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Effect of salivary gland hypofunction on the healing of extraction wounds: a histomorphometric study in rats.

The effect of salivary gland hypofunction (SGH) on oral wound healing is not well established. The present study evaluates the healing of extraction wounds in a SGH rat model. Experimental rats underwent removal of the submandibular and sublingual glands and ligation of the parotid ducts. Maxillary left first molars were extracted and healing was determined at 0, 1, 3, 5, 7, 10, 14, and 21 days after extraction. Salivary gland hypofunction caused a significant delay in socket healing. The inflammatory process was more intense and of longer duration. The formation of fibrous connective tissue and bone was relatively slow among the experimental rats. The results suggest that SGH patients undergoing oral surgery may have prolonged wound healing.

Alveolar Process↗

[Incidence and primary prevention of complications related to the placement of dental implants].

Despite high success rate with endosseous titanium implants, failures inevitably occur. At an early stage, lack of primary stability, surgical trauma, peroperative contamination and occlusal overload seem to be the most important causes of implant failure. Many authors have reported that implant failures after primary healing and osseointegration are mainly due to peri-implant infection and/or excessive occlusal stress. Like periodontal disease, peri-implant inflammatory lesions develop as a result of plaque accumulation and exhibit similar clinical and microbiological signs as encountered for periodontitis. Clinicians should therefore enforce preventive measures to decrease the prevalence of such causative agents. Therapeutic attempts should have their rationale in the restoration of a biomechanical and/or host-bacterial equilibrium. The major limitation at this point seems to be the detection of a pathological process. Aside from clinical evaluation, the interpretation of radiographic images is one of the most frequently applied diagnostic procedures in patients with osseointegrated implants. Post-therapeutic maintenance care is an integral part of the entire implant treatment approach.

Alveolar Process↗

[The morphological parameters of the dental arches in children with unilateral complete cleft lip and palate].

The size and proportions of dentitions and relationships between longitudinal, transverse, and vertical parameters of the upper and lower dentitions and palatine processes were examined in 42 children (22 girls and 20 boys), aged 5-6 years, with unilateral complete labiopalatine clefts before uranoplasty. Analysis of correlations in the findings was carried out and 12 reliable coefficients of correlations obtained.

Alveolar Process↗

Oral radiographic changes in patients with progressive systemic sclerosis (scleroderma).

Intraoral and panoramic radiographs were made of 35 patients with progressive systemic sclerosis. Of those patients, 13 (37%) were found to have abnormally thickened periodontal ligament spaces. Six of the 35 demonstrated mild to significant resorption of the posterior mandibular angle. Three patients, including two showing angle resorption also had some degree of coronoid process destruction. All patients with this disease should receive initial and follow-up panoramic radiographic examinations to determine any osseous changes.

Adult↗

Changes in mandibular rotation after muscular resection. Experimental study in rats.

The purpose of this study was to evaluate the effect of bilateral muscular resection on the rotational pattern of the rat mandible. The specific aim of the study was to seek possible changes in "articular growth" in the posterior (ramus and condyle of the mandible), and in the anterior part of the face (upper viscerocranium, and maxillary and mandibular dentoalveolar processes). The masseter, temporal, and suprahyoid muscles were bilaterally resected in three experimental groups of 21-day-old female Wistar rats. Another group of rats served as control. The results were evaluated at 42 (prepubertal) and 60 days after birth (pubertal rats). The craniofacial growth pattern, ramus dimension, condylar growth direction, histologic evaluation of condylar cartilage, and dentoalveolar processes height changes were studied. Two mandibular rotational patterns were found: one inferior after masseter muscles resection (MR), and the other superior after temporal muscles resection (TR). A less intense superior rotational pattern, after suprahyoid muscles resection (SR), was found also. Morphologic changes were more intense in older rats. On the contrary, more intense condylar histologic changes were found in younger rats. Changes in "articular growth" primarily take place at maxillary and mandibular dentoalveolar processes. Condylar growth amount could be modified to a limited extent. More important were the changes in condylar growth direction. An upward rotational pattern of the upper viscerocranium was detected when the inferior mandibular rotation pattern was produced.

Age Factors↗

Epithelial dysfunction in acute lung injury.

