Oral cancer after using Swedish snus (smokeless tobacco) for 70 years - a case report

Whereas the smoking habit has declined significantly in Sweden in recent decades, there has been a marked increase in the consumption of 'snus' (oral moist snuff). The use of this smokeless tobacco, exposing the user locally to carcinogenic nitrosamines, raises the question - will the increasing use of snuff eventually lead to a greater incidence of oral cancer? We report the case of a 90-year-old man who developed a localized squamous cell carcinoma in the gingival fold under the upper lip, at the exact place where he had regularly placed loose oral snuff for 70 years. Although this is a reminder of a prevailing cancer risk, the time frame indicates that the risk is slight. This is consistent with recent epidemiological reports regarding the minor risk of snuff-associated cancer in the Scandinavian countries.

Effects of long-term administration of cancer-promoting substances on oral subepithelial mast cells in the rat

The role of oral subepithelial mast cells in the defence against tumours is a matter of controversy. The effect of established and suggested carcinogens, such as the carcinogen 4-nitroquinoline-N-oxide (4-NQO) and Herpes simplex virus type 1 (HSV-1), in combination with oral snuff on lower lip subepithelial mast cells (MC) was studied in rats. The rats were exposed to prolonged use of oral snuff. The test substances were administered in a surgically created canal in the lower lip of the rats. There were 15 rats in each test group and 10 rats in the control group. The amount of countable subepithelial mast cells decreased significantly when the rat oral mucosa was exposed to the oral carcinogen 4-NQO but the effect of oral snuff and HSV-1 infection was weak. Our findings suggest that mast cells play a role in immunological cell defence against chemical carcinogens. Further studies are needed to clarify the mechanisms.

Sinus lifting procedure. I. One-stage surgery with bone transplant and implants

A prospective study of one-stage surgery with intrasinus bone transplant and implants has been performed in 26 patients (13 males and 13 females). The aim of the study was to evaluate the success rate with the one-stage sinus lifting procedure in patients with a need for bony augmentation of the alveolar process. Fifteen patients were partially dentate and 11 edentulous. The mean height of the alveolar ridge was 2.5 mm preoperatively (range 1-5.5 mm). 126 fixtures were inserted, 93 in grafted bone and 33 in alveolar bone. Twenty-two patients have been followed for three years, 21 for four years and 11 for five years. The clinical overall survival rate was 69.6% although only 61.2% in grafted bone. Ten of the patients had varying degree of sinusitis post-fixture installation. At the end of the study, 23 patients had permanent bridges. The survival rate was low for inlay supported implants when the one-stage surgical technique was applied. Two-stage surgery may be a safer method.

Volumetry of simulated bone grafts in the edentulous maxilla by computed tomography: an experimental study

OBJECTIVE

To determine the precision of CT for calculating the volume of bone grafts to the maxilla.

METHODS

Plaster of Paris was used to simulate bone as onlay and inlay grafts to the maxillary alveolus and sinus in a dry skull. Two mm thick axial CT scans were obtained. The area of the graft on each slice was measured and volumes calculated according to the formula V(graft)=Sigma of areas x the thickness of each section. Scans were repeated with the skull at approximately +5 degrees and -5 degrees to the horizontal plane and the calculations repeated. The real volume was calculated by the displaced water technique. Precision was estimated as reliability coefficient.

RESULTS

The reliability coefficients for the right and left inlay and the onlay grafts were 0.97, 0.6 and 0.96 respectively.

CONCLUSION

Calculations of the volume of both inlay and onlay grafts to the maxilla from axial CT is precise.

A clinical study of changes in the volume of bone grafts in the atrophic maxilla

OBJECTIVES

To evaluate the volumetric changes in bone grafts to the severely atrophic edentulous maxilla over 6 months.

METHODS

Ten edentulous patients received autogenous bone as buccal onlay grafts to the maxilla and bilaterally particulate bone grafts to the maxillary sinus. Two mm contiguous axial CT scans were obtained 1 to 2 weeks and 6 to 7 months postoperatively. The area of each graft was measured and the volume calculated according to the formula V(graft)=Sigma of areas x the thickness of each section.

RESULTS

The volume of the inlay and onlay grafts was reduced by an average of 49.5 and 47% respectively of the initial volume. The coefficient of variation was greater in the onlay group (0.79) compared with the inlay group (0.38).

CONCLUSIONS

The volumetric changes in buccal onlay and sinus inlay grafts after 6 months of healing seem similar although there was a wide range in both groups.

Presence of human papilloma viruses in intraosseous ameloblastoma

PURPOSE

This study investigated the possibility that human papilloma virus (HPV) is a possible etiologic agent in the development of ameloblastoma.

MATERIALS AND METHODS

DNA was extracted from 18 formalin-fixed, paraffin-embedded biopsy specimens and assayed for the presence of HPV DNA by PCR using the L1 consensus primer and specific primers for HPV types 6/11, 16 and 18.

RESULTS

Eight samples (67%) were positive for HPV. Of the 8 HPV-positive samples, 7 were positive for HPV 18. Four of the HPV 18-positive samples were also positive for HPV 6/11. One HPV-positive sample was not positive for any of the type-specific primers.

CONCLUSIONS

No conclusions can be drawn about the etiologic role of HPV from this study, but surgical manipulation is suggested to be one of the reasons for HPV presence attributable to contamination from the surface mucosal epithelium in these tumors.

Epstein-Barr virus and human papillomavirus in snuff-induced lesions of the oral mucosa

Epstein-Barr virus (EBV) and human papillomavirus (HPV) have been associated with benign as well as malignant oral lesions. We examined 43 patients with snuff-induced lesions and 22 control patients with clinically healthy oral mucosa for the presence of HPV and EBV. Polymerase chain reaction was performed on fresh frozen oral biopsies with degenerate consensus primers for HPV and nested primers for EBV. None of the 43 snuff-induced lesions or the 22 control biopsies were HPV-positive. Seven of the 43 (16.3%) snuff-induced lesions and one of the 22 (4.5%) controls were positive for EBV. The snuff-induced lesions were classified according to clinical severity, grade 1 lesions being the least severe and grade 4 the most severe. Eleven percent of grade 2 lesions, 15.8% of grade 3 lesions and 20% of grade 4 lesions were EBV-positive. Neither EBV nor HPV seem to be associated with snuff-induced lesions.

A randomized, double-blind, placebo-controlled clinical evaluation of a nicotine sublingual tablet in smoking cessation

AIMS

Evaluation of the clinical efficacy and safety of a nicotine 2-mg sublingual tablet in smoking cessation.

DESIGN

A randomized, double-blind, placebo-controlled study of smokers using the 2-mg tablet for 3-6 months with follow-up to 12 months. Dosing was established according to baseline nicotine dependence, scored on the Fagerström Tolerance Questionnaire (FTQ): FTQ > or = 7, two tablets/hour (maximum 40/day); FTQ < 7, one tablet/hour (maximum 20/day).

