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Reliability of hypocycloidal tomography for the evaluation of the distance from the alveolar crest to the mandibular canal.

When implants are to be inserted in the mandible posterior to the mental foramen, tomography is required to determine the exact location of the mandibular canal and assess the dimensions of the body and alveolar process. Previous studies have shown discrepancies between the true distance between the alveolar crest and the upper border of the mandibular canal and that measured from computed tomograms. This study evaluates the reliability of such measurements made from hypocycloidal tomograms. Six examiners, three radiologists and three oral surgeons, independently measured the distance from the alveolar crest to the upper border of the mandibular canal in transverse hypocycloidal tomograms of the mandible. Analysis of variance showed an average standard deviation between observers of 1.33 mm. This variation, which is the total of inter- and intra-observer variation conditional upon patient and radiograph, was mainly due to the latter which amounted to a mean of 1.04 mm. Calculation of lower confidence limits showed that these could be decreased by the use of several observers. Various confidence levels, equal to the probabilities of obtaining lower confidence limits which are below the true values, can be used to choose acceptable levels of risk in overestimating the true distance.

Alveolar Process↗

Extraradicular cemental fragments in the alveolar bone of prehistoric American Indians: report of three cases.

Heretofore unreported, grossly observable structures composed of cementum were found in the superficial alveolar bone--but not attached to the tooth root--in three prehistoric American Indian skeletons from South Dakota. The macroscopic, radiographic, and histologic morphology of these fragments is described and compared with other cemental structures that occur in the alveolar process.

Alveolar Process↗

Modified Thurow appliance: a clinical alternative for correcting skeletal open bite.

Open bite malocclusion is frequently discussed in orthodontics; diagnosis, treatment, and retention can be difficult because this malocclusion has numerous correlated etiological factors. The earlier this malocclusion is corrected, the better the prognosis will be, especially when the problem is skeletal. This article presents a patient with skeletal open bite who was treated in the mixed dentition with an orthodontic appliance that included an acrylic occlusal splint and an expansion screw, based on the original Thurow appliance, to guide the vertical force against the posterior teeth and the alveolar process.

Alveolar Process↗

Dento-alveolar development in unilateral cleft lip, alveolus and palate.

BACKGROUND AND OBJECTIVE: Palatal surgery for cleft lip, alveolus and palate is considered to have the most powerful negative impact on maxillary growth. The aim of this study was to compare dento-alveolar development of the permanent dentition and morphology of the palate after surgery in unilateral cleft lip, alveolus and palate patients following two types of palatoplasty: supraperiosteal flap vs mucoperiosteal flap technique. PATIENTS: Thirty-eight patients born between 1976 and 1983 with a complete unilateral cleft of lip, alveolus and palate were studied. Fifteen patients were treated with supraperiosteal flaps (SP group), and the other 23 patients with mucoperiosteal flaps (MP group). In this cross-sectional study, dental casts of stage IV A of Hellman's dental age in each patient were used. METHODS: The following distances were measured: (1). transverse distance C-C', (2). transverse distance M-M', (3). palatal length, (4). palatal height. RESULTS: No statistically differences were seen between the SP and MP groups regarding C-C' and M-M'. However, palatal length and palatal height were significantly greater in the SP than in the MP group. CONCLUSION: The technique that leaves no denuded palatal bone is considered to be advantageous for the development of the alveolar process.

Adolescent↗

[Contraindications to the use of extraoral forces in dentofacial orthopedics].

Following a brief and non-exhaustive review of the various types of extra-oral traction, the author stresses certain contra-indications which, in his opinion, should be borne in mind by the operator. These contraindications, are, essentially, a pathological mesiodistal orientation of the adult molars, reflecting dento-maxillary disharmony in the anterior segments, and an abnormality of inclination of the alveolar processes for which aetiological treatment is more rational.

Adult↗

Fourier and fractal analysis of maxillary alveolar ridge repair using platelet rich plasma (PRP) and inorganic bovine bone.

