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PubMedDate not supplied

Aesthetic and prosthetic principles for single tooth implant procedures: an overview.

Loss of anterior maxillary teeth always results in bone resorption and loss of interdental papillae, making a single tooth replacement by an implant very difficult. When infections have been present and previous surgery at the apex of the root has taken place, bone destruction is substantial, increasing the resorption defect and aesthetic and prosthetic problems. The learning objective of this article is to describe the steps necessary for implant surgery and prosthetics. It includes bone regeneration procedures, implant placement, second stage surgery, reconstruction of interdental papillae, abutment selection, and the various prosthetic procedures. Several cases are used to illustrate.

Adult↗
PubMed2000

An in vitro comparison of 5 techniques for impressing dowel space preparations.

PURPOSE: This in vitro study compared 5 different dowel space impression techniques using polyvinyl siloxane impression material to determine which method produced fewer voids in the dowel space impression. MATERIALS AND METHODS: Five techniques were used to make impressions of a prepared dowel space in a simulated endodontically treated tooth. Technique I used a 25-gauge anesthetic needle to act as a vent at the apex of the preparation to reduce voids produced during the expression of light body impression material. The anesthetic needle was removed after the impression material was injected, and an impression post was then inserted to the depth of the preparation. Twenty impressions made using this technique were compared with other techniques that used the vent without a post, no vent with a post, no vent without a post, and a lentulo spiral with a post (Techniques II through V, respectively). The percentage of impressions with voids from each group was compared to determine which technique consistently produced a void-free impression of the complete preparation length. If voids were observed in the impression, the specimen was considered inadequate. RESULTS: The percents of void-free impressions using Techniques I through V were 100%, 70%, 40%, 60%, and 20%, respectively. CONCLUSIONS: Using a 25-gauge needle as a vent while expressing impression material into the dowel space followed by placing the impression post consistently produced void-free dowel space impressions.

Dental Impression Materials↗
PubMedDate not supplied

Detecting the apical constriction in curved mandibular molar roots--preflared versus nonflared canals.

BACKGROUND: Achieving and maintaining correct working length is critical to success in endodontic therapy. This involves placing the file in to the canal to feel the apical constriction, preparing the canal upto that extent and then filling the entire canal upto the apical constriction with gutta percha points. Detection of the apical constriction is affected if the coronal part of the canal is narrow or obstructed due to dentine deposition. This usually happens in curved canals and gives the operator a false feeling of the apical constriction. The aim of this study was to compare the effect on tactile detection of apical constriction in mandibular molars with curved roots, between the preflared and non-flared root canals. METHODS: This study was carried out at Armed Forces Institute of Dentistry, Rawalpindi, Pakistan, from February to April 2002. Seventy patients coming for the endodontic treatment of their mandibular first molars were selected. The study included only mandibular molars with curved mesial canals. The total no of patients were divided equally into the preflared and non-flared groups. In both groups a No. 15 K file was used to detect or feel the apical constriction but in the preflared group the coronal portion of the canal was flared/prepared using Hedstrom files (No. 25-55) and Gates Glidden Drills No. 02 to No. 05 before inserting the No. 15 file. The tooth was radiographed at this moment and the distance between the tip of the file and the radiographic apex was measured. The location of the tip was classified as: a) Within 1 mm of the radiographic apex, b) Under extended, more than 1 mm of radiographic apex, and c) Over extended, beyond the radiographic apex. RESULTS: In the non-flared group 31.4% belonged to group 'a', 40% to group 'b', and 28.57% to group 'c'. In the flared group 80% belonged to group 'a', 5.7% to group 'b', and 14.28% to group 'c'. CONCLUSIONS: Results of this study suggest that preflaring greatly improves the tactile sense to feel the apical constriction in curved canals.

Case-Control Studies↗
PubMed1999

Changes in root length from early to mid-adulthood: resorption or apposition?

