The Influence of Selected Materials Used in Reconstructive Prosthetics on Tissue Reaction in Vitro Studies

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The Influence of Selected Materials Used

in Reconstructive Prosthetics on Tissue Reaction

in Vitro Studies

Wpływ wybranych materiałów stosowanych

w protetyce odtwórczej na reakcję tkanek w badaniach in vitro

1_{Chair and Department of Dental Prosthetics, Pomeranian Medical University, Szczecin, Poland} 2_{Department of Biochemistry and Medical Chemistry, Pomeranian Medical University, Szczecin, Poland} 3_{Department of Pathology at the Medicine Faculty, Pomeranian Medical University, Szczecin, Poland} 4_{Department of Conservative Dentistry, Pomeranian Medical University, Szczecin, Poland}

Dent. Med. Probl. 2009, 46, 1, 33–39 ISSN 1644−387X

ORIGINAL PAPERS

© Copyright by Wroclaw Medical University and Polish Stomatological Association

Abstract

Background. Continuous development of new materials and ever−growing demands and expectations from both

dentists and patients, result in the effort of dental material producers to introduce more and more functional and mod− ern products. In dentistry, products used for denture construction are usually synthetics or metal alloys. The most commonly used denture materials are made of methyl polymethacrylate belonging to the group of acrylate masses.

Objectives. In this paper the authors examined the influence of chromium−cobalt alloy and acetal resin on cir−

cumjacent tissues.

Material and Methods. At the Pomeranian Medical University’s Department of Dental Prosthetics, the authors

made chromium−cobalt−molybdenum plates and acetal resin plates, according to manufacturer recommendations. Research on the reaction of tissues to these prosthetic materials was carried out on 30 white male Wistar rats under normal conditions. The rats were observed for 6 weeks, and weighed every 2 weeks. After six weeks of the exper− iment, the rats were put down to obtain samples of tissues surrounding the implanted plate, i.e. from the mucous membrane of the cheek, the parotid gland on the side of the plate and cervical lymph nodes. Then, at the Chair of the Pathology, in the PAM Faculty of Medicine, the histological preparations were stained with hematoxylin and eosin, and examined using various magnifications under a light microscope.

Results. Microscopic images of the mucous membrane in the area of the metal−plates did not differ significantly.

No purulent secretory inflammatory reactions were observed. In all the animals, the authors observed inflammato− ry infiltration consisting of lymphoid cells, in the parenchyma and connective tissue barriers of the parotid glands. Four animals had a slight proliferation of the connective tissue. Number of histocytes surrounding implanted plates of the acetal resin was significantly higher then in the chromium−cobalt group on the level p = 0.049.

Conclusions. The authors determined that both the alloy and the acetal resin caused similar slightly inflammatory

reactions in the circumjacent tissues. In all animals, the authors observed inflammatory infiltration consisting of lymphoid cells, in the parenchyma and connective tissue barriers of the parotid glands. Four animals had a slight proliferation of the connective tissue. (Dent. Med. Probl. 2009, 46, 1, 33–39).

Key words: chromium−cobalt alloy, acetal resin, removable prostheses, reaction of tissues.

Streszczenie

Wprowadzenie. Nieustanny postęp w materiałoznawstwie oraz coraz większe wymagania i oczekiwania zarówno

lekarzy, jak i pacjentów sprawiają, że producenci materiałów stomatologicznych wprowadzają na rynek doskonal− sze i nowocześniejsze produkty. W stomatologii do wykonywania protez stosuje się m.in. tworzywa uzyskane syn− tetycznie oraz stopy metali. Najczęściej używane tworzywa protez wywodzą się z polimetakrylanu metylu należą− cego do grupy mas akrylowych.