This report concerns the regeneration of the maxillary alveolar process in a 17-year-old patient who had lost the upper central incisors together with alveolar bone as a result of a car accident. Three months later, GBR (guided bone regeneration) was started with the use of autogenic platelet rich plasma (PRP) and inorganic bovine bone. The regenerated bone was analysed after 10 months and compared with intact bone using Fourier analysis of radiograms. The radial and spatial distribution of Fourier transforms showed that the original trabecular pattern existing in the intact bone on both sides of the defect was replicated in an evident way in the regenerated bone. Fractal analysis of intact and regenerated bone showed a higher fractal dimension for intact bone in comparison with regenerated bone, confirming a lower complexity of the newly formed trabecular structures. Replication of the original trabecular pattern in regenerated bone allows us to conclude that genetic mechanisms are influencing the organization of the trabecular pattern of regenerated bone tissue, probably under the influence of the growth factors contained in autologous PRP.

Adolescent↗

[Micro- and macrodistraction of the jaw. A sure method of adding new bone].

Vertical distraction osteogenesis (VDO) has been developed by our study group to move dentulous and edentulous segments of the alveolar process vertically with a device in microplate-design. Besides these techniques of vertical distraction of the atrophic alveolar crest some further modifications as Micro- and Macro-distraction are available. Micro-distraction can be used in localised small defects of the alveolar crest with microplates and screws of 1.0 mm in diameter. In a pilot study we could treat 6 patients especially after traumatic bone loss of the alveolus. The lengths of the segments were 12.6 mm, the vertical distraction rate was 9.2 mm in average. Macro-distraction we call the distraction of the severely resorbed mandible in order to rebuild the vertical dimension of the weakened mandible. Vertical distraction osteogenesis of 13.6 mm was completed successfully in five patients with large segments of 119 mm lengths in average in a sandwich-technique. With a solid 2.3 basic plate a secure stability of the weakened mandible could be achieved. In contrast to bone transplantation an earlier mineralisation in the vertically distracted area could be seen by radiological examination and biopsy. We could insert dental implants in both pilot groups 3 months after distraction procedure. Main advantages of vertical distraction osteogenesis are: 1. No bone harvesting, 2. decreased resorption, 3. lower morbidity compared with conventional techniques, 4. lower infection rate and 5. feasibility to insert dental implants 3 months after distraction procedure, 6. gain of soft tissue.

Adolescent↗

Rate of mesial translation of mandibular molars using implant-anchored mechanics.

Retromolar dental implants served as anchorage to close first molar extraction sites in five adult patients. Rates of unidirectional space closure for mandibular second molars were assessed with periapical radiographs superimposed on anatomical landmarks and retromolar anchorage implants. Regression analysis revealed that mesial displacement of the midroot area of the leading root was less variable (r = 0.97) than for other landmarks on the same teeth: crown (r = 0.83), alveolar crest (r = 0.82) or apex (r = 0.90). When mesial root movement (uprighting) was the principal feature of the initial mechanics (4 of the 5 patients), mesial movement of the apex was about 0.60 mm/mo for the first 8 months and then decreased to about 0.34 mm/mo as the trailing (distal) root of the second molar engaged the relatively dense bone formed by the leading (mesial) root. During the last year of space closure, radiolucent foci were noted 1-2 mm ahead of the distal root. These data suggest: (1) sustained orthodontic translation is a physiological manifestation of bone modeling and remodeling throughout the adjacent alveolar process, and (2) rate of mandibular molar translation is inversely related to the apparent radiographic density of the resisting alveolar bone.

Adult↗

Nonsurgical rapid maxillary alveolar expansion in adults: a clinical evaluation.