SETTING

Smoking cessation programme in a department of oral and maxillofacial surgery.

PARTICIPANTS

A total of 247 adult smokers, smoking > or = 10 cigarettes/day for > or = 3 years, of whom 123 received active and 124 placebo treatment. The study was powered to detect difference at 6 months.

MEASUREMENTS

Efficacy and safety were evaluated at 6 weeks and 3, 6 and 12 months. Self-reported abstinence was verified by exhaled CO < 10 p.p.m.

FINDINGS

Success rates for complete abstinence (no slips after 2 weeks) for active vs. placebo were 50% vs. 29% at 6 weeks, 42% vs. 23% at 3 months, 33% vs. 18% at 6 months and 23% vs. 15% at 12 months (p < 0.001, 0.001, 0.005 and p = 0.14), respectively. Craving during the first 8 days was significantly reduced among highly dependent smokers on active treatment compared to placebo. Baseline mucosal lesions among abstinent subjects were reduced during the treatment period and at the non-treatment follow-up. Adverse events were mild and tolerable, the most common being irritation and soreness in the mouth and throat.

CONCLUSION

The nicotine sublingual tablet increased the smoking cessation rate compared to placebo, reduced craving in highly dependent smokers and was well tolerated.

Human papilloma viruses in oral lesions

Oral mucosa biopsies from 53 patients with different oral diseases, and from 12 healthy control patients, were examined by the PCR-technique using the L1 consensus primers and type-specific primers for HPV 6/11, 16 and 18. Three out of 24 (12.5%) oral cancer biopsies were HPV positive, 1 for HPV 18, 1 for HPV 16 and 6/11 and 1 for none of the specific primers. Six out of 22 (27.3%) lichen planus were HPV positive, 5 for HPV 18 and 1 for none of the specific primers. Seven leukoplakias were included in the study and 2 (29.6%) were positive for both HPV 16 and 6/11. None of the 12 control patients was HPV positive. No statistical difference between the use of tobacco and alcohol and HPV prevalence was found. An association between HPV infection and oral lesions was demonstrated in the studied population but the pathogenic influence of HPV infection remains unclear.

Hydroxyapatite Granule/Carrier Composites Promote New Bone Formation in Cortical Defects

BACKGROUND

A great deal of interest has been focused on finding substitutes for autogenous bone grafts. Among the most interesting materials are different calcium phosphate compositions (e.g., hydroxyapatite [HA]), due to their biocompatible properties in hard and soft tissue.

PURPOSE

The bone response to porous ceramic HA granules in combination with two lipid and one polysaccharide carrier was evaluated in an experimental bone defect model in rabbits.

MATERIALS AND METHODS

Circular defects (Ø 4 mm) were made in both tibias of 32 rabbits. The 64 defects were divided into four groups. Group A was augmented with a composite of HA granules and a phospholipid-diacetyl-glycerol carrier, group B with HA granules and a phospholipid carrier, group C received HA granules and a sodium hyaluronan carrier, and group D served as control. The animals were killed after 6 weeks and ground sections were evaluated using light microscopic morphometry. X-ray microfluorescence (XRF) was applied in order to evaluate the suitability of this method to examine bone-biomaterial interfaces. Calcium distribution was studied using x-ray fluorescence line scans at selected interface regions of two sections in group B.

RESULTS

The HA/phospholipid composites were easier to shape and handle than the HA/hyaluronan composite. Group A had 36% newly formed bone area within the defect. Groups B and C showed significantly more newly formed bone within the defect (47% and 49%, respectively) compared to the control group (31%). The XRF analysis revealed that the amount of calcium in the newly formed bone was similar to that observed for the HA granules and slightly lower when compared to the mature, lamellar bone.

CONCLUSIONS

Synchrotron radiation may be a new, suitable technique to study the interface between bone and biomaterials with regard to mineral content. The results suggest that HA granule/lipid and HA granule/hyaluronan composites have interesting properties as bone-substitute materials.

High-throughput DNA extraction from old paraffin-embedded biopsies

We have developed a rapid and reliable microporous spin-column-based method for high-throughput extraction of DNA from old paraffin-embedded biopsies. The method was developed specifically for PCRs and molecular genetic studies. De-waxing and DNA extraction from tissues is performed in only one vessel, minimizing pipetting steps and eliminating supernatant/pellet procedures. All steps are performed at 60 degrees, 55 degrees and 95 degrees C minimize deleterious DNase activity. The amount of the extracted DNA was measured spectrophotometrically, and the quality of the extracted DNA and the PCR products was controlled on ethidium bromide-stained 3% agarose gel. The presented method for DNA extraction is less laborious and more convenient than previously published methods. It provides means by which extensive, paraffin-embedded material can be subjected to molecular genetic studies.

Surface analysis of failed oral titanium implants

The aim of the present study was to investigate the surface topography, composition, and oxide thickness of consecutively failed, oral Brånemark implants in order to determine possible causes for failure. The failure criterion was lack of osseointegration manifested as implant mobility. Ten implants were retrieved before loading (early failures) and 12 during a period of function up to 8 years (late failures). At retrieval, early losses did not display any clinical sign of infection. All late failures were radiographically characterized by peri-implant radiolucency and did not show infectious signs with one exception. No implant seemed to be lost due to peri-implantitis (plaque-induced progressive marginal bone loss). Twelve implants were analyzed by scanning electron microscopy (SEM), Auger electron spectroscopy (AES), and depth profiling using a blind protocol. Two pristine fixtures, which underwent the same preparation as the failed implants, were used as controls. In the SEM, control samples were essentially free from macroscopic contamination, whereas failed implants contained varying amounts of tissue residues. AES showed that all surfaces consisted of Ti oxide and varying amounts of additional elements, with C dominating in most cases. Nitrogen and sometimes Na, Ca, P, Cl, S, and Si were detected. The Si contamination was most likely due to ion leaching from the glass vials used for storage. Depth profiles showed a typical oxide thickness of 5-8 nm for all samples. In conclusion, no significant changes in the oxide layer composition or thickness as a result of implantation were observed. The results do not indicate any material-related cause for the failures of these implants. Possible reasons for these failures were impaired healing, asymptomatic infection, and overload.

The long-term effect of nicotine on the oral mucosa

AIMS

Although nicotine replacement therapy (NRT) has been used to aid smoking cessation for the last 20 years, little information exists on the effect of nicotine products on the oral mucosa, particularly with regard to the direct effect at the site of application. This study aimed to assess the oral safety of a new sublingual tablet containing 2 mg nicotine with regard to lesions at the site of application.

DESIGN

Prospective follow-up to 12 months of smokers using the 2-mg sublingual tablet over a period of 3-6 months.

SETTING

A smoking cessation programme.

PARTICIPANTS

Thirty smokers.

