Is the Resorption External or Internal?

Forensic exploration of endodontic cements: Unveiling macroscopic and radiographic changes under high temperatures

OBJECTIVE

To evaluate macroscopically and radiographically the behavior of four endodontic sealers submitted to high temperatures, with forensic purposes.

METHODS

Sixty-four lower anterior teeth were included. All teeth were endodontically treated, and simulation of external cervical resorption (ECR) was performed. Half of the sample was filled with AH-Plus™ cement and had ECR sealed with Bio-C-Repair™. The other 32 teeth were filled with Bio-C-Sealer™ cement and had their respective ECR sealed with MTA-Repair™. Then, all teeth were introduced into a bovine bone block to simulate the alveolar bone. The teeth were submitted to incineration at temperatures of 600, 800, 1000, and 1140 °C. All teeth were radiographed before and after incineration. The pre-and post-incineration radiopacity of cements and dentin were evaluated using the ImageJ™ software and compared using a t-test for paired samples.

RESULTS

It was possible to confirm color change and appearance of cracks in the tissues and dental materials tested, varying according to the temperature. Radiographically, it was observed that the dental crowns completely detached at 1000 ° and 1140 °C, and, only at 1140 °C, the roots showed cracks. Regarding the radiopacity, there was a significant difference in the shades of gray in AH-Plus™ when subjected to 1000 ° and 1140 °C, and at 600 ° and 1000 °C in Bio-C-Sealer™. In Bio-C-Repair™ and MTA-Repair™, a difference was observed at 600 ° and 1140 °C.

CONCLUSIONS

There were macroscopic and radiographic alterations of the materials. This data is important in Forensic Dentistry and may contribute to identifying carbonized victims.

Pathogenesis of non-infection related inflammatory root resorption in permanent teeth: A narrative review

BACKGROUND

The mechanism of action of root resorption in a permanent tooth can be classified as infection-related (e.g., microbial infection) or non-infection-related (e.g., sterile damage). Infection induced root resorption occurs due to bacterial invasion. Non-infection-related root resorption stimulates the immune system through a different mechanism.

OBJECTIVES

The aim of this narrative review is to describe the pathophysiologic process of non-infection-related inflammatory processes involved in root resorption of permanent teeth.

METHODS

A literature search on root resorption was conducted using Scopus (PubMed and Medline) and Google Scholar databases to highlight the pathophysiology of bone and root resorption in non-infection-related situations. The search included key words covering the relevant category. It included in vitro and in vivo studies, systematic reviews, case series, reviews, and textbooks in English. Conference proceedings, lectures and letters to the editor were excluded.

RESULTS

Three types of root resorption are related to the non-infection mechanism of action, which includes surface resorption due to either trauma or excessive orthodontic forces, external replacement resorption and external cervical resorption. The triggers are usually damage associated molecular patterns and hypoxia conditions. During this phase macrophages and clastic cells act to eliminate the damaged tissue and bone, eventually enabling root resorption and bone repair as part of wound healing.

DISCUSSION

The resorption of the root occurs during the inflammatory phase of wound healing. In this phase, damaged tissues are recognized by macrophages and neutrophiles that secrete interlaukines such as TNF-α, IL-1, IL-6, IL-8. Together with the hypoxia condition that accelarates the secretion of growth factors, the repair of the damaged perioduntiom, including damaged bone, is initiated. If the precementum and cementoblast are injured, root resorption can occur.

CONCLUSIONS

Wound healing exhibits different patterns of action that involves immune stimulation in a bio-physiological activity, that occurs in the proper sequence, with overlapping phases. Two pathologic conditions, DAMPs and hypoxia, can activate the immune cells including clastic cells, eliminating damaged tissue and bone. Under certain conditions, root resorption occurs as a side effect.

Multiple idiopathic cervical root resorption: A systematic review

The current literature on multiple idiopathic cervical root resorption (MICRR), a rare and aggressive form of external root resorption, is limited to case reports and series. Therefore, we performed a systematic review of this condition. A comprehensive search of PubMed, Embase, Web of science, Cochrane Library, CNKI, and WANFANG was conducted using key terms relevant to MICRR, supplemented by a grey literature search. Risk of bias was assessed using Cochrane's and Joanna Briggs Institute's tools. A total of 36 studies with 47 cases were included. MICRR is more common among younger females and may be related to hormonal changes and denosumab use. Initially, the premolars are usually affected but all permanent teeth may eventually be involved. Cone-beam computed tomography is recommended for diagnosis and assessment of resorptive lesions. The management is focused on complete removal and restoration of the resorptive tissue to maintain the tooth's structural integrity. However, MICRR usually has a poor prognosis. Due to its invasive and aggressive behavior, MICRR requires greater attention.

Periodontal Fibroblasts-Macrophage Crosstalk in External Inflammatory Root Resorption

INTRODUCTION

This study aimed to understand the influence of periodontal fibroblasts (PDLFs) on clastic differentiation of macrophages (Mφ) in different resorptive environments.

METHODS

PDLF-Mφ direct coculture (juxtacrine) was seeded on dentin, cementum, and polystyrene with/without lipopolysaccharide, macrophage colony-stimulating factor, and receptor activator of nuclear factor kappa beta ligand for 7 and 14 days and stained for tartrate-resistant acid phosphatase (TRAP) activity. PDLF-Mφ cocultured on polystyrene were immunostained for CD80, CD206, NFATc1, STAT6, and periostin, and cell culture supernatants were assessed for cytokines on days 2 and 7. Mφ grown in conditioned media of PDLFs (paracrine) and Mφ monoculture were used as controls. Data was analyzed using Student t test and one-way analysis of variance with the Tukey multiple comparisons test (P < .05).

