Variability in human tooth cementum thickness reflecting functional processes

OBJECTIVE

The aim of this study was to investigate the thickness of acellular extrinsic fibre cementum (AEFC) at four root positions of anterior and posterior teeth with special focus on functional aspects. Furthermore, the correlations between cementum thickness and chronological age and sex are investigated.

BACKGROUND

While numerous studies confirm continuous cementum apposition with age, masticatory forces as well as physiological and orthodontically induced tooth movements also have the potential to affect tooth cementum thickness.

MATERIALS AND METHODS

Undecalcified teeth were embedded in resin and transverse-sectioned in the cervical third of the root. Two sections per root were selected, and digital images at four positions were obtained (mesial, distal, oral, and vestibular) using light microscopy. The AEFC thickness of 99 teeth (anterior = 66, posterior = 33, male = 54, female = 45) were measured in both sections. The differences in mean values between root positions and the association of root position variation with tooth type, age, sex, and subject as well as the overall effects of age and sex were analysed using a mixed model.

RESULTS

First incisors and canines showed the greatest mean AFEC thickness, in contrast to premolars which had the lowest values. Differences were found across the four root positions, with a pattern varying considerably between anterior and posterior teeth and between maxilla and mandible in the anterior teeth. An interaction between root position and subject pointed to the existence of an individual component in the variation of AEFC thickness across the four root positions. There was an age trend with an almost linear increase in cementum thickness of 1 μm per year. Overall, females tended to exhibit a significantly lesser AEFC thickness compared to males.

CONCLUSIONS

Distinct differences in the pattern of thickness values across the four root positions in anterior and posterior teeth support the assumption that the AEFC is strongly affected by functional processes. In addition to sex-specific differences and age-related trends, the root position variation of AEFC thickness varies from individual to individual.

Unusual imaging appearance of cemental tear in the maxillary first molar on cone-beam computed tomography: A case report

A cemental tear (CeT) is a definitive clinical entity and its radiographic appearance is well known in single-rooted teeth. However, the imaging features of CeT in multi-rooted teeth have not been clarified. We report a case of CeT which arose in the maxillary first molar and exhibited an unusual appearance in cone-beam computed tomography images. The torn structure was verified as cementum by micro-computed tomography and histological analysis. The hypercementosis, most likely induced by occlusal force, might have been torn from the root by a stronger occlusal force caused by the mandibular implant. An unusual bridging structure was created between the two buccal roots. These features may occur in multi-rooted teeth with long-standing deep pockets and abscesses that are resistant to treatment.

Cemental and alveolar bone defects after chronic exposure to amoxicillin in rats (histopathologic and radiographic study)

OBJECTIVES

This study aimed to shed new light on the potential detrimental effects on cementum and adjacent alveolar bone after chronic exposure to amoxicillin.

METHODS

Six pregnant adult Albino rats were equally divided into two groups. Saline solution and amoxicillin (100 mg/Kg) were given to rats of control and amoxicillin group, respectively from the 13th to the 21st day of pregnancy. The same treatment was given to the pups till the 42nd day. The cementum of the first molar teeth and the surrounding alveolar bone were examined qualitatively by histopathological and scanning electron microscope, and quantitatively by energy dispersive X-ray spectroscopy and cone beam computed tomography.

RESULTS

Amoxicillin group depicted cemental and alveolar bone defects along with resorption lacunae. Statistically significant decreases in calcium and calcium/phosphorus ratio in cementum and in calcium only in alveolar bone were evident (p ≤ 0.05). Overall cementum and alveolar bone densities also showed statistically significant decreases (p ≤ 0.05).

CONCLUSION

Chronic amoxicillin administration displayed destructive effects on cementum and the surrounding alveolar bone which may disturb tooth attachment integrity. Therefore, it is recommended to minimize its haphazard usage during pregnancy and early childhood.

Dental cementum virtual histology of Neanderthal teeth from Krapina (Croatia, 130-120 kyr): an informed estimate of age, sex and adult stressors

The evolution of modern human reproductive scheduling is an aspect of our life history that remains vastly uncomprehended. The present work aims to address this gap by validating a non-destructive cutting-edge methodology to infer adult life-history events on modern teeth with known life history and then applying it to fossil specimens. We use phase-contrast synchrotron X-ray microtomography to visualize the dental cementum of 21 specimens: nine contemporary humans; 10 Neanderthals from Krapina (Croatia, 130-120 kyr); one Neolithic Homo sapiens from Ajmana (Serbia); and one Mesolithic H. sapiens from Vlasac (Serbia). We were able to correctly detect and time (root mean square error = 2.1 years; R2 = 0.98) all reproductive (menarche, parturition, menopause) and other physiologically impactful events in the modern sample. Nonetheless, we could not distinguish between the causes of the events detected. For the fossil specimens, we estimated age at death and age at occurrence of biologically significant events. Finally, we performed an exploratory analysis regarding possible sexual dimorphism in dental cementum microstructure, which allowed us to correctly infer the sex of the Neolithic specimen, for which the true value was known via DNA analysis.

Forensic determination of dental age by cementum thickness of human teeth

The purpose of this study was to assess the correlation between the known chronological age and the dental cementum thickness (DCT) in male and female subjects in different age groups.

MATERIAL AND METHODS

The study sample consisted of 57 donor teeth of both sexes. Teeth were classified by donors' sex and divided into three age groups: 10-19, 30-39 and 60-69 years. Tooth roots were cut with transverse ground sections in the apical, middle, and cervical thirds. DCT measurements were made on photomicrographs of light microscope. The correlation between DCT and the chronological age was calculated using the Spearman correlation coefficient.

RESULTS

A positive correlation was found (r=0.47, p <0.001) between DCT and age of the donor. DCT decreased from apical to cervical ground section (median [IQR] apical section 216.72 [128.25-375.00] μm, middle section 158.44 [87.66-284.90] μm; cervical section 96.60 [70.05-165.59] µm). DCT variability was influenced by sex, number of tooth roots and the condition of the tooth crown. The influence differed depending on the location of the section, being most prominent cervically.

