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PubMed2003

Predictability of soft tissue form around single-tooth implant restorations.

The objective of this study was to answer important questions about gingival responses to single-tooth implants: (1) Are papilla regeneration and sulcular recession expected results? (2) Do soft tissue profiles retain their sulcular form over an extended period? and (3) Do single-implant replacements require special restorative handling to achieve predictable soft tissue form? A retrospective, photographic examination was used to follow 55 single-implant restorations in 51 patients for a period from 1 to 9 years (mean 3.5 years). Papillae regenerated in 83.9% of implants for a mean growth of 0.65 mm mesially and 0.62 mm distally. The sulcular apex receded in 59% of patients for a mean of 0.06 mm. Complete papilla fill was noted in 75% of patients examined. Short- to long-term measurements revealed that papilla regrowth continued slightly and that sulcular recession abated. Papilla regeneration around single implants was a predictable outcome in this population; sulcular recession was not a predictable finding. Papilla levels demonstrated a tendency toward increasing height, and sulcular levels remained fairly constant over the long term. Predictable soft tissue profiles were achieved with a simplified implant prosthetic protocol, progressing directly from healing abutments to definitive crowns in most cases.

Adolescent↗

PubMed1991

Retrograde root filling with composite and a dentin-bonding agent. 2.

Investigations on retrograde root filling using a composite resin, Retroplast, bonded to the root surface with the dentin-bonding agent Gluma have been described. Here, detailed information is given about the surgical procedures. The aim was to obtain a thin retrograde composite filling on the root apex, made slightly concave, sealing the main root canal, accessory canals as well as dentinal tubules. Hemostasis was obtained primarily by applying 1% adrenaline and by using a needle suction tip, and care was taken not to damage the surrounding tissues by the various chemicals. The healing results, after up to 1 year, of 388 cases of various tooth types, treated with either retrograde composite or with amalgam were compared. The healing classification included four categories: 1) complete healing; 2) fibrous healing; 3) uncertain; and 4) failures. In the composite group, the healing rates were as follows: 74% showed complete healing, 4% fibrous healing, 15% uncertain, and 7% were failures. In the amalgam group, 59% showed complete healing, 3% fibrous healing, 30% uncertain, and 8% were failures. Complete healing occurred significantly more often after filling with Retroplast than after filling with amalgam (p less than 0.00005). Significantly fewer cases with complete healing occurred in lower front teeth in proportion to other tooth types. The number of immediate postoperative complications did not differ significantly between the composite and the amalgam groups.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1988

Differences between the bony interfaces of titanium and hydroxyapatite-alumina plasma-sprayed titanium blade implants.

Histopathologic study was done to reveal the difference of bony interface in the mandibular bone between titanium blade implants and titanium implants coated with the mixture of hydroxyapatite-alumina by the plasma-spray technique, using the improved undecalcified histologic technique and the image analyzing system. In 4 adult shepherd dogs, the implantation was performed in the molar region of the mandible 2 months after tooth extraction. The coated implants and the non-coated ones were inserted respectively in the mandibles. They were sacrificed on the 5th, 7th, 14th and 28th day postoperatively. In 5-day implant after insertion, granulation tissues or fibrous connective tissues were observed around both implants in bone tissues. In 7-day implant, osteoid tissues regenerated around the apex of both implants, but attached a little to them. In 14-day implant, osteoid tissues or woven bone regenerated around both implants and attached more to the coated implant (approximately 13.7%) than the non-coated one (approximately 6.0%). In 28-day implant, regenerative woven or lamellar bone attached much more to the coated implant (approximately 63.4%) than the non-coated one (approximately 8.8%). Bony interface increased remarkably in the coated implants, chronologically. The results showed that the plasma-sprayed hydroxyapatite-alumina coating was effective for the initial fixation of endosseous dental implants.

Aluminum Oxide↗

PubMed1992

Development of a teaching model for coronal access to the canine dentition.

A dolichocephalic canine skull was utilized to develop a teaching and study model for coronal access cavity preparation of the dentition. The teeth from the right side of the skull were extracted. Each tooth was radiographed in two planes to localize the "ideal" endodontic access point. Barium markers were placed over these points and each tooth was radiographed again to confirm the appropriate location of the marker. Access was created by drilling through the barium marker. Then, K-files were inserted through the access preparation into the root canal system. The teeth were radiographed with the K-files in place to verify straight pathways to the apices. Straight line access to the apex was obtained in all teeth. Creation of this model provides an opportunity for the veterinary dental student to develop and refine skills used in performing endodontic therapy. The model can be utilized by the veterinary dental practitioner in clinical practice.

