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PubMed2005

Radiographic evaluation of dental implants placed using an osteotome technique.

BACKGROUND: The osteotome technique has been successfully used for implant placement when a limited vertical height is available at posterior maxilla. However, it is not clear if new bone is formed at the apical portion of the implant placed by this technique without any bone graft. The aim of this study was to radiographically evaluate bone formation around dental implant surfaces exposed to the space created at the sinus floor without the presence of any graft material. METHODS: Forty patients (21 male, 19 female; mean age 46.7 years) who received a total of 75 dental implants together with indirect sinus lifting procedure were included. Initial and 6-month postoperative panoramic films were scanned and analyzed using a commercially available software program. Implants were divided into two groups: initial alveolar bone height <9 mm or > or =9 mm. This helped determine the effect of available bone and exposed implant surface on bone formation in a system where the shortest implant was 8 mm. RESULTS: The mean implant length placed at locations with <9 mm initial bone height (mean 7 +/- 1.3 mm, N = 29 implants) was 11 +/- 1.7 mm; gain in bone height was 3.9 +/- 1.9 mm. At locations where minimum bone height was 9 mm (mean 10.4 +/- 0.7 mm), 44 implants were placed with a 13.5 +/- 1.06 mm mean length. Mean gain in bone height was 2.9 +/- 1.2 mm at these sites. Two implants were lost at stage 2 surgery. The success rate after 25 months of loading was 97.3%. CONCLUSIONS: It is possible to radiographically observe a gain of approximately 3 to 4 mm of bone from the sinus floor to the implant apex. The amount of initial alveolar bone height, presence of sinus membrane perforation, and the amount of exposed implant surface appear to play a role in the presence or absence of radiopacity within the elevated sinus floor, following 6 months of healing.

Alveolar Process↗
PubMed1993

Cortical bone mineral density in the mandible and osteoporosis status in postmenopausal women.

Mineral density of the cortical bone of the mandible was determined by single-energy QCT (quantitative computed tomography) for 77 menopausal women. Bone mineral densities (BMD) were measured in the buccal and lingual layers of the cortex, distally from the foramen mentale, on both sides of the mandible. All the women were edentulous in that region, and the alveolar processes were far resorbed. These results were compared with the BMD values of the femoral neck, lumbar spine, and trabecular portion of the mandible between the detected layers of cortex. The BMD of the buccal cortex correlated remarkably well with all values, except those of the trabecular portion. Of the women tested, the correlations were lowest in the least osteoporotic group. The values for the lingual cortex did not correlate with other variables as well as did those for the buccal cortex, but in the most osteoporotic part of the sample the lingual cortex values correlated significantly with the BMD of the trabecular portion. The BMD values for the buccal cortex were significantly higher than those for the lingual cortex.

Absorptiometry, Photon↗
PubMedDate not supplied

Supracrestal bone formation around dental implants: an experimental dog study.

To test the osteopromotive activity in large non-spacemaking alveolar bone sites, a total of 20 titanium dental implants were placed superior to a previously modified mandibular alveolar process in five adult beagle dogs. The supracrestal implant position resulted in a mean buccal dehiscence of 5.1 +/- 1.03 mm and a mean supracrestal bone deficit of 2.69 +/- 0.45 mm. Three treatment groups were randomly assigned: group I, ten implants treated with a titanium-reinforced expanded polytetrafluoroethylene (ePTFE) membrane (TR); group II, six implants treated with a standard ePTFE membrane (ST); and group III, four implants that received no membrane (control). Before mucoperiosteal flap closure, the bone surface was perforated and peripheral blood was injected around the implants and underneath the membranes. Clinical evaluation of submerged implant sites showed evidence of complete regeneration of the peri-implant bone defects in groups I and II, minimal bone formation in control group III, and a widening of the ridge in group I. Corresponding histologic examination of undecalcified sections demonstrated large amounts of newly formed bone beneath both types of membranes with a superficial layer of loose connective tissue. Mean gain of supracrestal regenerated bone amounted to 1.82 +/- 1.04 mm (TR group), 1.90 +/- 0.30 mm (ST group), and 0.53 +/- 1.34 mm (control group). Mean bone regeneration at the buccal dehiscences was 3.33 +/- 1.44 mm (TR group), 2.46 +/- 0.51 mm (ST group), and 2.76 +/- 0.84 mm (control group). The TR membranes showed evidence of increased alveolar bone width compared to ST membranes and control sites. These results suggest that supracrestal bone regeneration can successfully be enhanced by a submerged membrane technique in the dog model and that the titanium-reinforced membranes were able to maintain a large, protected space for blood clot stabilization without the addition of bone grafts and produced a larger bone quantity when compared to standard membranes.