RESULTS

PDLF-Mφ coculture showed a higher number of TRAP-positive multinucleated cells than Mφ monoculture on dentin and polystyrene. No TRAP-positive multinucleated cells were observed in paracrine and cementum. The expression of CD80 and CD206 in PDLF-Mφ was similar at day 2, whereas CD206 was greater than CD80 at day 7. The expression of STAT6 was greater than NFATc1 at both days 2 and 7 (P < .05). Periostin expression in the presence of the lipopolysaccharide, macrophage colony-stimulating factor, and receptor activator of nuclear factor kappa beta ligand combination was down-regulated in PDLF monoculture, whereas it was up-regulated in PDLF-Mφ coculture. The cytokine profile of PDLF-Mφ on day 2 was predominated by interleukin (IL)-1β, tumor necrosis factor alpha, and MMP9 and MMP2 on day 7. IL-6 and IL-8 showed steady expression at both days 2 and 7.

CONCLUSIONS

The study highlights the juxtacrine effect of PDLFs on the clastic differentiation of Mφ with a difference in clastic activity between dentin and cementum. The study also emphasizes the temporal effect of tumor necrosis factor alpha, MMP2, MMP9, and IL-1β on intercellular crosstalk in resorptive environments.

Farklı tamir materyalleriyle tedavisi yapılan eksternal servikal kök rezorbsiyonuna sahip dişlerin kırılma dayanımlarının değerlendirilmesi: Bir in vitro çalışma

Amaç: Bu in vitro çalışmanın amacı; farklı tamir materyalleri (MTA Angelus, RetroMTA, Biodentin) ile tedavi edilen eksternal servikal kök rezorpsiyonuna sahip dişlerin kırılma dayanımını değerlendirmektir. Gereç ve Yöntem: Bu çalışmada tek köklü 75 adet üst çene santral insan dişi kullanıldı. 15 örnek, hiçbir işlem yapılmadan pozitif kontrol grubu olarak ayrıldı. Kalan 60 örnekte simüle eksternal servikal rezorpsiyon defektleri oluşturuldu. Bu dişlerin bukkal yüzeyinin servikal üçlüsünde, mine sement sınırının hemen altında 2 mm derinliğinde, 2 mm uzunluk ve 4 mm genişliğinde rezorpsiyon kaviteleri su soğutması altında elmas frez kullanılarak hazırlandı. Dişler farklı tamir materyalleri ile tedavileri yapılmak üzere 4 gruba ayrıldı(n=15). Negatif kontrol grubu herhangi bir materyal ile doldurulmadan boş bırakıldı. Diğer 3 grup MTA Angelus, RetroMTA ve Biodentin ile üretici firmanın talimatları doğrultusunda hazırlanarak kaviteye yerleştirildi. Tüm numuneler 14 gün boyunca 37°C'de ve % 95 bağıl nemde bir inkübatörde tutulduktan sonra akril bloklara gömüldü. Dişlerin kırılma direnci, universal test cihazı kullanılarak Newton cinsinden ölçüldü. Veriler,tek yönlü anova ve post hoc tukey testi ile %5 anlamlılık düzeyinde analiz edildi (p≤0.05). Bulgular: Biodentin, RetroMTA ve MTA Angelus grupları arasında istatistiksel olarak anlamlı bir fark bulunamamıştır. Kullanılan tamir materyallerinin kırılma dayanımı değerleri negatif kontrol grubundan anlamlı derecede yüksek, pozitif kontrol grubundan anlamlı derecede düşük bulunmuştur. Sonuç: Yapılan bu çalışmayla ECR’a sahip dişlerin kırılma dayanımının azaldığı tespit edildi. Bununla birlikte; bu defektler MTA, Biodentin ve RetroMTA ile tamir edildiğinde dişlerin kırılmaya daha dayanıklı hale geldiği bulundu.

Impact of orthognathic surgery on root resorption: A systematic review

OBJECTIVE

This systematic review was performed to assess the potential influence of orthognathic surgery on root resorption (RR).

MATERIAL AND METHODS

An electronic search was conducted using PubMed, Web of Science, Cochrane Central and Embase for articles published up to April 2022. Following inclusion and exclusion criteria, a total of six articles were selected that reported on RR following orthognathic surgery. Risk of bias assessment was performed according to the ROBINS-1 and ROB-2 tools.

RESULTS

The design of five studies was retrospective and one randomized clinical trial was included, with a follow-up period ranging between six months and ten years. The assessment methodologies mostly relied on two-dimensional imaging modalities where only one study used cone-beam computed tomography (CBCT) for objective quantification via linear measurements. The percentage of teeth affected by RR varied between approximately 1 and 36%, where surgically assisted rapid maxillary expansion (SARME) and Le Fort I osteotomy showed the highest percentage of RR followed by bilateral sagittal split osteotomy.

CONCLUSIONS

The present data tend to indicate that specific orthognathic procedures such as SARME and Le Fort I osteotomy may induce or reinforce RR. Yet, considering lack of evidence related to objective quantification of RR following orthodontic and/or orthognathic treatment, further CBCT-based prospective studies are required for an improved understanding of RR following different surgical procedures.