MEASUREMENTS

Oral mucosa was inspected and photographed at each visit. At 6 months, subjects were asked for consent to take a biopsy from the site of application.

FINDINGS

Spontaneous smoking cessation outcome at 12 months was 27% allowing for lapses. At baseline 21 mucosal lesions were diagnosed in 15 subjects. After 6 months eight lesions were observed in six subjects. The predominant diagnosis at all visits was melanin pigmentation. Eight subjects had lesions in the floor of the mouth during the 6-month medication period, all of which appeared in the first 1-6 weeks of treatment. By the 6-month visit all such lesions had resolved. The local symptoms were all mild and tolerable.

CONCLUSION

The sublingual tablet appears to be a safe form of administration of nicotine with mild and transient effects on the floor of the mouth.

The Swedish snus and the Sudanese toombak: are they different?

In Sweden, snuff (locally known as snus), was introduced since the year 1637. Presently, Sweden has the highest per capita consumption and sale figures of snuff in the world, and the habit is becoming increasingly popular. Snus is manufactured into a dry form used in the nasal cavity and a moist form used in the oral cavity. Snus manufactured for oral use is a moist ground tobacco of Dark Kentucky or Virginia species mixed with an aqueous solution of water and other blending ingredients. This form of snuff is found in two types: (1) loose and (2) portion-bag-packed. These are the most widely used. The loose moist form (1-2 g a quid) is the most popular type consumed by 73% of the males, followed by the portion-bag-packed form (0.5-1 g a quid), consumed by 13% of the males, while 14% of the males are mixed users. The majority of snus users place the quid in the vestibular area of the upper lip, and the prevalence among persons 15 years of age or older in 15.9% among males and 0.2% among females. The pH of snus has declined from a previous range of 8-9 to a range of 7.8-8.5, moisture content ranges 35-60% and nicotine content is in the order of 5-11 mg/g dry wt tobacco-specific N-nitrosamines (TSNAs) in micrograms (N'-nitrosonornicotine: NNN 5-9; 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone: NNK 1-2; N'-nitrosoanatabine: NAT 2-5). In the Sudan, snuff, locally known as toombak, was introduced approximately 400 years ago. It is always processed into a loose moist form, and its use is widespread in the country. Tobacco used for manufacture of toombak is of the species Nicotiana rustica, and the fermented ground powder is mixed with an aqueous solution of sodium bicarbonate. The resultant product is moist, with a strong aroma, highly addictive and its use is widespread particularly among males. Its pH range is 8-11, moisture content ranges 6-60% and nicotine content is from 8 to 102 mg/g dry wt, and TSNAs contents in micrograms (NNN 420-1 550; NNK 620-7 870; NAT 20-290). Snus and toombak dippers develop a clinically and histologically characteristic lesion at the site of dipping. Probably due to control of the TSNAs in snus, this type of snuff is associated with a lower risk of cancer of the oral cavity (relative risk: RR 5-6-fold), whereas the risk for cancer of the oral cavity among toombak users was high (RR 7.3-73.0-fold). In conclusion, the two snuff products significantly differ in many aspects. Most notable differences are tobacco species, fermentation and ageing, nicotine and TSNAs content, pH, expression of the p53 tumour suppressor gene, and keratin types 13, 14, and 19. It was, therefore, the object of the present study to highlight the oral health hazards of toombak, and to compare it with snus regarding the aforementioned differences.

Studies of the healing of bone grafts, and the incorporation of titanium implants in grafted bone: an experimental animal model

An insufficient quality and amount of bone often necessitate the clinical use of implants together with bone transplants. The present study describes an experimental animal model for the study of implants in bone grafts. Circular defects were made bilaterally in the tibia of 36 rabbits. The defects received either autologous cortical bone (control), demineralized bone matrix (DBM), plasma-augmented DBM or were left empty (without bone graft). In all defects a titanium implant was centrally placed and anchored in the opposite cortex. Evaluation with light microscopic morphometry showed that the insertion of a threaded titanium implant centrally in a cortical defect was followed by a spontaneous healing of the defect after 6 mon. After 6 wk, all implants in cortical grafts were well integrated with a significantly higher bone-to-implant contact than in the DBM and plasma-augmented groups. After 6 mon, all experimental groups had a mean bone area within the threads ranging between 69% and 80% and a mean bone-to-implant contact between 31% and 42%. The results from the present study indicate that the model allows comparative studies on the early formation, resorption and remodelling of bone around implants after modification of implant, graft and host properties.

Biological factors contributing to failures of osseointegrated oral implants. (II). Etiopathogenesis

The aim of the present review is to evaluate the English language literature regarding factors associated with the loss of oral implants. An evidence-based format in conjunction, when possible, with a meta-analytic approach is used. The review identifies the following factors to be associated with biological failures of oral implants: medical status of the patient, smoking, bone quality, bone grafting, irradiation therapy, parafunctions, operator experience, degree of surgical trauma, bacterial contamination, lack of preoperative antibiotics, immediate loading, nonsubmerged procedure, number of implants supporting a prosthesis, implant surface characteristics and design. Excessive surgical trauma together with an impaired healing ability, premature loading and infection are likely to be the most common causes of early implant losses. Whereas progressive chronic marginal infection (peri-implantitis) and overload in conjunction with the host characteristics are the major etiological agents causing late failures. Furthermore, it appears that implant surface properties (roughness and type of coating) may influence the failure pattern. Various surface properties may therefore be indicated for different anatomical and host conditions. Finally, the histopathology of implant losses is described and discussed in relation to the clinical findings.

Biological factors contributing to failures of osseointegrated oral implants. (I). Success criteria and epidemiology

The aim of this review was to offer a critical evaluation of the literature and to provide the clinician with scientifically-based diagnostic criteria for monitoring the implant condition. The review presents the current opinions on definitions of osseointegration and implant failure. Further, distinctions between failed and failing implants are discussed together with the presently used parameters to assess the implant status. Radiographic examinations together with implant mobility tests seem to be the most reliable parameters in the assessment of the prognosis for osseointegrated implants. On the basis of 73 published articles, the rates of early and late failures of Brånemark implants, used in various anatomical locations and clinical situations, were analyzed using a metanalytic approach. Biologically related implant failures calculated on a sample of 2,812 implants were relatively rare: 7.7% over a 5-year period (bone graft excluded). The predictability of implant treatment was remarkable, particularly for partially edentulous patients, who showed failure rates about half those of totally edentulous subjects. Our analysis also confirmed (for both early and late failures) the general trend of maxillas, having almost 3 times more implant losses than mandibles, with the exception of the partially edentulous situation which displayed similar failure rates both in upper and lower jaws. Surgical trauma together with anatomical conditions are believed to be the most important etiological factors for early implant losses (3.60% of 16,935 implants). The low prevalence of failures attributable to peri-implantitis found in the literature together with the fact that, in general, partially edentulous patients have less resorbed jaws, speak in favour of jaw volume, bone quality, and overload as the three major determinants for late implant failures in the Brånemark system. Conversely, the ITI system seemed to be characterized by a higher prevalence of losses due to peri-implantitis. These differences may be attributed to the different implant designs and surface characteristics. On the basis of the published literature, there appears to be a number of scientific issues which are yet not fully understood. Therefore, it is concluded that further clinical follow-up and retrieval studies are required in order to achieve a better understanding of the mechanisms for failure of osseointegrated implants.