CONCLUSION

The present study showed correlation of DCT with age, with significant influence of sex, number of tooth roots, condition of the tooth crown and location of the root section.

A robust, semi-automated approach for counting cementum increments imaged with synchrotron X-ray computed tomography

Cementum, the tissue attaching mammal tooth roots to the periodontal ligament, grows appositionally throughout life, displaying a series of circum-annual incremental features. These have been studied for decades as a direct record of chronological lifespan. The majority of previous studies on cementum have used traditional thin-section histological methods to image and analyse increments. However, several caveats have been raised in terms of studying cementum increments in thin-sections. Firstly, the limited number of thin-sections and the two-dimensional perspective they impart provide an incomplete interpretation of cementum structure, and studies often struggle or fail to overcome complications in increment patterns that complicate or inhibit increment counting. Increments have been repeatedly shown to both split and coalesce, creating accessory increments that can bias increment counts. Secondly, identification and counting of cementum increments using human vision is subjective, and it has led to inaccurate readings in several experiments studying individuals of known age. Here, we have attempted to optimise a recently introduced imaging modality for cementum imaging; X-ray propagation-based phase-contrast imaging (PPCI). X-ray PPCI was performed for a sample of rhesus macaque (Macaca mulatta) lower first molars (n = 10) from a laboratory population of known age. PPCI allowed the qualitative identification of primary/annual versus intermittent secondary increments formed by splitting/coalescence. A new method for semi-automatic increment counting was then integrated into a purpose-built software package for studying cementum increments, to count increments in regions with minimal complications. Qualitative comparison with data from conventional cementochronology, based on histological examination of tissue thin-sections, confirmed that X-ray PPCI reliably and non-destructively records cementum increments (given the appropriate preparation of specimens prior to X-ray imaging). Validation of the increment counting algorithm suggests that it is robust and provides accurate estimates of increment counts. In summary, we show that our new increment counting method has the potential to overcome caveats of conventional cementochronology approaches, when used to analyse three-dimensional images provided by X-ray PPCI.

The effect of hydrochloric acid (HCl) on permanent molars: A scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) study

It is well established that acid disposal is a potentially effective method used by criminal syndicates to hinder the identification of victims. This study documents the effects of continuous immersion in hydrochloric acid (HCl, 37%) on molars using macroscopic analysis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The goal of this study is to aid in distinguishing visually unrecognizable fragments of dental remains when drastic changes in morphology have occurred as a result of acid exposure. Macroscopic, SEM, and EDS analysis were conducted on seven maxillary molars before and after HCl treatment. Molars reduced in weight relative to the length of time immersed in HCl and the dissolution time was over 40 hours longer than reported in previous studies, at just over 66 hours. SEM and EDS analysis showed acid-treated teeth exhibited morphological patterns such as cracking and layering visible at high magnification. Calcium/phosphorous ratios fell within the expected range of 1.6-2.5, indicating that HCl-treated teeth are still identifiable as osseous or dental tissue even when not visually identifiable as teeth. This is the first study to present SEM images of molar cementum before and after immersion in HCl and to present EDS results. This information can assist researchers and investigators in determining the presence of dental tissue in a forensic context associated with acid disposal.

Aberrantly elevated Wnt signaling is responsible for cementum overgrowth and dental ankylosis

Vertebrate teeth are attached to the jawbones using a variety of methods but in mammals, a fibrous connection is the norm. This fibrous periodontal ligament (PDL) allows teeth to move in the jawbones in response to natural eruptive forces, mastication, and orthodontic tooth movement. In some disease states the PDL either calcifies or is replaced by a mineralized tissue and the result is ankylosis, where the tooth is fused to the alveolar bone. To understand how the PDL maintains this fibrous state, we examined a strain of mice in which tooth movement is arrested. Daβcat^Ot mice express a stabilized form of β-catenin in DMP1-positive alveolar bone osteocytes and cementocytes, which results in elevated Wnt signaling throughout the periodontium. As a consequence, there is an accrual of massive amounts of cellular cementum and alveolar bone, the PDL itself calcifies and teeth become ankylosed. These data suggest that to maintain its fibrous nature, Wnt signaling must normally be repressed in the PDL space.

Detecting demineralization of enamel and cementum after gamma irradiation using radiographic densitometry

The purpose of this study was to evaluate the ability of radiographic densitometry in detecting the early demineralization of human enamel and cementum in irradiated and non-irradiated teeth. Sixty extracted teeth were divided into two groups: irradiated group and non-irradiated group. After irradiation, the groups were subjected to demineralization-remineralization (PH) cycling. Radiographic densitometric measurements (gray values) of a selected area of interest in the enamel and in the cementum of each tooth were performed at baseline and after PH cycling. After PH cycling, there was a significant reduction in gray values for both groups. The difference between "baseline" and "after PH cycling" values represents the reduction in the mineral content of the hard tissue, i.e., the demineralization. Results show that the demineralization of irradiated tooth enamel and cementum was significantly higher compared to that of non-irradiated tissues as determined by gray-level values. It is concluded that densitometric measurements by means of digital radiographs allow for the detection of demineralization of enamel and cementum, and can be used successfully for diagnosis of the early carious lesions in patients who received head and neck radiotherapy. This will allow implementation of remineralizing therapy and avoid the risk of progression of radiation caries. Furthermore, it is concluded that gamma irradiation with typical therapeutic doses for head and neck carcinoma is a direct cause of demineralization of tooth enamel and cementum.