Tooth root resorption: A review

Tooth root resorption is multifactorial, leading to progressive destruction and eventual loss of tooth root dentin and cement. There are internal and external types of root resorption, each having its variety. The etiology and pathogenesis of tooth root resorption are poorly understood, and the most significant etiological factors are trauma, pulpal infection, tooth bleaching, and orthodontic treatment. Tooth root resorption is primarily asymptomatic; thus, it is revealed accidentally by radiographic examination. Progressive clinical manifestations are pain, tooth discoloration, tooth mobility, and other conditions. Awareness of the causes and risk factors allowing tooth root resorption, and regular radiographic examination, in case of necessity, make it possible to reveal resorption at an early stage and to prevent its further development. Thus, the aim of this study is to present etiopathogenesis, a clinical course, and diagnostic peculiarities of internal and external types of tooth root resorption, enabling practicing dentists to timely diagnose root resorption and take appropriate measures to avoid further complications. Within the limitation of this review, even though the etiopathogenesis of tooth root resorption is yet not fully understood, it is suggested that the etiological factors fall into two groups (endogenic and exogenic) to enhance further understanding of the possible causes and mechanisms of root resorption and allow practitioners to monitor high-risk patients and make timely diagnoses. Moreover, radiographic examination and CBCT are indispensable for the diagnosis of root resorption.

Tooth resorption-Part 2: A clinical classification

Tooth resorption is either a physiological or a pathological process resulting in loss of dentin and/or cementum. It may also be associated with bone loss. Currently there is no universal classification for the different types of tooth resorption. This lack of a universal classification leads to both confusion amongst practitioners and poor understanding of the resorptive processes occurring in teeth which can result in incorrect/inappropriate diagnoses and mis‐management. When developing a classification of diseases and/or conditions that occur within the body, several criteria should be followed to ensure a useful classification. The classification should not only include pathological conditions but also physiological conditions. Since tooth resorption can be either pathological or physiological, a classification of tooth resorption should include both of these categories. Any classification of diseases should be possible to use clinically, meaningful, useful, clear and universal. It should enable easy storage, retrieval and analysis of health information for evidenced‐based decision‐making. It should also be possible to share and compare data and information between different institutions, settings and countries. A classification of tooth resorption should be developed by combining anatomical, physiological and pathological approaches. For some types of resorption, the aetiological approach should also be incorporated. A classification of tooth resorption that uses simple, relevant and appropriate terminology based on the nature and location of the resorptive process occurring in teeth is proposed. There are two broad categories of internal and external tooth resorption which are sub‐divided into three types of internal tooth resorption (surface, inflammatory, replacement) and eight types of external tooth resorption (surface, inflammatory, replacement, invasive, pressure, orthodontic, physiological, idiopathic). The clinician's understanding, diagnosis and management of tooth resorption can be facilitated by using this simple classification which should ideally be used universally by the entire dental profession to ensure clarity and to avoid confusion.

Tooth Resorption - Part 1: The evolvement, rationales and controversies of tooth resorption

In 1966, Andreasen and Hjørting‐Hansen were the first to describe a relationship between tooth resorption and dental trauma. However, Andreasen's original classification did not include other resorptive processes which have since been identified. Numerous articles have been published suggesting new terminology and definitions for tooth resorption. A uniform language with universally accepted terminology is crucial to eliminate the multiplicity of terms and definitions which only cause confusion within the profession. An electronic literature search was carried out in the PubMed database using the following keywords for articles published in English: “root resorption,” “inflammatory root resorption,” “replacement resorption,” “cervical resorption,” “trauma,” “ankylosis,” “surface resorption,” and “internal resorption.” The search also included textbooks and glossaries that may not have surfaced in the online search. This was done to identify articles related to tooth resorption and its etiology in dentistry. The aim of this review was to present the history that has led to the variety of terms and definitions for resorption. This review emphasizes the need for a clearer, simpler, and more comprehensive nomenclature for the various types of tooth resorption which are presented in Part 2 of this series.

Ectopic Eye Tooth Management: Photobiomodulation/Low-Level Laser Emission Role in Root Resorption after Fixed Orthodontic Treatment

Aim: This study evaluates the role of low-level laser emission/photobiomodulation (LE/P) in quantitative measurements of root resorption (QRR). The application of LE/P performed after each orthodontic activation with four types of treatment intervention (TI) on the root resorption (RR) after fixed orthodontic treatment (FOT) of the upper arch with ectopic eye tooth/teeth [EET] was investigated. Materials and Methods: Thirty-two orthodontic patients scheduled for FOT were selected and assigned to the four groups. These were LE/P + Self ligating bracket (SLB), LE/P + Conventional bracket (CB), non-photobiomodulation (non-LE/P) + SLB and non-LE/P + CB. Standard management stages of FOT were followed in the maxilla. Each patient received a single application of LE/P labially/buccally and palatally, a total of five different points were used during each activation or appointment. The main outcome measure was QRR in maxillary anteriors before and after FOT, assessed via cone-beam computed tomography (CBCT) using 3D OnDemand software. Results: Insignificant QRR was found between before and after FOT in SLB, CLB, and LE/P, non-LE/P groups (p > 0.05). QRR in the SLB vs. CB and LE/P vs. non-LE/P group was significantly different in 11, 13, and 23 (p < 0.05). QRR in the LE/P + SLB group (p < 0.05) was significantly different in 11, 13, and 23 than that in the other groups. The most severe QRR was found on 13 (0.88 ± 0.28 mm and 0.87 ± 0.27 mm) and 23 (1.19 ± 0.14 mm and 1.16±0.13 mm) in the CB and non-LE/P group (p < 0.001). LE/P + SLB showed a highly significant superior outcome (p < 0.001) in relation to non-LE/P + CB, the QRR of 23 were 0.813 ± 0.114 mm and 1.156 ± 0.166 mm, respectively. Conclusion: Significantly higher amounts of QRR were found in EET patients after FOT treated with the CB, non-LE/P, and non-LE/P + CB system and warrant further investigation to explore potential specific causes.