Cel pracy. Ocena wpływu stopu chromokobaltowego i żywicy acetalowej na otaczające tkanki oraz ślinianki przy−

Continuous development of new materials and ever−growing demands and expectations from both dentists and patients, result in the effort of dental material producers to introduce more and more functional and modern products. In dentistry, products used for denture construction are usually synthetics or metal alloys. The most commonly used denture materials are made of methyl poly− methacrylate, belonging to the group of acrylate masses [1]. Any dental prosthesis should be con− structed and fixed into the stomatognathic system in such a way that it does not become an iatrogenic factor. Rather, it should have a healing and pre− ventative function. However, making a good pros− thesis is impossible without proper material. Choosing such a material depends not only on its physical and chemical properties, but also on how the material behaves in the oral cavity. Prosthodontists are especially interested in plaque, bacteria adhesion to the denture’s surface, and any potential allergic properties of the material. Both doctors and patients are also very much interested in the appearance of the selected product, most of all in the durability of the denture’s shade of the prosthetic material. This durability of the den− ture’s shade is crucial in attempts to achieve required aesthetic effects, both in non−invasive dentistry and prosthodontics. Reconstructive cos− metic dentistry does not only mean porcelain, implants or zircon. It also includes other prostho− dontic fillings which should not be visible in the patient’s mouth. Recently, a new material for such temporary prostheses was introduced to the Polish market; an acetal resin called Acetal Pressing. Acetal resin is a thermoplastic polymer with a monomerless crystal structure and is a product of formaldehyde polymerisation. It is highly resistant to grinding, perfectly extensible, mechanically durable, resilient, has a low level of thermal con− ductivity, and adequate stiffness in the denture’s stem. It is non−toxic and non−allergic, and is an

adequate substitute for acrylic resins and metals in many prosthodontic applications. Produced in 14 shades, it may be used in most prosthodontic practice, including novel and non−typical thermal injection moulding. Acetal resin has only recently been introduced to dentistry, yet enjoys wide pop− ularity; it is used for frame dentures, clasps for standard frame dentures, functionally unstable partial dentures, bridges, bridges with telescopic crowns, prosthodontic elements on implants, occlusal and stabilization splints, retaining elements on crossbars (which are at the same time an enhanced stem of the denture) and many others. Prostho− dontic elements made of this resin are chemically and mechanically stable. Their resistance to pH ranges between 4 and 9 pH. Acetal resin may be an alternative to various metal alloys used for frame dentures. Its aesthetic value is higher and more accepted amongst patients. However, it has been introduced only recently and no long−term obser− vations of the material have been carried out yet. The introduction of removable dentures made of standard chromium−cobalt−molybdenum alloys or acetal resin entails either short or prolonged con− tact of the mouth tissues with the foreign materi− als. Consequently, conditions arise for incompati− bility between the host and the applied prosthetic material. The possibility of rejection of the foreign matter varies, as it concerns organic changes in the psychogenous rejection. Organic changes occur in the form of atrophy, hypertrophy and inflamma− tion [2–4]. Making a good denture is impossible without good basic material. Inadequate basic material can cause life−threatening and pathologi− cal reactions, and thwart even the most rational prosthetic treatment planning. Besides such ex− treme threats caused by the presence of a denture in the oral cavity, there exist some less serious side effects, although they are also important in the general evaluation of the treatment [5]. So what are the key factors in the selection of a prosthetic

Materiał i metody. Z badanych materiałów protetycznych wykonano niewielkie, owalne płytki, które następnie

wszczepiano szczurom w znieczuleniu ogólnym pod błonę śluzową policzka. Po 6 tygodniach trwania doświad− czenia szczury usypiano i dokonywano sekcji, podczas których pobierano wycinki z błony śluzowej policzka, wę− złów chłonnych szyjnych i ślinianki przyusznej. W Zakładzie Patomorfologii Wydziału Lekarskiego PAM wyko− nano preparaty histologiczne, które zabarwiono hematoksyliną i eozyną. Preparaty oceniano w różnych powięk− szeniach w mikroskopie świetlnym. W analizie statystycznej wyników zastosowano metody nieparametryczne.

Wyniki. U wszystkich zwierząt w otoczeniu wszczepionych płytek z metalu stwierdzono odczyn zapalny złożony

z małych histocytów, fibroblastów i komórek limfoidalnych. U zwierząt w otoczeniu wszczepionych płytek z ży− wicy acetalowej stwierdzono: utkanie błony śluzowej pokrytej nabłonkiem wielowarstwowym płaskim z cechami rogowacenia, widoczne nacieki zapalne złożone z histocytów, fibroblastów i limfocytów. We wszystkich przypad− kach w obrazach mikroskopowych ślinianek przyusznych były widoczne w podścielisku nacieki zapalne złożone z komórek limfoidalnych.

