Tooth-bearing Areas Research Articles

Trabecular Bone Structures in the Edentulous Diastema of Osteoporotic Sheep

The edentulous ovine diastema represents a suitable region for implantological research. Due to distinctive embryonic origin and mechanical loading, the edentulous diastema may respond differently to osteoporosis than tooth-bearing areas. To test this assumption, we subjected geriatric sheep to ovariectomy, calcium-/vitamin-D-restricted diet, and methylprednisolone administration. Adult control sheep remained untreated. Structural parameters and bone mineral density were determined by microcomputed tomography and conventional computed tomography, respectively. We report that the trabecular microstructure in the diastema was preserved from catabolic changes. In contrast, the premolar maxillary region of osteoporotic sheep had diminished trabecular bone mineral density, with the corresponding structural deteriorations. These results suggest that maxillary trabecular bone of the edentulous diastema does not respond to catabolic changes which occur in the tooth-bearing area in osteoporosis. Our findings imply that regional anatomic domains must be considered in the planning of pre-clinical studies, taking osteoporotic changes into account.

Risk factors for development of infection in patients with mandibular fractures located in the tooth-bearing area

The aim was to identify the main risk factors for infection in patients with mandibular fractures located in the tooth-bearing area. Seven hundred and eighty-nine case histories were retrospectively reviewed regarding treatment results and nature of complications developed. The data concerning possible risks were analysed statistically to find out those factors that seemed to have a significant influence on the development of infection. The incidence of infection in patients with mandibular fractures located in the tooth-bearing area was determined by the following risk factors: social and organizational conditions of medical care, trauma pattern, preexisting medical status and treatment tactics. The main contributory factors were delayed medical care, accompanying pathological disorders, angular location, multiple and comminuted fractures and the type of antibiotic used.

Equalization about the Tooth Bearing Area for the Shaft Angle of Gear Coupling

The demands for gear coupling are to increase the load capacity and to reduce the gear noise. The load capacity of the gear is almost limited by surface durability that is closely related to the minimum value of contact-bearing surface area. This paper proposes a method to equalize the tooth surface bearing area for almost any shaft angle by means of changing the curvature along by tooth trace. This method gives us a larger minimum bearing area and a smaller tooth gap that is related to the gear tooth backlash-hit noise.

Peripheral adenomatoid odontogenic tumour

The adenomatoid odontogenic tumour (AOT) is a benign (hamartomatous), non-invasive lesion with a slow but progressive growth. It occurs in intraosseous as well as in peripheral forms. The peripheral variant is still by far the most rarely reported type constituting only 4.4% of all AOT cases. This article presents the clinical, radiological and microscopic features of a peripheral AOT occurring in the soft tissue overlying the tooth-bearing areas of the anterior maxilla in a 19-year-old female patient.

Peripheral Ameloblastoma: A Case Report

Peripheral ameloblastoma is an uncommon pathological variant of the more usual intraosseous central ameloblastoma. It most typically presents as a localized soft tissue mass occurring in the tooth-bearing areas of the jaws and is often provisionally diagnosed as an epulis. In this paper, a 43-year-old male presented with a three-year history of a painful, slowly enlarging gingival swelling. There was no evidence of bony involvement on radiographs but it was revealed histologically to be a peripheral ameloblastoma. Treatment was by wide local excision, including a bony margin, and primary closure. Long-term follow-up is imperative owing to possible recurrence and malignant potential.

Inhibition of SHH signaling pathway: Molecular treatment strategy of odontogenic keratocyst

Odontogenic keratocyst (OKC) is a relatively common cystic lesion occurred in the tooth-bearing areas of the jaws. This entity is thought to arise from the dental lamina or its remnant with significant growth capacity and recurrence potential. The Sonic hedgehog (SHH) signaling pathway plays a critical role in tooth development. Patched (PTCH) combines with Smoothened (SMO) to form a receptor complex for SHH ligand. Mutations in the PTCH resulting in aberrant activation of SHH signaling pathway were identified as the underlying genetic event of both sporadic and syndrome-related OKCs. We postulate that any strategy to develop antagonists of active receptor, transcriptional factors of SHH signaling pathway will be an effective treatment for OKC. These strategies include reintroducing a wild-type form of PTCH, inhibition of the SMO molecule by synthetic small antagonists and suppression of the downstream transcription factors of the SHH signaling pathway. It seems that inhibition of SMO by intracystic injection of antagonist protein of SMO is the most potential treatment choice.