Irrigant flow characteristics in the root canal with internal root resorption: a computational fluid dynamics evaluation

Irrigation dynamics of syringe irrigation with different needle designs (side-vented, double side-vented, notched) and ultrasonic irrigation in the root canal with internal root resorption were evaluated using a computational fluid dynamics model. A micro-CT scanned mandibular premolar was used for modeling internal root resorption. The needles and the ultrasonic tip were positioned at 2, 4, and 5 mm from the working length. The insertion depth and the irrigation model were found influential on the shear stress and the irrigant extension. The extension of the irrigant increased toward 2-5 mm from the working length. Ultrasonic irrigation revealed the highest shear stress values regardless of the insertion depth. The shear stress distribution on the resorption cavity walls gradually increased when the needles were positioned coronally. The residence time of the irrigant in the canal was affected by the needle position relative to the internal root resorption cavity and the needle type.

[External cervical tooth root resorption]

External cervical tooth root resorption is one of the most aggressive types of pathological resorption. Due to the uncontrolled growth of resorptive tissue, irreversible loss of dentin and cement occurs. To date, there is no common position regarding the etiological factor and pathogenesis of invasive cervical resorption. The histological picture is similar to some fibro-bone lesions. The treatment outcome of the pathology is difficult to predict because elimination of the causative factor is often not sufficient for resorption arrest. Only the complete elimination of resorptive tissue helps to stop the process. The report describes a clinical case of a successful treatment of invasive cervical resorption of dental hard tissues.

Bone turnover markers in gingival crevicular fluid and blood serum of patients with fixed orthodontic appliances

AIM

Bone remodelling can be followed through the bone turnover markers (BTMs). Aim of the present study was to record the fluctuation of an osteoclastic and an osteoblastic BTM [C-terminal telopeptide of type I collagen (CTX) and N-terminal pro-peptide of type I pro-collagen (PINP), respectively] in both the gingival crevicular fluid (GCF) and the serum of orthodontic patients before and after the initial application of orthodontic forces.

MATERIALS AND METHODS

Twenty-one Caucasian patients were prospectively evaluated. GCF and blood samples were collected in order to measure the selected biomarkers by ELISA at three time-points: exactly before, 5 days, and 14 days after bonding of the appliances. Standardized sample handling and patient preparation procedures were adopted in order to reduce pre-analytical variability.

RESULTS

GCF and serum CTX levels were found to be independent of age, although higher in the serum of female subjects. PINP levels were found higher in the serum of patients ≥25 years old, as well as in the GCF of males. A positive correlation between serum and GCF baseline PINP levels was observed.

LIMITATIONS

The effect of orthodontic treatment on bone remodelling might not be absolutely representative of the local bone microenvironment as the levels of the specific BTMs where measured within the GCF of the lower front teeth.

CONCLUSIONS

This is the first time PINP and CTX have been evaluated in the GCF and serum of orthodontic patients with fixed appliances. No statistically significant alterations of CTX and PINP levels in the GCF and the serum of patients were recorded over time during the initial stages of orthodontic treatment.

Present status and future directions: Endodontic management of traumatic injuries to permanent teeth

The prognosis of traumatized teeth depends largely on the fate of the pulp and its treatment. This review aims to update the present status on the endodontic management of traumatic injuries to permanent teeth and to identify relevant research areas that could contribute to an improvement in diagnosis and treatment of traumatized permanent teeth. Future research should pay greater attention to (1) diagnostic methods to assess the perfusion of the pulp and enhance detection of tooth cracks and initial signs of root resorption; (2) improved materials for vital pulp treatment; (3) studies focusing on type and duration of splinting after root fractures; (4) antiresorptive intracanal medication in case of posttraumatic pulp necrosis and infection-related resorption and (5) long-term data on the apical barrier technique compared to revitalization.

Effect of Passive Ultrasonic Irrigation over Organic Tissue of Simulated Internal Root Resorption

This study aimed to evaluate the efficacy of passive ultrasonic irrigation (PUI) on dissolving the organic tissue inside simulated internal root resorption (IRR) using sodium hypochlorite (NaOCl) or chlorhexidine (CHX). A total of 40 human lower premolars were collected based on dimensional and morphological similarities. The roots were embedded in cylinders (3 cm diameter; 2.5 cm height) of self-cured acrylic resin, and then an IRR was simulated. The specimens were divided into 4 groups (n = 10) according to irrigation protocols: group 1: CHX + PUI; group 2: CHX; group 3: NaOCl + PUI; group 4: NaOCl. The total irrigation time was 150 s at a flow rate of 5 mL/min. A tissue mass of porcine palatine mucosa was used to simulate the organic tissue, it was weighed before and after the irrigation using an analytic balance, and the difference between both readings was calculated and transferred to percentage values. Data were submitted to statistical analysis using two-way ANOVA (factors: irrigant type and with/without PUI) and Tukey's test for multiple comparisons among the experimental groups (α = 0.05). There was a significant difference in both factors (irrigant: p=0.04; PUI: p ≤ 0.001). The groups that used PUI were more effective in dissolving the organic tissue of the IRR simulation than the groups without PUI. PUI is more effective than the syringe and needle irrigation in organic tissue dissolution.

Survey based assessment of diagnosis through periapical radiograph and CBCT and treatment of root resorption with Brazilian and American dentists and endodontists

Background

This study assesses and compares the knowledge level of endodontists (ENDs) and general dental practitioners (GPs) from Brazil and United States of America (USA) in the diagnosis and treatment of internal and external inflammatory root resorptions through periapical radiographic (PA) and cone beam computed tomography (CBCT) examinations.