Alveolar Bone Loss↗
PubMed2003

Fate of monocortical bone blocks grafted in the human maxilla: a histological and histomorphometric study.

Local bone defects in the anterior maxilla are commonly grafted with monocortical blocks of autologous bone in order to restore the defect site prior to the placement of dental implants. Increasing evidence suggests that osteocytes are involved in the control of bone remodelling and thus may be important for optimalisation of bone structure around implants, and thus for implant osseointegration. However, it is not well known whether osteocytes will survive when bone blocks are grafted into defects. We grafted 19 patients with monocortical bone blocks derived from the symphysis, to the defect site in the maxillary alveolar process. The bone grafts were left to heal for times varying from 2.5 to 7 months. During implant installation, bone biopsies were removed using a trephine burr, and processed for hard tissue histology. Bone histology and histomorphometry were then carried out in order to gain insight into the density, viability and remodelling of the graft. Clinically, all the bone grafts were successful, with no implant failures, and little resorption was seen. Histologically, bone volume expressed as percentage of tissue volume at the implant site varied from 27% to 57% with an overall average of 41%. Bone fields with empty osteocyte lacunae were observed and measured. The amount of this so-called nonvital bone (NVB) varied between 1% and 34% of the total tissue volume. The amount of NVB decreased significantly with the time of healing. The data suggest that the majority of the osteocytes of the monocortical bone do not survive grafting. The results indicate that the NVB is progressively remodelled into new vital bone 7 months after grafting.

Adolescent↗
PubMedDate not supplied

A prospective clinical study evaluating the safety and effectiveness of narrow-diameter threaded implants in the anterior region of the maxilla.

The aim of the present study of single-tooth implants was to compare the success rate and marginal bone resorption of a narrow-diameter self-tapping implant placed in less available bone volume with the standard-diameter self-tapping implant placed in a well-dimensioned alveolar process. A new abutment technique and a different permanent abutment design were also evaluated. Fifty-five patients were included in the study; 27 patients received 28 standard-diameter (3.75-mm) implants, and 28 patients received 32 narrow-diameter (3.25-mm) implants replacing either a central or a lateral incisor in the maxilla. In an attempt to create an ideal emergence profile and to regenerate papillae, individual acrylic resin tooth-shaped temporary abutments were fabricated, based on impressions made immediately following implant placement, and connected to the implant after 6 months. A minimum of 2 months were then allowed before definitive restorative procedures were performed. Impressions were always made at the implant level. Follow-up examinations were performed at 6 months after loading and 1, 2, and 3 years after loading. Two narrow-diameter implants were lost after 6 months, but no other failures were subsequently observed in any of the groups after that. In both groups, marginal bone loss followed the same pattern and was recorded radiographically to be a mean of 0.4 mm from the first to the last examination.

Adolescent↗
PubMed1998

Evaluation of filling materials in membrane--protected bone defects. A comparative histomorphometric study in the mandible of miniature pigs.

In recent years, bone grafts and bone substitutes have been increasingly utilized underneath barrier membranes to optimize the treatment outcome of bone reconstructive therapy for defects in the alveolar process. In the present study, 4 different filling materials were evaluated in bone defects of similar dimensions in the mandible of miniature pigs. Blood clots and autografts were used as controls. The defects were covered with barrier membranes and allowed to heal for 4, 12 or 24 weeks. Histologic examination demonstrated that bone repair progressed through a programmed sequence of maturation steps closely resembling the pattern of bone development and growth regardless of whether bone grafts or substitutes were present or not. Histomorphometric analysis showed that autologous bone grafts (autografts) had the best osteoconductive properties during the initial healing period, with 39% of newly formed bone inside the membrane-covered defects at 4 weeks of healing. In addition, 87% of the graft surfaces were already covered by bone at this time. Both values were significantly higher for autografts than for the 4 alternative bone fillers (P < or = 0.05). At 12 weeks, these differences were no longer apparent, with all 5 filling materials showing similar values. Among the tested bone substitutes, tricalcium phosphate (TCP) showed a significantly higher percentage of bone fill at 24 weeks of healing. It can be concluded that sites filled with autografts clearly demonstrated the best results underneath barrier membranes in the early phase of healing. As far as degradation and substitution are concerned, TCP showed the most promising results. This filler, however, needs to be tested further in a more demanding animal model. Less favorable results were obtained for coral-derived hydroxyapatite granules and for demineralized freeze-dried bone allografts.

