IL-1β levels were estimated by enzyme-linked immunosorbent assay (ELISA). Peri-miniscrew tissue was examined for signs of inflammation, and also, miniscrew mobility was assessed with Periotest and handles of two mouth mirrors.

Results

IL-1β levels in all miniscrews were significantly higher at T1 and peaked again at T4 showing a bimodal peak. However, there was a gradual and statistically significant decrease in IL-1β till T5, while further changes till the end of the study were statistically not significant.

Conclusions

The changing levels of IL-1β levels in PMCF over a duration of 300 days are suggestive of the underlying inflammatory process. IL-1β levels in PMCF show a significant rise during miniscrew insertion and on immediate loading. The trend of gradually reducing IL-1β levels around the miniscrew over the period after loading towards baseline is suggestive of adaptive bone response to stimulus.

Cementum status in natural teeth opposing implant-borne bridgework in Macaca fascicularis

OBJECTIVE

The objective of this study was to investigate the cementum status in natural teeth opposing implant-supported bridgework.

METHODS

Maxillary premolars and molars opposing immediate-loading (IL) and delayed-loading (DL) mandibular implant-supported bridgework in 4 Macaca fascicularis were harvested after 3 months of functional loading. Another 2 monkeys without mandibular fixed prostheses served as control. The cervical (CCW) and apical cementum width (ACW), and resorption craters (RCs) were measured.

RESULTS

No significant differences were observed between test and control groups for mean CCW (control = 26.79 ± 3.28, IL = 21.29 ± 9.12, and DL = 20.32 ± 5.65 μm) and for ACW (control = 937.97 ± 353.74, IL = 955.26 ± 720.05, and DL = 750.56 ± 517.26 μm) (P > .05). In test and control monkeys, RCs were uncommon and showed no significant differences in width (control = 0.71 ± 0.38, IL = 1.02 ± 0.49, DL = 0.85 ± 1.02 mm) and depth (control = 0.15 ± 0.07, IL = 0.25 ± 0.40, DL = 0.22 ± 0.15 mm) (P > .05).

CONCLUSIONS

Present findings suggest that implant-supported bridgework does not produce any adverse effects on the cementum of opposing natural teeth after 3 months of functional loading.

A systematic review of methods for tissue analysis in animal studies on orthodontic mini-implants

Anchorage devices are increasingly used in orthodontics, and their clinical performance is directly dependent on the tissue response to these devices. This study aims to identify assessment parameters for evaluating tissue reactions around orthodontically loaded implants and to propose parameters to be included in a standardized method. Several electronic databases (PubMed, ScienceDirect, the Cochrane database) were explored for papers from January 1999 to December 2009. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement was used as a guideline for the methodology of systematic reviews. Twenty-five publications were selected from 123 potentially relevant abstracts. The selected studies mainly aimed to answer a clinical question and particularly the ability of immediate loading in orthodontics. Very few studies aimed to understand the healing mechanism around the devices leading to a lack of information on this topic. The most frequent combination of assessment methods was clinical evaluation, histology/histomorphometry and intravital bone labeling. Although the dog model is mainly used, pigs represent an interesting animal model, especially when studying devices in growing bone. Despite the extensive use of miniscrews in growing individuals, only few studies have included young subjects in their protocol. Moreover, in such studies, an oral hygiene program is absolutely necessary to avoid complications. Finite element analysis could improve the knowledge of the relationship between design and bone reaction; unfortunately, this elaborated method is complex and impossible to perform routinely. For standardization, the authors recommend to include specific criteria in study protocols when assessing tissue response to orthodontically loaded devices.

Effects of orthodontic tooth movement on alveolar bone density

The object of this study was to evaluate the relationship between changes in the alveolar bone density around the teeth and the direction of tooth movement by using cone-beam computed tomography (CBCT). CBCT was used to measure the bone densities around six maxilla anterior teeth before and after 7 months of orthodontic treatment in eight patients. Each root was divided into three levels (cervical, intermediate, and apical) to determine whether the bone density change varied with the tooth level. Moreover, each level was divided into four regions (palatal, distal, mesial, and buccal sides). Three-dimensional computer models of the maxilla before and after orthodontic treatment were created to detect the direction of tooth movement. The percentage for all 144 samples [8 (patients) × 6 (teeth) × 3 (levels)] in which the side (palatal, distal, mesial, or buccal sides) of maximum bone density reduction (before and after orthodontic treatment) coincided with the direction of tooth movement was calculated; this was referred to as the "coincidence percentage". The bone density around the teeth reduced by 24.3 ± 9.5%. The average coincidence percentage for the eight patients was 59.0%. The coincidence percentages for the eight patients were 62.5%, 62.5%, and 52.1% at the cervical, intermediate, and apical levels, respectively. The obtained results demonstrate that the direction of tooth movement is associated with the side of maximum bone density reduction, and that CBCT is a useful approach for evaluating bone density changes around teeth induced by orthodontic treatment.