Wnioski. Stwierdzono, że zarówno stop metali, jak i żywica acetalowa wywołują nieznaczne, porównywalne od−

czyny zapalne w otaczających tkankach. U wszystkich zwierząt odczyn zapalny był znacznie większy w ślinian− kach przyusznych niż w otaczających tkankach (Dent. Med. Probl. 2009, 46, 1, 33–39).

material, and what material should one consider appropriate? Generally, good basic material should be harmless, durable in the environment of the oral cavity, resistant to pressure caused by mastication, easily processed, not overly expen− sive and aesthetically satisfying [5, 6]. Every material that has contact with the environment of the oral cavity should also be subjected to a series of biological, chemical and physical tests, regard− less of the manufacturer's research, to ensure no harmful influence on the patient's body [7, 8].

Material and Methods

At the Pomeranian Medical University’s Department of Dental Prosthetics, the authors made chromium−cobalt−molybdenum plates and acetal resin plates, according to manufacturer rec− ommendations. Research on the reaction of tissues to these prosthetic materials was carried out on 30 white male Wistar rats under normal conditions. The rats were divided into two experimental groups, one with plates made of metal alloy (N = 11), the other with acetal resin plates (N = 13), and the control group (10) in which the mucous membrane of the cheek was incised and stitched with absorbable sutures, to eliminate the reaction of tissues to stitching. Before the implantation, the plates were placed for 20 minutes in 2% virkon, and then were rinsed with 3% hydrogen peroxide. The sterile plates were implanted into the mucous membrane of the rats' cheeks under anesthetic (ketamine hydrochloride was injected intramuscu− larly, 130 mg/kg body weight). Then, the mucous membrane was incised, the plate was implanted and the incision stitched with absorbable sutures. The rats were observed for 6 weeks, weighed before the the experiment and then every 2 weeks. On the six week of the experiment, the rats were put down and blood was sampled straight from their hearts after the prior opening of the chest. The obtained samples were subjected to peripher− al blood morphology examinations (number of leukocytes and erythrocytes, hematocrit, and hemaglobin concentration) and hepatic tests (total bilirubin concentration, activity of asparagine aminotransferase and alanine aminotransferase, and alkaline phosphatase). Analyses were carried out to determine the whole−body toxicity of the studied materials. The authors also obtained sam− ples of tissues surrounding the implanted plate, i.e. from the mucous membrane of the cheek, the parotid gland on the side of the plate and cervical lymph nodes, which were taken from 22 animals. The samples were placed in a 4% solution of for− malin neutralized with calcium carbonate. Then, at

the Chair of the Pathology, in the PAM Faculty of Medicine, the histological preparations were stained with hematoxylin and eosin, and examined using various magnifications under a light micro− scope.

Statistical analysis was carried out using non− parametric methods. The values of linear variables (e.g. body weight, hemoglobin, etc.) and rank vari− ables (e.g. the degree of inflammatory reaction in a histological test) were compared between the three groups of rats using the Kruskala−Wallis test, and then, individual groups were examined with the Mann−Whitney test. Dichotomous variables were examined using the chi−square test. The level of significance was the same for all calculations and was p < 0.05 [9–11].

Results

The implanted plates made of the examined materials did not inhibit the feeding of the animals, as the increases in their body weight were appro− priate to their age. Only the body weights of rats with the chromium−cobalt alloy plates were statis− tically significantly lower on the day of implanta− tion than the mean body weight of animals with the acetal resin plates (p = 0.019) and the control group (p = 0.0008). Yet after implantation there were no significant differences between all the groups with regard to their body weight increases. The activities of aminotransferases did not differ between the groups, and alkaline phosphatase activ− ity was slightly but significantly higher in the exper− imental group than in the control group (Tab. 1).

Group 1 – Control

The mucous membrane of the cheek (in the control group the mucous membrane of the cheek was incised and stitched with absorbable sutures, to eliminate the reaction of tissues to stitching).

The skin with all adnexa softly runs into tex− ture of the mucous membrane (Fig. 1). The mucous membrane has a well−developed corneous layer, similarly to the skin. On the border of the skin and the mucous membrane, there is a zone consisting of small histiocytes, lymphoid cells and small neutrophils.

