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PubMed1992

Measurements of tooth length in panoramic radiographs. 1. The use of indicators.

The aim of this study was to investigate both the actual and the radiographic tooth lengths of the maxillary first molar and second premolar and the mandibular premolars in panoramic radiographs. The actual length of 64 extracted teeth was measured. Steel balls were then attached to the cusp and apex and the teeth embedded in plastic moulds. Each pair of plaster casts with their set of teeth was radiographed with an Orthopantomograph twice at an interval of 1 month. The actual and the radiographic tooth length was measured twice by one observer. The mean tooth length of the molar was shorter than that of the premolars. The mean difference between the repeated measurements of the actual tooth length was small and ranged between 0.47 and 1.16% of the tooth length. The mean difference between repeated measurements of the radiographic tooth length was also small, with a method error of 0.13-0.21 mm. The vertical magnification in panoramic radiography was lower for mandibular premolars (13-15%) than for the maxillary second premolar and first molar (17-28%). The palatal root of the maxillary first molar had the highest vertical magnification (28%). Following the second set of radiographs, the mean difference between the measurements was small, except for the palatal root of the maxillary first molar (P < 0.001). Radiographic measurements of this root should therefore be used with caution. The results for the other roots examined indicate that these could be measured with high reproducibility.

Humans↗
PubMed2003

Differential mesowear in occluding upper and lower molars: opening mesowear analysis for lower molars and premolars in hypsodont horses.

A new approach of reconstructing ungulate diet, the mesowear method, was recently introduced by Fortelius and Solounias ([2000] Am Mus Novitat 3301:1-36). Mesowear is based on facet development on the occlusal surfaces of the teeth. Restricting mesowear investigation to maxillary cheek teeth would allow mesowear investigation only in assemblages of large numbers of individuals and therefore would generally restrict this method to relatively few assemblages of recent and fossil ungulates. Most of the fossil, subfossil, and recent ungulate osteological assemblages that may be assigned to a single taxon have smaller numbers of individuals. This results in a demand to extend the mesowear method to further tooth positions in order to obtain stable dietary classifications of fossil taxa. The focus of this article is to test if a consistent mesowear classification is obtainable for mandibular as well as for maxillary teeth. For statistical testing, large assemblages of isolated cheek teeth of the Vallesian hipparionine horse Hippotherium primigenium and of the recent zebra Equus burchelli were employed as models. The upper tooth positions P4, M1, M2, and M3 as suggested by Kaiser and Solounias (2003) as the model for the "extended" mesowear method and the lower tooth positions P4-M3 were tested for their consistency in classification of the mesowear variables. We found a considerable shift of the mesowear signature towards the grazing edge of the mesowear continuum in lower cheek teeth. In order to adjust the signal of lower teeth to the signal of the upper teeth, a calibration factor was introduced which allowed incorporation of lower cheek teeth into the same model of mesowear investigation together with upper cheek teeth. We propose that this model is particularly suited for the reconstruction of paleodiets in hypsodont hipparionine and equine equids. We further investigated the functional relation between the mesowear profiles and the distribution of dental tissues along the course of the occlusal contact. We therefore correlated mesowear profiles with enamel distribution profiles and found the mesowear profile to be strongly controlled by the attritional environment encountered by a given apex area. The differential signal observed in cusp apex morphology between upper and lower cheek teeth was found to be more closely related to attrition by the antagonistic tooth than to the distribution of dental tissues in the tooth under consideration. The results suggest a general extension of the mesowear method of paleodiet reconstruction and a basic scenario for the evolution of anisodont dentitions.

Animals↗
PubMed1994

[Esthetic and prosthetic procedures in single-tooth replacement].