A significant number of adults are seeking orthodontic treatment, therefore, it is important to determine the normal changes in root length (resorption or apposition) that occur at this stage of maturation, specifically between early and mid-adulthood. The purpose of the study was to determine on a longitudinal basis the changes in root length between 25 and 45 years of age in a normative untreated population. Two sets of complete mouth surveys were available at early and mid-adulthood, on a total of 26 subjects (12 males and 14 females). Each set consisted of at least 18 periapical radiographs. On each set of radiographs, the roots of 28 teeth were measured including incisors, canines, premolars, and first and second molars, in both the maxillary and mandibular arches. Root length was measured as the perpendicular from the root apex to a line connecting the mesial and distal points of the cementoenamel junction of each tooth. A total of 1456 teeth (1664 roots) were measured; 672 teeth in males and 784 teeth in females. Allowable intraexaminer and interexaminer measurement variability was predetermined at 0.5 mm. Paired and Student t tests were used to determine: (1) whether significant changes occurred with age; (2) whether there were differences between males and females for the incisors, canines, premolars, and molars; and (3) whether there were differences between the right and left sides. Statistical significance was predetermined at P </=.05. The present findings indicated that there were no significant changes in root length for all tooth types evaluated between 25 and 45 years of age, in both males and females. These findings are important for the orthodontist to recognize because they provide some assurance that there is no systematic shortening of root length between early and mid-adulthood.

Adolescent↗
PubMed1989

[Fundamental study of a local drug delivery system by means of intracanal medication. Influence of iontophoresis on the periphery of the root surface].

The purpose of this study was to evaluate a new system of drug delivery to periodontal pocket by means of intracanal dressing and additional iontophoresis in vitro. Forty extracted human teeth with a single root were used. After the root canal was prepared endodontically, the periphery root apex was painted with the Silux system (3 M Co.) to close the apical foramen. Each tooth was planted into an agar block. Three drugs (zinc iodide-iodine, penicillin G. potassium, minocycline HCl) were used (Table 1), and 50 microliters of each drug was injected into an individual root canal. Then a cathodic current (3 mA x 40 min) was applied using an automatic current volte regulater (PAV-200, Jooko Co.) with a platinum wire electrode inserted in the root canal (Fig. 1). The degree of drugs diffusion in the agar around teeth was estimated by individual color reactions zinc iodide-iodin test for starch, penicillin G. potassium test for phosphomolybdic acid, minocycline HCl test for ferric chloride). And also, the effects of root planing and etching by Quick Jet (Yosida Co.) on the root surface were evaluated in the same way. The results were as follow: 1. The degree of diffusion by intracanal electrical medication was greater in the cervical third area than the middle and apical third. 2. Several small areas stained by the iodo-starch color reaction were observed around the cervical root surface where greater diffusion was observed. 3. Many dentinal tubules were observed on a limited root surface where root planing and Quick Jet, were employed caused greater diffusion. 4. The results suggest the new delivery system for management of the microorganisms by intracanal medication and additional iontophoresis.

Humans↗
PubMed1992

Odontoblast-mediated regulation of the progression of dentinal caries.

Osteoblasts and odontoblasts are both derived from the same mesenchymal cell line. Our aim was to investigate whether the processes of bone destruction and dentinal caries are biologically similar. The working hypothesis was that after the initiation of caries in the enamel, its rate of progression in the dentine is regulated by cell-mediated factors. Experimental caries was induced in the rat with a high sucrose diet combined with Streptococcus sobrinus infection. Both destruction of dentine and its apposition in the pulp under the carious lesions were measured after vital staining with tetracycline. Caries progression and dentine apposition were higher in developing teeth prior to apex "closure" than in adult, fully-formed teeth. Rats placed on a cariogenic diet during tooth development had an increased rate of caries progression. Fluoride administration via the drinking water was associated with decreased dentine apposition and little progression of dentine caries during the developmental stages. Dentine apposition was enhanced in adult rats placed on fluoride administration, while caries progression was reduced, whereas in animals subjected to metabolic acidosis dentine caries progression was enhanced, with reduced dentine apposition. In contrast, alkalotic animals had less dentinal lesions and smaller ones than the controls. Three theories are advanced to explain the observed changes: (i) They may be associated with changes in alkaline phosphatase activity in the pulpo-dentinal complex, (ii) they may be mediated by ionic changes in the dentinal fluid, or (iii) they may reflect the liberation of growth factors from dentinal matrix.

Acidosis↗
PubMed1991

[Histologic observation of upper central incisors after surgical immediate torsion].