Cemento-Osseous Dysplasia With Associated Simple Bone Cysts

Cemento-osseous dysplasia (COD) is a nonneoplastic process usually confined to the tooth-bearing areas of the jaws or edentulous alveolar bone.1-4 Several clinicopathologic forms of this disease are recognized, including solitary, multiple, florid, and periapical subtypes.1-5 These lesions all share the same histologic spectrum consisting of admixtures of bone and cementum-like material in a fibrous stroma, but differ primarily in their extent of jaw involvement. In addition, a rare familial form of this disease has been described.

A Short Period of Maxillomandibular Fixation for Treatment of Fractures of the Mandibular Tooth-Bearing Area

This study was aimed to determine whether a short period of maxillomandibular fixation (MMF) followed by an arch bar splint wired to the lower jaw is a suitable alternative to conventional MMF for treatment of fractures of the mandibular tooth-bearing area. Thirty patients with mandibular fractures associated with no other facial fractures were selected. They were randomly assigned into 2 groups for treatment with conventional MMF (group A) and MMF for a short period of 2 weeks followed by an arch bar splint wired to the lower jaw (group B). Complications were recorded and post-treatment maximum interincisal mouth opening was measured at 1 week and 3 and 6 months. Age and gender-matched control groups were randomly selected. Groups were then compared for significant differences. A value of P < .05 was considered significant. The 2 patient groups were not significantly different in relation to site and cause of fracture (P =.995 and P = .682, respectively), the mean time from injury to MMF (P = .234), and the mean time required for fracture healing (P = .315). Delayed union and nonunion were not encountered, and there were no significant differences in relation to postoperative infection ( P = 1) and malocclusion (P = .598). When compared with group A patients, group B patients had an early significantly greater degree in mouth opening (P = .001); at no time was there a significant difference in the degree of mouth opening between group B patients and the control group (1 week, P = .079; 3 months, P = .166; 6 months, P = .378). In selected cases, a short period of MMF followed by an arch bar splint wired to the lower jaw is a suitable alternative to conventional MMF for treatment of fractures of the mandibular tooth-bearing area. The method is effective and significantly reduces the potential adverse effects of long-term MMF.

Do miniscrews remain stationary under orthodontic forces?

Miniscrews have been used in recent years for anchorage in orthodontic treatment. However, it is not clear whether the miniscrews are absolutely stationary or move when force is applied. Sixteen adult patients with miniscrews (diameter = 2 mm, length = 17 mm) as the maxillary anchorage were included in this study. Miniscrews were inserted on the maxillary zygomatic buttress as a direct anchorage for en masse anterior retraction. Nickel-titanium closed-coil springs were placed for the retraction 2 weeks after insertion of the miniscrews. Cephalometric radiographs were taken immediately before force application (T1) and 9 months later (T2). The cephalometric tracings at T1 and T2 were superimposed for the overall best fit on the structures of the maxilla, cranial base, and cranial vault to determine any movement of the miniscrews. The miniscrews were also evaluated clinically for their mobility (0: no movement, 1: ≤0.5 mm, 2: 0.5−1.0 mm, 3: >1.0 mm). The mobility of all miniscrews was 0 at T1 and T2. On average, the miniscrews tipped forward significantly, by 0.4 mm at the screw head. The miniscrews were extruded and tipped forward (−1.0 to 1.5 mm) in 7 of the 16 patients. Miniscrews are a stable anchorage but do not remain absolutely stationary throughout orthodontic loading. They might move according to the orthodontic loading in some patients. To prevent miniscrews hitting any vital organs because of displacement, it is recommended that they be placed in a non–tooth-bearing area that has no foramen, major nerves, or blood vessel pathways, or in a tooth-bearing area allowing 2 mm of safety clearance between the miniscrew and dental root.

