The Effect of Orthodontic Forces on Calcitonin Gene-related Peptide Expression in Human Dental Pulp

Long-term Outcome of Endodontically Treated Traumatized Immature Upper Incisors

INTRODUCTION

In a growing child, preservation of traumatized immature permanent upper incisors is challenging. This study aimed to evaluate the long-term outcome of endodontically treated traumatized immature upper incisors and associated variables.

METHODS

A total of 183 traumatized immature upper incisors treated with pulpotomy, apexification, or regenerative endodontic procedure (REP), with follow-up between 4 and 15 years, were assessed for presence of pulpal responses or periodontal/bone responses using standardized clinical and radiologic criteria. Logistic regression, including stage of root development, type and complexity of traumatic event, type of endodontic intervention, and history of orthodontic management, were used to estimate impact on tooth survival and occurrence of tissue responses. Study approved by Ethics Committee Research UZ/KU Leuven (S60597).

RESULTS

After a median follow-up of 7.3 years (interquartile range, 6.1-9.2), 159 teeth (86.9%) were still functional. From these teeth, 58 (36.5%) developed tissue responses. This was significantly associated with stage of root development at moment of trauma (root length <¾) and type of endodontic intervention (REP presenting worst outcome). Tooth loss (24 teeth, 13.1%) occurred after a mean time span of 3.2 years (±1.5) and was significantly associated with type and complexity of the traumatic event and type of endodontic intervention, with apexification showing better results than REP (odds ratio, 0.30; 95% confidence interval, 0.11-0.79).

CONCLUSIONS

A large number of endodontically treated traumatized immature teeth could be kept functional. Very immature teeth, teeth with periodontal tissue damage, and teeth treated with REP were at highest risk for an unfavorable outcome.

The interaction between the nervous system and the stomatognathic system: from development to diseases

The crosstalk between the nerve and stomatognathic systems plays a more important role in organismal health than previously appreciated with the presence of emerging concept of the "brain-oral axis". A deeper understanding of the intricate interaction between the nervous system and the stomatognathic system is warranted, considering their significant developmental homology and anatomical proximity, and the more complex innervation of the jawbone compared to other skeletons. In this review, we provide an in-depth look at studies concerning neurodevelopment, craniofacial development, and congenital anomalies that occur when the two systems develop abnormally. It summarizes the cross-regulation between nerves and jawbones and the effects of various states of the jawbone on intrabony nerve distribution. Diseases closely related to both the nervous system and the stomatognathic system are divided into craniofacial diseases caused by neurological illnesses, and neurological diseases caused by an aberrant stomatognathic system. The two-way relationships between common diseases, such as periodontitis and neurodegenerative disorders, and depression and oral diseases were also discussed. This review provides valuable insights into novel strategies for neuro-skeletal tissue engineering and early prevention and treatment of orofacial and neurological diseases.

Effect of orthodontic force on dental pulp histomorphology and tissue factor expression

OBJECTIVES

To evaluate the effects of orthodontic force on histomorphology and tissue factor expression in the dental pulp.

MATERIALS AND METHODS

Two reviewers comprehensively and systematically searched the literature in the following databases: Latin American and Caribbean Health Sciences, Embase, Cochrane, PubMed, Scopus, Web of Science, and Grey literature (Google Scholar, OpenGrey, and ProQuest) up to September 2020. According to the Population, Intervention, Comparison, Outcomes, Studies criteria, randomized clinical trials (RCTs) and observational studies that evaluated the effects of orthodontic force on dental pulp were included. Case series/reports, laboratory-based or animal studies, reviews, and studies that did not investigate the association between orthodontic force and pulpal changes were excluded. Newcastle-Ottawa Scale and Cochrane risk-of-bias tool were used to assess the risk of bias. The overall certainty level was evaluated with the Grading of Recommendations Assessment, Development and Evaluation tool.

RESULTS

26 observational studies and five RCTs were included. A detailed qualitative analysis of articles showed a wide range of samples and applied methodologies concerning impact of orthodontic force on the dental pulp. The application of orthodontic force seems to promote several pulpal histomorphological changes, including tissue architecture, cell pattern, angiogenesis, hard tissue deposition, inflammation, and alteration of the expression levels of 14 tissue factors.

