Histological Techniques for the Study of the Dentogingival Junction: A Scoping Review Using the Anatomical Quality Assurance Checklist (AQUA) / Técnicas Histológicas para el Estudio de la Unión Dentogingival: Una Revisión de Alcance Utilizando el Anatomical Quality Assurance Checklist (AQUA)

SUMMARY: The dentogingival junction (DGJ) is an adaptation of the oral mucosa composed of epithelial and connective tissues intimately related with the mineralised tissues of the tooth. The histological evidence available is mainly based on studies in animals, separate evaluations of hard and soft tissues, and studies using conventional histological techniques that eliminate the enamel from preparations. The aim of this study was to carry out a review of the existing evidence on histological techniques available for study of the tooth and periodontium in conjunction in humans. A scoping review was carried out of the available literature referring to study of the tooth and the periodontium in conjunction in humans, in the Web of Science (WoS), EMBASE, Scopus and SciELO databases, using the terms "Histological Techniques"[Mesh]) and "Epithelial Attachment"[Mesh]. One hundred and fifty-nine articles were found, of which 54 were selected for full- text reading. Ten were finally included in the qualitative synthesis, and we applied the Anatomical Quality Assurance (AQUA) checklist for analysis the methodological quality of the selected articles. The results showed that the only articles with a low risk of bias in all five domains according to the AQUA criteria corresponded to Silva et al. (2011) and Agustín-Panadero et al. (2020). Finally, we conclude that the quality of the histological sections to observe tissues that simultaneously contain the tooth and the periodontium, is conditioned by the selected technique and by the care required in certain specific tasks during the histological processing of the samples.

La unión dentogingival (DGJ) es una adaptación de la mucosa oral compuesta por tejidos epitelial y conectivo íntimamente relacionados con los tejidos mineralizados del diente. La evidencia histológica disponible se basa principalmente en estudios en animales, evaluaciones separadas de tejidos duros y blandos y estudios utilizando técnicas histológicas convencionales que eliminan el esmalte de las preparaciones. El objetivo de este estudio fue realizar una revisión de la evidencia existente sobre las técnicas histológicas disponibles para el estudio del diente y el periodonto en conjunto en humanos. Se realizó un scoping review de la literatura disponible referente al estudio del diente y el periodonto en conjunto en humanos, en las bases de datos Web of Science (WoS), EMBASE, Scopus y SciELO, utilizando los términos "Histological Techniques"[Mesh]) y "Epithelial Attachment"[Mesh]. Se encontraron 159 artículos, de los cuales 54 fueron seleccionados para lectura de texto completo. Diez fueron finalmente incluidos en la síntesis cualitativa, y se aplicó la lista de verificación Anatómica Quality Assurance (AQUA) para el análisis de la calidad metodológica de los artículos seleccionados. Los resultados mostraron que los únicos artículos con bajo riesgo de sesgo en los cinco dominios según los criterios AQUA correspondían a Silva et al. (2011) y Agustín-Panadero et al. (2020). Finalmente, concluimos que la calidad de los cortes histológicos para observar los tejidos que contienen simultáneamente el diente y el periodonto, está condicionada por la técnica seleccionada y por el cuidado requerido en ciertas tareas específicas durante el procesamiento histológico de las muestras.

Observation and determination of periodontal tissue profile using optical coherence tomography.

BACKGROUND AND OBJECTIVE: Diagnosis is a crucial step in periodontal treatment. The aim of this study was to evaluate the effectiveness of optical coherence tomography (OCT) for observation and determination of periodontal tissue profiles in vivo. MATERIAL AND METHODS: In experiment 1, refractive indices of purified water, porcine gingiva and human gingiva at 1330 nm were determined for the analysis of OCT images of periodontal tissues. In experiment 2, OCT examination was performed in the midlabial apico-coronal plane of mandibular anteriors in 30 Asian volunteers with healthy gingiva. Sulcus depth was measured on intra-oral photographs taken during probing. In the OCT images, the gingival, epithelial and connective tissue thickness, and the position of alveolar bone crest were determined and finally, the biologic width was measured. RESULTS: Refractive indices of purified water, porcine gingiva and human gingiva were 1.335, 1.393 and 1.397, respectively. Cross-sectional images of gingival epithelium, connective tissue and alveolar bone were depicted in real-time. The sulcular and junctional epithelium could be visualized occasionally. Laser penetration and reflection were limited to a certain depth with an approximate maximal imaging depth capability of 1.5 mm and OCT images of the periodontal structure were not clear in some cases. The average maximal thickness of gingiva and epithelium and biologic width at the mandibular anteriors were 1.06 ± 0.21, 0.49 ± 0.15 and 2.09 ± 0.60 mm, respectively. CONCLUSION: OCT has promise for non-invasive observation of the periodontal tissue profile in detail and measurement of internal periodontal structures including biologic width in the anterior region.

