Immunoprofile of the adenomatoid odontogenic tumor.

This study was focused on the immunohistochemical profile of the adenomatoid odontogenic tumor. A Pub/Medline search revealed a number of immunohistochemical studies including cytokeratin profiles, extracellular matrix proteins, Integrins, ameloblast-associated proteins resorption regulators (RANK, RANKL), p53, PCNA, MDM2 protein, cyclin D1, Ki-67, Bcl-2 metallothionein, metalloproteinases, D56 hepatocyte growth factor, c-met, DNA methyltransferase, podoplanin, TGF-ßI, Smad-2/3, Smad-I-5/-8, Smad 4, beta- catenin, calretinin, and clonality. Careful interpretation of the findings indicates that the adenomatoid odontogenic tumor may be more of a hamartomatous than neoplastic nature.

Comparison of life history parameters of two Frankliniella occidentalis (Thysanoptera: Thripidae) strains in New Zealand.

Two strains of western flower thrips, Frankliniella occidentalis (Pergande), are reputedly found in New Zealand. One strain was recorded in 1934, and it is most common in flowers of Lupinus arboreus outdoors (lupin strain); the other strain was first recorded in New Zealand in 1992 and is found mostly indoors on greenhouse crops (greenhouse strain). Laboratory studies were conducted to compare the life history parameters of these two strains. Thrips from each strain were fed sucrose solution and capsicum or lupin pollen and reared at 25 degrees C, >60% RH, and 16 L:8 D photoperiod. Significant differences in life history parameters were found. Preoviposition time was significantly shorter, and oviposition rate and fecundity were markedly higher (four-fold) for the greenhouse than for the lupin strain. The lupin strain performed significantly better on the capsicum pollen, laying more than twice as many eggs than on the lupin pollen over a 14-d period. The greenhouse strain development time from larvae to adult was marginally faster (0.7-1.1 d less) than the lupin strain because of a shorter prepupal and a marginally shorter pupal development time. Females of the greenhouse strain lived on average 69% longer than females from the lupin strain. Large differences in the intrinsic growth rate (r(m)) were found, with r(m) being 1.4-1.8 times higher for the greenhouse strain than the lupin strain, depending on pollen source. The results are discussed in relation to different ecological requirements and pest status of the two strains.

[Oral submucous fibrosis in a 31-year-old Indian women: first case report from Germany]. / Orale submuköse Fibrose bei einer 31-jährigen Inderin: Erster Fallbericht aus Deutschland.

BACKGROUND: Oral submucous fibrosis (OSF) is a chronic disease characterized by subepithelial collagen deposition with formation of bands involving the oral cavity and adjacent structures. Oral submucous fibrosis is a precancerous condition. It is caused by chewing of betel quid (Areca catechu L., Piper betle, lime and tobacco) and ready-made products like pan masala and gutka which also contain areca nut. These products are available all over South Asia. The hallmark of OSF is extremely restricted mouth opening. CASE REPORT: A 31-year-old Indian woman who has lived in Germany since 1997 presented herself because of limitation of mouth opening. She reported that she has chewed pan masala and gutka since she was 17 years of age. History, clinical and histological findings clearly pointed to the diagnosis of OSF. DISCUSSION: Conservative as well as surgical interventions for OSF have not resulted in adequate long-term results. Since OSF may occur in children and young adults, the primary aim should be to avoid progression of the disease, initially by physiotherapy. Surgical interventions should not be applied at an early stage of the disease because recurrences and further surgical interventions are often necessary. Due to the increasing numbers of migrants from South Asia more cases of OSF will probably also be observed in Germany, where areca nut-containing products are also available.

[Occurrence of epithelium in the soft tissues associated with routine surgical removal of 150 mandibular third molars]. / Pathohistologische Varianten des Befundes Epithel bei 150 Osteotomien unterer Weisheitszähne.