CONCLUSIONS

Although the included articles suggest that orthodontic forces may promote histomorphological changes in the dental pulp, due to the very low-level of evidence obtained, there could be no well-supported conclusion that these effects are actually due to orthodontic movement. Further studies with larger samples and improved methods are needed to support more robust conclusions.

Interval Vibration Reduces Orthodontic Pain Via a Mechanism Involving Down-regulation of TRPV1 and CGRP

BACKGROUND/AIM

The transient receptor potential vanilloid 1 (TRPV1) ion receptor is involved in the release of calcitonin gene-related peptide (CGRP), a major contributor to orthodontic pain. Approaches that attenuate expression of TRPV1 and CGRP may reduce orthodontic pain. We explored the ability of high-frequency interval vibration to reduce orthodontic pain.

MATERIALS AND METHODS

Orthodontic force (50 g) was applied to both maxillary first molars in 8-week-old Wistar rats (n=72). Vibration was applied at 125 Hz for 15 min/day. Duration of face grooming was assessed as a measure of orthodontic pain. Immunofluorescence and western blotting were used to assess TRPV1 and CGRP in the trigeminal ganglia.

RESULTS

Compared to orthodontic force alone, application of vibration significantly decreased the duration of face grooming at 24 h and day 3 and reduced expression of TRPV1 and CGRP at 24 h.

CONCLUSION

Vibration represents a promising mechanical approach to reduce orthodontic pain.

Expression of substance P, calcitonin gene-related peptide and vascular endothelial growth factor in human dental pulp under different clinical stimuli

BACKGROUND

The aim of this study was to measure the dental pulp inflammatory response through neuropeptides (SP and CGRP) as a response to occlusal trauma, orthodontic movements and a combination of both, as well as the angiogenic defense mechanism through VEGF expression, which could be the initial step to mineralized tissue formation.

METHODS

Forty human dental pulp samples were collected from healthy first premolars with extraction indicated due to orthodontic reasons from a sample of 20 patients. Patients were divided into four groups with 10 premolars each (1 mandibular and 1 maxillary premolar from each patient): healthy pulp control group, occlusal trauma group, moderate orthodontic forces group; and occlusal trauma plus moderate orthodontic forces group. Stimuli were applied for 24 h before tooth extraction in all experimental groups. All samples were processed, and SP, CGRP, and VEGF were measured by radioimmunoassay. The Kruskal-Wallis test was performed to assess significant differences among groups and Mann-Whitney's U post hoc pairwise comparisons were also performed.

RESULTS

The highest increase in SP, CGRP, and VEGF expressions was found in the occlusal trauma plus orthodontic forces group, followed by the moderate orthodontic forces, the occlusal trauma and the control groups, with statistically significant differences between all groups for each of the 3 peptides analyzed (Kruskal-Wallis p < 0.001). All possible pairwise post-hoc comparisons were also significant for each peptide analyzed (Mann-Whitney's U p < 0.001).

CONCLUSION

SP, CGRP, and VEGF expressions significantly increase in human dental pulps when stimulated by occlusal trauma combined with moderate orthodontic forces, as compared with these two stimuli applied independently. Name of the registry: Importance of Neurogenic Inflammation in the Angiogenic Response of the Dental Pulp as a Defensive Response.

TRIAL REGISTRATION NUMBER

NCT03804034. Date of registration: 01/15/2019 Retrospectively registered. URL of trial registry record: https://clinicaltrials.gov/ct2/show/NCT03804034?term=NCT03804034&draw=2&rank=1 .

Pulp sensitivity changes during orthodontic treatment at different time periods: a prospective study

Objective

The purpose of this investigation was to recognize pulp sensitivity changes in teeth receiving orthodontic treatment by means of an electric pulp tester (Vitality Scanner Model 2006; Kerr Corporation, Brea CA, USA).

Materials and methods

An electric stimulus response threshold of eight teeth in 22 patients was measured prior to positioning orthodontic attachments, immediately before ligation of a nickel titanium archwire, immediately after ligation of a stainless steel archwire and 9 to 15 months after having achieved the clinical purposes established with the nickel titanium archwires. The first measurement served as baseline.