Assessment of gingival symmetry with digital measuring tools and its reproducibility.

OBJECTIVE: The aim of this study was to investigate the accuracy of digital measuring tools to measure the position of gingival zeniths and to assess its reproducibility between different examiners. MATERIALS AND METHODS: A total of 108 subjects were photographed at the Louisiana State University School of Dentistry. The settings, positioning of the digital camera, and subjects' Frankfurt levels were standardized. A photograph was taken of the six anterior maxillary teeth of each subject, and their corresponding free gingival margins. Digital caliper measurements were taken intraorally from the zenith to the incisal edge of the right maxillary central incisor. A reference line was drawn across the screen on each image at the level of the zenith of tooth 8. Three calibrated examiners then measured the distance from the reference line to the zeniths of the other five anterior maxillary teeth. RESULTS/CONCLUSIONS: There was no statistically significant difference between the examiners regarding any of the measurements. Central incisors were at the same level in 84.24% of the subjects, and lateral incisors were within 0.5 mm of central incisors in only 58% of the subjects. Canine zeniths were within 0.5 mm of each other in 43% of the subjects. Only 28% of the subjects presented with zeniths of tooth 6 to tooth 11 within 0.5 mm of each other. Lateral incisors were at or beneath the line drawn from central incisors to cuspids in 90.8% of the subjects. Standardized digital photography taken with the aid of a stadiometer and used to evaluate esthetic parameters allowed for reproducible measurements.

Clinical assessment of interdental papilla competency parameters in the esthetic zone.

BACKGROUND: Interdental papilla occupies the space between two adjacent teeth. Its contour and health are regarded with utmost importance in esthetic dental therapy. The loss of papillary height can result in open gingival embrasures, phonetic problems, food impaction, and esthetic concerns: therefore in order to prevent its loss and to better understand the challenges of regenerating the lost gingival papillae, it is crucial to recognize the factors that influence papilla form. AIM: The purpose of this study is to evaluate various factors associated with the fill of interdental spaces by gingival papillae MATERIAL AND METHODS: 150 interdental papillae in 30 patients were assessed with clinical and study models. Papilla score (PS), tooth form/shape, gingival thickness, crest bone height, facio lingual thickness and gingival angle were recorded. RESULTS: In the study it was observed that complete papilla fill was associated with bone crest-contact point distance ≤ 5 mm and crown width: length ≥0.88 while interproximal gingival tissue thickness and gingival angle were significantly higher in competent as compared to incompetent papilla group. CONCLUSION: Interdental papillae appearance was associated significantly with tooth form/shape (CW/CL), crestal bone height, gingival thickness and gingival angle. CLINICAL SIGNIFICANCE: Presence of appropriately positioned interdental papillae in the anterior dentition is essential. Its deficiency leads to complex esthetic and functional problems while its reconstruction poses a formidable challenge. Thus a prior understanding of the various factors that affect its integrity in the anterior region allows for better management of the papillae leading to a more predictable outcome.

Periointegración / Periointegration

Se busca entender cuáles son las respuestas biológicas que se dan en diferentes etapas de la implantología, centrando la atención en la influencia de la tecnología en la formación del ancho biológico. Se analiza cómo fue evolucionando la ciencia en la búsqueda de mejores respuestas y cuáles serán los factores decisivos para que la tecnología influencie a la biología y poder aproximarse cada vez más a lo natural.

The aim of this paper is to understand the biological responses at the different stages of implantology, with a focus on the influence of technology in the formation of the biological width. It presents a study of the evolution of science towards better responses and the determining factors for technology to influence biology, which allow us to get closer to what is natural.