BACKGROUND: The aim of the study was to classify epithelial structures (ES) and to determine the prevalence of cysts associated with mandibular third molars (M(3)). MATERIAL AND METHOD: Sections of HE-stained soft tissue specimens and panoramic radiographs of 150 consecutive patients undergoing surgical removal of M(3) were evaluated. ES were classified as islands and/or strands of odontogenic epithelium (OE), reduced enamel epithelium (REE), stratified cyst epithelium (SCE), oral mucosa (OM), and pocket epithelium (PE). The diagnostic criteria were defined as a pericoronal translucency >2.5 mm and SCE for dentigerous cysts (DC) and a distal translucency >2.5 mm, SCE, and inflammation for inflammatory paradental cysts (IPC). RESULTS: Median age was 24.4 years: 23.0 years for 86 (57.3%) female patients and 25.7 years for 64 (42.7%) male patients (p=0.017). ES were found in 95.3%, classified as OE in 53.3%, REE in 34.7%, SCE in 28%, OM in 30.7%, and PE in 10.7%. Both REE and SCE were found in 6%. The total number of cases with REE and/or SCE was 56.7%. Median age of cases with SCE was 28.7 years compared to 20.7 years in cases with REE (p<0.001). Pericoronal translucencies were found in four M(3), of which three were associated with SCE. Distal translucencies were found in 47 M(3), of which 15 were associated with SCE and inflammation. The prevalence was 2% for DC and 10% for IPC. CONCLUSIONS: A differentiated application of histological and radiological criteria enables the prevalence of cystic lesions to be more accurately determined than does the use of one criterion alone.

The inflammatory paradental cyst: a critical review of 342 cases from a literature survey, including 17 new cases from the author's files.

BACKGROUND: A total of 325 cases of inflammatory paradental cysts (IPCs) and 17 own cases were reviewed. Although known since 1930, the IPC is still unrecognized by many clinicians. The IPCs show a relative frequency of 0.9-4.7%. The majority of cysts occur distally or distobuccally to vital, permanent mandibular molars with a history of pericoronitis (IPC/3rd mandibular molar alone accounts for 64.9%). Radiologically, the cyst appears as a well-defined, semilunar unilocular radiolucency. MATERIALS AND METHODS: Cases of inflammatory paradental cysts and related lesions were retrieved from a worldwide literature survey. In addition, 17 new cases from the files of the authors have been added. RESULTS: The mean ages for patients with IPC/1st, 2nd and 3rd mandibular molars are 8.7, 17.4 and 27.6 years, respectively. The male:female ratio was 1 : 0.9 for IPC/1st and 2nd mandibular molars, and 1 : 0.4 for 3rd mandibular molar. CONCLUSION: Reduced enamel epithelium, cell rests of Malassez and remnants of the dental lamina stimulated by inflammation are thought to play a role in the pathogenesis of IPC. Histological features are indistinguishable from those of the inflammatory, periapical (radicular) cyst.

[Proliferative verrucous leukoplakia. Report of five cases]. / Proliferative verruköse Leukoplakie. Bericht über 5 Fälle.

BACKGROUND: Proliferative verrucous leukoplakia (PVL) is a rare variant of oral leukoplakia (OL) with a high tendency for malignant transformation. PVL starts as a flat hyperkeratosis. During the course of the disease verrucous lesions develop. AIM OF THE STUDY, MATERIAL AND METHODS: Due to the scarcity of reports on PVL five cases of PVL are presented. Clinical and histopathological findings in five female patients with PVL were evaluated retrospectively. RESULTS: The clinical appearance of PVL was characteristic as compared to criteria described in the literature. The average period of observation in these cases was short (1.7 years). There were 3.6 different localizations observed per patient. The buccal mucosa, gingiva, and edentulous alveolar ridge were most often affected. One patient had already developed squamous cell carcinoma prior to referral. The others developed malignancies during follow-up. Recurrences and secondary malignancies could not be avoided using different therapeutic modalities. Two patients died from PVL. The characteristic spectrum of histopathological findings in PVL was observed. Homogeneous flat leukoplakias are characterized by acanthosis, hyperkeratosis, and often parakeratosis. Epithelial dysplasia is not seen. The proliferative verrucous stage of the disease is characterized by papillomatous epithelial growths with signs of slight epithelial dysplasia and subepithelial infiltration with immunocompetent cells. Stages of transformation may result in verrucous carcinoma or squamous cell carcinoma. CONCLUSIONS: PVL is associated with a very high rate of malignant transformations. These, as well as recurrences, cannot be avoided with present-day therapies. In order to define the biological profile of PVL more clearly, multicenter studies are necessary to reveal possible etiologic factors and concepts for therapy.