The cervical lymph node: the histological image does not differ significantly from that of the human lymph node. The only difference is the increased quantity of lacunar/antral/sinusoid histi− ocytes, in the cytoplasm of which the authors noticed fragments of phagocytized cell nuclei.

The parotid saliva gland: the saliva gland with The Influence of Selected Materials Used in Reconstructive Prosthetics on Tissue Reaction in Vitro Studies 35

Tabela 1. Porównanie analizowanych parametrów między badanymi grupami szczurów

Parameter Control Metal Acetal Statistical

(Parametr) (Grupa (Metal) (Acetal) significance

kontrolna) N = 11 N = 13 (Istotność

N = 10 statystyczna p)

General parameters (Parametry ogólne)

Weight before surgery 442 ± 28 403 ± 35** 426 ± 27* 0.0029

(Waga przed zabiegiem) [g]

Weight 2 weeks after surgery 441 ± 27 411 ± 43* 432 ± 30 0.029

(Waga 2 tyg. po zabiegu) [g]

Weight 4 weeks after surgery 454 ± 29 425 ± 47* 447 ± 32 0.060

(Waga 4 tyg. po zabiegu) [g]

Weight 6 weeks after surgery 485 ± 29 452 ± 57* 475 ± 37 0.061

(Waga 6 tyg. po zabiegu [g]

Leukocytes 3.23 ± 1.00 3.29 ± 1.11 4.03 ± 2.49 0.74 (Leukocyty) [G/L] Erythrocytes 8.92 ± 0.65 9.09 ± 0.30 9.28 ± 0.49 0.35 (Erytrocyty) [T/L] Hemoglobin 9.22 ± 0.37 9.47 ± 0.35 9.64 ± 0.36* 0.036 (Hemoglobina) [mmol/L] Alkaline phosphatase 71 ± 8 91 ± 30** 88 ± 39* 0.017

(Fosfataza alkaliczna) [U/L]

Mucous membrane histology (Histologia błony śluzowej)

Giant cells 0% 0% 15% 0.18 (Komórki olbrzymie) Pseudocyst 0% 18% 8% 0.34 (Torbiel rzekoma) Fibroblasts 0.9 ± 0.9 1.1 ± 0.5 1.0 ± 0.8 0.67 (Fibroblasty) Lymphoid cells 0.3 ± 0.5 0.6 ± 0.7 1.2 ± 0.7** 0.015 (Komórki limfoidalne) Cyst 30% 9% 8% 0.27 (Torbiel) Eosinophils 0.2 ± 0.4 0.4 ± 0.9 0.4 ± 0.9 0.96 (Eozynofile) Histiocytes 0 ± 0 0 ± 0 0.5 ± 0.8# _0.029 (Histiocyty) Macrophages 0.1 ± 0.3 0.55 ± 0.69 0.6 ± 1.0 0.19 (Makrofagi)

Saliva gland histology (Histologia ślinianki)

Lymphoid cells 1.4 ± 0.8 1.5 ± 0.7 1.4 ± 1.0 0.93

(Komórki limfoidalne)

Eosinophils 0% 0% 8% 0.44

(Eozynofile)

Connective tissue proliferation 0 ± 0 0.5 ± 0.7* 0.2 ± 0.6 0.057

(Rozplem tkanki łącznej)

Lymph node histology (Histologia węzła chłonnego) N = 22

Lacunar reaction 0.4 ± 0.5 0.8 ± 1.0 0.9 ± 0.8 0.44

(Odczyn zatokowy)

Follicular reaction 0.1 ± 0.4 0.3 ± 0.8 0 ± 0 0.52

(Odczyn grudkowy)

The values are presented as means with ± standard deviation for linear and rank variables, and as a percentage of the group for dichotomous variables. Rank variables were ascribed consecutive numbers representing their degree of intensity for a given histological variable: (–) = 0, (+) = 1, (++) = 2, (+++) = 3 etc.

^ Kruskal−Wallis test for linear and rank variables, and the chi square test for dichotomous variables. * p < 0.05; **p < 0.01 for the difference in comparison with the control group; Mann−Whitney's test.