More than a quarter century has passed since Ashbaugh and colleagues postulated that abnormalities of surfactant are causally related to the abrupt and severe organ dysfunction that occurs in individuals with acute lung injury (ALI). In this time, much progress has been made in expanding our understanding of the normal functions of the alveolar epithelium and how these functions may be disrupted in the context of ALI. Alveolar epithelial cells are a key structural component of the spatial separation of gas and plasma, essential for normal gas exchange in the lung. In addition, alveolar epithelial cells synthesize, secrete, and take up surfactant, which, by reducing surface tension, is a key determinant of intra-alveolar pressure. Surfactant is qualitatively and quantitatively abnormal in lung injury due to changes in synthesis, secretion, intra-alveolar metabolism, and biophysical inhibition by protein and lipid inhibitors. Alveolar epithelial cells also subserve additional host defense functions, such as modulation of lymphocyte, macrophage, and neutrophil function; production of prostanoids, complement proteins, and nitric oxide; and display of major histocompatibility complex II molecules and intracellular adhesion molecule-1. Although the physiologic and pathogenic significance of some these functions is not absolutely clear, they are of potential relevance in the context of lung injury, wherein they may participate in the process of alveolar injury and repair.

Acute Disease↗

Digitized pattern recognition in the diagnosis of periodontal bone defects.

Radiography is an important tool in the diagnosis of periodontal bone lesions. Due to subjective factors in the interpretation by the observer, however, an error-free diagnosis of bone lesions in an early stage is very difficult. The aim of this study was to reduce the influence of observer subjectivity by means of computer-assisted image processing and pattern recognition in dental radiographs. The findings of the study show that periodontal lesions can be recognized and described in an objective way by means of digitized pattern recognition.

Alveolar Process↗

Vital apicoectomy of the teeth: a 1-4 week histopathological study in Macaca mulatta.

Several studies have reported devitalization of teeth following surgical procedures in the area of the root apices. The purpose of this investigation was to observe the 1-4-week wound healing pattern in monkey dental tissues following intentional vital apicoectomy (IVA). Two adult Macaca mulatta were used in this study. All of the teeth were surgically transected within the apical one-third with a bur. The soft tissues were then closed. At death, a maxillary and a mandibular quadrant for 1, 2, 3 and 4 weeks following surgery were obtained after vascular perfusion. Each quadrant was demineralized in EDTA, processed, serially sectioned at 7 microns and alternately stained with hematoxylin and eosin, Preece's modified trichome, and McKay's bacterial stains. Examination of sequential IVA cuts showed an initial disruption of the pulpal neurovascular supply resulting in pulpal necrosis. The pulpal tissues underwent a process of replacement with PDL-like connective tissues and deposition of cementum on all cut dentin surfaces of the tooth roots as well as in some of the pulp chambers. No abscesses, external resorption or ankylosis were found.

Alveolar Process↗

Periodontal repair in dogs: healing in experimentally created chronic periodontal defects.

A need exists for well-defined animal models to objectively evaluate surgical principles and a possible role for biochemical wound conditioning and biomaterials in promoting periodontal regeneration. To test an existing model for its usefulness in quantitative evaluation of periodontal wound healing, large supraalveolar periodontal defects were surgically created around the mandibular premolars (P2, P3, P4) in left or right jaw quadrants in 5 beagle dogs. The defects were exposed to the oral environment for 6 months and were then subjected to reconstructive flap surgery (chronic defects). Healing in these defects was compared to healing following reconstructive surgery in similar contralateral defects which had not been exposed to plaque and calculus (acute defects). The animals were sacrificed after a 4-week healing period and tissue blocks including teeth and surrounding structures were processed for histometric analysis. Mean defect height (+/- s.d.) for chronic and acute defects amounted to 4.6 +/- 0.3 and 4.4 +/- 0.4 mm, respectively. Mean connective tissue repair to the root surface in chronic defects amounted to 62% (range 49% to 74%) of the defect height. Mean connective tissue repair in the acute defects exceeded 94% of the defect height in 4 of the dogs, but amounted to only 48% in 1 dog. Regeneration of alveolar bone and cementum was limited under both experimental conditions. Root resorption was frequently encountered, whereas ankylosis was seen in only few teeth. This study indicates that healing may vary not only as a result of controlled experimental variables, but also due to differences in biological response between dogs or to fortuitous traumatic factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗

The immediate replacement of teeth by dental implants using homologous bone membranes to seal the sockets: clinical and radiographic findings.

Placement of dental implants into fresh extraction sockets has several advantages compared to the original protocol. However, the soft-tissue handling is often complicated and the aesthetic results less rewarding. A method to use a homologous bone membrane as the sole sealer of the extraction socket after immediate implant placement is introduced and the outcome of 34 cases is presented. In 4 cases early losses of the membranes occurred (2 of these iatrogenic damage) in all other cases the homologous membranes were covered by proliferation of the surrounding mucosa within 2-4 weeks. In 2 of the 4 cases where the membranes were lost, the implants did not integrate, in the other 2 cases the implants did integrate but the sockets did not fill completely with bone and the aesthetic results were not acceptable. In all other cases bone filling of the socket occurred, the implants were stable at 180 days after insertion (functional success rate 94.1%) and the aesthetic results were excellent. The method thus seems very promising but the healing process is delicate and the operation site highly vulnerable during the first postoperative weeks. It should also be stressed that the present study offers conclusions neither about the quality of the newly formed bone nor about the quality of osseointegration offered by this bone.