Familial Florid Cemento-osseous Dysplasia

Florid cemento-osseous dysplasia is an uncommon disease of cemento-osseous tissue calcification in the tooth-bearing area of the jaw. Although most patients with florid cemento-osseous dysplasia do not have a family history of the disease, a few familial cases have been reported. This report is of a 29-year-old Japanese woman with florid cemento-osseous dysplasia. The patient's wisdom tooth was extracted due to pericoronitis, which was followed by intensive intravenous antibiotic therapy, although surgical procedures are usually not recommended for patients with florid cemento-osseous dysplasia. Radiological examination of the patient's father, who had a history of prolonged osteomyelitis of the upper jaw, also revealed typical features of florid cemento-osseous dysplasia.

Central giant cell granuloma

The central giant cell granuloma (CGCG) is an uncommon benign bony lesion that accounts for less than 7% of all benign lesions of the jaws in tooth-bearing areas. Its etiology is unknown and its biological behavior is poorly understood. This condition is a slow-growing, asymptomatic lesion that usually affects children and young adults, predominantly females. The following report illustrates the differential diagnosis, surgery, final diagnosis and pathology of a fast-growing CGCG in a 4-year-old girl.

Pathology of the desmoplastic ameloblastoma.

Desmoplastic ameloblastoma is a rare variant of ameloblastoma and only 54 cases have been previously reported in the English literature. We report ten cases of desmoplastic ameloblastoma of the jaw observed between 1972 and 1998 and discuss the pathogenesis of the tumor. Eight of the ten tumors were located in the anterior region of the jaw. Radiographically, six cases showed mixed radiolucent/radiopaque appearance with ill-defined margins and the other four cases lacked typical findings of ameloblastomas. The tumors were located mainly in the alveolar region and occupied the tooth-bearing area, without tooth resorption or impacted teeth. Histologically, the desmoplastic ameloblastomas were characterized by extensive stromal desmoplasia, and small tumor nests of odontogenic epithelium were scattered in the stroma. Oxytalan fibers stained by potassium monopersulfate-aldehyde fuchsin were demonstrated in the stroma of all desmoplastic ameloblastomas. From these findings, we presumed that the desmoplastic ameloblastomas might have developed in the periodontal membrane.

Peripheral ameloblastoma: biological profile based on 160 cases from the literature.

The present profile of the peripheral ameloblastoma (PA) is based on a literature survey of 160 published tumour cases. The PA is an exophytic growth localized to the soft tissues overlying the tooth-bearing areas of the jaws, the initial diagnosis often being fibrous epulis. In most cases there is no radiological evidence of bone involvement, but a superficial bone erosion--known as cupping or saucerization--may be detected at operation. The PA accounts for 2-10% of all ameloblastomas. The overall average age is 52.1 years, slightly higher for males (52.9 years) than for females (50.6 years). Thus, the PA occurs at a significantly higher age than the intraosseous ameloblastoma (IA; 37.4 years). The male/female ratio amounts to 1.9:1, as opposed to 1.2:1 for the IA. The male/female ratio for the Japanese cases included in this survey is 2.5:1 as opposed to that of non-Japanese cases 1.4:1. As to the location of PA, the maxilla/mandible ratio is 1:2.6. The mandibular premolar region accounts for 32.6% of all sites. Five extra-gingival lesions have been reported under the term PA. As these cases most likely represent salivary gland tumours, they are not accepted under the diagnosis of PA. The odontogenic gingival epithelial hamartoma shows clinical, histological and behavioural features almost identical to the PA, and it is discussed whether this lesion and the PA should be considered one and the same entity. Pathogenetically, two major sources are discussed: remnants of the dental lamina and the oral surface epithelium. Histologically, the PA consists of proliferating odontogenic epithelium exhibiting the same histomorphological cell types and patterns as seen in the IA. The stroma is that of a mature, fibrous connective tissue. The indolent biological behaviour dictates a conservative therapeutical approach. It is discussed whether PA is a true neoplastic counterpart of the IA or rather an odontogenic hamartomatous lesion. Six cases of malignant PA have been reported.

Proliferative verrucous leukoplakia of the gingiva.

