Volchansky, A.

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J. Dent. Ass. S. Afr. Vol. 30, No. 9, pp. 727 - 730A study of the connective tissue surrounding the developing tooth in the vervet monkeyAVolchanskyDental Research Unit of the University of the Witwatersrand and the South African Medical Research Council, Johannesburg, South Africa.SUMMARYDeveloping teeth in the Vervet monkey (Cercopithe- cus aethiops) were examined at various pre-eruptive stages. A longitudinal arrangement o f  periodontal fibres was seen grouped alongside the hone and ce- mentum and parallel to them. These fibres later ex­tended coronally, passing around the reduced enamel epithelium. It was difficult to compare this study to other species as there were differences in terminology and in the precise stages o f  development described. There was however a suggestion that the pre-eruptive periodontalfibre arrangement in the vervet monkey is similar to that in man.OPSOMMINGOntwikkelende tande in die blouapie (Cercopithicus aethiops) is op verskillende voor-erupsie stadia onder- soek. Die periodontale vesels is in die lengte gerang- skik en teenaan die been en sementum, en parallel met hulle saam gegroepeer. Hierdie vesels het later in die koronale vlak verleng, en het dm die verminderde glasuurepiteelgegroei. Dit was nie moontlik om hier­die ondersoek met die van ander spesie te vergelyk nie aangesien beskrywings en terminologie verskil sowel as stadia van ontwikkeling. Daar was eg ter ’n aan- duiding dat die voor-erupsie periodontale veselrang- skikking in die blouapie soortgelyk aan die van die mens is.Non-human primates have been used as experimental models in a variety of studies on periodontal disease, (Levy, 1971; Ammons, Scheckmann and Page, 1972). It has been suggested that for a primate to be used in such studies, the teeth and periodontium should closely resemble that in man (Ammons et al, 1972). A metrical study was undertaken by Volchansky and Cleaton-Jones (1973) using the vervet monkey (Cer- copithecus aethiops), in which a morphological simi­larity seemed to exist in the relationship between the gingiva and the alveolar bone around the premolar and molar teeth in this animal and man.These findings have prompted further studies on the veryet monkey periodontium and a continued investi­gation of the suitability of this animal as an experi­mental model for periodontal research is being under­taken.Studies on collagen fibre arrangement around the de­veloping teeth in both man and experimental animals, have mainly been conducted in association with stu­dies on tooth eruption. The connective tissue sur­rounding the molar teeth in the Cyomologous mon­key {Macaca irus cuv) was described by Magnusson (1968). The pre-eruptive teeth were surrounded by a loose vertical network of fibres resembling those in the dental sac, and from a thin layer of cementum on the roots a dense rim of short fibres was present. These fibres gradually lengthened horizontally or slightly coronally and intermingled and joined with vertical fibres.In the Rhesus monkey, Glenwright (1970) searched for the circular collagen fibres described by Arnim and Hagerman (1953) in man. He found a distinct band of fibres which persisted throughout eruption, coronal to the erupting incisor teeth. Glenwright termed these longitudinal gingival fibres, and con­sidered them different from the circular fibres ofArnim and Hagerman, in man. Levy and Bernick (1968), using conventional terminology, described four groups of fibres present during development and organisation of the periodontal ligament of deciduous teeth in the marmoset monkey. These were termed free gingival fibres, alveolar crest fibres, horizontal and oblique fibres.In further studies on the development of deciduous and permanent teeth in the marmoset, Grant and Ber­nick (1972) and Grant et al (1972), described fibres arising from firstly the cementum, and shortly there­after from bone. These fibres radiated out into the periodontal space to form an intermediate plexus which persisted until the onset of function.The fibre arrangement during tooth development in man has been described by Sicher (1972). He stated that the periodontal ligament was derived from the dental sac which envelops the developing tooth germ. Three groups of fibres were noted around the tooth germ. There was an outer group of fibres related to the bone, an inner group of fibres adjacent to the tooth, and an intermediate zone of unorientated fibres be­tween the other two.This