Consideraciones periodontales y protéticas para el tallado de piezas dentarias / Periodontal and prosthetic considerations for teeth grinding

Las preparaciones dentales para prótesis fija, involucran al tejido duro, además la proximidad que existe con la encía hace necesario la comprensión de su estructura y la función del aparato de protección, para que las restauracionesno invadan el ancho biológico constituido por el epitelio de unión y las fibras gingivales; basándonos en los estudios de Gargiulo en 1961, donde la inserción del tejido conjuntivo mide 1.07 mm y la adherencia epitelial 0.97 mm en promedio, sumados al espacio del surco gingival. El biotipo periodontal es de vital importancia para la elección de la altura de terminación del hombro de la preparación, donde el mismo deberá establecerse, previo sondaje óseo a no menos de 2.5 mm de la cresta según Kois (2008). La utilización de materiales y técnicas para la toma de impresiones definitivas deben ser amigables con los tejidos blandos a fin de no producir alteraciones y que las restauraciones sean predecibles, tanto funcional como estéticamente en el transcurso del tiempo

Dental preparations fixed prosthesis, involving the hard tissue, there is also proximity to the gum is necessary to understand the structure and function of the protection device, to restorations without invading the biologic width consisting of the epithelium junction and the gingival fibers; based on Gargiulo studies in 1961, where the insertion of the connective tissue and epithelial measured 1.07 mm 0.97 mm in average adhesion, coupled with sulcular space. The periodontal biotype is of vital importance for the choice of the termination of the shoulder height of the preparation, where it must be established prior tobone sounding no less than 2.5mm crest according Kois (2008). The use of materials and techniques for making final impressions should be friendly soft so as not to alter tissues and restorations predictable, both functionally and aesthetically over time.

Finding Z: a mathematical method for predicting tissue position after implant abutment-restoration placement.

A visible abutment-restorative interface is a problematic consequence, especially in the esthetic zone. This article presents formulas to predict the vertical tissue position around the abutment-restoration, which can be used both as a guide to the clinical situation and as an aid to computer-aided design and computer-aided manufacturing design.

Morphological and functional characteristics of human gingival junctional epithelium.

BACKGROUND: This study aims to observe the morphological characteristics and identify the function characteristics of junctional epithelium (JE) tissues and cultured JE cells. METHODS: Paraffin sections of human molar or premolar on the gingival buccolingual side were prepared from 6 subjects. HE staining and image analysis were performed to measure and compare the morphological difference among JE, oral gingival epithelium (OGE) and sulcular epithelium (SE). Immunohistochemistry was applied to detect the expression pattern of cytokeratin 5/6, 7, 8/18, 10/13, 16, 17, 19, and 20 in JE, OGE and SE. On the other hand, primary human JE and OGE cells were cultured in vitro. Cell identify was confirmed by histology and immunohistochemistry. In a co-culture model, TEM was used to observe the attachment formation between JE cells and tooth surface. RESULTS: Human JE was a unique tissue which was different from SE and OGE in morphology. Similarly, morphology of JE cells was also particular compared with OGE cells cultured in vitro. In addition, JE cells had a longer incubation period than OGE cells. Different expression of several CKs illustrated JE was in a characteristic of low differentiation and high regeneration. After being co-cultured for 14 d, multiple cell layers, basement membrane-like and hemidesmosome-like structures were appeared at the junction of JE cell membrane and tooth surface. CONCLUSIONS: JE is a specially stratified epithelium with low differentiation and high regeneration ability in gingival tissue both in vivo and in vitro. In co-culture model, human JE cells can form basement membrane-like and hemidesmosome-like structures in about 2 weeks.

Effects of a new implant abutment design on peri-implant soft tissues.

The purpose of this study was to assess the effects of a modified implant abutment design on peri-implant soft and hard tissues in dogs. Three months after extraction of mandibular premolar teeth, 3 dental implants were placed in each side of the jaw using a 1-stage approach. Implants on one side of the mandible received standard abutments (control), and implants on the contralateral side received modified, patented, grooved abutments (test). Two months after implant placement, animals were euthanized and specimens were prepared for histologic and histomorphometric assessment. The linear distance (in micrometers) was measured from the implant shoulder (IS) to the following landmarks: gingival margin (GM; distance IS-GM), most apical position of the junctional epithelium (JE; distance IS-JE), and bone crest (BC; distance IS-BC). Percent of bone-to-implant contact was also measured. Histologic assessment revealed that all implants were osseointegrated and that interimplant gingival fibers between test abutments appeared to be more numerous and organized than control abutments. The IS-GM and IS-JE distances in test implants were greater than the corresponding distances in control implants (P = .024 and P = .015, respectively), whereas crestal bone loss (IS-BC) was greater for control implants than test implants (P = .037). There were no differences between control and test implants in bone-to-implant contact (P = .69), which averaged close to 50%. These results suggest that the modified groove design incorporated in standard abutments confers both soft and hard tissue benefits.