The purpose of this study was to describe the clinical-pathologic features of what appears to be a gingival form of proliferative verrucous leukoplakia. Ten adult patients with recurrent and histologically progressive gingival leukoplakias who were diagnosed and treated at the University of California, San Francisco between 1994 and 1999, comprised the subject group for this investigation. Clinical and microscopic features were reviewed. Proliferation indices and p53 expression were evaluated immunohistochemically, and the presence of human papillomavirus (HPV) DNA was determined by using polymerase chain reaction (PCR) amplification. Lesions presented as solitary or regional flat/papillary/verrucal leukoplakias of the free and attached gingiva (tooth-bearing areas only). With time, flat lesions developed a papillary or verruciform profile. Although lesions were recurrent, they were confined to the gingiva, and multiple lesions did not develop. Half the patients used tobacco, and HPV could not be detected by using PCR. Microscopically, 6 cases began as hyperkeratotic lesions, and 4 initially exhibited a psoriasiform pattern with a marked inflammatory component. With recurrences, the lesions became progressively atypical histologically. The proliferation indices for these lesions showed modest increases over normal epithelium, and positive p53 staining was evident in 4 of 10 cases, indicating a disruption of the keratinocyte cell cycle in these lesions. The mechanism associated with the positive p53 staining (protein binding to wild type p53 versus mutation of the p53 gene) was not determined. Lesions recurred after conservative scalpel or laser excision, and many developed into verrucous or squamous cell carcinoma. Proliferative verrucous leukoplakia of the gingiva (PVLG) appears to be a subset of oral proliferative verrucous leukoplakia. It can be characterized as a solitary, recurring, progressive white patch that develops a verruciform architecture and may not be associated with HPV. PVLG has an unpredictable course and is at risk for development into verrucous or squamous cell carcinoma. Currently, there is no way to determine or predict which gingival white lesions will follow the clinical course described for this group of patients with PVLG.

Immunohistochemical localization of nerve fibres during development of embryonic rat molar using peripherin and protein gene product 9.5 antibodies

Nerve fibres were localized during the initiation and early morphogenesis of the first molar tooth in rat embryos by immunoperoxidase detection of the intermediate-filament protein peripherin and protein gene product 9.5 (PGP 9.5). Nerve fibres from the trigeminal ganglion were detected in the developing first branchial arch of E12-14 embryos. Nerves were not seen in the vicinity of the developing tooth germ before the buid stage (E15), when they were seen around the condensed dental mesenchyme. During transition from the bud to the cap stage (E15), nerve fibres were detected not only in the area of the future dental follicle but also in the mesenchyme next to dental epithelium on the buccal side of the tooth germ. During later cap and bell stages nerve fibres persisted in the dental follicle, but they were not seen in the epithelial dental organ or dental papilla mesenchyme. Absence of trigeminal nerve fibres from the presumptive tooth-bearing area indicates that they are not involved in the initiation of rat tooth development. In addition, the localization of nerve fibres shows that there are some differences in the innervation of rat teeth compared with human and mouse teeth. These results provide data for further studies on the regulation of embryonic rat tooth innervation.

Effect of head positioning in panoramic radiography on vertical measurements: an in vitro study.

To assess whether it is possible to make accurate vertical measurements of the jaws from panoramic radiographs. Five dry skulls were shifted 5 mm forwards and backwards and tilted 5 degrees up and down in the sagittal plane. Panoramic radiographs of each skull were obtained in nine different positions. In the maxilla, three reference lines were used and vertical measurements were made at the distal surfaces of the first premolar and first molar and in the midline. In the mandible, measurements were made at the distal surfaces of the first premolar and first molar, and at the mental foramen on both sides, and in the midline. The points and lines were marked manually and the radiographs were digitized, magnified and measured. Sagittal shifting and tilting had only a slight effect on measurements in the mandible. Sagittal tilting of the head had the greatest effect on all the measurements made from the line between the articular eminences to the alveolar crest, as well as measurements in the maxillary midline. The line between the articular eminences is unsuitable as a reference line for measurements of the tooth-bearing areas. A slight misalignment of the head does not significantly affect the vertical measurements in the mandible or of the posterior maxilla if the reference lines are in the same vertical plane as the teeth.