[Inflammatory paradental cyst. Report of 6 cases]. / Entzündliche paradentale Zyste. Bericht von 6 Fällen.

BACKGROUND: The inflammatory paradental cyst has been described as an entity in the WHO classification of odontogenic tumors and cysts (1992). It is mainly located at mandibular molars, in particular third molars of the lower jaw. Radiologically, involved molars show a circumscribed, mostly half-moon shaped translucency distal or distobuccal to the involved tooth. Patients frequently report episodes of infection (pericoronitis). The histological findings are identical to those of inflammatory radicular cysts. The inflammatory paradental cyst has been described infrequently in the international literature. There are no reports available in German. AIM OF THE STUDY AND CASES: The aim of the present study was to present six of our own cases of inflammatory paradental cysts. Five men and one woman with an average age of 29.5 years were affected. In two cases paradental cysts occurred bilaterally. Three patients reported recurrent previous infections (pericoronitis). Radiologically, the typical translucency with clear demarcation distal to the third molars was observed. All of the third molars were vertically retained. Histologically, the inflammatory paradental cysts showed features identical to those of radicular cysts. The inflammatory paradental cyst is a clear indication for osteotomy of lower wisdom teeth. Postoperative complications or recurrences of the inflammatory paradental cysts have not been described. DISCUSSION: A correct clinical, radiological, and histopathological diagnosis of paradental cysts is mandatory, and more reports are needed in order to compile more information about relative frequency and pathogenesis of this cyst variant.

Verruciform xanthoma--biological profile of 282 oral lesions based on a literature survey with nine new cases from Japan.

The biological profile of oral verruciform xanthoma (VX) is presented based on a world-wide literature survey of 282 cases. From 1979 onwards, extraoral cases have also been reported. This rare, harmless lesion with a sessile or pedunculated base is a red/pink, papillary/granular/verrucous mucosal growth, occurring in females (mean age, 54.9 yrs) and males (mean age, 44.2 yrs) in a female:male ratio of 1:1.1. The most common location is by far the gingival margin and other areas of the masticatory oral mucosa. Comparison between 173 non-Japanese and 109 Japanese patients with oral VX showed few discrepancies in epidemiological data, indicating only few significant ethnic differences between the two cohorts. Histomorphologically, the epithelium covering the lesion can be divided into three groups: (A) a verrucous, (B) a papillary and (C) a flat pattern. The hallmark of all VX, irrespective of the lesion being intra- or extraoral is, however, the presence of vacuolated, foam or xanthoma cells which ultimately replace the connective tissue between the epithelial ridges. The xanthoma cells have been shown to be cells of the monocyte/macrophage lineage. The present concept of the etiology and pathogenesis of VX, including the possible viral (HPV) association is revised, based on both intra- and some extraoral cases, and it is concluded that it is still far from being clarified.

[Revision of the 1992 edition of the WHO histological typing of odontogenic tumors. A suggestion]. / Revision der WHO-Klassifikation odontogener Tumoren von 1992. Ein Vorschlag.

The WHO classification of odontogenic tumors (1992, OT) was revised. The following main changes were proposed: (1) OT are not only "related to" odontogenic tissues but are derived from these; (2) the stroma of the epithelial tumor group (1.1.1) is of a fibrous nature and does not contain any ectomesenchymal component; (3) subtypes of ameloblastomas have to be differentiated (intra-, extraosseous, desmoplastic, unicystic); (4) eponyms are no longer used in the revised classification; (5) the AOT is reclassified as an epithelial OT; (6) a neoplastic and non-neoplastic line of the ameloblastic fibroma and ameloblastic fibrodentinoma is proposed; (7) the calcifying ghost cell odontogenic tumor is included in the classification; (8) the simple and the WHO type of odontogenic fibroma are included in the classification; (9) the classification of malignant OT is adapted from Eversole (1999) with a few changes. In particular, ameloblastic carcinoma is differentiated from malignant ( metastasizing) ameloblastoma; (10) the term carcinoma in intraosseous (peripheral) ameloblastoma is introduced. Also, the malignant epithelial odontogenic ghost cell tumor is termed calcifying ghost cell odontogenic carcinoma; (11) the clear cell odontogenic tumor is termed clear cell odontogenic carcinoma; (12) the so-called pseudocysts are termed "cavities" (aneurysmal bone cavity, simple bone cavity, lingual and buccal mandibular bone cavity, focal marrow-containing jaw cavity).