Palatal expansion in adults has traditionally been performed on a very limited basis. The expansion has been thought to be limited in scope and stability and to be associated with unacceptable complications. Instead, surgically assisted rapid maxillary expansion (SA-RME) has been advocated. Five adults with transverse arch deficiency are presented to illustrate the feasibility of nonsurgical expansion using the Haas appliance. Transmolar expansions of 3.9 to 7.5 mm, sufficient to correct the malocclusions, were achieved. Limiting the rate of appliance activation is thought to be important to avoid pain, swelling, and ulceration. Measurements of molar axial angulation, facial divergence, and clinical crown heights demonstrated modest molar tipping, stable mandibular divergence, and only minimal gingival recession. Radiographs revealed minimal observable root resorption of the maxillary molars and premolars. Contour tracings of the palate indicated that most of the correction of the maxillary transarch deficiency occurred at the level of the lateral walls of the palate (the alveolar process) rather than in the skeletal base of the maxilla. For this reason the technique is defined as rapid maxillary alveolar expansion (RMAE). RMAE is an acceptable alternative to SA-RME in adults for most cases of maxillary transarch deficiency. This article is followed by a commentary by Robert L. Vanarsdall Jr., and by an author's response.

Adult↗

Desmoplastic fibroma of the maxilla.

A case of desmoplastic fibroma of the right maxilla is reported. The lesion presented as a painless mass in the right posterior alveolar ridge of a 22-year-old white man. Histologically, the lesion was composed of interlacing fascicles of benign-appearing fibroblasts in a varying ground substance of collagenous and myxoid tissue. The lesion was not encapsulated histologically and was invading between bone trabeculae resulting in resorption of the bone. A review of the literature reveals that a total of 30 cases of desmoplastic fibroma of the jaws have been reported. All of the mandibular lesions except two were reported to have occurred in the left side, with the molar-ramus region favored. The case reported here is, to the best of our knowledge, the first reported case of desmoplastic fibroma occurring in the maxillary alveolar process.

Adult↗

Mechanism of Pneumocystis carinii attachment to cultured rat alveolar macrophages.

Pneumocystis carinii (PC) pneumonia begins as an intra-alveolar process resulting in injury to the alveolar epithelium with subsequent invasion of the lung interstitium. The clearance of PC organisms from the alveolar space is a critical function of alveolar macrophages (AM), the resident alveolar phagocytic cells. In this study the mechanism of PC attachment to AM was determined using 51Cr-labeled organisms, with PC attachment reaching a maximum of 18.9 +/- 2.5% after 4 h. Attachment was significantly decreased by preincubation of the AM with a monoclonal anti-fibronectin antibody directed against the cell attachment site of fibronectin (from 17.8 +/- 2.2% to 8.3 +/- 1.0%, P less than 0.01), or by addition of the fibronectin cell binding site analogue Arg-Gly-Asp-Ser (RGDS) (from 18.1 +/- 2.3% to 2.9 +/- 0.8%, P less than 0.01). An anti-fibronectin monoclonal antibody directed against the heparin binding domain of fibronectin had no effect on PC attachment. Addition of the specific calcium ion chelating agent EGTA to the culture media similarly decreased attachment from 16.9 +/- 2.0% to 5.1 +/- 1.1% (P less than 0.01). Fibronectin-mediated attachment of PC to AM did not result in phagocytosis of the organisms by the AM as determined by chemiluminescence measurements. Therefore, the data indicate that PC attachment to AM is a calcium-dependent process mediated by the cell binding domain of fibronectin which does not trigger a phagocytic response by the AM.

Amino Acid Sequence↗

Radiographic findings in 224Ra-caused dental resorptions.

Dental resorptions as a delayed effect of Thorium X (224Ra) were observed in four patients. The radiographic findings showed distinct and representative patterns. Apparently, the observed changes are typical for delayed alterations related to 224Ra-specific disturbances in the alveolar process. Degenerative and inflammatory reactions may also be involved in the pathogenesis.

Adult↗

Different responsiveness of alveolar and tibial bone to bone loss stimuli.