[Mixed radiopaque and radiolucent jaw lesions]

Neoplasic and non neoplasic lesions of the jaws are regularly classified as radiopaque or radiolucent, odontogenic or not odontogenic.However, a significant number of pathologies can be classified as mixed or are initially radiolucent to later become radiopaque or mixed. Certain diseases present different stages of development that are radiolucent, radio opaque or mixed. The purpose of this article is to provide a better understanding of the imaging of these lesions based on a literature review ,and illustrated by personal clinical observations.

Observations of the Periodontal Ligament and Cementum in Cats with Dental Resorptive Lesions

The etiology of feline dental resorptive lesions is unknown, but some evidence suggests that interactions between components of the periodontium may be initiating factors in the development of these lesions. In the present study, 22 clinically normal teeth were harvested from 7 cats. The teeth and periodontium were radiographed and examined histologically. In addition, 14 of the 22 teeth were examined histometrically. Two teeth were histologically normal with an open apical foramen and two were normal with a closed apical foramen. Histological evidence of periodontal ligament degeneration without cementum resorption was observed in 8 teeth, and varying degrees of cementum resorption were observed in 10 teeth. Mandibular molar and premolar teeth had distal drift, and mandibular canine teeth had mesial drift. Alterations in the periodontal ligament may represent a preclinical stage of dental resorption.

Concrescence: assessment of case by periapical radiography, cone beam computed tomography and micro-computed tomography

The aim of this article was to describe imaging aspects of concrescence analyzed by three imaging modalities. A second molar joined together with a third molar was imaged using digital periapical radiography, cone beam computed tomography (CBCT) and micro-computed tomography (Micro-CT). On periapical radiograph, the mesial root of the third molar is superimposed on the distal root of the second molar. On CBCT images, a large cementum union between bulbous roots was detected, confirming the diagnosis of concrescence. On micro-CT images, the cementum union appeared limited to the apical third of the roots. In conclusion, both computed tomography modalities allowed for the diagnosis of concrescence. However, only micro-CT provided the real extension of the cementum union.

The plastic nature of the human bone-periodontal ligament-tooth fibrous joint

This study investigates bony protrusions within a narrowed periodontal ligament space (PDL-space) of a human bone-PDL-tooth fibrous joint by mapping structural, biochemical, and mechanical heterogeneity. Higher resolution structural characterization was achieved via complementary atomic force microscopy (AFM), nano-transmission X-ray microscopy (nano-TXM), and microtomography (MicroXCT™). Structural heterogeneity was correlated to biochemical and elemental composition, illustrated via histochemistry and microprobe X-ray fluorescence analysis (μ-XRF), and mechanical heterogeneity evaluated by AFM-based nanoindentation. Results demonstrated that the narrowed PDL-space was due to invasion of bundle bone (BB) into PDL-space. Protruded BB had a wider range with higher elastic modulus values (2-8GPa) compared to lamellar bone (0.8-6GPa), and increased quantities of Ca, P and Zn as revealed by μ-XRF. Interestingly, the hygroscopic 10-30μm interface between protruded BB and lamellar bone exhibited higher X-ray attenuation similar to cement lines and lamellae within bone. Localization of the small leucine rich proteoglycan biglycan (BGN) responsible for mineralization was observed at the PDL-bone interface and around the osteocyte lacunae. Based on these results, it can be argued that the LB-BB interface was the original site of PDL attachment, and that the genesis of protruded BB identified as protrusions occurred as a result of shift in strain. We emphasize the importance of bony protrusions within the context of organ function and that additional study is warranted.

[Evaluation of periodontal tissue during orthodontic tooth movement in rats: a micro-computed tomography study]

OBJECTIVE

To observe the microstructure changes of rat alveolar bone around tooth root under orthodontic force loading.

METHODS

Ten 10-week-old rats were included in the study. Upper first molars were moved mesially with 0.196 N of force. The alveolar bone around the root of upper first molar was scanned by a micro-computed tomography scan system (SkyScan-1076) in different period after the initiation of orthodontic force loading (on the 3rd, 7th, 14th day after force loading) and analyzed by a specially-designed software to measure the microstructure parameters of alveolar bone (bone volume fraction, bone surface to volume ratio, structure model index, trabecular thickness, trabecular separation, trabecular number).

RESULTS

From the 7th day, bone volume fraction [(41 ± 14)%], structure model index (1.51 ± 0.52) and trabecular separation [(90 ± 30) µm] changed significantly in the compressive area compared with those [(64 ± 15)%, (0.51 ± 0.85), (56 ± 10) µm] on the 3rd day. From the 14th day, bone volume fraction [(78 ± 14)%], structure model index (0.28 ± 0.20) and trabecular separation [(29 ± 13) µm] changed significantly in the tension area compared with those [(67 ± 14)%, (0.40 ± 0.41), (48 ± 15) µm] on the 7th day. No difference on trabecular number was found between the compressive area and tension area (P > 0.05).

CONCLUSIONS

The significant resorption of the alveolar bone was observed on the 7th days in the compressive area and the deposition of the alveolar bone was observed on the 14th day in the compressive area after orthodontic force loading.

Ultrasound stimulation induces PGE(2) synthesis promoting cementoblastic differentiation through EP2/EP4 receptor pathway

The present study aims to provide insights into how ultrasound treatment (US) can affect the regenerative response of cementum by evaluating the role of prostaglandin E(2) induced by ultrasound stimulation on cementoblastic differentiation. The mouse cementoblast cell line OCCM-30 was exposed to low-intensity ultrasound and the cyclooxygenase-2 (COX-2) mRNA expression and prostaglandin E(2) (PGE(2)) production were quantified. The role of the US-induced PGE(2) in mineralization was examined using COX-2 inhibitor and prostaglandin receptors (EP-receptors) agonists and antagonists. In addition, gene expression of differentiation markers related to mineral metabolism was evaluated. Ultrasound significantly enhanced COX-2 mRNA expression and PGE(2) production. PGE(2) induced by US mediated mineral nodule formation, whereas COX-2 inhibitor treatment eliminated the enhancement of mineralization induced by US stimulation. Mineral deposition was also inhibited by treatment with EP2 or EP4 antagonist. Moreover, up-regulation of differentiation markers induced by US was suppressed by treatment with COX-2 inhibitor. The present findings provide evidence that US stimulation has a positive effect on mineralization ability of cementoblasts through the activation of EP2/EP4 pathway, suggesting that US can be a promising therapeutic tool for cementum repair.