Loss of anterior maxillary teeth always results in bone resorption and loss of interdental papillae, and the resorption makes a single tooth replacement by a dental implant very difficult. When infections have been present and the patient's history shows previous surgery at the apex of the root, bone destruction is substantial, which results in an increased resorption defect, thereby further increasing the aesthetic and prosthetic problems. This paper describes the steps necessary for implant surgery and the prosthetics; a brief summary is provided. The quality and quantity of bone, along with the space available between the adjacent teeth, are the basic factors in treatment planning and determine the type of implant to be used. Some resorption and bone defects are usually present after a tooth extraction, and bone regeneration procedures can be performed either before or simultaneously with the implant placement, with numerous flap designs available. Soft tissue augmentation can be achieved by taking a connective tissue graft from the palatal side. Antirotational devices (eg, hex lock abutments) are necessary for all implants in single tooth replacement. Screw-retained abutments can be used in posterior areas and in angled positions in facial areas as well. With proper single tooth implant position, cementation of laboratory fabricated crowns can be considered.

Alveolar Bone Loss↗
PubMed1989

[Prognosis for the deciduous molars of juvenile dogs after root canal filling using apatite root sealer].

There are various restrictions on the root canal filling of deciduous roots after root canal treatment unlike in the case of permanent teeth, because deciduous molars undergo physiological root resorption with aging. Among the restrictions, it is most important that the root canal filling material be similarly absorbed and disappear along with the deciduous root so that it does not prevent the eruption of the permanent successors. Hardly any of the root canal filling materials currently on the market, however, are suitable for deciduous molars because some of them disappear earlier than the deciduous root without becoming indurated in the root canal, while some delay tooth replacement because they are resorbed with great difficulty, and continue strongly to stimulate the surrounding tissue of the root apex. Root canal filling materials utilizing alpha-TCP and hydroxyapatite with excellent biocompatibility have recently been put on the market by Sankin Kygyo Co. Type-III, in particular, contains only 5% iodoform, causing only very slight stimulation, and is a relatively good product from a practical standpoint, i.e., filling the root canal using a lentulo. Root canal filling was performed immediately after dental pulp extraction from the deciduous mandibular molars of juvenile dogs to determine the feasibility of filling deciduous teeth with root canal filling materials. Three dogs were then observed for sequential changes in the resorption of the deciduous roots, presence/absence of adverse effects on permanent successors, and influence on the process of eruption by means of radiographic examination every week. The results obtained were as follows: 1. The type-III apatite root sealar or Vitapex used for root canal filling was not absorbed, and there was almost no resorption of the root. Thus, the deciduous teeth on the experimental side were ejected and shed. 2. There was no significant difference in the amount of tooth germ formed between the experimental and control sides. 3. The amount of eruption tended to be delayed because of insufficient resorption of the root of the deciduous predecessor, but this tendency was considered to be due to the influence of the timing of root canal filling and individual difference. In the final analysis, no definite conclusions could be drawn.

Animals↗
PubMed1975

Periapical tissue reactions after pulp exposure in rat molars.

Apical periodontal lesions were produced in the rat molar by exposing the pulp to the oral environment. The natural history of the undisturbed lesion was studied at time intervals ranging from 2 days to 1 year postoperatively. The earliest reactions were usually inflammatory infiltration at the apex. The severity of the lesions was related to the amount of vital pulp still present in the tooth rather than to the time lapse after exposure. After 1 month most pulps has undergone necrosis and the lesions about the apices which followed showed two main types of reaction. In the case of the suppurative reaction, pus drained along a root surface, destroying the periodontal ligament and interradicular bone until it emerged at the gingival sulcus. The sinus tract could become lined with oral epithelium. In the reparative type of reaction, suppuration was absent or minimal and the apices were surrounded by fibrous connective tissue. The fiber bundles occasionally formed a collagenous scar, but they were usually replaced by cementum and bone with a new periodontal ligament. The width of the periodontium was never restored to its normal dimensions. Secondary destruction of the teeth occurred by fracture of cusps followed by caries which started in the exposed pulp chamber. Despite the predominance of destructive factors, spontaneous repair indicated good healing potential of the apical periodontal tissues.