Animals↗

PubMed1992

The effects of colony-stimulating factor-1 on tooth eruption in the toothless (osteopetrotic) rat in relation to the critical periods for bone resorption during tooth eruption.

The toothless (tl) rat is an osteopetrotic mutation characterized by a generalized skeletal sclerosis, reduced bone resorption, few osteoclasts and a total absence of erupted teeth. This mutation is not cured by bone marrow transplants from normal littermates. It is known that the skeletal defects in tl rats are greatly improved after treatment with colony-stimulating factor-1 (CSF-1). This investigation concerns the effects of CSF-1 on the development and eruption of the dentition of tl rats. Untreated tl rats had no erupted teeth by 56 days after birth, and the roots of incisors and molars were severely distorted by compression against bone. The apex of the mandibular incisor did not extend past the first molar and continued growth of its apical end produced odontoma-like masses consisting of distorted dentine and enamel matrices. In addition, few osteoclasts were seen on alveolar bone surfaces surrounding the developing teeth. Mutants given CSF-1 were characterized by delayed eruption of all molars and sometimes incisors. The incidence of incisor eruption was related inversely to the age at which CSF-1 treatment began. Molars of treated tl rats had well-developed roots similar to those in normal rats. Treated mutants had numerous osteoclasts in alveolar bone and well-developed haemopoietic marrow spaces in the mandible. Histochemical staining for both tartrate-resistant acid phosphatase and tartrate-resistant acid ATPase was reduced or negligible in osteoclasts of untreated tl rats, heavy in normal osteoclasts and of intermediate intensity in CSF-1-treated mutants.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Intraosseous lipomas: clinical features of a mandibular case with possible aetiology.

There are few reported cases of intraosseous lipoma of the jaws in the literature. The exact nature of these lesions is debatable, but it is widely accepted that they represent true benign tumours. In this presentation discussion is centered on a case of a lipomatous lesion of the mandible and is the first to be reported in relation to a retained apex. The features for and against this lesion being of a neoplastic origin are discussed. The characteristic histopathological finding was the presence of only mature adipose fat cells.

Female↗

PubMed2003

A preliminary in vitro study of the incidence and position of the root canal isthmus in maxillary and mandibular first molars.

AIM: To investigate in vitro the incidence and position of the root canal isthmus in extracted mesiobuccal roots of maxillary and mesial roots of mandibular first molars. METHODOLOGY: Fifty maxillary and 50 mandibular molars were included in the study. The mesiobuccal roots of maxillary molars and the mesial roots of mandibular molars were sectioned from their crowns in the furcation region and embedded in clear resin. Transverse serial 1-mm-thick sections from the apical 6 mm were prepared. The apical side of each section was stained with India ink and observed through a light microscope. The sample images were saved to disk using a digital camera and the root canals in terms of the number present and the incidence and classification of isthmuses. RESULTS: In the mesiobuccal root of the maxillary first molars, 70% had one canal, whereas 29.5% had two canals. In the mesial root of mandibular molars, 41% had one canal, whereas 59% had two canals. In some sections, more than two canals were found close to the apical foramen. The isthmus incidence was greatest 3-5 mm from the apex. In teeth having two canals, a complete or partial isthmus was frequently observed in the sections between 3 and 4 mm from the apex. Of the isthmuses present, 22% were complete and 37% partial in mandibular molars and 17.3% were complete and 11.7% partial in maxillary molars. CONCLUSIONS: The incidence of isthmus in the mesiobuccal root of the maxillary first molars and in the mesial root of the mandibular first molars was high, particularly in sections 3-5 mm from the apex. Cleaning the isthmus is a major challenge during root canal treatment.

Dental Pulp Cavity↗

PubMed1996

Initial stress differences between tipping and torque movements. A three-dimensional finite element analysis.

The aim of this study was to analyse the distribution of the stress on dental and periodontal structures when a simple tipping dental movement or torque movement is produced. A tridimensional computer model based on finite element techniques was used for this purpose. The model of the lower canine was constructed on the average anatomical morphology and 396 isoparametric elements were considered. The three principal stresses (maximum, minimum and intermediate) and Von Mises stress were determined at the root, alveolar bone and periodontal ligament (PDL). It was observed how the distribution of stress is not the same for the three structures studied. In all loading cases for bucco-lingually directed forces, the three principal stresses were very similar in the PDL. The dental apex and bony alveolar crest zones are the areas that suffer the greatest stress when these kind of movements are produced.

Alveolar Process↗

PubMed1985

A comparison of two- and three-dimensional incisor angles.