Physical properties of root cementum: Part 9. Effect of systemic fluoride intake on root resorption in rats

INTRODUCTION

Orthodontically induced inflammatory root resorption is a common complication in orthodontic treatment. Fluoride has been reported to have a beneficial effect against root resorption in dental traumatology. The effect of fluoride on orthodontically induced inflammatory root resorption has not been investigated. This study was undertaken to investigate the effect of fluoride on the incidence of root resorption.

METHODS

Thirty-two female 8-week-old Wistar rats were separated into 4 groups. Two groups (6 rats per group) were controls; they did not undergo orthodontic tooth movement. The other 2 groups (10 rats per group) had orthodontic tooth movement consisting of activated 100-g closing nickel-titanium coils (NiTi 10-000-06, GAC International, Bohemia, NY) connecting the mandibular first molar to the incisors. Fluoridated water (100 ppm) was given ad libitum to 1 control and 1 experimental group. The other 2 groups received deionized water. After 2 weeks, the animals were killed, and the samples were harvested. Resorption craters were scanned with a Micro CT (SkyScan 1072, Aartselaar, Belgium). Software analysis of the scanned samples provided a volumetric measurement of the resorption craters on the mandibular molar cementum surface.

RESULTS

Resorption sites were found in the control samples, especially on the distal surfaces; this could be attributed to normal physiological tooth drift. Resorption sites were significantly (P <.05) increased in the groups receiving orthodontic tooth movement.

CONCLUSIONS

Fluoride reduces the size of resorption craters, but the effect is variable and not statistically significant (P >.05).

Synchrotron radiation-based microtomography of alveolar support tissues

OBJECTIVES

To study the alveolar support structures using synchrotron radiation (SR)-based microtomography with particular focus on the alveolar surface.

DESIGN

High-resolution microtomography of jaw segments of various species and subsequent three-dimensional (3D) reconstruction.

SETTING AND SAMPLE POPULATION

Microtomography was performed at the DORIS-ring of the synchrotron facility of HASYLAB/DESY in Hamburg, Germany. The samples consisted of human, simian and porcine jaw segments.

RESULTS

With SR being monochromatic, no beam-hardening artifacts could occur and the grey values in the scans were therefore directly related to the local tissue densities. Apart from the mineralized tissues, the beam energy was low enough to allow for the visualization of soft tissues like the fibers of the periodontal ligament (PDL) and blood vessels. 3D reconstructions of the alveolar bone showed that it can be rough and sharply edged. Furthermore, an intricate network of marrow cavities and blood vessels penetrates its surface. Differences in the local grey value distribution in the alveolar bone pointed to remodeling activity in the close vicinity of the PDL.

CONCLUSION

The assumption that the alveolar bone surface is smooth and continuous is not correct. This means that even small orthodontic loads can already give rise to high local stresses and strains in the bone and thus initiate remodeling processes.

Physical properties of root cementum: Part 8. Volumetric analysis of root resorption craters after application of controlled intrusive light and heavy orthodontic forces: A microcomputed tomography scan study

INTRODUCTION

Intrusion is a critical type of orthodontic tooth movement in relation to external root resorption. Our aims in this prospective randomized clinical trial were to quantify, 3 dimensionally, the amount of root resorption when controlled light and heavy intrusive forces were applied to human premolars and to establish the sites where root resorption is more prevalent.

METHODS

Fifty-four maxillary first premolars, orthodontically indicated for extraction from 27 patients (left and right maxillary first premolars from each), were intruded for 28 days with buccal and palatal beta-titanium-molybdenum alloy 0.017 x 0.025-in cantilever springs. The patients were randomly divided into 3 groups, and various levels of force were used: group 1, heavy force (225 g) on 1 side and control force (0 g) on the contralateral side; group 2, light force (25 g) on 1 side and control force (0 g) on the contralateral side; group 3, light force (25 g) on 1 side and heavy force (225 g) on the contralateral side. After the experimental period, the teeth were extracted under a strict protocol to prevent root surface damage and analyzed by using a microcomputed tomography scan x-ray system (SkyScan-1072, Skyscan, Aartselaar, Belgium) and specially designed software for direct volumetric measurements.

RESULTS

The volume of the root resorption craters after intrusion was found to be directly proportional to the magnitude of the intrusive force applied. The results showed that the control group had fewer and smaller root resorption craters, the light force group had more and larger root resorption craters than the control group, and the heavy force group had the most and the largest root resorption craters of all groups. A trend of linear increase in the volume of the root resorption craters was observed from control to light to heavy groups, and these differences were statistically significant. The mean volumes of the resorption craters in the light and heavy force groups were 2 and 4 times greater than in the control groups, respectively. The mesial and distal surfaces had the greatest resorption volume, with no statistically significant difference between the 2 surfaces.

[Resorption of root cement studied with resorption indices]

PURPOSE

The aim of this work was to assess the influence of orthodontic treatment with fixed thin wire appliances on hard tissues of the tooth.

MATERIAL AND METHODS

The effect of mechanical forces from the fixed appliance on root cement was studied during and after orthodontic treatment. Root cement was examined microscopically following extraction of the affected tooth.

RESULTS

The study group comprised 35 patients who underwent pantomography because of possible root resorption during orthopedic treatment. Reduced root length was noted in 30 patients (85.7%). In most cases, apical resorption was noticed in upper (84.3%) and lower central incisors (61.4%).