#_{p < 0.05 for the difference in comparison with the group with metal plates; Mann−Whitney's test.}

Wartości przedstawiono jak średnia ± odchylenie standardowe dla zmiennych ciągłych i rangowych oraz jako odsetek grupy mający daną cechę dla zmiennych dychotomicznych. Zmiennym rangowym przypisywano kolejne wartości liczbowe opisujące nasilenie danej cechy histologicznej: (–) = 0, (+) = 1, (++) = 2, (+++) = 3 itd.

^ test Kruskala−Wallisa dla zmiennych ciągłych i rangowych oraz test χ2_{dla zmiennych dychotomicznych.}

* p < 0,05; **p < 0,01 dla różnicy względem grupy kontrolnej; test Manna−Whitneya.

the view of the serous gland. No inflammatory cells were observed (Fig. 2).

Group 2 – with

Chromium−Cobalt Plates

In all the rats, an inflammatory reaction consist− ing of small histiocytes, fibroblasts and lymphoid cells was observed near the implanted plates. In rats no. 6 and 8, the epithelial stroma of the mucous membrane was observed to have symptoms of swelling. In rat no. 4, a small number of individual eosinophils were observed (Fig. 3), and in rat no. 8 inflammatory granulation tissue was observed, con− sisting mainly of eosinophils. In two cases, pseudo− cysts were observed, and in rat no. 3 in the stroma of the mucous membrane, the authors observed a cyst lined by multi−layered flat epithelium.

Microscopic images of the mucous membrane in the area of the metal−plates did not differ signif−

icantly. No purulent secretory inflammatory reac− tions were observed.

Microscopic images of cervical lymph nodes: in two cases the authors observed slight lacunar reaction, and in one rat a lacunar and follicular reaction. In the remaining seven rats, the authors did not observe any perceptible inflammatory reactions in lymph nodes.

In all the animals, the authors observed inflam− matory infiltration consisting of lymphoid cells, in the parenchyma and connective tissue barriers of the parotid glands. Four animals had a slight pro− liferation of the connective tissue (Fig. 4).

The increase in this proliferation was statisti− cally significantly greater than the proliferation of the connective tissue in the parotid saliva glands in the control group (p = 0.039).

The Influence of Selected Materials Used in Reconstructive Prosthetics on Tissue Reaction in Vitro Studies 37

Fig. 1. Mucous membrane of the cheek

(Group 1 – control); the multi−layered flat epithelium becoming corneous, dispersed lymphoid cells in the stroma (stain HE; magnified ×150).

Ryc. 1. Błona śluzowa policzka (grupa I – kontrolna);

nabłonek wielowarstwowy płaski rogowaciejący, w podścielisku rozproszone komórki limfoidalne (barwienie HE; pow. 150×)

Fig. 2. Image of a healthy parotid saliva gland of the

serous type (Group 1 – control; stain HE; magn. ×80)

Ryc. 2. Prawidłowy obraz ślinianki przyusznej typu

surowiczego (grupa I – kontrolna; barwienie HE; pow. 80×)

Fig. 3. The implantation site after removal of

a chromium−cobalt plate; visible inflammatory granu− lation tissue consisting mostly of eosinophils. In the mucous membrane stroma, symptoms of swelling (stain HE; magn. ×150)

Ryc. 3. Miejsce po wszczepionej płytce ze stopu chro−

mokobaltowego; widoczna ziarnina zapalna złożona głównie z eozynofilów. W podścielisku błony ślu− zowej cechy obrzęku (barwienie HE, pow. 150×)

Fig. 4. Image of a parotid saliva gland after the

removal of a metal plate; in the parenchyma, visible individual lymphoid cells and a slight proliferation of the connective tissue (stain HE; magn. ×150)

Ryc. 4. Obraz ślinianki przyusznej po wszczepionej

płytce ze stopu metalu; w miąższu widoczne poje− dyncze komórki limfoidalne i niewielkiego stopnia rozplem tkanki łącznej (barwienie HE; pow. 150×)

Group 3 – with Acetal

Resin Plates

In all the animals, in the area of the implanted acetal resin plates, the authors observed: (1) tex− ture of the mucous membrane covered by multi− layered flat epithelium with symptoms of keratini− sation, (2) visible inflammatory infiltration with histiocytes, fibroblasts and lymphocytes. In rats no. 13 and 16 the authors observed eosinophils and a few multinucleated giant cells located near the foreign body (Fig. 5). In one preparation, the authors observed a small cyst, lined with multi− layered flat epithelium. The number of inflamma− tory cells (lymphoid cells) in the mucous mem− brane around the implanted acetal resin plates was statistically significantly higher than the number of these cells in the control group p = 0.005.