Adolescent↗

Biologic and clinical considerations for autografts and allografts in periodontal regeneration therapy.

Although complete periodontal regeneration is unpredictable with any regenerative therapy currently used, periodontal bone grafts show strong potential. A large body of clinical evidence clearly indicates that grafts consistently lead to better bone fill than nongrafted controls. Regardless of which material is used, the average bone fill is 3 mm, or about 60% defect fill according to reported studies. In addition, histologic analyses now show conclusively that regenerative treatment with bone grafting leads to some degree of regenerated bone, cementum, and periodontal ligament. Although bone grafts and other periodontal treatments have improved clinicians' ability to promote osteogeneration, the outcomes are still somewhat unpredictable. Part of the problem is that it is still unclear how periodontal disease affects the supporting bone's regenerative potential and what specific biologic factors are involved. In recent years, however, clinicians have begun to learn much more about how periodontal regeneration works on a cellular and molecular level. This is a key step to developing strategies and materials that allow clinicians to promote periodontal regeneration predictably. Since its introduction during the last decade, GTR has been an invaluable addition to the armamentarium, as has the recognized importance of early wound stability. As more is learned about the biologic process of periodontal regeneration, new materials and techniques, such as growth factors, absorbable membranes, and new graft materials, are expected to make the task of periodontal regeneration even more predictable. It is likely that some combination of techniques may eventually prove to yield the best results.

Alveolar Process↗

The conception of fusion pores as rate-limiting structures for surfactant secretion.

It is well established that the release of surfactant phospholipids into the alveolar lumen proceeds by the exocytosis of lamellar bodies (LBs), the characteristic storage organelles of surfactant in alveolar type II cells. Consequently, the fusion of LBs with the plasma membrane and the formation of exocytotic fusion pores are key steps linking cellular synthesis of surfactant with its delivery into the alveolar space. Considering the unique structural organization of LBs or LB-associated aggregates which are found in lung lavages, and the roughly 1-microm-sized dimensions of these particles, we speculated whether the fusion pore diameter of fused LBs might be a specific hindrance for surfactant secretion, delaying or even impeding full release. In this mini-review, we have compiled published data shedding light on a possibly important role of fusion pores during the secretory process in alveolar type II cells.

Animals↗

Measurement of submucosal forces transmitted to dental implants.

Early loading of dental implants after placement is believed to be a major cause for premature implant failure. If a transitional denture or partial denture is used during the healing period, occlusal forces may be transmitted to the submerged implant, leading to poorly differentiated growth of bone cells and/or potential inhibition of osseointegration at the bone-implant interface. The objective of this study was to develop an experimental model to measure the force transmission and to characterize the effect of selected loading conditions and relief methods on the forces transmitted to the implant. The loading conditions studied included unilateral and bilateral loading of the prosthesis. Forces were measured at two different relief conditions (relief with and without soft liner) and were compared against a control with no relief. The results show that fabrication of the prosthesis with a proper relief at the implant-denture junction can eliminate the submucosal force transmission to the implant on loading the denture both under unilateral and bilateral loading conditions. When a soft liner is used at the relief site, the transmitted force is small, but a finite value is reproducibly recorded. With no relief, the submucosal force transmission is high and may adversely affect the healing process or osseointegration. The experimental model is valuable in measuring and understanding the submucosal forces that are transmitted to the implant by loading the transitional prosthesis, and such measurement may assist in the proper design of the prosthesis for improved clinical durability and for other uses.

Alveolar Process↗

Extraction site reconstruction for alveolar ridge preservation. Part 1: rationale and materials selection.

Alveolar ridge resorption has long been considered an unavoidable consequence of tooth extraction. While the extent and pattern of resorption is variable among individuals, there is a progressive loss of ridge contour as a result of physiologic bone remodeling. Over the long term, prosthodontic complications, loss of function, and inadequate bone for the placement of dental implants may result. Guided bone regeneration techniques and the use of bone replacement materials have both been shown to enhance socket healing and modify the resorption process. This review describes the process of alveolar bone loss, materials for extraction site grafting, and proposed mechanisms for ridge preservation.

Absorbable Implants↗

Computer-guided surgery utilizing a computer-milled surgical template.