[Glandular cheilitis. 2 case reports]. / Cheilitis glandularis. 2 Fallberichte.

BACKGROUND: Glandular cheilitis (GC) is a rarely recognized disease of the accessory salivary glands of the lips, particularly of the lower lip. Clinically, three variants have been described: cheilitis glandularis simplex, cheilitis glandularis suppurativa, and cheilitis glandularis apostematosa. Most cases are diagnosed as the simple form of glandular cheilitis, which is characterized by enlarged excretory ducts, induration, and enlargement of the salivary glands as well as production of a rather mucopurulent saliva. CASE REPORTS: Two patients are described who revealed the characteristic changes of cheilitis glandularis simplex (case 1, 75-year-old male patient; case 2, 83-year-old female patient). In case 1 the patient developed a retention cyst of the upper lip probably as a consequence of GC. DIAGNOSIS: Histologically, ectasia of glandular ducts and chronic sialadenitis are typical features. Therapy formerly consisted of antibiotics and locally applied corticosteroids; an optimal oral hygiene, however, is mandatory. Advanced stages have to be treated surgically. Glandular cheilitis has been considered a precancerous lesion, although no definite scientific proof has ever been presented. Cheilitis granulomatosa, cheilitis exfoliativa, and self-induced changes (Munchausen syndrome) have to be considered in the differential diagnosis of glandular cheilitis.

Lingual and buccal mandibular bone depressions: a review based on 583 cases from a world-wide literature survey, including 69 new cases from Japan.

OBJECTIVES: To review present knowledge of so-called lingual and buccal mandibular bone depressions (n = 583) based on studies of 247 contemporary and 267 archaeological cases from a world-wide literature survey in addition to 69 new cases from Japan. METHODS: The 69 cases from Japan were retrieved through examination of 42,600 consecutive panoramic radiographs. RESULTS: Bone depressions can be divided into four topographical variants: (1) lingual anterior mandibular body (incisor-canine- premolar area) above the mylohyoid muscle; (2) posterior to the mandibular angle-first permanent molar area, below the mandibular canal, and a third located to the ascending, lingual mandibular ramus, posterior to the lingual foramen, just below the neck of the condyle. An excessively rare fourth variant is located to the buccal aspects of the ascending mandibular ramus. CONCLUSIONS: The present concept favours that all variants have a common origin: a hyperplastic/hypertrophic lobe (or aberrant lobe) of the sublingual, submandibular or parotid salivary gland, exerting pressure upon the cortex of the mandible by the respective gland, leading to focal atrophy or resorption of the bone. The bone depressions take years to develop, appearing radiographically not until the 5th to 6th decades.

Molecular modelling of chain end effects in separating oligomers by reversed-phase gradient polymer elution chromatography; adsorption transition as revealed by a self-consistent-field theory for polymer adsorption.

HPLC experiments to separate butyl-terminated polystyrene (B-PS) oligomers have been mimicked by equilibrium self-consistent-field calculations based upon the Scheutjens Fleer formalism for polymers at interfaces. The adsorption-desorption transition as a function of the fraction of good solvent in a non-solvent (water)-solvent (tetrahydrofuran) mixture has been analysed and correlated to corresponding experiments. Much attention is paid to keeping the modelling as realistic as possible; for example, the effects of the solvent mixture on the C18-alkyl tails that are grafted on the silica surface are retained in the calculations. It is shown that the butyl end groups affect the elution properties up to chains with approximately 30 styrene units. Excellent semi-quantitative comparison is found with experiments for a realistic set of interaction parameters. Molecular-level information is available for the adsorption layer as a function of the solvent quality. Going from poor to good solvent, it is typical to find that the B-PS is fully absorbed inside the alkyl brush, then adsorbed on top of it, and finally depleted from it. The depletion effect in good solvents increases with increasing molecular mass.

Desmoplastic ameloblastoma (including "hybrid" lesion of ameloblastoma). Biological profile based on 100 cases from the literature and own files.