UNLABELLED: Mandibular and systemic bone loss are poorly associated. We compared the effect of isocaloric protein undernutrition and/or ovariectomy on BMD and microstructure of mandibular alveolar and proximal tibia sites in adult rats. Mandibular bone was significantly less affected. INTRODUCTION: Whether mandibular bone and axial or peripheral skeleton respond similarly to systemic bone loss remains a subject of controversy. We have previously shown that mechanical loading during mastication influences bone mass and architecture of the mandibular alveolar bone. Isocaloric protein undernutrition and ovariectomy are known to cause bone loss and deterioration of bone microarchitecture at various axial and peripheral skeletal sites. We studied how the mandible, which is subjected to heavy, abrupt, and intermittent forces during mastication, responds to low-protein intake and/or ovariectomy and compared this response to that of the proximal tibia in adult rats. MATERIALS AND METHODS: Forty-four 6-month-old female Sprague-Dawley rats underwent transabdominal ovariectomy (OVX; n=22) or sham operation (n=22) and were pair-fed isocaloric diets containing either 15% or 2.5% casein (sham 15%, n=11; sham 2.5%, n=11; OVX 15%, n=11; and OVX 2.5%, n=11) for 16 weeks. BMD and bone microarchitecture parameters (e.g., bone volume fraction [BV/TV] and trabecular thickness and number) of the mandible and the proximal tibia were measured at the end of the experiment using DXA and microCT. RESULTS: Mandibular alveolar bone was negatively influenced by both protein undernutrition and OVX, but to a significantly lesser extent than the proximal tibia. In sham-operated animals, low-protein intake led to a 17.3% reduction of BV/TV in the mandible and 84.6% in the tibia (p<0.001). In normal protein diet-fed animals, OVX led to a reduction of BV/TV of 4.9% in the mandible but 82% in the tibia (p<0.001). In the mandible, protein undernutrition resulted in thinner trabeculae (p<0.05), whereas OVX led to a reduction of trabecular number (p<0.05). CONCLUSIONS: Mandibular alveolar bone was found to be less sensitive to either protein undernutrition or OVX than the proximal tibia spongiosa. We hypothesize that the mechanical loading of the alveolar process during mastication may protect the alveolar bone from the detrimental effects observed in other skeletal sites, such as the proximal tibia. Morphological and embryological differences between the two skeletal sites might also play a role.

Alveolar Bone Loss↗

Bite force and its correlations in different denture types.

Maximal bite force was measured and intraoral condition was examined in 89 patients at the Institute of Dentistry, University of Turku. These patients formed three different denture groups: those with complete dentures, those with full maxillary denture and partial mandibular denture, and those with natural dentition or skeleton-supported partial maxillary denture and partial mandibular denture. There were three age groups: greater than or equal to 70, 60-69, and less than or equal to 59 years old. Maximal bite force was recorded with an appliance at seven different measuring points by placing a biting fork between the antagonistic teeth while at the same time the occlusion was stabilized contralaterally with a plastic tube. Maximal bite force had a correlation with age and sex (P less than 0.01). In partial-denture groups high bite force had a correlation with the breaking of dentures (P less than 0.001 and P less than 0.05, respectively). Satisfied patients had a higher bite force than dissatisfied ones. When there was some disturbance in occlusion, the bite force was smaller, especially in full-denture groups (P less than 0.001). Full-denture wearers also had a good bite force, but the best biting area was located more posteriorly than in patients who still had some natural teeth left in both jaws. Changes in the denture-bearing mucosa in patients with complete dentures and negative height of the mandibular alveolar process decreased the bite force slightly.

Age Factors↗

Quantitative effects of a nickel-titanium palatal expander on skeletal and dental structures in the primary and mixed dentition: a preliminary study.