Influence of Implant transmucosal design on early peri-implant tissue responses in beagle dogs.

OBJECTIVES: This study was undertaken to evaluate the influences of concave, machined and concave-roughened profiles of transmucosal implant designs on early peri-implant tissue responses. MATERIALS AND METHODS: Implants were used and classified by transmucosal profile and surface type as straight-machined implants (SM), concave-machined implants (CM), or concave-roughened implants (CR). A total of 30 implants (10 per each type) with matching transmucosal profiles were placed directly on alveolar crests in randomized order in the edentulous mandibular ridges of three beagle dogs. Healing abutments were connected 4 weeks after implant placement, and prostheses were connected 8 weeks after implant placement and functionally loaded. All animals were sacrificed at 16 weeks. Peri-apical radiographs were obtained and measured to evaluate peri-implant marginal bone levels. Histological specimens were prepared to measure bone resorption, connective tissue contact, epithelial tissue height, biological width, and length of implant-abutment junction to the apical portion of junctional epithelium. RESULTS: Radiographic and histometric analysis showed that least bone resorption occurred around CM implants and greatest bone resorption around SM implants (P < 0.05). Histometric analysis showed that highest connective tissue attachment and shortest biological width had formed around CM implants. CONCLUSION: Concave-machined profiled implants with a transmucosal design may induce less bone resorption and better connective tissue attachment around implants than the straight-machined profiled implants during the early healing phase.

Manejo del espacio biológico: revisión de literatura / Management of biological width: Literature review

Dentro de los diagnósticos de las patologías Periodontales, la clasificación número VIII según el último workshop de la Academia Americana de Periodoncia incluye a factores localizados y relacionados con un diente que predisponen a enfermedades gingivales inducidas por la biopelícula o la periodontitis; muchos de estos diagnósticos involucran directamente al espacio biológico. El espacio biológico es una zona variable, ya sea por la edad, el sexo, la pieza dentaria, la posición dentro de la arcada, etc. Sin embargo su función siempre es la misma, servir de soporte y de ser una zona fisiológicamente activa frente a la agresión bacteriana y mecánica. El presente artículo resume las múltiples fuentes de información de la literatura científica para abordar al detalle los aspectos a considerar al momento de diagnosticar las alteraciones del espacio biológico así como los protocolos para el tratamiento que permita su restauración...

Within the diagnoses of periodontal diseases, the classification number VIII according to the last workshop of the American Academy of Periodontology includes tooth localized factors and related that predisposing plaque-induced gingival diseases or Periodontitis, many of these diagnoses involve directly the biological width. Biological width is a variable area, either due to age, sex, the tooth, the position within the arcade, etc. However, its function is always the same, provide support and be a physiologically active zone against bacterial aggression and mechanics. This article summarizes the multiple sources of information in the scientific literature to address in detail the aspects to consider when diagnosing disorders of the biological width and the protocols for the treatment to its restoration or alteration...

Expression of odontogenic ameloblast-associated and amelotin proteins in the junctional epithelium.

Two novel proteins - odontogenic ameloblast-associated protein and amelotin - have recently been identified in maturation-stage ameloblasts and in the junctional epithelium. This article reviews the structure and function of the junctional epithelium, the pattern of expression of odontogenic ameloblast-associated and amelotin proteins and the potential involvement of these proteins in the formation and regeneration of the junctional epithelium.

An introduction to single implant abutments.

UNLABELLED: This article is an introduction to single implant abutments and aims to provide basic information about abutments which are essential for all dental personnel who are involved in dental implantology. CLINICAL RELEVANCE: This article provides a basic knowledge of implants and implant abutments which are of paramount importance, as replacement of missing teeth with oral implants has become a well-established clinical procedure.

Biologic width dimensions--a systematic review.