The primary objective of implant placement is to support prosthetic restorations that return patients to proper oral form, function, and aesthetics. Since correct implant placement can be a technique-sensitive process, it is performed in conjunction with various diagnostic and guidance procedures. For accurate diagnosis, radiographic templates, computed tomography scans, and surgical simulation software are unparalleled. This article demonstrates the manner by which computer-guided surgery and computer-milled surgical templates can enable precise implant placement for the entire implant team.

Alveolar Process↗

[An experimental study on transplantation of frozen autogenous tooth-mandible compound].

OBJECTIVE: To study the feasibility of reserving the teeth in the transplantation of frozen autogenous mandible. METHODS: Forty adult Wistar rats were used for these operations of transplantation of frozen autogenous tooth-mandible compound (ATMC) and fresh ATMC. Then the healing process after transplantation of frozen ATMC and fresh ATMC was compared by clinical, radiographical, histological and microangiographical observation. RESULTS: There were no significant differences between the healing process of frozen ATMC and that of fresh ATMC, and the fibres of regenerated periodontal membrane which maintained the dental root in normal position could be imbedded in the newly formed cementum. CONCLUSION: It is feasible to transplant the frozen ATMC for reconstructing the mandible and improving its function in clinic.

Alveolar Process↗

The effects of short-term application of a combination of platelet-derived and insulin-like growth factors on periodontal wound healing.

Polypeptide growth factors are a class of potent natural biologic mediators which regulate many of the activities of wound healing including cell proliferation, migration, and metabolism. Platelet-derived growth factor (PDGF) and insulin-like growth factor-I (IGF-I) have been shown to regulate DNA and protein synthesis in bone cells in vitro and to interact synergistically to enhance soft tissue wound healing in vivo. We have hypothesized that the combination of PDGF and IGF-I may, therefore, enhance regeneration of both the soft and hard tissue components of the periodontium. To test this hypothesis we performed conventional periodontal surgery on all 4 quadrants of the mouth of 13 beagle dogs with naturally occurring periodontal disease. Following flap reflection, degranulation, and root planing, all premolar teeth in 2 quadrants of each dog received a combination of 3 micrograms of recombinant PDGF-B and IGF-I in a methylcellulose gel, while the premolar teeth in the contralateral quadrants received the gel alone. Teeth in 4 additional animals also received 125I-PDGF or 125I-IGF-I in the treated sites. The clearance rate of the 125I-labeled protein, changes in local bone metabolism, and amount of new bone and cementum with inserting collagen fibers were measured. The clearance studies revealed that the half-life of the factors at the site of application was 3.0 hours for IGF-I and to 4.2 hours for PDGF-B. Greater than 96% of the radio-labeled proteins was cleared by 96 hours and no radioactivity was detected 2 weeks after application. There was a significant (P less than 0.01) 2-fold increase in uptake of the bone-seeking radiopharmaceutical Technetium 99-MDP at 2 and 4 weeks in growth factor treated sites compared to controls, indicating that there was increased metabolic activity within the bone at these sites. Computer-aided histologic analyses of biopsies obtained at 2 and 5 weeks post-operatively revealed a significant (P less than 0.01), 5 to 10 fold increase in new bone and cementum in PDGF-B/IGF-I treated sites at both time points compared to controls receiving the placebo gel. The height and total area of new bone continued to increase from 2 to 5 weeks. The new bone underwent a normal maturation process as judged by histologic appearance. A physiologic periodontal ligament space was also formed between the new bone and new cementum. There was no increase in ankylosis in the treated sites.(ABSTRACT TRUNCATED AT 400 WORDS)

Alveolar Bone Loss↗

Present status of osseous grafting procedures.

Osseous grafting techniques represent one mode of therapy to manage combination pocket-osseous defects. They have their greatest applicability in the intrabony defect although encouraging results have been noted in furcation and suprabony sites. Like all treatment modalities, their usage is dictated by the therapeutic objectives for specific problems and whether their respective advantages and limitations outweigh other management techniques. They are neither a panacea nor an unproven experimental venture. When properly employed, they are a valuable component of currently accepted therapy. When compared with other treatment approaches, the following relative advantages and limitations have been noted with osseous grafts: Advantages 1. Reconstruct lost periodontium. 2. Idealistic therapeutic objective. 3. Reversal of disease process. 4. Increase tooth support. 5. Enhance esthetics. 6. Improve function. Limitations 1. Additional treatment time. 2. Autograft disadvantages. 3. Availability of graft material. 4. Additional postoperative care. 5. Unique postoperative problems. 6. Variations in repair. 7. Longer post-treatment evaluation interval. 8. Predictability. 9. Greater expense. 10. Multistep therapy common. 11. Vulnerability to recurrence.

Alveolar Process↗