CONCLUSIONS

The results of the it can be seen on photographs from the optical microscope that root cement reacted differently to forces of traumatic occlusion. Resorptive loss reached as far as the dentine border.

Florid cemento-osseous dysplasia in a young Indian woman. A case report

We present a rare case of florid cemento-osseous dysplasia (FCOD) occurring in a 27-year-old Indian woman. She presented with three lesions, two of them symmetrical, at the posterior region of the mandible. Another lesion appeared nine months later, symmetrical to the existing third lesion. This confirmed the diagnosis of florid cemento-osseous dysplasia as being symmetrical asymptomatic bone lesions occurring in the jaw. The diagnosis was made radiographically depending on a series of radiographs, as biopsy is contraindicated. No treatment was required as the lesions were asymptomatic, causing no problem to the patient. The patient continues to be reviewed annually. The case is rare in its unusual combination of the disease itself (FCOD), age (27 years) and race (Indian). Clinical and radiological features are presented.

Directing ultrasound at the cemento-enamel junction (CEJ) of human teeth: I. Asymmetry of ultrasonic path lengths

The diagnosis of degenerative changes in human teeth is of general interest because early detections can avoid greater health problems and further weakening effects. Since the wear of teeth determines their stability and lifetime in relation to the physiological load, an ultrasonic survey of any dimensional changes of the enamel layer and especially of the dentin wall thickness may be very helpful. However, an ultrasonographic diagnosis requires first to determine the anisotropic human tooth properties at clinically relevant locations and to simulate wave propagation phenomena in inhomogeneous tooth models with proper dimensions. The first article of a series that provides modular data of mineralized tissues in human teeth at the cemento-enamel junction (CEJ) deals with an ultrasonic method for measuring the asymmetry of dimensional characteristics of extracted human teeth and their ultrasonic path lengths (UPL). Heavily attenuating tooth halves were investigated with respect to the symmetry of normal and inclined oppositely directed radial ultrasonic paths. The measured UPLs ranged from 1.2 mm to 4.4 mm. The relative difference in inclined UPLs between the left and the right tooth halves reaches almost 30%. This reveals a large asymmetry. The mean difference of angles that represent fastest path lengths was 2.2+/-8.1 degrees, which indicates large asymmetry and anisotropy. Several aspects, which are required for a proper integration of asymmetric data into models designed for medical element engineering and simulation (MEES), are discussed.

Severe localized periodontal destruction associated with cervical cemental separation

Cemental separations and tears are secondary etiological factors that may lead to rapid periodontal destruction if the lesion communicates with the oral cavity and allows bacterial invasion. Although many cemental tears that occur on proximal surfaces can be diagnosed radiographically, separations on the facial or lingual surface that cannot be detected on radiographs may present a diagnostic dilemma. This article describes a case of lingual cemental separation on a maxillary incisor, with subsequent successful surgical correction utilizing an osseous graft.

The corono-apically varying ultrasonic velocity in human hard dental tissues

The speed of ultrasound at 20 MHz is measured for hard dental tissues inside human teeth. This includes the cementum, for which no data are available. The spatial distribution, extrema, and means of the longitudinal ultrasound velocity (LUV) are determined with an emphasis on the apical thirds and an extended spectrum. Tissue areas are investigated by optical means and by acoustical scanning, in order to compare apical regions-of-interest with the complete mineralized wet porous tissue that lies beneath the enamel cap. The maximal LUV in a single dentin specimen varies from 3903 m/s to 4226 m/s. The dentin's frequency distribution of LUV at 20 degrees C exhibits a predominant peak feature comprising several Voigt functions. Introducing standardized relative tooth width portions, the corono-apical decrease in LUV of 21 specimens is approximated by LUV=4224 - (257* ln(y)) along reduced distances in dentin. Abnormal teeth require a higher resolution and an approximate equation of the form LUV= (sigma(ai*yi))/(1 + sigma(bi+1*y(i+1. It can be used each time the corono-apical variation has to be quantified in each of the three tissues. Ten coefficients are numerically exemplified. An error evaluation is performed, which denotes errors of 0.2% +/- 1.3% (enamel), -0.1% +/- 1.6% (cementum), and acceptable residual errors for dentin.

Clinico-pathological conference 2002

INTRODUCTION

Six cases are reported, each presented at the 11th Biennial Congress of the International Association of Oral Pathologists as an instructive case for differential diagnosis on the basis of clinical, imaging or histological features.

CLINICAL PICTURE

Case diagnoses included a large, possibly intraosseous, myofibroma presenting with an oral mass; Langerhans cell histiocytosis with facial skin lesions; an intraosseous vascular hamartoma of the maxilla with worrying radiological features; an unusual mixed radiolucency of the jaw caused by cemento-ossifying fibroma; an osteosarcoma of the posterior mandible causing a well-defined radiolucency and an intraoral squamous cell carcinoma in a child.

EM evaluation of bacterial biofilm and microorganisms on the apical external root surface of human teeth

The aim of this study was to evaluate the presence of bacterial biofilm on the external surface of the root apex in teeth with pulp necrosis, with and without radiographically visible periapical lesions, and in teeth with a vital pulp. Twenty-one teeth were extracted, eight with pulp necrosis and periapical lesions, eight with pulp necrosis without radiographically visible periapical lesions, and five with a vital pulp. The roots were sectioned, and the root apexes (+/- 3 mm) were processed for scanning electron microscope evaluation. The surface of the apical root was evaluated for the presence of microorganisms, root resorption, and biofilm. There were no microorganisms on the apical root surface of either teeth with pulp vitality or with pulp necrosis with no radiographically visible periapical lesions. Microorganisms were always present in teeth with pulp necrosis and radiographically visible periapical lesions. These included cocci, bacilli, and filaments and the presence of an apical biofilm. Apical biofilm is clinically important because microbial biofilms are inherently resistant to antimicrobial agents and cannot be removed by biomechanical preparation alone. This may cause failure of endodontic treatment as a consequence of persistent infection.