The purpose of this study is to verify the treatment results of rotated teeth by using surgical immediate torsion method. Seven upper central incisors in four monkeys were chosen in our experiment. The surgical treatment was accomplished by rotating the teeth in about 45 degree. The animals were sacrificed at 2, 3, 4 and 12 weeks after operation. The results showed that two of seven dental pulps were necrosis, three were injured and two were normal. Absorption of dental cementum and dentine occurred at the apex and the middle third of the root. There was no evidence of ankylosis between the tooth and bone tissues. According to our experiment, we think that the surgical immediate torsion method for treating rotated teeth is not available.

Animals↗
PubMed1988

Taurodontism: an anomaly of teeth reflecting disruptive developmental homeostasis.

Two models concerning morphometric traits occurring frequently in aneuploidy states posit, respectively, 1) that they reflect the expression of specific major oligogenes for that trait on the chromosome involved or 2) that they result from a generalized disruption of developmental homeostasis. In contrast to previous studies that have investigated variations in morphometric traits in a single aneuploidy state, this study investigates a single morphometric trait, taurodontism, as it occurs in otherwise normal individuals, in nonchromosomal syndromes, and in aneuploidy syndromes to determine whether the trait best fits the oligogene or the disrupted developmental homeostasis model. Taurodontism is diagnosed from dental radiographs. It is an extreme variation in tooth form seen in multirooted teeth in which the bifurcation or trifurcation of the roots is displaced toward the apex of the root, resulting in increased size of the pulp chamber. The point of furcation, and consequently the size of the pulp chamber, is a quasicontinuously distributed trait. The results indicate that taurodontism most likely is the result of disrupted developmental homeostasis.

Adolescent↗
PubMed2004

Surgical extrusion technique for clinical crown lengthening: report of three cases.

Although a number of techniques have been proposed for clinical crown lengthening procedures, all have some limitation in terms of function and esthetics. This report presents the clinical and radiographic results of a surgical extrusion technique for clinical crown lengthening. Atraumatic surgical extrusion using a specially designed instrument (Periotome) was performed in three cases in which it was expected that extensive resective osseous surgery would have to be used for crown lengthening. Full-thickness mucoperiosteal flaps were raised both labially and palatally. The tooth was carefully luxated and extruded to the desired position without damaging the marginal bone area or root apex. No rigid splint was applied. Clinical examinations performed for more than 1 year after surgery revealed probing depths < or = 3 mm around the teeth at all sites, without bleeding on probing. The teeth functioned normally, with near-normal mobility. Radiographs showed normal periodontal contour consistent with new bone formation in the periapical area. Radiographic analysis did not show any evidence of root or crestal bone resorption or endodontic problems. The technique presented could constitute an alternative surgical approach to performing crown lengthening; it does not induce functional or esthetic deformities, especially in the anterior region.

Adult↗
PubMed1999

Deposition of calcified tissue around an overextended gutta-percha cone: case report.

CASE REPORT: Root canal treatment was performed in a mandibular right second premolar with a periapical lesion and apical resorption. The root canal was prepared with K-files using the step-back technique and 3% NaOCl as an irrigant; during obturation gross overfilling of gutta-percha occurred. The tooth was permanently restored with a post and core along with a crown. Although healing of the periapical lesion occurred and the patient reported that he was symptom-free, the tooth was extracted after 4 years because of a subgingival root fracture. Following extraction the tooth was examined with SEM. The examination revealed the presence of newly formed calcified tissue at resorption sites on the root apex. This newly formed tissue extended from the surface of the root around the apex to the extruded gutta-percha cone to which it was well adapted, forming a bridge between the cone and the root.

Adult↗
PubMed2000

Biomechanics of cervical tooth structure lesions and their restoration.