Histological images of cervical lymph nodes: in four cases texture of the lymph node with the lacunar reaction. In all cases, microscopic images of parotid glands showed the stroma to have inflammatory infiltration made of lymphoid cells. Moreover, in two cases the authors observed the proliferation of fibrous connective tissue and a swelling of the stroma. In rat no. 18, the authors noticed some eosinophils, not many however (Fig. 6). The number of histiocytes in the inflam− matory granulation tissue around the implanted acetal resin plates was significantly higher than in the group with chromium−cobalt plates (p = 0,049).

Discussion

Prosthetic treatment aims at restoring dentition and establishing balance in the stomatognathic system. It is possible due to removable or fixed

dentures, made of materials with diverse chemical constructions, including metal alloys and, since recently, acetal resin.The use of dentures entails potential incompatibility between the host and the applied prosthetic material [12–14]. Reasons for the foreign body’s intolerance are various and widely reported in literature [15, 16]. One of the exogenous factors that induces stomatopathy is the toxicity of various substances included in the pros− thetic material [3, 17], a factor highlighted by many authors [3, 17, 18]. The quality of a denture depends on good basic material. The large diversi− ty of prosthetic materials on the market is one of the reasons the authors carried out this comparison of the influence of chromium−cobalt alloy and acetal resin on circumjacent tissues. Inflammation caused by the examined materials was character− ized by moderate inflammatory infiltrations con− sisting of lymphoid cells, fibroblasts and histio− cytes. In two rats which were exposed to metal and acetal resin plates, a small number of eosinophils was observed. The observed eosinophils can be associated with the allergic properties of both the chromium−cobalt alloy and acetal. The histologi− cal preparations of cervical lymph nodes did not differ from the control. Only in the group with metal plates, two cases were observed to have a lacunar reaction, and in one case lacunar and fol− licular. In the group with the acetyl plates, two rats were observed to have a lacunar reaction of their lymph nodes. Numerous reports indicate that the parotid gland quickly reacts to chemical poison− ing. The report by Jarzynka confirms the opinion that clinical symptoms of such poisonings are fre− quent disorders in the secretion of saliva [19]. That is one of the reasons why in this work the authors examined the morphological image of the parotid

Fig. 5. Site of implantation after the removal of an

Acetyl Pressing D plate; in the stroma, infiltration consisting of fibroblasts, histiocytes and quite a numerous amount of eosinophils; visible small cells near the foreign matter (stain HE; magn. ×200)

Ryc. 5. Miejsce po wszczepionej płytce z Acetylu

Pressing D; w podścielisku nacieki złożone z fibrob− lastów, histocytów i dość licznych eozynofilów oraz widoczne nieliczne komórki wokół ciała obcego (bar− wienie HE; pow. 200×)

Fig. 6. Image of the parotid saliva gland after removal

of the acetal plate; in the stroma, visible inflammatory infiltration consisting of lymphoid cells, and a prolif− eration of the fibrous connective tissue and a sparse number of eosinophils (stain HE; magn. ×200)

Ryc. 6. Obraz ślinianki przyusznej po wszczepionej

płytce z żywicy acetalowej; w podścielisku widoczny naciek zapalny złożony z komórek limfoidalnych oraz rozplem tkanki łącznej włóknistej i nieliczne

gland 6 weeks after the implantation of plates. Both in rats with metal plates and acetyl plates, the authors observed the stroma of the parotid gland to have an inflammatory reaction consisting of lym− phoid cells. In the group with plates from chromi− um−cobalt, in four cases the authors observed pro− liferation of the connective tissue, and in the group with the acetyl, in two cases. But in the acetal group, in one case, eosinophils appeared in the parotid gland. It means that the substances includ−

ed in the examined materials exerted a morpho− logically perceptible and adverse effect on the parotid glands. In this research, the authors carried out a comparative analysis of the influence of the chromium−cobalt alloy and the acetal resin on cir− cumjacent tissues. The comparison of the exam− ined materials indicates that they cause a moderate inflammatory reaction in circumjacent tissues, considerably greater in parotid glands, accompa− nied by a proliferation of connective tissue. The Influence of Selected Materials Used in Reconstructive Prosthetics on Tissue Reaction in Vitro Studies 39