Material and Methods

A cross-sectional online questionnaire-based survey was presented to the volunteers containing questions regarding personal and professional profile, as well as three clinical cases of internal and external inflammatory root resorption. A series of multiple-choice questions about the diagnosis and treatment options were surveyed. The data collected was analysed by the Chi-square test with Yates correction with a significance level of 5 %.

Results

Most answers were considered adequate when all three questions about the diagnosis and all two questions relating to the treatment were answered accurately. A total of 374 dentists answered the survey (n: 229 from Brazil vs. 145 from USA) being 41% END and 59% GP. END presented higher level of knowledge than GP regarding to diagnosis and treatment of inflammatory root resorptions both in Brazil and USA (p<0.05); USA presented higher level of adequate responses than Brazil (p<0.05).

Conclusions

END achieved a level of knowledge of the diagnosis and treatment of root resorption superior to the GP. Comparing the results obtained in both countries, it was observed that the USA had a higher correct response rate than Brazil. Key words:Internal root resorption, external root resorption, management, diagnosis, treatment.

Runx1/miR-26a/Jagged1 signaling axis controls osteoclastogenesis and alleviates orthodontically induced inflammatory root resorption

BACKGROUND

MicroRNAs (miRNAs) are involved in the regulation of osteoclast biology and several pathogenic progression. This study aimed to identify the role of miR-26a in osteoclastogenesis and orthodontically induced inflammatory root resorption(OIIRR).

METHODS

Rat orthodontic tooth movement (OTM) model was established by ligating a closed coil spring between maxillary first molar and incisor, and 50 g orthodontic force was applied to move upper first molar to middle for 7 days. Human periodontal ligament (hPDL) cells were isolated from periodontium of healthy donors, and then subjected to compression force (CF) for 24 h to mimic an in vitro OTM model. The levels of associated factors in vivo and in vitro were measured subsequently.

RESULT

The distance of tooth movement was increased and root resorption pits were occurred in rat OTM model. The expression of miR-26a was decreased in vivo and vitro experiments. CF treatment enhanced the secretion of inflammatory factors receptor activator of nuclear factor-kappa B ligand (RANKL) and IL-6, osteoclast marker levels, and the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts, while miR-26a overexpression reversed these results. Furthermore, miR-26a overexpression inhibited the osteoclastogenesis and rescued the root resorption in OTM rats through inhibition of Jagged1. Additionally, Runx1 could bind to miR-26a promoter and promote its expression, thereby suppressing the osteoclastogenesis.

CONCLUSION

We concluded that Runx1/miR-26a/Jagged1 signaling axis restrained osteoclastogenesis and alleviated OIIRR.

External cervical resorption: Radiological diagnosis and literature (Review)

External cervical resorption (ECR) is a relatively unknown and insidious pathology characterized by the loss of hard dental tissues such as: Enamel, cementum and dentine due to clastic function. It begins as a localized resorptive process that initiates on the area of the root beneath the epithelial attachment and the coronal part of the alveolar process, involving vital and non-vital tissues. Despite the fact that there are several potential predisposing factors related to ECR, its aetiology still remains poorly understood and more research is needed to establish the cause-and-effect relationship of all the etiological factors. Improved radiographic detection using cone-beam computed tomography (CBCT) is required in order to correctly classify and assess this entity. This provides a three-dimensional insight into the lesion, regarding the location, the size, the depth and the circumferential spread of the ECR defect. It also allows establishment of the most efficacious treatment plan and management. The purpose of this literature review is to cover the relevant literature concerning the etiology, pathogenesis, clinical and radiological presentation and management of ECRs (based on the CBCT findings).

External cervical resorption-a review of pathogenesis and potential predisposing factors

External cervical resorption (ECR) refers to a pathological state in which resorption tissues penetrate into the dentin at the cervical aspect of the root. Despite being latent in its initial phase, ECR could cause severe damage to mineralized dental tissue and even involve the pulp if not given timely diagnosis and treatment. Nevertheless, the etiology of ECR is still poorly understood, which adds to the difficulty in early diagnosis. ECR has received growing attention in recent years due to the increasing number of clinical cases. Several potential predisposing factors have been recognized in cross-sectional studies as well as case reports. In the meantime, studies on histopathology and pathogenesis have shed light on possible mechanisms of ECR. This review aims to summarize the latest findings in the pathogenesis and potential predisposing factors of ECR, so as to provide pragmatic reference for clinical practice.

Dentinal Lesions in Dogs with Dental Calculus

Histopathological changes in tooth structures in dogs with calculus have not been described. The aim of this study was to evaluate the frequency of various histopathological changes in the dentine of teeth that had been surgically extracted from dogs with calculus. Data including breed, sex, age, reason for tooth extraction and dental history were obtained for each animal. A total of 158 teeth (45 incisors, 31 canines, 35 premolars and 47 molars) with calculus were extracted from 74 dogs of various ages and breeds. The teeth were decalcified, processed in paraffin wax and stained with haematoxylin and eosin for histopathological analysis. Of the 158 analysed teeth, 71 had dentinal changes, including 45 with external resorption cavities, 11 with osteodentine, six with internal resorption cavities, four with tertiary dentine, four with dentinal degeneration or fragmentation, and one with predentine degeneration or fragmentation. Canine teeth were the least commonly affected. Areas of dentinal degeneration or fragmentation unrelated to resorption cavities were only seen in the incisor and molar teeth. Dentinal changes and their frequencies were similar among the incisor, premolar and molar teeth. The presence or extension of dental calculus was not associated with the type or frequency of dentinal changes.