OBJECTIVE: The purpose of this study was to evaluate photoelastically the effects of a cervical tooth structure lesion and its restoration on stress distribution within a tooth. METHOD AND MATERIALS: Three-dimensional composite models of a maxillary first premolar with a buccal cervical lesion were fabricated. Two types of cervical lesion were tested: one was wedge shaped and had a sharp line angle at the apex of the lesion, and the other was more rounded and saucer shaped. Vertical loads of 10 lb were applied to the unrestored and restored models at the tip of the buccal cusp, the tip of the lingual cusp, and the center of the occlusal surface. The resulting stresses within the tooth model were monitored and recorded photographically in the field of a circular polariscope arrangement. RESULTS: In the unrestored situation, stress concentrated at the apex of the lesion, regardless of the lesion configuration. However, the sharper, wedge-shaped lesion demonstrated a more severe stress concentration. In the restored situation, stress around the lesion apex and the lingual cervical lesion decreased, while stresses at the gingival and occlusal margins of the lesion increased, compared with the unrestored situation. These tendencies were most obvious when the buccal cusp was loaded. CONCLUSION: The presence of a cervical lesion changed occlusal load-induced stress distribution and concentrated stress at the apex of the lesion. The shape and dimension of the lesion governed the severity of stress concentration. Restoration of the cervical lesion relieved concentrated stress at the apex of the lesion.

Bicuspid↗
PubMed2004

Surgical removal of supernumerary teeth and the fate of incisor eruption.

AIM: The aims of this study were firstly to determine the fate of unerupted permanent maxillary incisor teeth following supernumerary tooth removal and secondly to make recommendations regarding the management of such incisor teeth following supernumerary tooth extraction. STUDY DESIGN: This is a retrospective study. METHODS: Records of children attending the Departments of Paediatric Dentistry, Edinburgh Dental Institute, Lothian Primary Care NHS Trust and Dundee Dental Hospital, Tayside University Hospitals Trust between 1995 and 2002 were examined with regard to non-eruption of one or both maxillary central incisors in association with supernumerary teeth requiring surgical removal. Subsequent permanent maxillary incisor eruption was recorded and in those cases of incisor non-eruption, further surgical interventions were noted. RESULTS: In all 118 sets of patient records were included in the study (87 males, 31 females) with a mean age at presentation of 8.8 years (range 5.3-11.6 years). Failure of eruption of the associated permanent maxillary central incisor teeth occurred in 27% of cases, in relation to both conical and tuberculate supernumerary teeth. All tuberculate supernumerary teeth associated with non-eruption cases were palatally placed and 59% were adjacent to maxillary incisors with near complete apex formation. To facilitate incisor eruption in these cases, 41% required surgical exposure of the non-erupted incisor tooth and 59% required surgical exposure with bonding of an orthodontic bracket and gold chain for orthodontic traction. CONCLUSION: Non-erupted permanent maxillary incisor teeth with near complete apical formation, associated with palatally placed, tuberculate-shaped supernumerary teeth, may benefit from having an orthodontic bracket and gold chain placed at the same time as the surgical procedure to remove the supernumerary tooth to facilitate future orthodontic traction.

Child↗
PubMed2004

Central adenoid cystic carcinoma of the mandible manifesting as an endodontic lesion.

AIM: To present a case of adenoid cystic carcinoma (ACC) in the mandible, and manifesting as a periapical lesion. SUMMARY: A 56-year-old male suffered from pain around the right mandibular first molar for approximately 1 week. Oral examination revealed that the involved tooth was restored by a full coverage crown with no obvious abnormalities. A periapical radiograph revealed two ill-defined radiolucencies associated with the tooth, one over the mesial and another over the distal roots of the tooth; incomplete root filling and furcation involvement also being noted. The affected tooth was extracted based on the clinical impression of apical periodontitis. The surrounding tissue of the root apex was curetted and sent for histopathological examination, which revealed ACC. KEY LEARNING POINTS: Adenoid cystic carcinoma affecting the mandible may mimic a periapical lesion. Proper diagnosis of such a lesion is dependent on thorough clinical, radiographic and microscopic examinations. Such a case highlights the benefits of biopsy and histological examination of collected tissues. Diagnosis of lesions in the mandible should include salivary gland tumours.

Carcinoma, Adenoid Cystic↗
PubMedDate not supplied

[Observations of fleas of small mammals at the Gran Paradiso National Park (Italian Occidental Alps)].