Animals↗
PubMed1995

Canal configuration of the mesiobuccal root of the maxillary second molar.

The purpose of this study was to investigate the canal configuration in the mesiobuccal root of the maxillary second molar. The canal configuration of the mesiobuccal root of the maxillary second molar need not be the same as that of the maxillary first molar. Several studies have been attempted to clarify the configuration of the second molar, usually via postoperative evaluation, sectioning, or radiography. To follow more closely the clinical procedure, this study involved access cavity preparation and radiographs taken with files in place. Of the 73 extracted maxillary second molars investigated, 67 teeth (91.8%) had 3 roots whereas 6 teeth (8.2%) had 2 roots. In the three rooted teeth, the mesiobuccal roots of 40 (59.7%) were classified as type I (single canal from orifice to apex), 14 (20.9%) were type II (two canals merging short of the apex into a single canal at the apex), 11 (16.4%) were type III (two separate and distinct canals from orifice to apex), and 2 (3%) were type IV (single canal at the orifice, dividing in midroot into two canals exiting at the apex).

Dental Pulp Cavity↗
PubMed1975

Modification of stresses in alveolar bone induced by a tilted molar.

Stresses induced in the supporting bone by a tilted molar tooth under load have been investigated by both the photoelastic and the finite element model systems. The following conclusions were reached. 1. Altering the angle of the load applied to the unsupported molar from 0 (axial) to 30 degrees resulted in a fourfold increase in compressive stress in the supporting bone mesial to the tooth. 2. Increasing the load from 30 to 90 pounds while maintaining a 30 degree angle of application resulted in a linear increase in the shear stress on the supporting bone mesial to the tooth. 3. Following the placement of a fixed partial denture, the induced stress at a point on the mesial aspect of the molar tooth, subjected to a 60 pound load at 30 degrees to the long axis, was reduced from 241 to 43 p.s.i. 4. The introduction of a fixed partial denture resulted in a decrease in the compressive stress in the bone adjacent to the apex of the mesial root of the molar from 481 to 174 p.s.i. 5. A distributed 120 pound load applied over the length of the fixed partial denture compared against individual tooth loadings of 60 pounds revealed that placement of the fixed partial denture favored the tilted molar at the expense of the premolar.

Alveolar Process↗
PubMed1996

Pulp management in dens evaginatus.

A 12-yr-old Guamanian girl presented with seven premolars displaying dens evaginatus. The pulp of one tooth was necrotic secondary to fracture of the evagination. Calcium hydroxide treatment was used to induce closure of this root apex, and subsequent routine canal obturation resulted in clinical success. Three teeth had fractured evaginations and compromised coronal pulps, but the radicular pulp tissue was vital. Coronal calcium hydroxide pulpotomy procedures were performed, and root development continued on all three teeth. In one of these teeth, endodontic treatment was completed, and in the other two the radicular pulp remained vital. Three teeth had intact evaginations and vital pulps. In an attempt to protect these evaginations from trauma, composite reinforcements were placed around the evaginations. These pulps remained vital and the roots completed normal development. Early diagnosis and treatment should be sought in cases of dens evaginatus to provide the greatest opportunity for complete root development.

Bicuspid↗
PubMed2000

[Application of enamel matrix derivative for tooth transplantation and replantation].

OBJECTIVE: The purpose of this study was to clarify the effects of enamel matrix proteins on the regeneration of periodontal ligament (PDL), during transplantation and replantation therapy. MATERIALS AND METHODS: [Exp 1] The crown and root apex of extracted dog teeth were removed and the remaining root separated longitudinally. Two-thirds of crown-side PDL and cementum were removed. Prepared teeth were covered with propyleneglycol alginate (PGA) both with and without enamel matrix derivative (EMD) and cultured for 0-14 days. The outgrowth length of the tooth was measured and histological observation done. [Exp 2] The incisal teeth of adult dogs were extracted and 2/3 of crown side PDL and cementum removed. Prepared teeth were treated with PGA containing EMD (EMD group). No tooth treatment was done in the control group. Following PGA treatment, teeth were replanted. The animals were sacrificed at 2 and 4 weeks after replantation and histological observation performed. RESULTS: [Exp 1] The outgrowth length of the EMD group was longer than that of the other groups. The width of proliferated cell layer on the tooth in the EMD group was thicker. [Exp 2] Ankylosis surface of the EMD group was smaller than that of the control group. In the control group, the region of ankylosis increased longitudinally. In the EMD group, the newly-formed cementum was predominantly cellular cementum. CONCLUSION: The results suggested that enamel matrix protein enhance the regeneration of PDL and prevent tooth ankylosis in transplantation and replantation therapy.