The present study analysed the six-month effects of a nickel-titanium (NiTi) palatal expander on the dental and palatal structures of four primary (mean age 5.8 years) and nine mixed dentition children (mean age 8.7 years), with a posterior unilateral crossbite. Standardized dental and palatal landmarks were digitized using a three-dimensional (3D) electromagnetic instrument. Collected data were analysed with geometric-mathematical models. During a six-month interval, the natural growth and development of the dental arches and hard tissue palate was negligible, as assessed in seven control children (two in the primary dentition, mean age 4.4 years; five in the mixed dentition, mean age 7.7 years). In all children the crossbite was completely corrected. Indeed, dental expansion was always more than or corresponded to the palatal expansion. A smoothing of the size-independent (shape) palatal curvature in the transverse plane was observed. No differences in maximum palatal height were noted. Symmetrical derotation of the anchorage teeth in a distal direction occurred in almost all children. The inclination of the facial axis of the clinical crown (FACC) in the anatomical transverse plane of those teeth with differences between dental and palatal expansion always showed significant modifications (vestibular inclination up to 16.7 degrees). The clinical crown height of anchorage teeth remained nearly the same in all patients. No significant modifications in mandibular arch size were observed. The increase in maxillary arch width, especially in younger children, was probably due to a combination of different effects: opening of the midpalatal suture, tipping of the alveolar process, and molar tipping.

Alveolar Process↗

Histologic studies on the extension of the inflammatory infiltrate in human periodontitis.

This study was undertaken to re-examine early and recent morphologic descriptions of gingival and periodontal inflammation based on a study of gingival biopsies and block sections of human jaws. A collection of 350 autopsy and surgically retrieved jaw sections containing multiple teeth and displaying various stages of periodontal inflammation were subjected to routine histologic preparation and analyzed with step serial sections. 105 gingival biopsies, serially sectioned, including 15 clinically normal specimens, were also studied. The results of these investigations suggest that the inflammatory lesion extends into the alveolar process and elicits a response, often before evidence of crestal resorption or connective tissue attachment loss has occurred. Similarly, deep penetrations of inflammatory cells into the alveolar bone, periodontal ligament and periapical tissues, along with fibrosis and enlargement of the marrow spaces, were common findings with advancing disease. More widespread distributions of inflammatory cells than previously described were found in clinically normal gingiva, while in more inflamed gingiva, the inflammatory cell types found and their pattern of distribution varied greatly from individual to individual. These observations cast doubt on the perception of human periodontitis as a localized and marginal disease and suggest that its effects may be much more pervasive than previously thought.

Adult↗

The basic and applied biology of tooth eruption.

The dentition and the alveolar process of each jaw develop simultaneously so that, by the time the crown is completed and eruption begins, the crown is enclosed in a crypt within alveolar bone. Thus, the eruption of a tooth to its functional position involves discretely localized, bilaterally symmetrical bone resorption to produce an eruption pathway and bone formation to fill in the space previously occupied by the crown and growing roots. Studies of crypt surfaces during eruption confirm this polarization of alveolar bone metabolism around a tooth with respect to both bone cells and mineralized surface topography. Experimental studies of tooth eruption have shown that the dental follicle, the dense connective tissue investment of the tooth, is necessary for eruption and that neither bone resorption nor bone formation occur without the adjacent part of the dental follicle. Early in eruption the coronal part of the follicle accumulates mononuclear cells which have cytochemical and ultrastructural features of osteoclasts and the apical part of the follicle, a site of intense cell proliferation, binds epidermal growth factor (EGF). The dental follicle contains a variety of proteins and the concentration of several change during eruption. Prominent among them are a reduction in matrix metalloproteinases and an increase in protoglycans as eruption proceeds. The contribution of these changes to those in cell proliferation, migration and differentiation during tooth eruption present experimental opportunities for developmental biologists. The rate-limiting factor of the earliest (intraosseous) stage of tooth eruption is bone resorption and eruption can be accelerated or retarded by the local delivery of factors which increase or decrease the activity of osteoclasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Process↗