Results

All teeth responded to an electrical stimulus at all times. No statistical differences were observed between the response thresholds obtained at different treatment times. The mean response threshold of the second measurement showed a decreasing response threshold tendency when compared with those of the baseline measurement. The mean response threshold of the third measurement showed an increasing tendency when compared with those of the baseline measurement. The first maxillary incisor and canine showed the lowest decreasing response threshold after the second measurement and the highest increasing response threshold after the third measurement. Less noticeable, but similar decreasing and increasing response threshold tendencies were observed in all other teeth after the second and third measurements, respectively.

Conclusions

The results obtained in this investigation suggest that pulp sensitivity can be monitored during orthodontic treatment by means of an electric pulp tester.

Clinical relevance

The importance of monitoring the pulp status during orthodontic treatment.

Successful pulp revascularization of an autotransplantated mature premolar with fragile fracture apicoectomy and plasma rich in growth factors: a 3-year follow-up

AIM

This case report demonstrates a positive outcome of the adjuvant use of fragile fracture (FF), which is a technique used to harvest dental pulp stem cells (DPSCs), and platelet-rich plasma (PRP) in a mandibular premolar (tooth 44) with a completely formed root that was transplanted into a surgically created socket and which maintained pulp vitality and function.

SUMMARY

After virtual surgical planning, a 3D tooth replica of tooth 44 was fabricated. A surgical socket was created in the position of tooth 14; then, tooth 44 was extracted and the root dentine was abraded using a turbine diamond bur 3 mm from the apex until a circular groove was prepared around the outer circumference of the root; and then, an FF was performed without damaging the pulp tissue. PRP was placed in the socket, after which the donor tooth was inserted in the recipient area. At 2 weeks post-treatment, orthodontic traction was applied. At 3-year follow-up, the tooth had adequate alignment and was asymptomatic. Response to pulp testing was positive, and the presence of pulp canal obliteration was observed as a sign of pulpal healing.

KEY LEARNING POINTS

Autotransplantation is a good alternative for replacing missing teeth, with repair of tissues and pulp revascularization. Revascularization of an autotransplanted mature tooth using the fragile fracture technique and PRP scaffold is a feasible option and might have positive effects on the long-term outcome of the procedure. Including completely formed teeth as donors in autotransplantation, maintaining vitality and their functions is an option that warrants further study.

Pulp analysis of teeth submitted to different types of forces: a histological study in rats

Objective:

The purpose of this study was to histologically evaluate pulp and dentin under induced tooth movement (ITM) with different types of forces.

Material and Methods:

The maxillary right first molars of rats were submitted to movement with continuous (CF), continuous interrupted (CIF) and intermittent (IF) forces during 5, 7 and 9 days with nickel-titanium (NiTi) closed-coil springs exerting 50cN force magnitude. The groups were histologically evaluated as for cellularity pattern, presence of dystrophic, hemodynamic alterations in the pulp as well dentin alterations. The main observed alterations were related to hemodynamic pulp characteristics, such as presence of thrombosis, vascular congestion and hemorrhages. The hemodynamic alterations were statistically evaluated by Shapiro-Wilk normality test and analysis of variance by the Kruskall-Wallis test.

Results:

There was no significant differences observed between groups in the different types of applied forces and duration of ITM (vascular congestion, p=1.000; hemorrhage, p=0.305; thrombosis, p=1.000).

Conclusions:

Pulp tissue alterations resulting from ITM were limited to hemodynamic events, without progressing to irreversible degeneration, regardless of the type of force applied.

Application of the chronic constriction injury of the partial sciatic nerve model to assess acupuncture analgesia

PURPOSE

To validate and explore the application of a rat model of chronic constriction injury to the partial sciatic nerve in investigation of acupuncture analgesia.

METHODS

Chronic constriction injury of the sciatic nerve (CCI) and chronic constriction injury of the partial sciatic nerve (CCIp) models were generated by ligating either the sciatic nerve trunk or its branches in rats. Both models were evaluated via paw mechanical withdrawal latency (PMWL), paw mechanical withdrawal threshold (PMWT), nociceptive reflex-induced electromyogram (C-fiber reflex EMG), and dorsal root ganglion immunohistochemistry. Electroacupuncture (EA) was performed at GB30 to study the analgesic effects on neuropathic pain and the underlying mechanisms.