Two- and three-dimensional incisor angulations are compared in 40 patients using lateral radiographs and direct dental cast measurement using the Reflex Metrograph coupled to a computer. The two-dimensional upper and lower incisor angulations to the occlusal plane were also compared by the two methods. It was found that: The two-dimensional radiographic and three-dimensional dental cast inter-incisor angulation showed a significant difference at a probability level 0.01 greater than p greater than 0.001. The two-dimensional radiographic and two-dimensional dental cast upper left and right incisor angulations to the functional occlusal plane showed a significant difference at a probability level of 0.01 greater than p greater than 0.001. The significant differences can be attributed to the measurement of the incisor crown angulation in the dental cast measurement and the incisor tip and apex assessment in the radiographic technique. The system of dental cast measurement arguably provides a more realistic and reliable assessment of incisal angles than conventional radiographic measurement techniques.

Cephalometry↗

PubMed1990

[Experimental study on apatite ceramics used as endodontic endosseous implant].

UNLABELLED: The purpose of this study was to investigate the possibility of applying hydroxyapatite ceramics as endodontic-endosseous implants. The upper medial incisors of 3 monkeys (Macaca fuscatae) were used. To prepare the implant cavity, the teeth were extracted and drilled from the apex by steel burns under water-cooling. Then, dense hydroxyapatite implants, 10mm in length, 2mm in maximum diameter and 1/20 tapered, were inserted into the cavity to have the implant project 3-4mm above the apex. When the teeth with the implants were replanted, the bone around the apex was removed. The teeth were splinted to the neighbouring teeth for 1 month. Five months after the operation, the specimens were taken out and fixed by 10% formalin alcohol. They were embedded in polyester resin and undecalcified sections were prepared. The sections were stained with toluidine blue and observed under light microscope. RESULTS: 1) At 5 months, no ankylosis between the tooth and the surrounding alveolar bone was observed. 2) There was newly formed hard tissue which extended from the cementum, on the surface of the implant. 3) Fiber bundles were observed around the implants which connected the newly formed hard tissue to the surrounding bone tissue. The results suggest that the application of hydroxyapatite ceramics as an endodontic-endosseous implant is effective.

Animals↗

PubMed1994

Radiographic determination of canal length direct digital radiography versus conventional radiography.

This research compared the length determination images produced by Trophy and Regam direct digital radiographic systems with conventional E-speed radiographs. Size #15 K files were placed in the canals of 19 teeth of cadaver specimens and radiographed in a geometrically standardized bench device. Three evaluators estimated the length adjustment necessary to position the file at the apex. The mean estimated adjustment lengths were compared with the true, anatomically determined adjustment lengths. Statistical analysis with analysis of variance and the Student-Newman-Keuls test indicated no significant difference between direct digital thermal print images and conventional radiographs (p > 0.10). Length adjustment estimates with conventional radiographs were significantly more accurate than Regam high-resolution computer monitor images (p < 0.01). Additionally, it was determined that length adjustment estimates were significantly more accurate when the file was placed short of the apex (p < 0.001). The clinical relevance of these differences is discussed.

Analysis of Variance↗

PubMed2000

Endodontic anatomy of the root canals of lower incisors.

Ninety lower incisors of known age (18 to 20 yr, 30 to 40 yr and over 50 yr) were grouped into 2 sets of 45 pieces each. Cross sections of the root at 4 levels (coronal, middle and apical thirds and 2 mm from the apex) were employed to study: 1. The shape of the canals 2. The changes in diameter induced by age 3. The correlation at the apex of the maximum diameter of the root canal with the Dzero diameter of endodontic instrument. The results showed that the canal anatomy of lower incisors is not as simple as it appears to be and that it is characterized by the predominance of flat shapes even in the vicinity of the foramen. The statistical analysis showed that the dentin deposits, typically age-associated, are influenced by the morphological changes that take place. A true compensation occurs between the different buccolingual and mesiodistal diameters, particularly in the vicinity of the apex, to guarantee irrigation in old age and avoid calcification fo the canal. The correlation between the maximum diameter of the canal at 2 mm from the apex and the Dzero diameter of the instruments evidenced the difficulties involved in adequate apical preparation of these teeth, regardless of age.

Adolescent↗

PubMed1991

[Determination of working length in endodontics. 2. Endometric determination of canal length].

Electronic determination of endodontic working length has become very popular in the past few years. Nevertheles it has shown that the use of electronic apex locators cannot replace radiographic length determination, but can be a useful additional device in endodontics. Indication, benefits and limits of electronic length determination are described in this paper.