Biological factors contributing to failures of osseointegrated oral implants. (I). Success criteria and epidemiology

The aim of this review was to offer a critical evaluation of the literature and to provide the clinician with scientifically-based diagnostic criteria for monitoring the implant condition. The review presents the current opinions on definitions of osseointegration and implant failure. Further, distinctions between failed and failing implants are discussed together with the presently used parameters to assess the implant status. Radiographic examinations together with implant mobility tests seem to be the most reliable parameters in the assessment of the prognosis for osseointegrated implants. On the basis of 73 published articles, the rates of early and late failures of Brånemark implants, used in various anatomical locations and clinical situations, were analyzed using a metanalytic approach. Biologically related implant failures calculated on a sample of 2,812 implants were relatively rare: 7.7% over a 5-year period (bone graft excluded). The predictability of implant treatment was remarkable, particularly for partially edentulous patients, who showed failure rates about half those of totally edentulous subjects. Our analysis also confirmed (for both early and late failures) the general trend of maxillas, having almost 3 times more implant losses than mandibles, with the exception of the partially edentulous situation which displayed similar failure rates both in upper and lower jaws. Surgical trauma together with anatomical conditions are believed to be the most important etiological factors for early implant losses (3.60% of 16,935 implants). The low prevalence of failures attributable to peri-implantitis found in the literature together with the fact that, in general, partially edentulous patients have less resorbed jaws, speak in favour of jaw volume, bone quality, and overload as the three major determinants for late implant failures in the Brånemark system. Conversely, the ITI system seemed to be characterized by a higher prevalence of losses due to peri-implantitis. These differences may be attributed to the different implant designs and surface characteristics. On the basis of the published literature, there appears to be a number of scientific issues which are yet not fully understood. Therefore, it is concluded that further clinical follow-up and retrieval studies are required in order to achieve a better understanding of the mechanisms for failure of osseointegrated implants.

Expression of keratin 13, 14 and 19 in oral hyperplastic and dysplastic lesions from Sudanese and Swedish snuff-dippers: association with human papillomavirus infection

Changes in the expression of keratins (Ks), indicating disturbed tissue differentiation, is one possible marker of malignant potential in stratified squamous epithelia. The presence of human papillomaviruses (HPVs) in the epithelium of the uterine cervix is increasingly regarded as a marker of risk for cervical cancer: However, a similar role in oral cancer and precancer remains controversial. To address these questions, potentially malignant oral mucosal lesions from Sudanese (9 hyperplasias/40 dysplasias) and Swedish (15 hyperplasias) snuff-dippers were examined by immunohistochemistry for expression of K types 13, 14 and 19 using monoclonal antibodies directed against each. HPV infection was searched for by in situ hybridization (ISH) using the cocktail HPV OmniProbe and the ViraType probe. For the Sudanese lesions, moderate to intense expression of both K13 (basal, basal/intermediate, basal/intermediate/superficial and intermediate/superficial cell layers) and K14 (basal, basal/intermediate cell layers) was found in 49/49 (100%). For the Swedish lesions, weak to moderate expression of K13 (basal, basal/intermediate cell layers) was found in 12/15 (80%) and 10/15 (67%), respectively. In the Sudanese lesions, expression of K13 showed a distinct pattern through the oral mucosa and its verrucous projections, with an increase towards the superficial cell layers of dysplastic, but not hyperplastic epithelium. K19 was expressed in the basal cell layer in 16/49 (33%) of the Sudanese lesions, while all the Swedish lesions were negative. HPV was found in only 2 Sudanese cases, both of which harboured both type 6 and type 11: both these cases demonstrated mild epithelial dysplasia, The present study shows that a) there is a high prevalence of expression of both K13 and K14 in oral lesions from Sudanese toombak dippers indicating dysregulation of keratinocyte maturation b) one-third of the Sudanese oral lesions expressed K19, regarded as a basal keratin representing epithelial dedifferentiation, which may prove to be a valuable risk marker in follow-up studies c) HPV genome is found infrequently in oral lesions from Sudanese toombak-dippers, suggesting that these viruses may not play a prominent role in the early stages of carcinogenesis in these subjects. These markers were less often expressed in the Swedish lesions, consistent with their much lower rate of malignant transformation.

Failure patterns of four osseointegrated oral implant systems

The aim of this metanalysis was to investigate possible differences in failure patterns among four different osseointegrated oral implant systems. Only systems with a supposed scientific validation, based on long-term follow-up studies, were selected for this analysis, i.e. the Brånemark system, the Calcitek Integral system, the Interpore IMZ system and the Straumann ITI system. While several prospective reports could be found on the Brånemark system, only a few retrospective investigations concerning the ITI and the IMZ systems were available. No data on the Integral system could be employed. Despite these limitations, a substantial difference in failure patterns among various implant systems was observed. The Brånemark implants showed a higher incidence of early failures, though sharply decreasing over time. On the contrary, IMZ implant characterized by rougher surfaces displayed a lower incidence of early failures, but showed constant or increased failure rates over time. For the ITI implants, for example, a higher prevalence of late failures, attributable to chronic bacterial infection (peri-implantitis), was observed when compared to the Brånemark system. With the exception of the latter implant system, prospective long-term follow-up studies, using similar and well-defined success criteria, are needed for the others to confirm the current preliminary findings.

Immunotoxic effects of smokeless tobacco on the accessory cell function of rat oral epithelium

Smokeless tobacco (ST) is known to adversely effect the oral mucosa, but knowledge about the influence on immune defence is limited. Few studies have investigated the effect of ST on the local immune response. In the present study, we have assessed the effect of a crude Swedish moist snuff (SS) extract, alkaloids, and nitrosamines on T-cell mitogenic response to Con A using epithelial cells, including Langerhans cells, of the rat oral mucosa as accessory cells. SS extract at a concentration of 4% reduced the T-cell proliferation by 50% (IC50 = 4%). Pretreatment of either oral epithelial cells or T-cells with SS extract also gave a significant inhibition of T-cell proliferation. This effect was not obtained following preincubation with SS components as alkaloids and different tobacco-specific nitrosamines (TSNA). None of the tested compounds were found to possess any mitogenic properties. This in vitro study showed that SS extract can evoke an immunosuppressive effect on mitogen-driven T-cell proliferation using cells from oral epithelium as accessory cells. This effect was more pronounced when SS extract was employed compared to when the single SS components were used alone.