RESULTS

Following ligation of the common peroneal and tibial nerves, CCIp rats exhibited hindlimb dysfunction, hind paw shrinkage and lameness, mirroring those of CCI rats (generated by ligating the sciatic nerve trunk). Compared to presurgery measurements, CCIp and CCI modeling significantly decreased the PMWL and PMWT. EA at GB30 increased the PMWL and PMWT in both CCI and CCIp rats. Calcitonin gene-related polypeptide and substance P expressions were apparently increased in both CCI and CCIp groups, but were not different from each other. The C-fiber reflex EMG of the biceps femoris was preserved in CCIp rats, but it could not be recorded in CCI rats on the 5th day after nerve ligation. The C-fiber reflex EMG was reduced at 0, 1, and 2 minutes after EA in CCIp rats, but only at 0 and 1 minute after EA in normal rats.

CONCLUSION

The CCIp model is better than the CCI model for studying acupuncture analgesia on chronic neuropathic pain and the underlying mechanisms.

Orthodontic force application upregulated pain-associated prostaglandin-I2/PGI2-receptor/TRPV1 pathway-related gene expression in rat molars

This study aimed to analyze the mRNA expression and protein localization of prostaglandin I₂ (PGI₂) synthase (PGIS), the PGI₂ receptor (IP receptor) and transient receptor potential cation channel, subfamily V, member 1 (TRPV1) in force-stimulated rat molars, toward the elucidation of the PGI₂-IP receptor-TRPV1 pathway that is in operation in the pulp and possibly associated with orthodontic pain and inflammation. Experimental force was applied to the maxillary first and second molars by inserting an elastic band between them for 6-72 h. PGIS, PTGIR (the IP receptor gene), and TRPV1 mRNA levels in the coronal pulp were analyzed with real-time PCR. PGIS, IP receptor, and TRPV1 proteins were immunostained. The force stimulation induced significant upregulation of PGIS at 6-24 h, and PTGIR and TRPV1 at 6 and 12 h in the pulp. PGIS was immunolocalized in odontoblasts and some fibroblasts in the force-stimulated pulp. The IP receptor and TRPV1 immunoreactivities were detected on odontoblasts and some nerve fibers. It was concluded that PGIS, PTGIR, and TRPV1 in rat molar pulp were significantly upregulated shortly after the force application, and that the IP receptor was co-expressed on TRPV1-expressing nerves and odontoblasts. These findings suggest that the PGI₂-IP receptor-TRPV1 pathway is associated with the acute phase of force-induced pulp changes involving odontoblasts and nerves.

Angiogenic mechanisms of human dental pulp and their relationship with substance P expression in response to occlusal trauma

Angiogenesis is the formation of new blood vessels based on a pre-existing vasculature. It comprises two processes, sprouting of endothelial cells and the division of vessels due to abnormal growth of the microvasculature. It has been demonstrated that substance P (SP) can induce angiogenesis either by modulating endothelial cell growth (direct mechanism) or by attracting cells with angiogenic potential to the injury site (indirect mechanism). Therefore, the purpose of this article is to review the angiogenic mechanisms that regulate mineralized tissue formation in human dental pulp tissue and their relationship with SP expression as a defence response to stimuli such as the masticatory function and occlusal trauma. Articles included in this review were searched in PubMed, Scopus and ISI Web of Science databases, combining the following keywords: human dentine pulp, angiogenesis, angiogenic growth factors, neuropeptides, substance P, neurogenic inflammation, dentine matrix, dentinogenesis, occlusal trauma and dental occlusion. It is concluded that human dental pulp tissue responds to occlusal trauma and masticatory function with a neurogenic inflammatory phenomenon in which SP plays an important role in the direct and indirect mechanisms of angiogenesis by the action evoked via NK1 receptors at different cells, such as fibroblasts, endothelial and inflammatory cells, leading to new blood vessel formation which are needed to stimulate mineralized tissue formation as a defence mechanism.

Influence of orthodontic forces on human dental pulp: a systematic review

AIM

The aim of the present study was to systematically review the influence of orthodontic force on human dental pulp.