Histologic and radiographic assessment of caries-like lesions localized at the crown margin

STATEMENT OF PROBLEMS

Little is known about the impact of crown margins on the demineralization and remineralization process or on the interpretation of radiographs for the detection of early secondary caries.

PURPOSE

The aim of this study was to correlate the findings from 2 different radiographic techniques with the results of a histologic assessment of carieslike lesions at the crown margin.

MATERIAL AND METHODS

Ten fully impacted third molars were extracted and restored with complete metal crowns with chamfer preparations. For each tooth, the prepared margin ended in enamel on one side and extended into cementum/dentin on the other. After being thoroughly cleaned, the teeth were covered with wax except for a 2- x 3-mm window at the crown margin in each of 2 test areas localized at the interproximal enamel and cementum/dentin junction. During demineralization with 6% hydroxyethyl cellulose gel at pH 4.9, direct digital radiographs or conventional radiographs were made at baseline and after 7, 14, 21, and 28 days. Each radiograph was blinded and examined for the presence/absence of lesions by 3 calibrated observers who used predetermined criteria required for receiver operating characteristic (ROC) analysis. After 28 days, the teeth were imbibed with methyl methacrylate and serially ground sectioned for assessment of the lesions in polarized light. Morphometric analysis of lesion extension included the calculation of mean values and standard deviations. Kappa and ROC analysis were applied to assess radiographs made at different demineralization time periods, localization of the crown margins in enamel or cementum/dentin, and direct digital and conventional radiographs. Data were tested for normal distribution (QQ plot), and statistical differences were calculated with Tukey's honestly significant difference post hoc test.

RESULTS

Radiographic evaluation revealed only slight interexaminer agreement (Kappa) for enamel lesions (direct digital 0.19, conventional radiographs 0.2) and a fair interexaminer agreement for cementum/dentin lesions (direct digital 0.35, conventional radiographs 0.33). ROC analysis revealed no differences between the radiographic techniques. Lesions localized in cementum/dentin (direct digital 0.86 +/- 0.14, conventional radiographs 0.86 +/- 0.09) were diagnosed more reliably than those in enamel (direct digital 0.79 +/- 0.05, conventional radiographs 0.72 +/- 0.10). As microscopically assessed, the depth of lesions in enamel was less than that of lesions in cementum/dentin (49.3 +/- 7.3 microm vs 89.5 +/- 13.2 microm). Erosions were found in cementum/dentin (depth 25.2 +/- 5.3 microm).

CONCLUSION

Within the limitations of this study, small artificial lesions were detected equally well by conventional and direct digital radiography. However, because of low interexaminer agreement, the radiographic assessment did not reproduce true histopathologic lesion characteristics documented by morphometry of serial ground sections.

[Clinicopathological studies on localized cemento-osseous dysplasia of the jaws]

The aim of this study was to clarify the entity of localized cemento-osseous dysplasia (COD), which occurs mainly in the posterior mandible. The clinical, radiographical, and histopathological features of 51 patients with COD were retrospectively studied. Radiographic features of the COD were classified into four types, according to the appearance of calcified bodies with related teeth and without related teeth. Pathological features of the COD were classified into four grades, based on the maturation of cemental masses. The results are summarized as follows: 1. Forty-four (86%) of the 51 patients were women. The mean age of the total group was 52.5 years, and 98% of COD lesions occurred in the posterior mandible. Clinical symptoms of COD were significantly more frequent in cases without related teeth (87%) than in cases with related teeth (55%). 2. The radiolographical calcification of COD was not related to the mean age, but it was related to the grade of histopathological maturation. 3. The four progressive stages of COD were recognizable both radiographically and histopathologically. The early stage is the osteolytic process, the intermediary stage is the cementoblastic process, the mature stage is the cementosclerotic process, and the end stage is necrotization of the cemental mass. These results suggested that localized COD in the posterior mandible had progressive stages both radiographically and histopathologically. The entity of localized cemento-osseous dysplasia was identified with focal cemento-osseous dysplasia, which was reported by Summerlin and Tomich.

Periapical cemental dysplasia: a case of misdiagnosis

The correct diagnosis of pathological lesions of endodontic origin should allow for differentiation from those arising from other sources. A case of periapical cemental dysplasia (cementoma) is presented, whereby incorrect diagnosis resulted in not only inappropriate treatment, but an endodontic mishap and the superimposition of acute apical periodontitis in a previously disease-free site. This case report highlights the need for appropriate examination, simple special tests and diagnosis prior to management of lesions of questionable aetiology.

Clinical, radiographic, and histologic evaluation of human periodontal defects treated with Bio-Oss and Bio-Gide

This study evaluated the clinical, radiographic, and histologic response to Bio-Oss porous bone mineral when used alone or in combination with Bio-Gide bilayer collagen membrane in human periodontal defects. Four intrabony periodontal defects were treated: two received Bio-Oss alone and two were treated with a combination of Bio-Oss and Bio-Gide. Radiographs, clinical probing depths and attachment levels were obtained preoperatively and 6 to 9 months postoperative, and teeth and surrounding tissues were biopsied. Both treatments significantly improved clinical probing depths and attachment levels, and the radiographic appearance suggested osseous fill. Histologic evaluation revealed that both treatments produced new cementum with inserting collagen fibers and new bone formation on the surface of the graft particles; this regenerative effect was more pronounced using the Bio-Oss/Bio-Gide combination, which resulted in 7 mm of new cementum and periodontal ligament and extensive new bone incorporating the graft. The membrane was intact at 7 months and partially degraded by 9 months after treatment. This human histologic study demonstrates that the porous bone mineral matrix used has the capacity to stimulate substantial new bone and cementum formation and that this capacity is further increased when the graft is used with a slowly resorbing collagen membrane.