Glandular odontogenic cyst. Report of seven cases

This study describes the clinical, radiographic and histopathological features of seven glandular odontogenic cysts. These cysts comprised 0.012% of 5800 jaw cysts diagnosed in a 19-year period. There was strong predilection for the mandible (five of the seven cases). Both clinical and radiographic features were nonspecific. The main histological findings were a nonkeratinized, stratified squamous epithelium lining to the cyst cavity which varied in thickness with superficial eosinophilic cuboidal cells and mucous pools within the spinous cell layer. Daughter cysts were found in the wall of 2 cysts. At surgery, most walls were found to be thin and lumen to contain a serous, low viscosity exudate. Because of the high rate of recurrence found in three cases out of the seven after conservative surgical treatment, careful clinical and radiographic follow-up is recommended.

Immunohistochemical detection of p53 in non-malignant and malignant oral lesions associated with snuff dipping in the Sudan and Sweden

Immunohistochemistry was used to examine the expression of p53 in pre-malignant oral lesions and oral squamous-cell carcinomas (SCCs) from Swedish and Sudanese snuff-dippers, as well as in pre-malignant oral lesions and oral SCCs from non-snuff-dippers from the Sudan, Sweden and Norway. Of the 14 SCCs from Sudanese snuff-dippers, 21% (3/14) expressed p53. Of the 14, 60 and 41 SCCs from non-snuff-dippers from the Sudan, Sweden and Norway, 64% (9/14), 65% (39/60) and 68% (28/41) expressed p53, respectively. A statistically significant difference in expression of p53 was found in SCCs from Sudanese snuff-dippers compared to those from non-snuff-dippers from all/or any of the 3 countries. None of the suspected pre-malignant oral lesions from Sudanese snuff dippers or non-snuff-dippers expressed p53. Only 2 out of the 15 oral fibro-epithelial hyperplastic lesions from Swedish snuff-dippers expressed p53. Some of the oral epithelial dysplastic lesions, as well as the carcinoma in situ lesions from Norwegian non-snuff-dippers, expressed p53, while the oral fibro-epithelial hyperplastic lesions did not. The low relative frequency of p53 expression found in oral SCCs from snuff-dippers compared to those from non-snuff-dippers might suggest differences in mechanisms of oncogenic action induced by snuff. Alternatively, the pathogenesis of malignant oral lesions from snuff-dippers may follow a p53-independent pathway. In view of the unusually high levels of the tobacco-specific nitrosamines (TSNA) found in the type of snuff used in the Sudan, investigations of p53 mutations or oncogenes are needed.

Assessment of p53 and Ki-67 expression in snuff-induced lesions

An immunohistochemical study of snuff-induced lesions with a monoclonal antibody (DO-7) specific to p53 mutant and wildtype antioncogene product demonstrated nuclear overexpression of the mutant protein in 45.9 nuclear profiles/mm2 epithelium (SEM 10.8; n = 15) compared with only 0.18 positively stained nuclear profiles/mm2 in the control group (SEM 0.18; n = 4). Furthermore, the biopsy material was also stained with the antibody Ki-67, which has been shown to be excellent for the estimation of the growth fraction in both normal and malignant human tissues. Ki-67 stained positive in 566.1 nuclear profiles/mm2 epithelium (SEM 85.0; n = 15) in the snuff-group compared with 20.2 nuclear profiles/mm2 (SEM 4.9; n = 4) in the control group. To the best of our knowledge, this is the first study showing overexpression of p53 protein and Ki-67 in snuff-induced lesions. The results may indicate that the p53 gene is involved in the initial events leading to subsequent malignant transformation of oral mucosa exposed to snuff. Furthermore, mutations of the p53 gene have been associated with increased cellular proliferation with greater risk of perpetuation of mutations and malignant transformation.

Fixture stability and nerve function after transposition and lateralization of the inferior alveolar nerve and fixture installation

Twenty-four posterior mandibular segments in 18 patients were operated on placing implants after mobilisation of the neurovascular bundle. Two different surgical techniques, transposition and lateralization was used. The overall survival rate of fixtures was 92.1%. Performing lateralization resulted in 100% success, while transposition resulted in 80% stable fixtures in the involved segments. The mean time to full restoration of nerve function was 3.8 weeks after lateralization and 5.7 weeks after tranposing the nerve. Three patients exhibited persisting slight hyposthesia, but all, subjectively negligible disturbances in nerve function.

Recrudescence of herpes simplex virus type 1 in latently infected rats after trauma to oral tissues

Tooth extraction in rats was used to trigger a latent HSV-1 infection. HSV-1 was inoculated unilaterally in the rat palates. Eight weeks later two molars were removed bilaterally. The trigeminal ganglia were co-cultivated and HSV-1 was isolated from 63% of the ganglia on the infected sides but from only 11% on control sides. The immune response pattern was analysed by immunoblotting of rat serum, and strong reactivity to HSV-1 specific cell polypeptides and glycoproteins (ICP6, gC, pgC, gD) was seen after reactivation. The extraction sockets were histopathologically evaluated and showed healing on the infected side in 26% compared to 63% in contralateral control sockets. The effect of acyclovir (ACV) treatment was elucidated and was found to influence the subsequent development of antibodies and to promote healing of the sockets. Vesiculation in intra- and subepithelial tissue was present on the infected side in 58% but in only 12% of ACV-treated animals. The present study in rats has shown that a latent HSV-1 infection can be established and reactivated by tooth extraction. Reactivation resulted in delayed healing of sockets on the latently infected side but not on the contralateral control side. HSV-1 reactivation was demonstrated serologically by immunoblotting. Healing was significantly promoted by administration of ACV, which also supports the contention that HSV-1 interferes with the healing process.

Reactivated herpes simplex virus infection as a possible cause of dry socket after tooth extraction

This study was designed to evaluate a possible association between reactivated herpes simplex virus type 1 (HSV-1) infection after lower third molar extraction and development of dry socket (DS). The HSV-1 antibody response was analyzed before and after tooth removal by enzyme-linked immunosorbent assay and immunoblotting in 208 patients. History of previous possible oral herpes reactivation was evaluated by a questionnaire that was based on self-rated frequency of oral cold sores. Tobacco users were identified. The anatomic proximity of the root apex to the mandibular nerve canal was classified radiographically before extraction. Fifteen patients (7%) developed DS after tooth extraction. Eleven of the 15 DS patients (73%) were HSV seropositive as compared with 7 of 15 (47%) in the matched control group. Seven of the 11 seropositive DS patients have shown HSV-1 reactivation by an increase of specific polypeptides, predominantly gB, gC, gD and ICP 4 and 6, in the immunoblot test. No change in HSV-1 reactivity was observed in control sera. DS patients reported a high frequency of oral cold sores (64%) compared with the controls (33%). Tobacco use was not found to influence the frequency of cold sores or the development of DS. A close radiographic proximity between the mandibular canal and root apex was more common (P < .05) in DS patients. The results indicate that extraction of a mandibular third molar could be a possible cause of reactivation and recurrence of an HSV-1 infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Measures of dental beliefs and attitudes: their relationships with measures of fear

Emergency dental and fearful dental patients were questioned in order to investigate the relationship between dental fear and different dental beliefs. The instruments used were the dental anxiety scale and the dental beliefs survey. The study also evaluated a Swedish version of the beliefs survey. The mean anxiety scale scores were 9.4 for emergency and 16.8 for fearful patients. The average beliefs survey item values ranged from 1.6 to 2.6 and 1.7 to 3.8 among the two groups respectively. There were clinical meaningful and statistically significant correlations between the anxiety scale and the beliefs survey. Each of the four dimensions of the beliefs survey (communication, control, belittlement and trust), also correlated with the anxiety scale of which the most clearly defined was belittlement.