The profile of the desmoplastic ameloblastoma (DA) is presented, based on a survey of 100 cases. DA is a benign, locally invasive variant of the intraosseous, infiltrative ameloblastoma (IA). Radiologically, the DA shows ill-defined borders with a soap bubble appearance. The finding of a mixed radiolucency-radiopacity in 52% of the cases often leads to a preoperative diagnosis of a fibro-osseous lesion. Association with an unerupted tooth is not a typical finding. The DA accounts for 4-13% of all ameloblastomas. The over-all average age is 42.9 years, higher for males (45.9 years) than for females (39.7 years). Thus, the DA occurs at a slightly higher age than the intraosseous ameloblastoma (37.4 years). The male/female ratio is 1:1. The maxilla/mandible ratio is 1/0.9 as opposed to 1/5.4 for the IA. Seven maxillary tumours involved an entire quadrant and 15 maxillary and mandibular tumours crossed the midline of the jaws. Pathogenetically, it seems that the DA is derived from the same sources as the IA, and extra-osseous sources do not seem to play a role. Histologically, the DA reveals the following morphological characteristics: the odontogenic epithelium occurs as irregular, stellate or follicular islands and cords, the center often appearing hypercellular with spindle-shaped or squamatoid cells. Peripheral columnar or cuboidal cells rarely reveal an ameloblast-like appearance. Thus, there are only vague tendencies to mimic a follicular ameloblastoma with acanthomatous features. The most striking feature separating the DA from IA is to be found in the tumour stroma: in DA there is extensive stromal desmoplasia with an abundance of thick collagen fibres that seem to compress the epithelial islands. Nine cases of so-called "hybrid lesion of ameloblastoma" where areas of IA coexist with areas of DA are surveyed in addition to the 100 cases of DA. No conclusions can be drawn about the biological profile of this variant due to the insufficient number of cases.

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.

Calcifying epithelial odontogenic tumour: biological profile based on 181 cases from the literature.

The present profile of the calcifying epithelial odontogenic tumour (CEOT) is based on a literature survey of 181 published tumour cases. The CEOT is a benign, though occasional locally invasive, slow-growing neoplasm occurring as intraosseous (94%) and extraosseous (6%) variants. The intraosseous type appears radiographically as an irregular, uni- or multilocular radiolucent area containing radiopaque masses which increases in size and opacity with time. Some 60% of intraosseous CEOT are associated with an unerupted tooth (or odontoma). CEOT shows a relative frequency of 1-2%. The extraosseous variant is diagnosed slightly earlier (mean age 34.4 years) than the intraosseous type (mean age 38.9 years). Both variants have an almost 1:1 gender ratio. The intraosseous CEOT shows a maxilla:mandible site ratio of 1:2 and are mainly located in the premolar/molar region. The present authors present evidence that the CEOT originates from the complex system of dental laminae or remnants thereof. Histologically, the CEOT is characterized by the occurrence of sheets, nests and masses of polyhedral, eosinophilic epithelial cells which may show cellular abnormalities including giant cell formation and nuclear pleomorphism. Some cells increase in size and produce a homogeneous, eosinophilic, 'amyloid-like' substance which may become calcified and which may be liberated as the cells break down. The true nature of the amyloid-like material is still unresolved. Histological variants including CEOT with cementum-like components, clear-cell CEOT (15 cases reported so far), CEOT-containing Langerhans' cells, combined epithelial odontogenic tumour (CEOT/AOT) and CEOT with myoepithelial cells are discussed in detail. In view of the relatively indolent biological behaviour of the CEOT, mutilating procedures, such as wide resection or hemisection of the mandible, seem unwarranted. Enucleation with a margin of macroscopically normal tissue is, therefore, the recommended treatment for CEOT involving the mandible. Maxillary CEOT should, however, be treated more aggressively, as they tend to grow more rapidly and do not usually remain well confined. Generally, recurrences are rare. Five years is considered the absolute minimum follow-up period. The survey has revealed only one well-documented case of a mandibular CEOT in a 75-year-old man showing features of malignancy.

Pathology and clinical correlates in oral candidiasis and its variants: a review.