Alveolar Bone Loss↗
PubMed1999

Arterial blood supply of the maxillary sinus.

Knowledge of the arterial supply of the maxillary sinus region is essential for surgical treatment in this area (e.g., implantation of grafting materials, repair of injuries, sinus floor elevation). The goal of this study was to describe the arterial architecture of the maxillary sinus region in respect to sinus lift procedures. In 18 unfixed human cadavers, the arterial vessels of the head were injected with a mixture of latex and barium sulfate. Afterward, the arteries entering the maxilla were prepared. The number and calibers as well as anastomoses were carefully documented. In addition, we measured the distance between the alveolar ridge and the lower main branches. The arterial supply of the maxilla originated from the posterior superior alveolar artery as well as from the infraorbital artery. In all specimens we found an intraosseous anastomosis between these two vessels. The oral mucosa in the area of interest is supplied by the posterior superior alveolar artery and the infraorbital artery, and an extraosseous anastomosis was found in 44% of our cases. The two anastomoses build up a double arterial arcade, supplying the lateral wall of the antrum and parts of the alveolar process.

Aged↗
PubMed2000

Experimental observation, theoretical models, and biomechanical inference in the study of mandibular form.

Experimental studies and mathematical models are disparate approaches for inferring the stress and strain environment in mammalian jaws. Experimental designs offer accurate, although limited, characterization of biomechanical behavior, while mathematical approaches (finite element modeling in particular) offer unparalleled precision in depiction of strain magnitudes, directions, and gradients throughout the mandible. Because the empirical (experimental) and theoretical (mathematical) perspectives differ in their initial assumptions and their proximate goals, the two methods can yield divergent conclusions about how masticatory stresses are distributed in the dentary. These different sources of inference may, therefore, tangibly influence subsequent biological interpretation. In vitro observation of bone strain in primate mandibles under controlled loading conditions offers a test of finite element model predictions. Two issues which have been addressed by both finite element models and experimental approaches are: (1) the distribution of torsional shear strains in anthropoid jaws and (2) the dissipation of bite forces in the human alveolar process. Not surprisingly, the experimental data and mathematical models agree on some issues, but on others exhibit discordance. Achieving congruence between these methods is critical if the nature of the relationship of masticatory stress to mandibular form is to be intelligently assessed. A case study of functional/mechanical significance of gnathic morphology in the hominid genus Paranthropus offers insight into the potential benefit of combining theoretical and experimental approaches. Certain finite element analyses claim to have identified a biomechanical problem unrecognized in previous comparative work, which, in essence, is that the enlarged transverse dimensions of the postcanine corpus may have a less important role in resisting torsional stresses than previously thought. Experimental data have identified subperiosteal cortical thinning as a culprit in diminishing the role of cross-sectional geometry in conditioning the strain environment. These observations raise questions concerning the biomechanical significance of mandibular form in early hominids, fueling persistent arguments over whether gnathic morphology can be related to dietary specialization in the "robust" australopithecines. Nonmechanical explanations (e.g., tooth size or body size) for Paranthropus mandibular dimensions, however, are not compelling as competing hypotheses. Both theoretical and experimental models are in need of refinement before it is possible to conclude that the jaws of the "robust" australopithecines are not functionally linked to elevated masticatory loads.

Animals↗
PubMed2001

Follicular or dentigerous (tooth-containing) cyst in the premaxilla of an otherwise edentulous 65-year-old man.