Inhibition of herpes simplex virus replication and protein synthesis by non-smoked tobacco, tobacco alkaloids and nitrosamines

Inhibitory effects of snuff extract and the tobacco chemicals nicotine, anabasine, diethyl-N-nitrosamine (DEN), and the tobacco-specific nitrosamines (TSNA), N-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) on herpes simplex virus type 1 (HSV-1) replication in vitro and on HSV-1 protein synthesis in infected cells were analysed. Snuff extract and nicotine caused a significant reduction of HSV-1 attachment to cell membranes whereas anabasine, DEN, NNN and NNK did not affect adsorption of HSV-1. Virus production assays in the presence of snuff added after virus adsorption resulted in a significantly reduced production of virus at low multiplicities of infection (MOI), but at high MOI the inhibitory effect of snuff extract was less pronounced. DEN, NNN and NNK only affected virus production at toxic concentrations. Nicotine and anabasine reduced virus production in non-toxic doses but not at the concentrations present in snuff extract. In HSV-infected cells exposed to snuff extract, the immediate early (alpha-) infected cell proteins (ICPs) 4 and 27 (as well as the early (beta-) ICPs 6 and 8) were markedly increased, whereas the late (gamma-) ICPs 5, 11 and 29 were reduced. Nicotine had a less pronounced stimulating effect on the production of alpha-proteins but no detectable effect on production of beta- or gamma-proteins. Anabasine, DEN, NNN and NNK did not affect HSV protein synthesis at non-toxic concentrations. Synthesis of thymidine kinase and DNA polymerase was significantly reduced by snuff extract. Also nicotine and anabasine affected thymidine kinase and DNA polymerase but only at toxic concentrations. The production of the cellular protein actin, which almost disappears a few hours after HSV-1 infection, remained at a significant level in HSV-infected cells exposed to snuff. Thus snuff extract blocks the replicative cycle of HSV at an early stage, which results in an increased production of alpha-proteins in the infected cells and in prolonged maintenance of cellular functions. This may be of importance for HSV-induced transformation and the development of HSV-associated tumours.

Hemodynamic effects of the use of oral snuff

The hemodynamic effects during rest and exercise of oral snuff were investigated in an open, placebo-controlled study of nine habitual users of oral snuff. Blood pressure, heart rate, and central hemodynamics were measured noninvasively. Plasma concentrations of nicotine, cotinine, norepinephrine, and epinephrine, as well as neuropeptide Y-like immunoreactivity were measured before and after snuff intake during rest and exercise. Snuff intake induced a significant increase in heart rate and blood pressure and a decrease in stroke volume during rest. Hemodynamic changes were unrelated to nicotine or cotinine concentrations. Resting levels of norepinephrine and neuropeptide Y-like immunoreactivity were similar with or without snuff, whereas epinephrine was slightly increased 30 minutes after snuff intake. The exercise-induced increase in norepinephrine and neuropeptide Y-like immunoreactivity did not differ between the days subjects received snuff and the days they received placebo. In contrast, maximum work load was associated with a slight increase in circulating epinephrine after snuff intake. The findings suggest that snuff intake is associated with significant hemodynamic effects during rest but not during exercise. These effects could not be readily explained by activation of the sympathetic nervous system.

Non-random chromosome rearrangements in herpes simplex virus type 1 transformed diploid CHEF cells

The effects of Herpes simplex virus type 1 (HSV-1) on diploid, non-tumourigenic Chinese hamster embryo fibroblasts (CHEF/18-1D-3) were studied. Six independent lines transformed by HSV-1 alone or by HSV-1 in combination with acyclovir or aqueous tobacco extract were isolated. In contrast to uninfected CHEF/18-1D-3 cells, all transformants grew in soft agar and were tumourigenic in nude mice. Neither infectious virus nor viral antigens could be detected in any of the lines. Cytogenetic analysis revealed clonal chromosome abnormalities in all lines including trisomy for the long arm of chromosome 3 in five lines. In three of these the extra 3q was translocated onto 6p. All lines showed loss of the corresponding 3p arm. The remaining line had a hypodiploid stemline with loss of one chromosome 7. This line also showed a pronounced chromosomal instability with a multitude of mainly sporadic rearrangements. These results show that HSV-1 induced transformation and tumourigenesis in CHEF cells is associated with the induction of chromosome rearrangements, in particular trisomy for 3q.

Association between development of lower lip cancer and tobacco habits

Tobacco use is considered to increase the risk of tumor induction. The purpose of this case-controlled investigation was to assess the association of tobacco habits and development of squamous cell carcinoma of the lower lip. Sixty-one patients treated for lower lip cancer, aged between 42 and 90 years, were studied. Age- and sex-matched healthy controls showed a similar exposure to tobacco in years and a comparable distribution of tobacco habits. Although the mean exposure factor (duration times exposure) was greater in the tumor group, no intimate correlation between lip cancer and tobacco was demonstrated. However, an increased, although small, occurrence of herpes labialis lesions was found in cancer patients. The hypothesis is presented that smokers experiencing recurrent herpes simplex virus 1 (HSV-1) infections are more liable to tumor initiation, which issue will be subjected to a future study.

Reactivity against herpes simplex virus in patients with head and neck cancer

The relation between herpes simplex virus (HSV) and head and neck cancer was examined. A total of ninety patients were analyzed for IgG antibodies against HSV. Antibody titers were established with an enzyme-linked immunosorbent assay and antibodies against specific HSV-antigens were analyzed by Western blot. These patients' seroreactivity was compared to that of an age-matched control group of patients with arteriosclerotic disease in their lower limbs, a disease also closely related to heavy tobacco consumption. Prevalence of antibodies against HSV was around 90% and did not differ significantly between cancer patients and controls, but antibody titers against HSV were significantly higher in the cancer patients. The cancer patients also reacted more constantly (80%) in Western blot analysis against the early immediate protein, ICP-4, than controls (50%). This suggests a different course of an earlier herpetic infection in these patients with a prolonged exposure to early immediate HSV-proteins which may be related to an increased risk of developing head and neck cancer. We propose that heavy smoking may contribute to this phenomenon.