Pathophysiological mechanisms of root resorption after dental trauma: a systematic scoping review

Background

The objective of this scoping review was to systematically explore the current knowledge of cellular and molecular processes that drive and control trauma-associated root resorption, to identify research gaps and to provide a basis for improved prevention and therapy.

Methods

Four major bibliographic databases were searched according to the research question up to February 2021 and supplemented manually. Reports on physiologic, histologic, anatomic and clinical aspects of root resorption following dental trauma were included. Duplicates were removed, the collected material was screened by title/abstract and assessed for eligibility based on the full text. Relevant aspects were extracted, organized and summarized.

Results

846 papers were identified as relevant for a qualitative summary. Consideration of pathophysiological mechanisms concerning trauma-related root resorption in the literature is sparse. Whereas some forms of resorption have been explored thoroughly, the etiology of others, particularly invasive cervical resorption, is still under debate, resulting in inadequate diagnostics and heterogeneous clinical recommendations. Effective therapies for progressive replacement resorptions have not been established. Whereas the discovery of the RANKL/RANK/OPG system is essential to our understanding of resorptive processes, many questions regarding the functional regulation of osteo-/odontoclasts remain unanswered.

Conclusions

This scoping review provides an overview of existing evidence, but also identifies knowledge gaps that need to be addressed by continued laboratory and clinical research.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01510-6.

A Review of External Cervical Resorption

External cervical resorption (ECR) is a relatively uncommon yet aggressive form of dental hard tissue destruction. It is initiated at the cervical aspect of the root surface and extends apicocoronally and circumferentially inside the dentin. Despite the large number of case reports and clinical studies that have investigated ECR, its etiology remains unclear. Recent advancements in clinical assessment measures, such as the use of cone-beam computed tomographic imaging, have provided additional insights into the nature of this lesion. This has facilitated the continued development and improvement of treatment methods for this condition. In this article, we provide an overview of the latest research pertaining to the etiology, histopathology, predisposing factors, diagnosis, classification, and treatment of ECR. Furthermore, we provide a summary of the different classification schemes for ECR and highlight the relevant therapeutic principles.

Management of severe traumatic intrusion in the permanent dentition

Traumatic intrusion is considered one of the most severe luxation injuries to the permanent dentition. There are limited studies based on minimal evidence supporting suggested management protocols, owing to the rare occurrence of intrusion. The following case report details the multidisciplinary management and 18-month follow-up, in line with current UK guidelines, of a 23-year old adult male who sustained severe intrusion injuries to both permanent maxillary central incisor teeth. Timely, accurate diagnosis and subsequent appropriate management correlates with improved outcomes for traumatic injuries and it is therefore imperative those involved with the acute and long-term management of dentoalveolar trauma are aware of current guidelines.

Online-based software for guiding immediate implantation to replace a tooth with root resorption in the esthetic zone

This case report describes an alternative approach for the planning of immediate implant placement and provisionalization, which uses a new online dental software that predicts the esthetic outcome.

The ins and outs of root resorption

Root resorption is a poorly understood phenomenon and is often misdiagnosed and, as a result, inappropriately treated. The aim of this paper is to provide a practical guide for diagnosis of root resorption lesions using a simple classification, and to describe the principles of management of these resorptive defects in everyday practice.

[Dental root resorption etiology, diagnosis and treatment]

The process of resorption of hard tooth tissues is associated with the activity of osteoclasts. However, the initiation of resorption can be caused by many factors acting separately or simultaneously. The paper presents the characteristics of pathological tooth resorption. The main etiological factors, pathogenesis, clinical manifestations, as well as treatment of various forms of tooth resorption are described.

Root Resorption Diagnostic: Role of Digital Panoramic Radiography

INTRODUCTION

Root resorption is a pathological process characterized by loss of dental root substance, caused by bacterial infections, traumatic injuries or chemical irritation. Root resorption might be accidentally observed on digital panoramic radiography.

OBJECTIVE

The objective of the study was to identify characteristic radiological aspects for the different types of root resorption that could be observed on digital panoramic radiography, to make an easier diagnostic of root resorption.

MATERIAL AND METHOD

The retrospective study used the X-ray base from the Oral Rehabilitation and Dental Prosthetics Clinic of UMF Craiova to identify the most representative images for different types of root resorption. Digital panoramic radiographies were analysed by two investigators, of which the most suggestive images were selected and described.

RESULTS

Digital panoramic radiographies and dental charts of 240 patients were analyzed. 113 cases of root resorption were identified. External inflammatory root resorption (EIRR) was present in 27.07% of studied cases, external cervical root resorption (ECRR) was identified in 10.83% of all studied cases, external replacement root resorption (ERRR) was diagnosed in 7.08% of studied cases and internal root resorption (IRR) was the most rare type of root resorption, with only 2.08% from all studied cases. 16 cases were selected to describe the radiologic features of different types of root resorption, featuring the most interesting images of root resorption evident on digital panoramic radiographies.

DISCUSSION

Comparative analyses have been made between our results and the results of other specific studies, with both similar and different values. The radiological features which lead to the diagnostic of each type of RR were highlighted, assessing the causes that caused the lesions, as well as the treatment recommendations.

CONCLUSIONS

Digital panoramic radiography is a useful tool to identify root resorption, since it has become the most common radiological investigation for diagnostic in dentistry. Description of radiological aspects of different types of root resorption on panoramic digital radiography allows faster diagnosis. Still, the CBCT may be recommended in some cases to confirm the diagnosis.