METHODS AND RESULTS

The addressed focused question was "Do orthodontic forces affect the human dental pulp?" which was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a specific question was constructed according to the PICO (Participants, Interventions, Control, Outcomes) principle. Databases were explored from 1952 up to and including August 2014 using different combinations of the following keywords: "orthodontic force"; "dental pulp"; "reaction" and "tooth movement". Literature reviews, letters to the editor, commentaries and case-reports were excluded. Thirty studies were included. Six studies assessed the effect of orthodontic forces on pulpal blood flow and 20 studies investigated the pulpal cellular responses to orthodontic forces. In 4 studies, pulpal responses to orthodontic forces were compared between previously traumatized- and non-traumatized teeth.

CONCLUSIONS

There is insufficient scientific validation regarding the association between orthodontic forces and human dental pulp. However, a history of dental trauma maybe considered a risk factor for loss of pulp vitality during orthodontic treatment.

Expression of calcitonin gene-related peptide in rat pulp and periodontal tissues by indirect immunofluorescence method

The aim of this study was to investigate the expression of nerve fibers immunoreactive to calcitonin gene-related peptide (CGRP) in pulp and periodontal tissues of rats. Male Sprague-Dawley rats, aged 6 weeks, were sacrificed, and the jaws were excised, demineralized, and processed for indirect immunofluorescence staining. A considerably higher density of nerve fibers immunoreactive to CGRP was found in the dental pulp and gingiva than in periodontal ligament. The majority of pulpal CGRP immunopositive fibers that were located followed blood vessels parallel to the long axis of the root. A subodontoblastic network of fibers IR to CGRP was found in the coronal pulp in rat molars. In the periodontium, CGRP immunopositive fibers were mainly located in the periapical area and close to the alveolar bone. Gingiva was also well supplied with CGRP-IR nerves.

Transient apical breakdown and its relationship with orthodontic forces: a case report

INTRODUCTION

Transient apical breakdown (TAB) caused by orthodontic treatment is a reversible resorptive process in which the apex of a tooth shows some radiographic evidence of resorption and the crown may display some discoloration. It usually requires no treatment other than monitoring and elimination of the orthodontic forces applied to the tooth.

METHODS

This report describes the case of a 48-year-old man patient who was referred to the department of endodontics for evaluation of some discoloration of his upper right central incisor, which was undergoing orthodontic treatment. The tooth was nonresponsive to sensitivity tests, it was sensitive to percussion, and, radiographically, there was some evidence of root resorption and apical radiolucency.

RESULTS

Because TAB was the suspected cause of the signs and symptoms, no treatment was performed on the tooth except for periodic recalls, and lightening and eventual removal of the orthodontic appliances was indicated.

CONCLUSIONS

Ten weeks after the initial appointment and removal of the applied orthodontic forces, color improvement was observed, accompanied by a return of tooth sensitivity to cold tests.

Bortezomib treatment produces nocifensive behavior and changes in the expression of TRPV1, CGRP, and substance P in the rat DRG, spinal cord, and sciatic nerve

To investigate neurochemical changes associated with bortezomib-induced painful peripheral neuropathy (PN), we examined the effects of a single-dose intravenous administration of bortezomib and a well-established "chronic" schedule in a rat model of bortezomib-induced PN. The TRPV1 channel and sensory neuropeptides CGRP and substance P (SP) were studied in L4-L5 dorsal root ganglia (DRGs), spinal cord, and sciatic nerve. Behavioral measures, performed at the end of the chronic bortezomib treatment, confirmed a reduction of mechanical nociceptive threshold, whereas no difference occurred in thermal withdrawal latency. Western blot analysis showed a relative increase of TRPV1 in DRG and spinal cord after both acute and chronic bortezomib administration. Reverse transcriptase-polymerase chain reaction revealed a decrease of TRPV1 and CGRP mRNA relative levels after chronic treatment. Immunohistochemistry showed that in the DRGs, TRPV1-, CGRP-, and SP-immunoreactive neurons were mostly small- and medium-sized and the proportion of TRPV1- and CGRP-labeled neurons increased after treatment. A bortezomib-induced increase in density of TRPV1- and CGRP-immunoreactive innervation in the dorsal horn was also observed. Our findings show that bortezomib-treatment selectively affects subsets of DRG neurons likely involved in the processing of nociceptive stimuli and that neurochemical changes may contribute to development and persistence of pain in bortezomib-induced PN.