Maxillary sinus augmentation using mandibular bone grafts and simultaneous installation of implants. A surgical technique

This paper presents a specific technique for maxillary sinus augmentation and simultaneous placement of implants in partially edentulous patients. In such patients, there is from time to time insufficient interarch distance for any type of onlay grafting. Health, non-smoking patients without previous or present sinus pathology, where the radiological and clinical examination revealed insufficient height and/or width of the remaining alveolar process in the posterior maxillary region, were selected. They were operated on using a mandibular bone graft obtained from the symphyseal region between the mental foramina and placed in the maxillary sinus. The recipient site was prepared by cutting in a rectangular shape the lateral sinus wall into the sinus lining. The bone wall was then separated towards the lateral nasal wall by rotating the inferior portion of the cut sinus wall medially. In the space thus created, the bone graft was placed. Fixtures were installed at the same session. The method described has proved to be uncomplicated to perform under local anesthesia and no major disadvantages for the patient or pre- or postoperative complications have so far been observed.

Effect of repeated oral administration of tobacco snuff on natural killer-cell activity in the rat

The possible immune effect of oral snuff was investigated. In male adult rats, oral snuff given for 15 weeks significantly decreased NK-cell activity in peripheral blood against murine NK cell-sensitive target cells (YAC-1 lymphoma).

Primary herpes simplex virus (type 1) infection delays healing of oral excisional and extraction wounds in the rat

The effect of acute herpes simplex virus type 1 (HSV-1) infection on the healing process of intraoral wounds and tooth extraction sockets in the rat was studied. A standardized size of the buccal mucosa was excised and molars were extracted and a HSV-1 suspension was topically applied. The virus infected wounds were clinically characterized by erythema and swelling and histologically by heavy inflammation cell infiltrate and abscesses during the first week. The acute HSV-1 infection was found to significantly delay healing of both types of wounds by 3 days. Antiviral treatment with acyclovir (ACV) decreased the degree of inflammation and improved healing of the infected wounds. The present results indicate a delayed and disturbed healing of wounds in the oral cavity in the presence of HSV-1. The findings may have a clinical significance for primary or latent HSV-1 infections in conjunction with surgical intervention in the oral cavity.

Effects of acyclovir on herpes simplex virus type 1 infection in mice treated with 12-O-tetradecanoylphorbol 13-acetate

The purpose of this study was to determine whether infectious herpes simplex virus type 1 (HSV-1) has tumorigenic properties and, if so, whether inhibition of the cytolytic replicative cycle of the virus after infection enhances tumour development. Eighty mice were subjected to repeated inoculation of HSV-1 on their upper lips after scarification, and systemic administration of acyclovir (ACV). 12-O-tetradecanoylphorbol 13-acetate (TPA) was used as the tumour promoter. The tumour incidence was compared to control groups each of 40 mice that were either not treated with ACV, not treated with TPA, not infected with HSV or only scarified. In the virus-infected group treated with ACV and TPA, 25% of the animals developed tumours. In the HSV-infected group treated with TPA only, 25% of the animals also developed tumours. The uninfected animals which were not treated with TPA developed tumours to a significantly lesser degree. In conclusion, the combined effects of HSV-1 and TPA, with or without ACV treatment, resulted in a significant increase in the number of tumours in comparison to the control groups.

Snuff-induced carcinogenesis: effect of snuff in rats initiated with 4-nitroquinoline N-oxide

A canal in the lower lip to function as a reservoir for snuff was surgically created in 150 male Sprague-Dawley rats. The animals were randomized into five groups of 30 each: Group I received snuff twice a day, 5 days a wk; Group II was painted with propylene glycol (solvent control) on the hard palate 3 times a wk during 4 wk; Group III underwent painting on the hard palate with 4-nitroquinoline N-oxide (4-NQO) dissolved in propylene glycol, 3 times a wk for 4 wk; Group IV received 4-NQO as in Group III followed by snuff application as in Group I; and Group V received a cotton pellet dipped in saline twice a day, 5 days a wk. Treatment continued for up to 108 wk. There was no significant difference in mean survival time between the groups. Squamous cell tumors of the lip, oral and nasal cavities, esophagus, and forestomach were seen only in Groups I, III, and IV. Nine tumors of these organs were found in Group I (six carcinomas and three papillomas), nine in Group III (seven carcinomas and two papillomas), and ten in Group IV (eight carcinomas and two papillomas). The difference between each of these groups and the control groups (II and V) with regard to tumor incidence is statistically significant (P less than 0.05). In Group I, four oral cavity or lip carcinomas were found in 29 rats, a significant difference in relation to control rats (P less than 0.05). In addition, hyperplastic lesions of the lip, palate, and forestomach were significantly more common in Groups I and IV compared with Groups II, III, and V. The study has shown that snuff and 4-NQO by themselves have the potential to induce malignant tumors. Initiation with 4-NQO followed by snuff did not significantly enhance tumor formation.

Snuff tumorigenesis: effects of long-term snuff administration after initiation with 4-nitroquinoline-N-oxide and herpes simplex virus type 1

The tumor promoting effects of snuff was studied in Lewis rats initiated with 4-nitroquinoline-N-oxide (4-NQO) and Sprague Dawley rats repeatedly inoculated with herpes simplex virus type 1 (HSV-1). The test substances were administered in a surgically created canal in the lower lips of the rats. There were 15 rats in each test group and 10 rats in the control group. In the groups treated with 4-NQO and 4-NQO + snuff, 8 and 12 tumors (5 and 9 malignant) were found, respectively. In the group subjected to HSV-1 only, 3 tumors were found (2 malignant), in the group subjected to snuff only, 4 tumors were found (3 malignant) and in the group subjected to the combination of HSV-1 and snuff, 13 tumors were found (7 malignant). In the control group only one malignancy was found. The study did not show any promoting effects of snuff in the oral cavity after initiation with 4-NQO. Neither was there any increase in the number of oral tumors in rats treated with HSV-1 and snuff. However, there was a marked increase in the number of malignant tumors outside the oral cavity in the group treated with HSV-1 and snuff, underlining the importance of interactions between these two agents in the development of malignant lesions.

Autogenous free tooth transplantation in man by a 2-stage operation technique. A longitudinal intra-individual radiographic assessment

Insufficient nutrition to the root surface of autotransplanted mature human teeth after transplantation could be an explanation for the high rates of complications such as root resorption and loss of the tooth transplant. Insufficient nutrition is suggested as being due to the distance between the recipient site tissue and the root surface, and the presence of a blood-clot between the tissues. Improved nutrition could be achieved by transplanting into contact with the vascularised connective tissue of a healing wound. To test this hypothesis, a series of human teeth with fully developed roots were autotransplanted to recipient sites prepared and left to heal for 14 days before transplantation. This study is a follow-up of 57 transplants with a minimum observation time of 1 year. Periodic radiographic examinations of the teeth were performed up to 5 years after transplantation. The results presented, showed a lower incidence of root resorption and extractions than previously reported for teeth with fully developed roots.