A unilocular follicular or dentigerous cyst (FDC) with a diameter of 12 mm was observed incidentally in the premaxilla of a midsagittal section of the head of a 65-year-old cadaver. The mucosal lining of the cyst was grey in color and granular in texture: the osseous walls had a thickness of less than 1 mm. In the floor of the cyst, a slender, fully developed incisor tooth was fixed in a horizontal position. The alveolar processes of the maxilla and mandible were completely edentulous. Postmortem computer tomography showed the cyst in an osteolytic lesion of the premaxilla, and histology revealed a lining of non-keratinized stratified squamous epithelium supported by a lamina propria of dense connective tissue.

Aged↗
PubMed2002

Apparently new osteodysplastic and primordial short stature with severe microdontia, opalescent teeth, and rootless molars in two siblings.

A Thai man and his sister affected with a newly recognized syndrome of proportionate primordial short stature are reported. The patients had severe intrauterine and postnatal growth retardation, prominent nose and nasal bridge, small pinnae, large sella turcica, areas of hypo- and hyperpigmentation of skin, dry and thin scalp hair, and long and straight clavicles. Ivory epiphyses and cone-shaped epiphyses of the hands were found when they were young, but most of them disappeared as they grew up. Scaphoid and trapezium had angular appearance. The second toes were unusually long. Distal symphalangism of toes and barchymesophalangy of fingers were noted. The findings that appear to distinguish this syndrome from the previously reported syndromes are long second toes, opalescent and rootless teeth, severe microdontia, severely hypoplastic alveolar process, and unerupted tooth. The mode of inheritance is suspected to be autosomal recessive.

Abnormalities, Multiple↗
PubMed1980

Experimental stress analysis of topographic diversity in early hominid gnathic morphology.

Reconstructing the biomechanics of early hominid mastication is a key element in most models of hominid differentiation. Traditionally, osteological features marking muscle attachment surfaces have served as a reference system from which the vector geometry of the masticatory force system and resultant force distributions could be predicted. To augment traditional morphological and computational approaches, we developed a simulation system capable of replicating human and non-human primate chewing motions. The forces of occlusion are recorded as photoelastic fringes in a urethane alveolar process. Simulation experiments evaluating the functional correlates of topographic diversity in zygomatic root position and mandibular ramus height in early hominids indicated that the mandibles and dentitions of robust australopithecines are well adapted to sustain high magnitude, low gradient load distributions.

Animals↗
PubMed1983

Alveolar dehiscences and fenestrae in dried South African Negro mandibles.

The buccal and lingual roots of 1077 teeth from 100 mandibles of South African Negroes were examined for the presence of dehiscences and fenestrae. All specimens were obtained from cadavers of known sex, tribe, and stated age; 10.5% of teeth were affected. Canines and first premolars were the most common teeth associated with dehiscences and fenestrae. Dehiscences occurred more commonly than fenestrae (1:0.49). The defects were found exclusively in the buccal plate of the alveolar process.

Adult↗
PubMed1977

Location of progenitor cells in periodontal ligament of mouse molar stimulated by wounding.

Wounds were made in the alveolar process overlying the mesial root of the mandibular first molar of 35-g mice to expose periodontal ligament. Dividing cells were arrested in metaphase by injection of vinblastine sulphate three hours before death three, five and seven days after wounding. Serial 1-micron plastic sections of the wound were stained with hematoxylin and eosin. The distance between the mitotic figures and the nearest blood vessel, bone and cementum was measured in every fourth section. No mitotic figure was measured twice. The distances of at least 500 interphase cells from the closest blood vessel were measured in each wound. At all time periods the distribution of mitotic cells was significantly closer to blood vessels than that of interphase cells (p less than 0.01). From three days to seven days after wounding there was a significant shift of mitotic activity away from the bone side of the ligament, but not away from blood vessels (p less than 0.05). Approximately 10% of all mitotic cells lay close to cementum, but not close to blood vessels. The majority of the dividing cells were confirmed to be paravascular, and appeared to belong to two populations, one adjacent to bone, the other in the body of the ligament. A third population, not paravascular, lay adjacent to cementum.

Animals↗
PubMed2002

Histopathologic reaction of a calcium phosphate cement for alveolar ridge augmentation.