Comparing the Ability of Different Materials and Techniques in Filling Artificial Internal Resorption Cavities

Objective

This ex vivo study aims to investigate the root filling quality of warm vertical technique, single-cone technique with GuttaFlow2, Endoseal MTA and EndoSequence BC sealer as a sealer in artificial internal resorption cavity.

Methods

For this study, 40 human single-root teeth were selected. After root preparation, the roots were horizontally sectioned 7 mm from the apex. The hemisphere cavities were created on both sides, and then they were re-approximated. According to filling methods and materials, the samples were randomly as-signed to four experimental groups: I: warm vertical compaction technique (WVC), II: single-cone technique with GuttaFlow2 (GF), III: single-cone technique with Endoseal MTA sealer (EM), IV: single-cone technique with EndoSequence BC sealer (ES). Filled roots were radiographed in buccolingual and mesiodistal views to check the obturation, and stored in humid environment at the room temperature for 7 days. Each tooth was sectioned 7 mm from the root apex at the level of the previous cut, and it was then photographed un-der stereomicroscope. The photographs and radiographs of all samples were imported to an image-analysis software to calculate the percentage of sealer, gutta-percha, and voids. The results were statistically analyzed using one-way ANOVA and Kruskal-Wallis Dunn's tests.

Results

In buccolingual view of radiographs, the WVC and EM groups showed significantly lower percent-age of voids (P value<0.05) compared to that in the GF group. In mesiodistal view, the WVC and EM groups showed significantly lower percentage of voids (P value<0.05) compared to that in the GF and ES groups. In stereomicroscope evaluation, the WVC and EM groups showed significantly lower percentage of voids (P value<0.05) compared to that in the GF and ES groups. The differences observed between the WVC and EM groups (P value>0.05) or between the GF and ES groups (P value>0.05) were not significant.

Conclusion

WVC technique and single-cone technique with EM sealer are the optimum methods to fill ar-tificial resorption cavities.

Root Resorption Classifications: A Narrative Review and a Clinical Aid Proposal for Routine Assessment

Root resorption (RR) refers to noninfectious damage related to the loss of hard and soft dental tissue that results from clastic cell activity. It is observed as a pathologic process that is predominantly asymptomatic in the permanent dentition and physiological during the shedding of primary teeth. Roots are protected by unmineralized organic cementoid and predentine. RR occurs because of the inability of the clastic cells to adhere to unmineralized surfaces. Since the first RR classification was described by Andreasen in the 1970s, several classifications have been proposed with diverse terminology. A narrative literature review was undertaken on the current classification, diagnosis, pathophysiology, and treatment of RR. A bibliographic search resulted in 434 titles and abstracts, and from those, 17 articles were obtained that alluded to 15 RR classifications. A total of 28 articles that met the inclusion criteria were included. Results showed that Andreasen’s classification is the most widely used for classifying RR. In terms of epidemiologic data, studies are scarce, although RR pathophysiology is well described in the literature. Overall clinical guidelines are summarized in a new RR classification diagram. The choice of RR treatment application should be in line with the RR type and the dentist’s experience. However, an earlier and correct diagnosis will significantly improve final outcomes and long-term prognosis, especially with the current evolution of advanced imaging techniques, such as cone-beam computed tomography and bioceramic-based endodontic sealers.

External cervical resorption-part 1: histopathology, distribution and presentation

External cervical resorption (ECR) is the loss of dental hard tissue as a result of odontoclastic action. It is a dynamic process that involves periodontal, dental and in later stages pulpal tissues. Over the last two decades, ECR has attracted increased interest; this is in part due to novel micro-CT and histopathological techniques for its assessment and also improved radiographic detection using CBCT. This literature review will cover the aetiology, potential predisposing factors, histopathology and diagnosis of ECR. Part 2 will cover the management of ECR.

Fracture Resistance of Teeth with Simulated Perforating Internal Resorption Cavities Repaired with Different Calcium Silicate-based Cements and Backfilling Materials

INTRODUCTION

This study assessed the fracture resistance (FR) of teeth with simulated perforating internal resorption cavities repaired with different calcium silicate-based cements (CSCs) and backfilling materials.

METHODS

Ninety-six mandibular premolar teeth were used. Twelve of the teeth were assigned as negative control group. Remaining roots were instrumented with rotary files, and standardized internal resorption cavities were prepared on the middle half of roots with burs. Twelve of the samples were not further interfered and were assigned as a positive control group. The apical 4 mm of the remaining 72 root canals was obturated with single-cone technique and divided into 6 groups according to CSCs used for repairing of cavities and backfilling materials as follows: MTA + MTA, MTA + gutta-percha/sealer, Biodentine + Biodentine, Biodentine + gutta-percha/sealer, MTA Plus + MTA Plus, and MTA Plus + gutta-percha/sealer. Specimens were embedded in acrylic resin and then subjected to fracture testing. The forces when the fracture occurred were analyzed with analysis of variance and Bonferroni tests at P = .05.

RESULTS

No significant difference was found among CSCs irrespective of backfilling materials (P > .05). Groups MTA + gutta-percha/sealer, Biodentine + gutta-percha/sealer, and MTA Plus + gutta-percha/sealer showed significantly lower FR compared with groups MTA + MTA, Biodentine + Biodentine, and MTA Plus + MTA Plus, respectively (P < .05). The highest FR was observed in group Biodentine + Biodentine, and the lowest was in group MTA Plus + gutta-percha/sealer. FR of positive control group was statistically lower than groups completely filled with CSCs (P < .05), whereas FR of negative control group was statistically higher than the groups combined with gutta-percha and sealer (P < .05).