investigation was undertaken to study and des­cribe the connective tissue surrounding the molar and premolar vervet monkey teeth, and compare it with that occurring in other primates and man.MATERIALS AND METHODSThe specimens were obtained from vervet monkeys in the mixed dentition stage of development and con­sisted of pre-eruptive premolars and molars. They were removed together in a single block of mandibu­lar bone and fixed in 10% buffered formol saline, then decalcified in 5% formic acid, and serial paraffin sec­tions 7 pm thick were cut in the buccolingual plane inJournal of the D. A.S. A. — September 1975 727A Volchanskysome sections and in the mesio-distal plane in others. Sections were stained with either haematoxylin and eosin or Pacini’s stain (Romeis 1948).The ages of the animals from which specimens w'ere obtained for this study differed and could not be ac­curately determined as the animals were obtained from a wild population group. As the specimens were selected from animals in the mixed dentition stage of development, a good cross section of the stages of per­manent tooth development was present in the sample studied.This study encompassed tooth development from the formation of the dental follicle through the stages of development prior to tooth eruption in premolar and molar teeth.The connective tissue surrounding the developing teeth were studied around the apical area, mid-root area, the area of the reduced enamel epithelium and the coronal area of pre-eruptive teeth.RESULTSPre-eruptive developing toothThe development and orientation of the connective tissue surrounding the developing teeth was studied in four regions in the pre-eruptive teeth (Fig. 1.)i) Apical regionsThe connective tissue adjacent to the apex of the tooth consisted of fine groups of fibres running coronally parallel to the root between the cementum and the bone. Fibre orientation was such that only slight inter­mingling occurred in the intermediate area. At this stage there was no visible evidence of fibres running from the root to the surrounding bone (Fig. 2).ii) Mid-root regionThe fibres lying between cementum and the adjacent bone were consolidated into a dense fibrous band which formed a central fibrous core, which was joined by numerous short fibres arising from cementum. At this stage of tooth development there was no sign of Fibres transversing the longitudinal fibre or occupying the periodontal space (Fig. 3).iii) Amelo-cementaljunction regionThe longitudinal fibre group continued parallel to the reduced enamel epithelium and was joined by a band of fibres arising from the cementum at the amelo- cemental junction (Fig. 4).iv) Coronal regionIn the coronal area the reduced enamel epithelium was enclosed in a well-defined band of fibrous connec­tive tissue which was continuous with the fibrous ele­ments arising from the apical and mid-root longitu­dinal fibres. This connective tissue consisted of a dense well-defined parallel fibre arrangement, lying between reduced enamel epithelium and overlying bone (Fig. 5).Fig. 2. Apical region showing Fibres running adjacent to bone (b) and root, d =  dentine, with the longitudinal fibre (If) between the two. Pacini stain x 2S0.728 Tydskrif vandie T.V.S.A. — September 1975TISSUE SURROUNDING VERVET TOOTHFig. 3. Mid-root region where a core of fibres is seen to be joined by short fibres from the root surface, ree =  reduced enamel epithe­lium, es =  enamel space. Pacini stain x 25Q.kreees .Fig. 5. Coronal region showing the fibres passinglietween bone and die reduced enamel epithelium (ree). es =  enamel space. Haematoxylin and eosin stain x 500.Fig. 4. Amelo-cemental junction region with the longitudinal fibres joined by fibres from the root surface passing alongside the reduced enamel epithelium (ree). es =  enamel space. Haematoxylin and eosin x 440.epitheliumFig. 