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Address for correspondence:

Ewa Sobolewska

Department of Dental Prosthetic Pomeranian Medical University Powstańców Wielkopolskich 72 70−111 Szczecin Poland Tel. +48 91 466 1715 E−mail: zd.protetyki.stom@sci.pam.szczecin.pl Received: 23.02.2009 r. Revised: 5.03.2009 r. Accepted: 5.03.2009 r.

Praca wpłynęła do Redakcji: 23.02.2009 Po recenzji: 5.03.2009

Nazwa tytułu Skrót Kraj wydawcy Częstotliwość IF ukazywania się w roku

Czasopisma z zakresu chirurgii stomatologicznej, chirurgii szczękowo−twarzowej, implantologii oraz radiologii stomatologicznej

Oral Oncology Oral Oncol. W. Brytania 12 2,569

Clinical Implant Dentistry Clin. Impl. Dent. Res. USA 4 2,408

and Related Research

Clinical Oral Implants Research Clin. Oral Impl. Res. Szwajcaria 12 2,148

International Journal of Oral Int. J. Oral Max. Impl. USA 6 1,78

& Maxillofacial Implants

Oral Surgery Oral Medicine Oral Surg. Oral Med. USA 12 1,592

Oral Pathology Oral Radiology Oral Pathol.

Journal of Oral J. Oral Max. Surg. USA 12 1,37

and Maxillofacial Surgery

International Journal of Oral Int. J. Oral Max. Surg. W. Brytania 12 1,225 and Maxillofacial Surgery

Cleft Palate−Craniofacial Journal Cleft Pal−Craniofac. J. USA 6 0,962

Journal of Cranio−Maxillofacial J. Craniofac. Surg. Niemcy 8 0,995

Surgery

Dentomaxillofacial Radiology Dentomaxillofac. Rad. USA 8 0,899

British Journal of Oral &

Maxillofacial Surgery Brit. J. Oral Max. Surg. W. Brytania 6 0,834

Czasopisma z zakresu periodontologii i patologii jamy ustnej

Periodontology 2000 Periodontol. 2000 USA 3 3,581

Journal of Clinical Periodontology J. Clin. Periodontol. W. Brytania 12 2,678

Journal of Periodontal Research J. Periodontal Res. USA 6 2,146

Journal of Periodontology J. Periodontol. USA 12 2,086

Oral Diseases Oral Dis. W. Brytania 8 1,464

Journal of Oral Pathology & Medicine J. Oral Pathol. Med. Dania 10 1,711

Archives of Oral Biology Arch. Oral Biol. W. Brytania 12 1,554

Czasopisma z zakresu stomatologii zachowawczej i endodoncji

Journal of Endodontics J. Endod. USA 12 3,369

International Endodontic Journal Int. Endod. J. W. Brytania 12 2,15

Journal of Adhesive Dentistry J. Adhesiv. Dent. W. Brytania 6 1,723

Caries Research Caries Res. W. Brytania 6 1,636

Operative Dentistry Oper. Dent. USA 6 1,398

Czasopisma ortodontyczne

American Journal of Orthodontics AJO−DO USA 12 1,126

and Dentofacial Orthopedics

European Journal of Orthodontics Eur. J. Orthod. W. Brytania 6 1,022

Angle Orthodontist Angle USA 6 0,972

Czasopisma ze stomatologii dziecięcej

Pediatric Dentistry Pediatr. Dent. USA 6 1,622

Czasopisma z zakresu protetyki stomatologicznej i zaburzeń czynnościowych układu stomatognatycznego

International Journal

of Prosthodontics Int. J. Prosthodont. Kanada 6 1,572

Journal of Oral Rehabilitation J Oral Rehabil Dania 12 1,2

Journal of Prosthetic Dentistry J. Prosthet. Dent. USA 12 1,009

Journal of Cranio−Mandibular Practice Cranio USA 4 0,528