The objective of the present study was to evaluate the feasibility of using a calcium phosphate cement (CPC) in the reconstruction of a defective alveolar ridge in conjunction with implant placement. The CPC consisted of an equimolar amount of tetracalcium phosphate and dicalcium phosphate anhydrous. At the beginning of the experiment, all mandibular premolar teeth of mature beagle dogs were extracted. After 1 month of healing, alveolar bone was reduced to make a space for a CPC block that was prefabricated from a CPC mixed with water at a powder/liquid ratio of 5 g/mL. After an additional month, 8-mm long hydroxyapatite-coated titanium implants were placed in such a way that the apical half was embedded into alveolar bone and the coronal half in the preformed CPC block. The dogs were sacrificed and biopsies were obtained at 1, 3, and 6 months after surgery. Sections that included implants were evaluated for integration of the CPC block to the alveolar bone and of the implant to the alveolar bone. Additional sections without the implants served as controls. The results obtained from this study show that the CPC ridge augmentation gradually is replaced by natural bone. Six months after surgery, histopathologic features of the augmentation area were quite similar to those of natural alveolar bone. The coronal half of the implants, previously surrounded by the CPC block, was firmly fixed by natural bone. Therefore, this method may be useful for increasing the height of the alveolar ridge.

Alveolar Process↗
PubMed2002

Lymphatic networks in the periodontal tissue and dental pulp as revealed by histochemical study.

The structural organization and fine distribution of the lymphatic networks in the periodontal tissues (gingiva, periodontal membrane, and alveolar process) and dental pulp of animals and humans were reviewed with special reference to histochemical examination by light and electron microscopy. The distinction between lymphatics and blood vessels was made on cryostat sections of undecalcified and calcified teeth treated with EDTA solution and whole mount preparations of periodontal membranes using 5'-nucleotidase (5'-Nase)-alkaline phosphatase (ALPase) double staining. This staining procedure allowed lymphatic vessels in the periodontal tissue and dental pulp to be differentiated from blood vessels. The specificity and localization of the enzyme reactions were confirmed by comparative histochemical studies of the same specimen with light microscopy and scanning or transmission electron microscopy. Well-developed 5'-Nase-positive lymphatic networks were observed on the tissue sections and whole mount preparations of the gingiva, periodontium, and dental pulp. More lymphatic vessels were seen in the root area of the periodontium than in the cervical area. In the dental pulp, lymphatic vessels were more numerous in the central part than in the peripheral odontoblastic layer. These distributions of the lymphatic capillary networks are discussed in relation to their ability to supply lymph to the teeth.

5'-Nucleotidase↗
PubMed1978

Melanotic neuroectodermal tumor of infancy with highly differentiated neural component. Light and electron microscopic study.

A pigmented tumor was removed from the maxillar alveolar process of a 5-month-old boy. It was examined by light and electron microscopy and a diagnosis of melanotic neuroectodermal tumor was made. In addition to connective tissue, three main cell types were identified: undifferentiated (stem) cells, melanocytes, and nerve cells with processes forming an abundant neuropil. Numerous axo-dendritic and occasional axo-somatic synapses were observed. The neural component demonstrated better differentiation in this example than in any reported so far.

Axons↗
PubMed1989

[[Klippel-Trenaunay syndrome--an embryonic developmental disorder. A case report with reference to the orthodontic symptoms].

The Klippel-Trenaunay syndrome is a disturbance in the development of the mesodermal and ectodermal tissues occurring in utero. It is characterized by the clinical triad of unilateral soft tissue and bone hypertrophy, varicosities and hemangiomas. For dentists the orofacial manifestations of the syndrome are interesting: unilateral hypertrophy of the maxilla and mandible, mandibular joint and alveolar processes and tooth germs. In addition, the gingival margins are thickened, eruption is premature and there is marked facial asymmetry.

Angiomatosis↗
PubMed1991

[Active canine tooth movement by spongiosa graft in bilateral cheilognathopalatoschisis].

Bone grafting in the alveolar cleft offers a bony support in the alveolar process for the erupting canines and should be performed before the eruption of the teeth starts. Although bone grafting is done in time, the eruption of the canines does not always follow spontaneously. This is why a simultaneous ligation of the canines is sometimes indicated. The ligature can be threaded through the bone graft. Active eruption of the canines can begin eight weeks post operation. This procedure ensures a proper alignment of the canines in a well-defined processus alveolaris. The method is demonstrated in a bilateral cleft lip and palate patient.

Bone Transplantation↗