Animals↗
PubMed2002

[Optimization of structural characteristics of a root canal wall during retrograde tooth filling on a basis of scanning electron microscopy data].

Studies by scanning electron microscopy showed that dentin of the root stump (resection of the root apex is an obligatory condition of retrograde filling) has numerous regular dentin tubules, in contrast to the apical part of the root. Mechanical treatment of dentin during preparation of the platform for retrograde filling leads to the formation of a thick "lubricating" layer on the surface of these platform. This layer consists of corpuscles of destroyed tissue substance (smudge) and completely covers the ends of dentin tubules, thus preventing the formation of strong bonds between the filling material and dentin surface. Treatment (pickling) of the platform surface with the conditioner notably improved the adhesion of Russian filling material Dentis to dentin. The best adhesive effect of retrograde filling was attained with Kemfil, the material requiring no pickling pretreatment.

Adhesiveness↗
PubMed2006

Histochemical and immunocytochemical study of hard tissue formation in dental pulp during the healing process in rat molars after tooth replantation.

Dental pulp is assumed to possess the capacity to elaborate both bone and dentin matrix under the pathological conditions following tooth injury. This study was undertaken to clarify the mechanism inducing bone formation in the dental pulp by investigating the pulpal healing process, after tooth replantation, by micro-computed tomography (mu-CT), immunocytochemistry for heat-shock protein (HSP)-25 and cathepsin K (CK), and histochemistry for both alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP). Under deep anesthesia, the upper right first molar of 4-week-old Wistar rats was extracted and immediately repositioned in the original socket. In control teeth at this age, the periphery of the coronal dental pulp showed intense ALP-positive and HSP-25-positive reactions, whereas there were no TRAP-positive or CK-positive cells. Tooth replantation weakened or terminated ALP-positive and HSP-25-positive reactions in the pulp tissue at the initial stages. At 3-7 days after operation, the ALP-positive region recovered from the root apex to the coronal pulp followed by HSP-25-positive reactions in successful cases showing tertiary dentin formation. In other cases, TRAP-positive and CK-positive cells appeared in the pulp tissue of the replanted tooth at postoperative days 5-10 and remained associated with the bone tissue after 12-60 days. Immunoelectron microscopy clearly demonstrated that CK-positive osteoclast-lineage cells made contact with mesenchymal cells with prominent nucleoli and well-developed cell organelles. These data suggest that the appearance of TRAP-positive and CK-positive cells is involved in the induction of bone tissue formation in dental pulp.

Acid Phosphatase↗
PubMed1976

Optimizing anterior and canine retraction.