Microradiographic and microscopic investigation of a rare case of complex odontoma

An extremely rare case of odontoma that erupted into the oral cavity is presented. The lesion was surgically removed from a 14-year-old girl and examined by soft x-ray radiography, microradiography, and microscopy to determine whether the lesion was complex or compound. Macroscopically, the surface of the lesion was slightly lobular and solid, resembling the surface of an osteoma. The soft x-ray radiograph obtained from the surgical specimen showed radially arranged radiopaque spicules. Microradiographically, dentin was shown to be present in relatively large quantities and to form the bulk of the tumor, with irregular enamel and cementum in small quantities. There were numerous, comparatively well-formed, enamel-free, toothlike structures in the peripheral region of the tumor. Microscopically, the toothlike structures were seen to be arranged radially; this corresponded to the microradiographic findings. Each structure consisted of a central core of pulp tissue encased in a shell of dentin. In the central area of the mass, there was an irregular conglomerate of dentin, enamel, cementum, and pulp tissue. The findings showed that the lesion was a complex odontoma.

Macroscopic and microscopic aspects of incinerated teeth

Fifty-eight premolars, extracted for orthodontic reasons, were incinerated for one hour in a furnace at temperatures varying from 150 degrees C to 1150 degrees C, increasing at 100 degrees C intervals. Between 150 degrees C and 700 degrees C the teeth changed from light yellow to bluish-white passing through brown. The scanning electron microscope showed that at 150 degrees C cracks appeared in the enamel, increasing in number as the temperature rose. At 450 degrees C the internal surface detached from the dentine and showed the same cracked surface as the exterior. Above 1100 degrees C the enamel fragments had a prismatic structure difficult to identify due to their melted structure. Dentine retained its tubular structure up to 1150 degrees C even when the tubules' diameter decreased at 700 degrees C. The cementum cracked as the temperature increased. Certain cracked areas actually detached at 600 degrees C giving a corroded aspect to the cementum and the residual zones became irregular when the temperature rose and eventually at 1150 degrees C the cementum was no longer identifiable.

Distinguishing features of focal cemento-osseous dysplasia and cemento-ossifying fibromas. II. A clinical and radiologic spectrum of 316 cases

The distinguishing histopathologic features of focal cemento-osseous dysplasia (FCOD) (including lesions occurring in both anterior and posterior jaws) and cemento-ossifying fibroma (COF) (ossifying fibroma and cementifying fibroma) were demonstrated in our earlier work. The aim of the current study was to further refine their clinical and radiographic features. We have assessed 18 clinical and radiographic parameters by univariate comparisons (chi-squared and Student t tests), and a multivariate assessment (logistic regression) in 241 cases of FCOD and 75 of COF. These cases were diagnosed from a combination of clinical, radiographic, and histopathologic information. FCOD was seen predominantly in black women, with a peak incidence in the fourth and fifth decades, whereas COF showed no female predilection except in the fourth decade (p < 0.005). COF occurred in patients an average of 10 years younger than patients with FCOD (p < 0.0001). Most patients with FCOD were asymptomatic (62%); the average lesion size was 1.8 cm. More than half of patients with COF displayed jaw expansion and a considerably larger size lesion (mean 3.8 cm, p < 0.001). The mandible was the most frequent site for both FCOD (86%) and COF (70%). Radiographically, a well-defined border was observed in 53% of cases of FCOD and 85% of cases of COF (p < 0.01). Cases of FCOD mostly demonstrated an irregularly mixed radio-opacity (69%), whereas 53% of COFs presented as a radiolucency (p < 0.005). In FCOD, there was a close association with tooth apices (70.6%, p < 0.0001) or with previous extraction sites (21%, p < 0.05); however, the majority of COF cases (86%) showed no relationship with either. Combining the radiographic feature of a periapical location with the pathology of multiple curetted fragments and "ginger root" bony trabeculae, allowed 90% sensitivity and 89% specificity in a logistic regression model to predict the lesion to be an FCOD. These findings provide guidelines not only to distinguish these two entities clinically, but also aid in reaching an accurate diagnosis histopathologically.

Effect of non-erupted third molars on roots of approximal teeth. A radiographic, clinical and histologic study

This study was undertaken to evaluate clinically and histologically root resorption in extracted human second molars in close proximity to non-erupted third molars. The control group consisted of extracted second molars that were proximal to fully erupted third molars. Eight out of the 11 teeth in the study group presented different degrees of radiographic root resorption, nine presented clinical resorption, and all 11 had histologic evidence of root resorption. In the control group, no signs of root resorption were seen radiographically or clinically. Histologically, limited sites of resorption were identified in all teeth, which were partially repaired by cellular cementum. Histologic observation of study specimens revealed root surface resorption in 10 out of the 11 teeth, one showing replacement resorption as well. Inflammatory resorption was observed in the three most advanced cases in the study group. Reparative cementum partially lining resorbed areas was evident in all teeth with surface resorption. Within the limits of this study, radiographic identification of distal root resorption of second molars in close proximity to non-erupted third molars appears reliable. The findings may support the hypothesis that the presence of a non-erupted third molar in close proximity to the distal root of the second results in root resorption.

Transmission electron microscopy of cementum crystals correlated with Ca and F distribution in normal and carious human root surfaces

Root-surface caries, like enamel caries, develops as a subsurface type of mineral loss. Very little is known about the composition of the surface zone covering the body of the lesion, and the ultrastructure and composition of carious cementum are not known. The aim of this study was to correlate the ultrastructure and arrangement of the cementum crystals with the distribution of fluoride and calcium in root cementum from human teeth with sound, unexposed, or exposed root surfaces as well as in early stages of root-surface caries. Microradiographically, unexposed specimens showed a relatively homogeneous mineral distribution contrasting with the formation of an apparently highly mineralized surface layer in exposed and, in particular, in carious cementum. The electron-probe findings showed a substantial fluoride peak corresponding to the surface layers in carious tissues in particular, whereas the calcium profile in the surface did not reflect the apparent increase in mineralization. A substantial increase in size of the cementum crystals was found in specimens with formation of the fluoride-rich, well-mineralized surface zone. The crystal lattice intervals when observed along the (001) plane showed a hydroxyapatite spacing. The findings indicated that a significant crystal growth can be achieved in human cementum concomitant with fluoride accumulation.