The reversibility of the snuff-induced lesion: an experimental study in the rat

Snuff lesions were induced in 30 rats. Ten of the snuff-exposed rats were killed immediately after 13 months snuff exposure, as were the 10 control animals. Ten rats were killed 1 month and 10 rats 4 months after the snuff administration had ceased. The rats exposed to snuff for 13 months exhibited hyperplastic, hyperorthokeratotic epithelium with focal mild atypia, focal ulcerations and marked subepithelial fibrosis. These changes were markedly reduced or absent in rats exposed to snuff and killed after a snuff-free interval of 1 or 4 months. Similar differences between the test-groups were seen in the epithelium lining the gingival sulcus of the lower incisors. This area seems to be more sensitive to chemical exposure than the oral mucosa proper as more severe microscopical changes were seen here. Snuff exposure results in the development of a hyperplastic, reactive, reversible lesion of the oral mucosa, suggesting that snuff predominantly has promoting activity when administered for a relatively short interval of time.

Inhibition of herpes simplex virus replication by tobacco extracts

Herpes simplex virus type 1 (HSV-1) has been associated with the genesis of leukoplakias, epithelial atypia, and oral cancer. Tobacco habits, such as snuff dipping, are also definitely correlated with this type of lesion. The normal cytolytic HSV-1 infection can, after in vitro inactivation, transform cells. Extracts of snuff were prepared and assayed for their ability to inhibit HSV-1 replication. Plaque formation assays of HSV-1 in the presence of snuff extract showed that a reduced number of plaques was formed. Different batches of one brand of snuff were tested for inhibition of herpes simplex virus (HSV) production. More than 99% inhibition of 24-hr HSV production was obtained with undiluted batches. The 1:5 dilutions of snuff had an inhibitory effect of 85% and 1:25 dilutions, 39%. In agreement, the attachment of the virus to the host cell and penetration of the virus to the cell nuclei were found to be inhibited as was the synthesis of viral DNA. Nicotine had an inhibitory effect, while aromatic additions to snuff were found to have no major inhibitory effect on HSV replication. Snuff extracts were prepared from different brands of snuff reported to contain high and low quantities of tobacco-specific N-nitrosamines. Brands with reported high levels of tobacco-specific N-nitrosamines had significantly greater ability to inhibit HSV replication. In conclusion, this study has shown that extracts of snuff have inhibitory effects on the production of cytolytic HSV-1 infections. A chronic snuff dipper keeps tobacco in the mouth for the major part of the day. Thus, virus shed in the oral cavity in connection with a reactivated latent HSV-1 infection has great possibilities of being affected by snuff or derivatives of snuff. It is suggested that an interaction between tobacco products and HSV-1 might be involved in the development of dysplastic lesions in the oral cavity.

Effect of snuff and herpes simplex virus-1 on rat oral mucosa: possible associations with the development of squamous cell carcinoma

The purpose of this investigation was to study the effect of snuff and experimentally induced herpes simplex virus type 1 (HSV-1) infection in Sprague-Dawley rats. It was demonstrated that it was possible to obtain 100% development of acute HSV-1 infection in the rat oral mucosa, but only 10% of latent reactive infection of the trigeminal ganglia. The rats were, therefore, acutely infected monthly with virus to simulate recurrence of latent infection. Virus was applied topically to the mucous membrane twice with an interval of one month. Snuff was administered between the virus applications and afterwards to half the virus-exposed animals. Sham-infected rats were given snuff during the same period (18 months). A fourth group of rats were left untreated. A complete post-mortem examination was performed. Two rats exposed to snuff and HSV-1 in combination developed squamous cell carcinoma of the oral cavity. It was also found that rats exposed to snuff alone or in combination with HSV-1 had a higher incidence of tumours or tumour-like conditions than control rats exposed to HSV-1 only. The incidence of malignant tumours was significantly higher in rats exposed to snuff or HSV-1 and snuff in combination than in control animals (p less than 0.05). The results of the study indicate that HSV-1 in combination with snuff exposure may be associated with the development of squamous cell carcinomas of the oral cavity.

Effect of long-term application of snuff and herpes simplex virus 1 on rat oral mucosa. Possible association with development of oral cancer

In an animal model, the life-long effects of snuff administration were assessed alone and in combination with infection with herpes simplex virus (HSV-1). It was shown that exposure to standard and alkaline snuff and to HSV-1/snuff induced mild to severe hyperplasia, hyperorthokeratosis, varying degrees of vacuolization and acanthosis in the squamous epithelium, as well as atrophic and ulcerated lesions. Ulcerations and mild dysplasia of the squamous epithelium were seen most frequently in HSV-1/snuff-exposed rats, with moderate dysplasia in the crevicular epithelium. Rats exposed to snuff or to HSV-1 and snuff had a higher incidence of tumours or tumour-like conditions than control rats. Squamous-cell carcinoma of the oral cavity was found exclusively in rats exposed to snuff or to the combination of HSV-1 and snuff. Papillary squamous hyperplasia of the forestomach was found only in rats exposed to snuff or to HSV-1 and snuff in combination. The incidence of malignant tumours was significantly higher (p less than 0.05) in the group of rats exposed to snuff and HSV-1/snuff than in control animals.

Effect of long-term application of snuff on the oral mucosa: an experimental study in the rat

The long-term effect of snuff exposure was studied in Sprague-Dawley rats using a surgically-created test canal in the lower lip to retain snuff. The rats received standard snuff (n = 42) and highly alkaline snuff (n = 10) for 9-22 months, whereupon they were killed. Untreated rats with identical test canals (n = 15) served as controls. A complete post-mortem examination was performed. One rat exposed to standard snuff for 9 months developed a squamous cell carcinoma of the oral cavity. However, exposure to standard snuff usually resulted in a mild to moderate hyperplasia of the epithelium, hyperorthokeratosis and acanthosis. Rats exposed to snuff for 18-22 months showed vacuolated cells penetrating deeper into the epithelium with hyperplastic and atrophic lesions. In a few rats, severe dysplastic changes developed in the crevicular epithelium. Rats exposed to alkaline snuff differed little from the first group except that there was focally atrophic and ulcerated epithelium and less fibrosis. Pathological findings outside the oral cavity were rare. Squamous cell hyperplasia of the forestomach was found in rats exposed to snuff for 18-22 months, possibly caused by ingested snuff. In conclusion, this study has shown that exposure of rats to snuff for 10-16 hours per day 5 days a week for most of their life-span resulted in lesions mainly restricted to the epithelium and the underlying connective tissue of the surgically created test canal.