Vertical loops or modified vertical loops are basically frictionless springs which are used for canine and anterior tooth retraction. The design and selection of a proper loop or retraction spring should be based on a number of scientific criteria. Foremost among these would be a sufficiently high moment-to-force ratio so that root apices are not displaced mesially or anteriorly. A retraction spring with zero angulation of its horizontal-occlusal arms delivers a moment when activated to produce a force. The ratio of this moment and force is constant throughout the elastic range of activation of the spring. The higher the moment-to-force ratio, the greater is the clinician's control over the apices of the anterior teeth. An analysis of design factors demonstrates that the higher the loop occluso-gingivally, the shorter its horizontal length occlusally, and the greater the gingival horizontal length as in a T loop; these are significant factors in increasing the moment-to-force ratio. The placement of helices is a useful design consideration but the main effect is in reducing the load-deflection rate. By keeping these design factors in mind, the clinician can build into his retraction springs, without the placement of any gable bend, the largest possible moment-to-force ratio so as to optimize his tooth movement. Although it may be possible to design retraction springs to deliver an adequate moment-to-force ratio for controlled tipping around the apex of an incisor or a canine, translatory movements are not possible, considering the intraoral limitations on spring height. This can be overcome by the placement of gable bends or angulation in a vertical loop or retraction spring. Unfortunately, with the typically used high-load-deflection-rate vertical loops, activation to achieve the desired moment-to-force ratio is too critical, exacting, and changeable with small displaced movements of the tooth. This can be partly overcome by utilizing designs that have not only the highest possible moment-to-force ratio during pure horizontal activation of their arms but low-load deflection rates as well. Because of the low load-deflection rate, moment-to-force ratios are relatively more constant if a gable bend (angulation) is placed. The science of spring design as applied to the problems of canine and anterior tooth retraction in this article allows the clinician to optimize the design of his retraction springs. More important, with properly designed springs, it allows him to estimate with relative accuracy the force systems produced and to avoid undesirable side effects which might not have been apparent from superficial observation.

Biomechanical Phenomena↗
PubMedDate not supplied

Maxillary cyst associated with an invaginated tooth: a case report and literature review.

Dental invagination or dens in dente is a rare malformation with a widely varied morphology. Radiographically, the affected tooth shows an infolding of the enamel and dentin that can extend to within the pulp cavity and the root and sometimes to the root apex. It can occur in both primary and permanent teeth, and its prevalence is reported to be 1.7% to 10%. The dental anomalies observed in association with dental invagination include taurodontia, microdontia, supernumerary teeth, gemination, and dentinogenesis imperfecta. This article presents a clinical case in which a radiographic finding could be compatible with the presence of a nasopalatine or globulomaxillary cyst and a dens in dente. It was decided to extract the invaginated tooth, and by 15 days postextraction, the radiolucid area had completely disappeared. The complex surgery that would have been required to remove the patient's supposed cyst was thus avoided. Clinical and radiographic examination is suggested before making further decisions that could complicate treatment when a lesion is associated with other dental anomalies.

Child↗
PubMed1990

[An immunohistochemical study on the response of nerve fibers in the periodontium of rat molars during experimental tooth movement].

It is well known that orthodontic forces induce pain during tooth movement. However there have been few neurohistological studies on sensational periodontal tissue response to orthodontic tooth movement. So we have many unknown problems about reactions of periodontal nerve fibers during tooth movement. The present study deals with the response of nerve fibers in periodontal ligament of rat molar during experimental tooth movement by means of immunohistochemical method for calcitonin gene-related peptide (CGRP). The results obtained in this study were as follows: 1. In control sections, CGRP-immunopositive nerve fibers were observed both around the root apex and in the intermediate region of the periodontal ligament. Although most of those fibers was distributed around the blood vessels, a few nerves were recognized to terminate in the periodontal fibers. 2. At three days after tooth movement, the CGRP-positive nerves gradually increased in number around the blood vessels. After that, the number of CGRP-positive nerves decreased and no difference of distribution of CGRP-positive nerves was observed between the control sections and the experimental sections at seven days. 3. Especially, at three days when active remodeling of alveolar bone was taking place, a few nerve fibers showing CGRP-immunoreactivity were observed to concentrate around osteoclasts or to migrate Howship's lacunae. These findings showed the dynamic changes of CGRP-immunoreactive nerves in the periodontal ligament during tooth movement, and suggested that this reaction of the periodontal nerves might induce pain in patients. In addition to neurotransmitter function, it was supposed that CGRP directly or indirectly effected the cellular elements and surrounding tissues on peripheral organs such as vascular system and osteoclasts.

Animals↗