Glandular odontogenic cyst: A case report and literature review

In 1992, the World Health Organization (WHO) named glandular odontogenic cyst (GOC) as an independent pathologic entity and classified it as a developmental odontogenic epithelial cyst. 1,2 The WHO defined this lesion as “a cyst arising in the tooth-bearing areas of the jaws and characterized by an epithelial lining with cuboidal or columnar cells both at the surface and lining crypts or cyst-like spaces within the thickness of the epithelium.” 1 GOCs occur over a wide age range in both sexes and in either jaw, and have the propensity to recur and to become large. Radiographically, the GOC appears as an intrabony, unilocular or multilocular, sometimes honeycomblike, well-defined radiolucent lesion. Histologically, the lining epithelium may be partly squamous, without distinctive features. 1 However, in many areas, the stratified epithelium has a surface layer of eosinophilic cuboidal or columnar cells, often forming irregular papillary projections. 1 A variable number of ciliated and mucus-producing cells may also be interspersed in the surface layer. 1 Within the thickness of the epithelium there may be crypts and glandular or cystlike spaces lined by cells similar to those seen in the epithelial surface. 1 Pools of mucous material within the intraepithelial spaces and within the main cyst cavity are a prominent feature. Plaquelike and whirlpoollike epithelial thickenings also may be present. 1 The fibrous capsule is usually free of inflammatory cells. 1 Multicystic or botryoid varieties also occur. 1 Because this lesion has been characterized only recently, and only a few cases have been reported in the literature, 3–8 its biologic nature is uncertain. 1,2 However, the aggressive behavior and the recurrent tendencies of this lesion have been suggested, 1,2 even in the limited number of reported cases. 3–8 We report a case of GOC that exhibited histologic features suggesting the aggressive and somewhat neoplastic nature of this lesion. Furthermore, the clinicopathologic features of 17 cases reported in the literature 3–8 are reviewed, and the differential diagnosis of this rare lesion, especially from central low-grade mucoepidermoid carcinoma (MEC), as well as its treatment, are also discussed.

Focal cemento-osseous dysplasia: A clinicopathologic study of 221 cases

Classification of cemento-osseous lesions of the jaws has long been a dilemma for pathologists. A group of 221 cemento-osseous lesions exhibited sufficiently distinctive clinicopathologic features to be separated into a specific category: focal cemento-osseous dysplasia. This entity presents as an asymptomatic, focal, mixed radiolucent/radiopaque lesion with ill-defined borders in the tooth-bearing areas. It was found to occur with greater frequency in women (88%) and in the posterior mandible (77%). The average age at presentation was 37 years and a relative predilection for black patients was observed. At surgery these lesions were noted to be hemorrhagic, gritty, and adherent to the surrounding bone. The gross appearance of multiple hemorrhagic fragments is of diagnostic significance. Histologic features include a cellular connective tissue stroma punctuated by irregular osseous and/or cementum-like calcifications. Focal cemento-osseous dysplasia is thought to be of periodontal ligament origin and to be non-neoplastic in nature. Further surgical intervention is not necessary, but periodic follow-up is recommended, because occasional cases were observed to progress into florid osseous dysplasia. Care must be taken to differentiate focal cemento-osseous dysplasia from central cementifying and/or ossifying fibromas, which are true neoplasms and require surgical treatment.

Florid cemento-osseous dysplasia: Radiographic study with special emphasis on computed tomography

This article describes the computed tomographic and conventional radiographic findings for florid cemento-osseous dysplasia. A low-density thin layer or cystlike area was observed around the high-density masses in the tooth-bearing area in the seven cases studied. Expansion of the buccal and lingual cortical plates was observed in association with cystlike areas, but was infrequently observed in florid cemento-osseous dysplasia not having such areas. The computed tomographic number of the high-density masses ranged from 772 to 1587 Hounsfield Units and was equivalent to that of cementum or cortical bone.

Gigantiform cementoma occurring in two populations, London and Hong Kong.

The gigantiform cementoma presents as multiple opacities in the tooth-bearing areas of the jaws. Sixteen cases are presented, six of British Negresses and 10 of Hong Kong Chinese females. The differential diagnosis and management are briefly reviewed.