6. Composite diagram showing the various regions with a sum­marised fibre arrangement around the pre-eruptive developing tooth.DISCUSSIONThe findings in the various regions at various stages around the pre-eruptive developing tooth are sum­marised in the composite diagram shown in figure 6. In this diagram the gaps between the apical longitudi­nal and coronal fibres are present because of the diffe­rent stages of development examined. It would not be strictly accurate to join these although it is felt that they are continuous.Journal of the D.A.S.A. — September 1975 729A VolchanskyIt is obvious from the diagram that no fibres were seen passing into the bone from the cementum but fibres from the two linked and intermingled in the interme­diate periodontal space as they ran coronally.It is important to compare these findings with those of the other workers mentioned in the introduction taking into account the differences and the many diffi­culties encountered. Glenwright (1970) described the incisor region, which has proved to differ from the pre­sent study in the molar region. There is a similarity be­tween the findings regarding the longitudinal fibres in the present study and those of Magnussen in the Macaca irus cuv molar. He did not mention any coronal fibres.The fibres described in the present study in the vervet monkey did not however, correspond to those of Levy and Bernick (1968) in the marmoset. Their earliest des­cription of free gingival fibres resembled the longitudi­nal fibres described here just below the cemento- enamel junction but they did not mention the fibre grouping alongside bone, cementum and those fibres seen between the two groups. Similarly there was no mention of fibres overlying the crown. They concen­trated on the incisor teeth but although it is likely that there is a similar situation around the molars this has not yet been demonstrated. Their description was of deciduous teeth but once again there does not seem any reason why in the pre-eruptive stage this should be different to the permanent teeth.The intermediate plexus described by Grant and Ber­nick (1972) and Grant et al (1972) was not seen in the present study. Possibly the different species and stages of development in their study and mine can explain this absence. It was felt that a greater degree of fibre organisation might have been expected at such a late pre-eruptive stage than they observed.There is then an obvious confusion over the develop­ment of the periodontal membrane in the species men­tioned. This may be the result of a lack of standard ter­minology, different species studied; different situations in the mouth; and different stages of de­velopment. All this indicates that more work is needed in the field.One thing that has emerged from this study is the simi­larity between the findings in the developing vervet molar and the description of that in man by Sicher (1972). This does suggest that the vervet anatomy in the molar and premolar regions is close to that in man.ACKNOWLEDGEMENTSThe author wishes to thank Drs. P. Cleaton-Jones and J.C. Austin and the staff of the Dental Research Unit of the University of the Witwatersrand for their assistance in preparing this paper.REFERENCESAmmons, W.F., Scheckman, L.R. & Page, R.C. (1972) Host tissue response in chronic periodontal disease. Journal o f  Periodontal Research, 7, 131-143.Arnim, A. A. & Hagerman, D. A. (1953) The connective tissue fibres of the marginal gingiva. Journal o f  the American Dental Asso­ciation, 47,271 -281.Glenwright, H.D. (1970) Observations on circular and longitudinal gingival collagen fibres in the Rhesus monkey. Dental Practi­tioner, 20,337-341.Grant, D. & Bernick, S. (1972) Formation of the periodontal liga­ments. Journal o f Periodontology, 43,17-25.Grant, D., Bernick, S., Levy, B.M. & Dreizen, S. (1972) A com­parative study of periodontal ligament developments in teeth with and without predecessors in marmoset. Journal of Periodontology, 43,162-169.Levy, B. M. (1971) The non-human primate as an analogue for the study of periodontal disease. Journal o f  Dental Research, 50, 246-253.Levy, B.M. & Bernick, S. (1968) Studies on the biology of the periodontium of the marmosets: II Development and organi­sation of the periodontal ligaments of deciduous teeth in mar­mosets. Journal o f  Dental Research, 47,27-33.Magnusson, B. (1968) Tissue changes during molar tooth eruption. Transactions o f the Royal Schools o f  Dentistry. Stockholm and Umea — Umea Research Library, p. 30,50-53.Romeis, B. (1948) Mikroskopishe Technik. Leibniz Verlag. pp 348- 349.Sicher, H. (1972) In: Orban's Oral Histology and Embryology. C.V. Mosby&Co. 7thed. p. 183.Volchansky, A. & Cleaton-Jones, P. (1973) A metrical study of some periodontal structures in the Vervet monkey. Journal of the Dental Association o f South Africa, 28,168-171.730 Tydskrif van die T. V.S. A. — September 1975

A study of the connective tissue surrounding the developing tooth in the Vervet Monkey

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A study of the connective tissue surrounding the developing tooth in the Vervet Monkey

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