BACKGROUND: Consideration of the biologic width in restorative dentistry seems to be important for maintaining periodontal health. OBJECTIVE: To evaluate the dimensions of the biologic width in humans. MATERIALS AND METHODS: A systematic literature search was performed for publications published by 28 September 2012 using five different electronic databases; this search was complemented by a manual search. Two reviewers conducted the study selection, data collection, and validity assessment. The PRISMA criteria were applied. From 615 titles identified by the search strategy, 14 publications were included and six were suitable for meta-analyses. RESULTS: Included studies were published from the years 1924 to 2012. They differed with regard to measurements of the biologic width. Mean values of the biologic width obtained from two meta-analyses ranged from 2.15 to 2.30 mm, but large intra- and inter-individual variances (subject sample range: 0.2 - 6.73 mm) were observed. The tooth type and site, the presence of a restoration and periodontal diseases/surgery affected the dimensions of the biologic width. Pronounced heterogeneity among studies regarding methods and outcome measures exists. CONCLUSIONS: No universal dimension of the biologic width appears to exist. Establishment of periodontal health is suggested prior to the assessment of the biologic width within reconstructive dentistry.

Peri-implant soft tissues around implants with a modified neck surface. Part 1. Clinical and histometric outcomes: a pilot study in minipigs.

AIM: The goal of this study was to investigate the effect of a modified transgingival implant collar surface (acid-etched structure and hydrophilic properties) comparatively to a machined collar surface on the clinical and soft tissue integration to pure titanium implants (Ti) and titanium implants alloyed with zirconium (TiZr). MATERIAL AND METHODS: Twenty-seven implants belonging to the following groups (9 of each group): Ti modSLA with machined collar (Ti-M), Ti modSLA with machined, acid-etched surface collar (Ti-modMA) and TiZr modSLA with machined, acid-etched surface collar (TiZr-modMA) were placed in the mandible of 6 minipigs. After 8 weeks of healing, clinical measurements were taken and the sample sites were dissected and processed for histological evaluation. RESULTS: Eight weeks after implantation, the mucosa was generally located above the implant shoulder for all implant types. Histomorphometric evaluation revealed that the sulcular epithelium, junctional epithelium and the connective tissue contact were similar in the three groups. Adjusted comparisons showed that the first bone-to-implant contact was statistically more coronal for the Ti-modMA in comparison with the machined. CONCLUSION: The soft tissue dimensions around all implant prototypes were similar and not affected by the implant surface modification.

Relationships between different tooth shapes and patient's periodontal phenotype.

BACKGROUND AND OBJECTIVE: The purpose of the present study was to establish whether any correlation exists between tooth shapes and patient-related factors such as gingival and periodontal characteristics. MATERIAL AND METHODS: Clinical measurements, including the width and the height of maxillary central incisor crowns, the apico incisal height of the keratinized mucosa (KM), the buccal gingival thickness (GT), the depth of the sulcus (SD), the bone-sounding depth (BS) and the height of the interproximal maxillary central papilla (Ph), were investigated in 50 healthy individuals. These individuals were then divided into three groups based on the shape of their maxillary central incisor crowns: triangular; square; or square-tapered. The three groups were analyzed to determine any significant differences among the groups in the values obtained for clinical measurements. RESULTS: There were no significant differences among the three groups in terms of the SD (p = 0.11) or the BS (p = 0.54), whilst statistically significant differences were observed for the KM (p < 0.001), the GT (p = 0.012) and the Ph (p < 0.001). CONCLUSION: The results of this study indicate that different tooth shapes are associated with significantly different values for the extent of the KM, its bucco-lingual thickness and the height of the interproximal maxillary central papilla.

Dentogingival complex: dimension based on biotypes.