CONCLUSIONS

The backfilling with CSCs may be a preferable material rather than gutta-percha/sealer combination for the roots with perforated internal resorptions.

Management of extensive external apical root resorption leading to root perforation

Resorption is both a physiological and pathological process which results in loss of hard tissues of the tooth, i.e , cementum and dentine and the surrounding bone. External resorption is much more common than internal resorption and can occur when tooth is luxated or avulsed. If remained unchecked, resorption can eventually lead to loss of the tooth. Timely management of the affected tooth can slow down the resorptive lesion and increase the prognosis of the survival of the tooth. This case report describes the surgical management of extensive external root resorption leading to perforation of apical one-third of the root area which was managed through root canal along with periapical surgery and bone grafting. A 6-month follow-up showed arrest of the resorptive defect and progressive healing as evident on the cone-beam computed tomography.

Characteristics and treatment of invasive cervical resorption in vital teeth. A narrative review and a report of two cases

Invasive cervical resorption (ICR) is a significant defect of the root surface where the hard dental tissues are undermined and become translucent due to the resorptive granulomatous tissue. It is mainly detected on radiographs. The radiographic appearance of ICR is asymmetrical radiolucency with irregular margins and an unchanged root canal. The purpose of this study is to present a comprehensive review together with the characteristics and the treatment of ICR through two cases which were followed-up for 36 months. In both cases the teeth were vital and the management consisted of raising a flap, granulomatous tissue removal, thorough debridement, restoration of the resorptive defect by placing a suitable filling material and follow-up examinations. Our results indicate that the specific treatment protocol has very positive outcomes. After 36 months pulpal vitality tests revealed a healthy pulp, and clinical and radiographic examination confirmed a stable periodontal condition.

CBCT Post-Processing Tools to Manage the Progression of Invasive Cervical Resorption: A Case Report

Abstract This case report aimed to highlight the usefulness of cone beam computed tomography (CBCT) and its post-processing tools for the diagnosis, follow-up and treatment planning of invasive cervical resorption (ICR). A 16-year-old female patient was referred for periapical radiographic examination, which revealed an irregular but well demarcated radiolucency in the mandibular right central incisor. In addition, CBCT scanning was performed to distinguish between ICR and internal root resorption. After the diagnosis of ICR, the patient was advised to return shortly but did so only six years later. At that time, another CBCT scan was performed and CBCT registration and subtraction were done to document lesion progress. These imaging tools were able to show lesion progress and extent clearly and were fundamental for differential diagnosis and treatment decision.

The Use of Intentional Replantation to Repair an External Cervical Resorptive Lesion Not Amenable to Conventional Surgical Repair

Intentional replantation consists of purposefully extracting a tooth, correcting the defect and replanting it into its original socket. This case report describes how this technique was used to successfully restore an external cervical resorptive (ECR) lesion. A 22-year-old man was diagnosed with ECR of the mandibular right canine following clinical and radiographic examination. CBCT showed the lesion had been initiated distally and extended circumferentially around the root canal. The nature of the resorptive lesion meant that it was inaccessible to repair conventionally in a predictable manner. This report describes how intentional replantation was used to access and restore the lesion with minimal patient cooperation and postoperative discomfort. At an 18-month recall the tooth was clinically sound with no radiographic evidence of inflammatory or replacement root resorption. Intentional replantation should be considered a viable treatment option when ECR is inaccessible and cannot be restored using conventional techniques.

Root Resorption: Simplifying Diagnosis and Improving Outcomes

Root resorption is a condition resulting in the progressive loss of dental hard tissue. It may occur both within the root and upon the external aspect of the root. Diagnosis can be difficult and management challenging. Understanding the pathology is critical to understanding why and when this disease occurs and what the best management techniques involve. With such knowledge practitioners can confidently diagnose resorption, discuss prognoses and management strategies with the patient and either refer or begin treatment. Early intervention is paramount in improving outcomes. As such, if practitioners choose to refer patients they must be aware of what can be done immediately to mitigate risks until consultation and specialist treatment begins.

Idiopathic Radiographic Apical Root Resorption in Wind Instrument Players

Root resorption of the permanent teeth involves an elaborate interaction among inflammatory cells resulting in loss of dental hard tissues. This report describes three clinical cases where idiopathic root resorption occurred in wind instrument playing patients. These patients produce adequate non-orthodontic forces, while playing their instruments, to expose their teeth to root resorbing force. Careful clinical monitoring of patients' teeth should be undertaken, as the additive effects of orthodontic treatment and musical habits are unknown. CPD/Clinical Relevance: This paper advises that questioning about wind instrument playing during case history-taking would be beneficial to clinicians. Furthermore, careful clinical monitoring of these patients' teeth during orthodontic treatment should be undertaken.

Management of invasive cervical resorption in a maxillary central incisor

Invasive cervical resorption is often not diagnosed properly, leading to improper treatment or unnecessary loss of the tooth structure. Early diagnosis and appropriate treatment are the keys to a successful outcome of therapy. Invasive cervical resorption is often seen in the cervical area of the tooth, but because it is initiated apical to the epithelial attachment, it can present anywhere in the root. In the early stages, it may be symmetrical, but larger lesions have the tendency to be asymmetrical. It can expand apically or coronally.

Management of A Rare Case of Communicating Internal-External Inflammatory Resorption

The present case describes the successful management of a rare case of communicating internal-external resorption in which both internal and external resorption seem to develop independent of each other. The case report highlights the importance of correct diagnosis and need of revision of classification system of resorptive defects.