The Siphonaptera of small mammals (nearly 200 rodents, insectivora and mustelids) of the Parco Nazionale del Gran Paradiso (Western Italian Alps) have been collected and studied during the years 1973-75. All the animals have been captured at altitudes ranging from 1570 to 2400 m during different seasons. Twelve genera and sixteen species have been identified, namely: Chaetopsylla (C.) homoea homoea from Mustela erminea; Hystrichopsylla (H.) talpae talpae from Clethrionomys glareolus; Rhadinopsylla (A.) integella integella from Clethrionomys glareolus and Microtus nivalis; Ctenophtalmus (C.) agyrtes verbanus from Pitymys multiplex (collected by Beaucournu); Ctenophthalmus (C.) solutus solutus from Apodemus flavicollis and Apodemus sylvaticus; Ctenophthalmus (Medioctenophthalmus) nivalis nivalis from Clethrionomys glareolus, Microtus nivalis and Pitymys multiplex; Doratopsylla dasycnema cuspis from Sorex araneus and Clethrionomys glareolus; Palaeopsylla soricis rosickyi from Sorex araneus; Leptopsylla segnis from Apodemus sylvaticus and Mus musculus; Peromyscopsylla bidentata bidentata from Clethrionomys glareolus and Microtus nivalis; peromyscopsylla fallax from clethrionomgs glareous; Amphipsylla sibirica ssp. from clethrionomys glareolus and microtus nivalis; Malaraeus (Amalaraeus), penicilliger kratachvili from Clethrionomys glareolus, Microtus nivalis and Mustela erminea; Myoxopsylla laverani from Eliomys quercinus; Callopsylla saxatilis from Apodemus flavicollis, Microtus nivalis and Mustela erminea. Species of fleas not yet described in Italy are: Chaetopsylla (C.) homoea homoea; Rhadinopsylla (Actenophthalmus) mesa; Ctenophthalmus (Medioctemophthalmus) nivalis nivalis; Callopsylla saxatilis. The genus Callopsylla is identified for the first time in Italy. New identification of hosts for the species of fleas already described in Italy are: for Rhadinopsylla (Actenophthalmus) integella integella: Clethrionomys glareolus; for Ctenophthalmus (C.) solutus solutus: Apodemus flavicollis and Apodemus sylvaticus. All the 15 male specimens of M. laverani from E. quercinus captured in the Parco Nazionale del Gran Paradiso have characters more similar to M. l. traubi than to M. l. laverani: only one long and a much shorter spine in the superior half of the movable process, a distinct tooth in the anterior margin of the movable half of the movable process, a distinct tooth in the anterior margin of the movable process, crochets of phallosome shorter and more gradually tapered, apex of fixed process very acuminated. To the contrary the shape of the movable process is similar to that of M. l. laverani. A point of particular interest is to be found also in 2 specimens of Amphypsilla of the sibirica group, respectively collected from Mustela erminea and Microtus nivalis. They have a very atypical distribution of the spine in an abnormally shaped movable process: the reasons of the abnormality are due to castration, probably of parasitic origin (absence of phallosome, tendons, etc.).

Animals↗
PubMed1996

Radiographic evaluation of the effect of orthodontic retraction on the root of the maxillary canine.

OBJECTIVES: To evaluate possible apical root resorption following orthodontic retraction of the maxillary canine quantitatively and qualitatively. METHODS: Twenty maxillary canines in 12 patients were retracted using a prefabricated orthodontic spring. Twenty non-treated mandibular canines from the same patients served as controls. Standardized radiographs were taken of all upper and lower canines before (T0) and after (T2) retraction. Root length and tooth length were measured on the radiographs at T0 and T2, and the root length/tooth length ratio was calculated. Ten orthodontists assessed blind the root apex of the pairs of radiographs taken at T0 and T2 for resorption. Digital subtraction was performed between the pairs of radiographs taken at T0 and T2 and the mean density and the standard deviation of the grey shades of the root apex calculated. RESULTS: There were no significant differences between root length/tooth length ratio at T0 and T2 for either the maxillary (p = 0.45) or the mandibular canines (p = 0.79). There was considerable variation between observers judgements of root resorption: nine out of ten observers agreed that a resorption had taken place in only one tooth. There were no significant differences between the mean density values in the subtraction images of the upper and lower canines (p = 0.3). CONCLUSIONS: Quantitative assessment with conventional and subtraction radiography failed to demonstrate root resorption in the maxillary canines. Root resorption could be shown qualitatively in only one tooth. The standardized orthodontic force system used for canine retraction appeared to cause no resorption, or only a small degree of resorption of no clinical relevance.

Adult↗