OBJECTIVE: Estimate the DGC dimensions and determine whether the DGC dimension varies by gingival biotype. METHODS: A cross-sectional study was performed in the Undergraduate and Prosthodontic Graduate Program clinics of the School of Dental Medicine, University of Puerto Rico from August 2011 to April 2012. A total of 53 participants who needed restorative crowns in their teeth were recruited. Prior to crown preparation, the gingiva was classified as having a thin, mixed or thick biotype, according to transparency, using a standardized 15 UNC Hu-Friedy periodontal probe. The DGC dimension was measured by transulcus probing. Descriptive statistics were calculated in mesial, medial, and distal sites by phenotypes. Differences between and within the sites' DGC dimension mean were determined using a Friedman test. The level of significance was 0.05. RESULTS: Mean DGC dimensions, in millimeters, for all sites measured were: 3.09 (95% CI: 2.91-3.27), 3.40 (95% CI: 3.18-3.62), 2.70 (95% CI: 2.51-2.89), and 3.17 (95% CI: 2.94-3.41) in mesial, medial, and distal sites, respectively. In thick, mixed, and thin biotypes the mesial sites showed greater DGC dimension means than the medial and distal (p<0.05) sites. Mean DGC dimension was greater for the thin compared to mixed and thick biotypes at mesial, medial and distal sites (p<0.001). Nevertheless, the thick biotype presented the smallest DGC mean dimensions compared to mixed and thin biotypes at the same sites. CONCLUSION: The DGC dimensions in all sites were similar to those reported in the literature. DGC dimensions are different for thin, mixed and thick gingival biotypes.

The distribution and expression of S100A8 and S100A9 in gingival epithelium of mice.

OBJECTIVE AND BACKGROUND: Gingival epithelium protects against bacterial infection by producing antimicrobial peptides such as calprotectin. Calprotectin consists of proteins S100A8 and S100A9. Although in vitro assay has shown that neutrophils and gingival epithelial cells express calprotectin, the expression of S100A8 and S100A9 and colocalization of both S100 proteins in gingival tissue in vivo are not fully understood. The aim of this study was to investigate the distribution of S100A8 and S100A9 expression in gingival epithelium of mice in the presence and absence of infection. MATERIALS AND METHODS: A quantitative analysis of S100A8 and S100A9 mRNA in junctional epithelium (JE) and oral gingival epithelium (OGE) of both germ-free mice and conventional mice was performed using laser microdissection and real-time polymerase chain reaction (PCR). Confirmation of S100A8 and S100A9 mRNA expression in the JE was conducted by fluorescent immunohistochemistry. RESULTS: Real-time PCR analysis indicated that S100A8 and S100A9 expressions were mainly detected in JE and only slightly or not detected in OGE. Levels of both S100A8 and S100A9 mRNA expression in JE of conventional mice were significantly higher than those in JE of germ-free mice. Additionally, fluorescent immunohistochemistry showed that S100A8 expression was observed in the JE of both conventional and germ-free mice, whereas S100A9 was expressed in the JE of conventional but not germ-free mice. CONCLUSION: S100A8 protein is expressed in JE cells of mice in the presence and in the absence of infection with oral bacteria. S100A9 expression in JE cells in the presence of microflora is significantly increased compared with the absence of microflora, which suggests that S100A9 expression may be induced by infection of microflora. The production of calprotectin in gingival epithelial cells may be mediated through S100A9 induction by bacterial infection.

In vitro reconstruction of human junctional and sulcular epithelium.

BACKGROUND: The aim of this study was to develop and characterize standardized in vitro three-dimensional organotypic models of human junctional epithelium (JE) and sulcular epithelium (SE). METHODS: Organotypic models were constructed by growing human normal gingival keratinocytes on top of collagen matrices populated with gingival fibroblasts (GF) or periodontal ligament fibroblasts (PLF). Tissues obtained were harvested at different time points and assessed for epithelial morphology, proliferation (Ki67), expression of JE-specific markers (ODAM and FDC-SP), cytokeratins (CK), transglutaminase, filaggrin, and basement membrane proteins (collagen IV and laminin1). RESULTS: The epithelial component in 3- and 5-day organotypics showed limited differentiation and expressed Ki-67, ODAM, FDC-SP, CK 8, 13, 16, 19, and transglutaminase in a similar fashion to control JE samples. PLF supported better than GF expression of CK19 and suprabasal proliferation, although statistically significant only at day 5. Basement membrane proteins started to be deposited only from day 5. The rate of proliferating cells as well as the percentage of CK19-expressing cells decreased significantly in 7- and 9-day cultures. Day 7 organotypics presented higher number of epithelial cell layers, proliferating cells in suprabasal layers, and CK expression pattern similar to SE. CONCLUSION: Both time in culture and fibroblast type had impact on epithelial phenotype. Five-day cultures with PLF are suggested as JE models, 7-day cultures with PLF or GF as SE models, while 9-day cultures with GF as gingival epithelium (GE) models. Such standard, reproducible models represent useful tools to study periodontal bacteria-host interactions in vitro.