Expression of substance P, calcitonin gene-related peptide, β-endorphin and methionine-enkephalin in human dental pulp tissue after orthodontic intrusion: A pilot study

Objective:

To determine the levels of two sensory neuropeptides (substance P [SP] and calcitonin gene-related peptide [CGRP]) and two endogenous opioids (methionine-enkephalin [Met-Enk] and β-endorphin [β-End]) in dental pulp tissue samples subjected to controlled orthodontic intrusive forces.

Materials and Methods:

Sixteen healthy premolars were selected from eight patients who were undergoing extraction for orthodontic purposes. Eight were randomly used as controls, and the other eight were assigned to an experimental group (controlled orthodontic intrusive forces applied for 24 hours). After this period, teeth were extracted, and pulp samples were obtained. All samples were processed to quantify the expression levels of SP, CGRP, Met-Enk, and β-End using commercial radioimmunoassay kits.

Results:

All samples exhibited basal levels of both neuropeptides and endogenous opioids. After 24 hours of the intrusive stimulus, all patients reported a tolerable discomfort localized at the involved premolar. Only SP was significantly increased (P &lt; .05). For the other molecules, no statistically significant differences were observed (P &gt; .05); however, they expressed important increasing trends.

Conclusions:

The expression levels of SP and CGRP in dental pulp samples from the experimental group support the positive correlation between the symptomatic clinical scenario and increased expression levels of neuropeptides, clarifying the role of neurogenic inflammation in early injury response.

The Amazing Odontoblast

Odontoblasts are dentin-secreting cells that survive for the whole life of a healthy tooth. Once teeth are completely erupted, odontoblasts transform into a mature stage that allows for their functional conservation for decades, while maintaining the capacity for secondary and reactionary dentin secretion. Odontoblasts are also critically involved in the transmission of sensory stimuli from the dentin-pulp complex and in the cellular defense against pathogens. Their longevity is sustained by an elaborate autophagic-lysosomal system that ensures organelle and protein renewal. However, progressive dysfunction of this system, in part caused by lipofuscin accumulation, reduces the fitness of odontoblasts and eventually impairs their dentin maintenance capacity. Here we review the functional activities assumed by mature odontoblasts throughout life. Understanding the biological basis of age-related changes in human odontoblasts is crucial to improving tooth preservation in the elderly.

The effect of single-file reciprocating systems on Substance P and Calcitonin gene-related peptide expression in human periodontal ligament

AIM

To quantify the effect of two single-file reciprocating root canal preparation systems on Substance P (SP) and Calcitonin gene-related peptide (CGRP) expression in healthy human periodontal ligament (PDL).

METHODOLOGY

Forty PDL samples were obtained from healthy premolars where extraction was indicated for orthodontic reasons. Prior to extraction, 20 of these premolars were divided equally in two groups, and then, root canals were prepared using one of two different single-file systems: WaveOne and Reciproc. Ten premolars were prepared with hand files and served as a positive control group. The remaining 10 premolars where extracted without treatment and served as a negative control group. All PDL samples were processed, and SP and CGRP were measured by radioimmunoassay.

RESULTS

Greater SP and CGRP expression were found in the hand instrumentation group (1.220 pmol SP and 0.084 pmol CGRP per mg of PDL), followed by the WaveOne group (0.908 pmol SP and 0.046 pmol CGRP per mg of PDL) and the Reciproc group (0.511 pmol SP and 0.022 pmol CGRP per mg of PDL). The lower SP and CGRP values were associated with the intact control group (0.453 pmol SP and 0.018 pmol CGRP per mg of PDL). The Kruskal-Wallis test revealed significant differences between groups (P < 0.001). Post hoc Tukey HSD tests revealed significant differences in SP and CGRP expression between intact teeth in the control group and all the other groups (P < 0.001) except with the Reciproc group (P = 0.165 and P = 0.42 for SP and CGRP, respectively). Hand instrumentation was associated with significant differences with all the other groups (P < 0.001). Differences between the WaveOne and Reciproc groups were also significant (P < 0.001).

CONCLUSION

Substance P and CGRP expression in PDL cells increased when teeth were prepared with WaveOne as well as with hand instrumentation. Reciproc maintained SP and CGRP levels in line with the negative control group.