The width of radiologically-defined attached gingiva over deciduous teeth

The aim of the present cross-sectional study was to radiologically investigate the continuous eruption process in the deciduous dentition by assessing the difference in the width of radiologically-defined attached gingiva (RAG) in 6-year-old and 10-year-old children. The group of 6-year-olds had predominantly deciduous teeth and the 10-year-olds were in their mixed dentition period. The mucogingival junction was revealed with Schiller's iodine solution and marked mid-labially along the long axis of each tooth with a piece of metal wire prior to taking panoramic radiographs. The width of RAG over deciduous canines and molars was measured from the cementoenamel junction to the mucogingival junction. A significant increase in the width of RAG was found from 6 to 10 years of age.

Intense accumulation of Tc-99m MDP and Ga-67 in multiple periapical cemental dysplasia

A case of multiple periapical cemental dysplasia is presented and intensive accumulation of Tc-99m MDP and Ga-67 is described. A 53-year-old woman was admitted with an intermittent pain and swelling of the left buccal region. The radiograph showed multiple sclerotic masses covering entire periapical regions of the teeth, in both the maxilla and mandibula. Biopsy of the maxilla facilitated a definitive diagnosis of multiple periapical cemental dysplasia.

The influence of endodontic infection on progression of marginal bone loss in periodontitis

The purpose of the present investigation was to determine magnitude and rate of proximal radiographic attachment loss in relation to endodontic infection in periodontally involved teeth. The investigation was conducted as a retrospective longitudinal study on a periodontitis-prone randomly selected referral population, including 175 single-rooted, root-filled teeth in 133 patients. An observation period of at least 3 years was required. Periapical conditions of the selected sample at baseline and re-examination were evaluated on radiographs, independently by 3 investigators. Each single-rooted, root-filled tooth of the sample was given a score according to the combined registrations. Radiographic attachment level was measured as the distance between the most coronal point of the alveolar bone and the apex at the mesial and distal sides of the tooth, and expressed as relative radiographic attachment level (RRAL) (radiographic attachment level at baseline/root length) at proximal sites for every tooth. Multiple regression analysis was used to study change in RRAL over time. Teeth in periodontitis-prone patients with progressing periapical pathology indicating a continuous root canal infection were found to lose comparatively more radiographic attachment than teeth with no signs of periapical pathology or teeth with an established periapical destruction which subsided during the observation period. An approximate 3-fold amplification of the rate of marginal proximal radiographic bone loss by endodontic infection in periodontitis-prone patients was found with an average 0.19 mm/year, while 0.06 mm/year was lost for teeth without endodontic infection or subsiding endodontic involvement.

Radiographic amelocemental junction and alveolar crest: effect of X-ray beam angulation

The effect of X-ray beam angulation on the radiographic images of the amelocemental junction (ACJ) and alveolar crest (AC) and their positions relative to one another were assessed using a new laboratory model for radiographic studies. A total of 39 teeth with 62 usable approximal surfaces were included in the investigation. When all tooth types were combined, changes in vertical or horizontal angulation from baseline through 20 degrees had no significant effect on the distance between the marked (true) ACJ and marked (true) AC. However, the distance between the apparent (radiographic) ACJ and apparent (radiographic) AC was significantly reduced by varying the beam angulation in either a vertical or horizontal direction. Results for individual tooth types were qualitatively similar but larger discrepancies were found in molars followed by premolars and incisors. The results emphasize the importance of maintaining the ideal X-ray beam, tooth, bone, film relationship when taking radiographs for the assessment of periodontal destruction.

The width of radiologically-defined attached gingiva over permanent teeth in children

Several authors have determined clinically the width of attached gingiva (AG) over the deciduous and early permanent dentitions in children. They have noticed that when comparing the width of AG over deciduous teeth to the width of AG over the succeeding newly erupted permanent teeth, a clear diminishing in AG can be seen. The aim of the present cross-sectional study was to assess the width of radiologically-defined AG (RAG) over the permanent teeth of 6-, 10- and 12-year-old children. Altogether 123 subjects were recruited. The mucogingival junction (MGJ) was revealed with Schiller's iodine solution and marked over each tooth with a piece of metal wire before taking a panoramic radiograph. The width of RAG over permanent teeth was measured from the radiographs as the midfacial distance from the cementoenamel junction to the mucogingival junction. When comparing the width of RAG over 1st molars and the 1st and 2nd incisors, statistically significant differences were found between 6- and 10-year-olds, between 6- and 12-year-olds and between 10- and 12-year-olds. For the 1st maxillary incisor, the difference in width was not statistically significant between ages 10 and 12 years. The findings seem to justify the conclusion that an inadequate width of AG will correct itself from 6 to 12 years of age without interference by means of periodontal surgery.

Microradiography of the feline marginal periodontium with a microfocal high-resolution x-ray system

The present paper is a cross-sectional microradiographic study. Postmortem hemimandibles were radiographed with a microfocal high-resolution method. Microradiographic appearances of the feline periodontium are described and discussed. Mean relative alveolar bone support in clinically and histologically normal cats was 46.9%. Site-specific alveolar bone support (ABS) was calculated twice (blind). The 95% confidence limits of the method error for one observation were estimated. Differences between two site-specific measurements did not exceed +/- 2.72%. Microfocal radiography yielded valuable additional information about the feline periodontium and made it possible clearly to identify important dental and periodontal structures such as the CEJ (cementoenamel junction) and the bottom of infrabony defects.