Although Candida albicans is well recognised as the major agent of oral candidiasis, it is not clear why several variants such as pseudomembranous (PC), erythematous (EC) and hyperplastic candidiasis (HC) manifest in different individuals, sometimes singly and on other occasions, in combination. The present review focuses on recent histopathologic and immunocytochemical studies as well as the pathogenic attributes of the yeast, in an attempt to address the following queries. (1) Do histopathologic studies of the different variants of candidiasis in immunocompetent and immunocompromised individuals help explain these varying manifestations? (2) Under what circumstances does oral candidiasis manifest as a pseudomembranous rather than an erythematous lesion or vice versa? (3) Are there differences in immunoreactivity in closely adjacent mucosae so that the variable presentation of such lesions reflect differences in the local mucosal immune system? Recent studies of PC, EC and HC offer some insights into the pathogenic mechanisms involved. Histopathologic and immunohistochemical finding in cases of PC and EC in HIV-infected patients and controls appear to be comparable, with a marked reduction or even an absence of CD4+ cells. The latter phenomenon is marked in PC compared with the EC, and explicable in terms of a breakdown of the local immune response in the former, and a hypersensitivity reaction against Candida antigens in the latter. Hyperplastic candidiasis on the other hand could be considered a superficial cellular reaction against the pathogen, which cannot entirely be eradicated by the systemic or local host immune response. The virulent attributes of the fungus, such as the production of extracellular proteinases, do significantly differ within and between species and thereby play a contributory role in the genesis of the clinical variants. Although the available data do give a tantalising glimpse of the contributory mechanisms for the aetiopathology of PC, EC and HC, further research is warranted to elucidate response of the host to this ubiquitous fungal pathogen.

Multigenerational caregiving and well-being: distress of middle-aged daughters providing assistance to elderly parents.

This article investigates whether being a caregiver of an elderly parent and the caregiver's involvement in multiple roles increases distress in middle-aged women. Previous studies assumed that providing care to frail parents causes distress in women, in particular when they have other social roles as well. Longitudinal data were collected within a cohort of middle-aged women (n = 934; n = 743). The acquisition or loss of the caregiver role did not appear to affect levels of distress of middle-aged women, nor did additional roles of caregivers increase distress levels or caregiver role strain. Most distressed were women not performing any major social role, suggesting that the lack of social roles rather than the multiplicity of roles is associated with distress. The caregiver role might even reduce distress when women have very few other roles. Findings are explained in terms of the role scarcity, the role expansion and role accumulation hypotheses of role theory.

Adenomatoid odontogenic tumour: facts and figures.

The present profile of the adenomatoid odontogenic tumour represents an update based on data collected from 1991 onwards. Our present knowledge discloses the AOT being a benign (hamartomatous), slow growing lesion which occurs in several intraosseous (follicular (F) and extrafollicular (EF)) and one peripheral variant all having identical histology. The F and EF variants account for 96 per cent of all AOT's of which 71 per cent are F variants alone. F and EF variants together are more commonly found in the maxilla than in the mandible with a ratio of 2.1:1. Age distribution shows that more than two thirds are diagnosed in the second decade of life and more than half of the cases occur within the teens (13-19 years of age). The female:male ratio for all age groups and AOT variants together is 1.9:1. The marked female predominance (around 3:1) among certain Asian populations needs further clarification. The distribution of unerupted permanent teeth found in association with the F variant shows that all four canines account for 59 per cent and the maxillary canines alone for 40 per cent. Recent findings strongly indicate the AOT is derived from the complex system of dental laminae or its remnants. Occurrence of areas of CEOT-like tissue in an otherwise "classic" AOT should be considered a normal feature within the continuous histomorphological spectrum of AOT. Immunohistochemical and ultrastructural findings have revealed that the eosinophilic deposits or "tumour-droplets" most probably represent some form of enamel matrix.

The effects of primary nursing on work-related factors.

This study investigates the effects of a primary nursing care delivery system on some work-related factors of nurses in long-stay psychiatric care settings. In a quasi-experimental research design a cohort of 176 nurses was followed for 2.5 years. Results showed that as a result of primary nursing the primary nurses found more autonomy in their work and experienced it to be less complex. Furthermore, primary nurses performed personal care tasks less frequently and worked more according to a patient-oriented care model. Several additional analyses were performed owing to the two main problems encountered in this study, namely a high dropout due to job turnover among nurses and the imitation of the intervention by the control group.