Dental Pulp Cavity↗

PubMed2002

An immunohistochemical study on hard tissue formation in a subcutaneously transplanted rat molar.

While dental pulp undergoes calcification following tooth replantation or transplantation, we actually know little about these mechanisms. We therefore conducted histological and immunohistochemical evaluations of mineralized tissue that formed in the pulp of rat maxillary molar transplanted into abdominal subcutaneous tissue. One, 2, 3, and 4 weeks post-transplantation, the teeth were investigated immunohistochemically using antibodies to osteocalcin (OCN), osteopontin (OPN), bone sialoprotein (BSP), dentin sialoprotein (DSP), and tissue non-specific alkaline phosphatase (TNAP). In the 1st week after transplantation, cell-rich hard tissue was formed at the root apex. At 2 weeks, formations of hard tissue, with few cells in the root canals and bone-like tissue in the coronal pulp chamber, were noted. After 3 and 4 weeks, the amounts of these hard tissues were increased. The immunolocalization of OCN, OPN, and BSP was seen strongly in coronal and apical hard tissues, but weakly in the root hard tissue. Conversely, DSP localized in the root hard tissue, but not in other newly formed hard tissues. At 1 week, TNAP localized along the periphery of the apical hard tissue and the lower surfaces of root predentin. These results demonstrate that the newly formed hard tissues in the pulp cavity of subcutaneously transplanted molars could be classified into three types, suggesting that these might be formed by type-specific cells.

Animals↗

PubMed1994

Apex locators in endodontics: which, when and how?

To ensure that root canal treatment is successful the clinician must accurately determine the working length of the root canal. Traditionally this has been determined using radiography, but electronic apex locators are increasingly being used. This article describes the locators available, the principles behind their use and gives guidelines on how and where to use them.

Dental Pulp Cavity↗

PubMed1988

Moment to force ratios and the center of rotation.

The purpose of this study was to investigate the relationship between moment to force (M/F) ratios and the centers of rotation by use of the finite element method (FEM). A three-dimensional FEM model was developed for the upper right central incisor on the basis of average anatomic dimensions. The center of resistance and centers of rotation were determined for varying M/F ratios applied at the midpoint of the crown. The center of resistance was located at 0.24 times the root length measured apical to the level of alveolar crest. The centers of rotation varied with the M/F ratios following a curve of hyperbola. The M/F ratio was -9.53 for root movement (Co at the incisal edge), -8.39 for translation, and -6.52 for tipping around the apex. It was found that even a small difference in the M/F ratios produced clinically significant changes in the centers of rotation.

Biomechanical Phenomena↗

PubMed2006

Dens invaginatus in an immature maxillary lateral incisor: a case report of complex endodontic treatment.

This case report presents the surgical endodontic treatment of an Oehlers Class II invaginated immature tooth. In this case, communication between the invagination and the pulp caused pulp necrosis, periapical inflammation, and cessation of root formation. The initial treatment goal was to achieve apexification and then fill both the root canal and the canal of the invagination. After a 6-month treatment with calcium hydroxide dressings, there was no healing radiographically and no sign of a hard tissue barrier in the apex. Periapical surgery with the placement of mineral trioxide aggregate (MTA) root-end filling was deemed successful at the 1-year recall. To treat dens invaginatus, both conventional and surgical endodontic treatment techniques should be considered. In dens invaginatus, conventional endodontic treatment modalities may be unsuccessful because of inadequate debridement and disinfection; however, subsequent periapical surgery and retrofilling with MTA may promote healing.

Adult↗

PubMed1997

Reliability of different electronic apex locators to detect root perforations in vitro.

The aim of this study was to evaluate the accuracy of the electronic apex locator Root ZX compared to the Sono Explorer Mark II Junior and Apit III in detecting root perforations. Extracted human teeth (n = 30) were perforated artificially in the middle third of the root and embedded in a box containing alginate. Detection of all perforations were carried out with K-files attached to the apex locators tested. The teeth were radiographed after each electronic measurement. The actual location of the tip of the file in relation to the external root surface and the radiographic determination of the perforations were carried out using a stereomicroscope. The mean distance of the tip of the file from the external outline of the root surface was short for all instruments and clinically acceptable (0.06-0.25 mm). There was no clinically significant difference between the morphometric measurements and the radiographic measurements. No statistical significance was found between large perforations (0.55-0.60 mm) and small perforations (0.25-0.40 mm). Under the conditions of this study, all electronic apex locators tested were acceptable clinical tools in the detection of root perforations.

Analysis of Variance↗