|Year : 2016 | Volume
| Issue : 1 | Page : 44-49
Periodontal biotype: Basics and clinical considerations
Rucha Shah, NK Sowmya, Raison Thomas, Dhoom Singh Mehta
Department of Periodontics, Bapuji Dental College and Hospital, Davangere, Karnataka, India
|Date of Web Publication||10-Aug-2016|
Department of Periodontics, Bapuji Dental College and Hospital, Davangere, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Gingival/periodontal biotype is now known to influence the indications and outcomes of various therapies routinely performed in a dental clinic. The delicate thin biotype is more susceptible to injury and responds in a different way clinically as compared to the sturdier thick biotype. Assessment, identification, and indicated treatment considerations are now becoming the key to achieve predictable results, good esthetics, and stability of soft tissue margins. This review describes the various classifications, methods of assessment and clinical considerations for both the thick and thin tissue biotypes.
Clinical Relevance to Interdisciplinary Dentistry
In the era of evidence-based interdisciplinary dentistry, none of the dental disciplines are mutually exclusive. The treatment plan, treatment response, and prognosis of dental procedures vary greatly between teeth with different biotypes. Hence, the knowledge and assessment of gingival/periodontal biotype has become an important routine in clinical decision-making.
Keywords: Gingival biotype, periodontal biotype, periodontal therapy
|How to cite this article:|
Shah R, Sowmya N K, Thomas R, Mehta DS. Periodontal biotype: Basics and clinical considerations. J Interdiscip Dentistry 2016;6:44-9
| Introduction|| |
Gingiva is the part of the oral mucosa that covers the alveolar processes of the jaws and surrounds the necks of the teeth. A well-scalloped gingival line at the cemento-enamel junction (CEJ) of the teeth forms one of the pillars of a beautiful smile. Clinicians handle gingiva in several dental procedures and the resulting gingival architecture is not always ideal. In the era of esthetics-driven dentistry, it is of paramount importance that a clinician should be well-aware of all the factors that may influence the final esthetic outcome of a treatment. One such factor that clinicians should consider before starting any restorative, prosthetic, and periodontal procedure is the "tissue biotype."
Ochsenbein and Ross in their pioneer study indicated that there were two main types of gingiva morphology, namely the scalloped and thin or flat and thick gingiva.  The term "periodontal biotype" was later introduced by Seibert and Lindhe to categorize the gingiva into "thick flat" and "thin scalloped" biotypes.  In general, the term gingival biotype has been used to describe the thickness of the gingiva in the facio-palatal dimension. Whereas the term "periodontal biotype" encompasses not only the thickness of gingiva, but also other features such as contour of gingiva, alveolar bone contour and thickness, amount of keratinized gingiva present, and crown shape.  With the increase in the amount of literature on the topic, it is now understood that different gingival/periodontal biotypes behave in a different manner under similar clinical conditions. Furthermore, the treatment considerations for individuals with different biotypes differ.
| Gingival/periodontal biotype classifications|| |
Several classifications have been proposed for gingival/periodontal biotypes. Even while classifying periodontal biotypes, gingival thickness is considered an important factor as gingival and periodontal biotypes are considered to be closely related. Gingival/periodontal biotype may differ from tooth to tooth in a person; may differ with age, gender, and dental arch location.  There is no universally accepted classification for gingival/periodontal biotypes. There is also a lack of agreement between authors as to what thickness of gingiva would be considered thin or thick. Gingival biotypes were initially classified by Oschenbein and Ross as thin or thick. However, several classifications of gingival biotypes have been presented over time [Table 1]. ,,, In a recent systematic review, it was concluded that the available definitions of gingival/periodontal biotypes are unclear, and the three biotypes: Thin scalloped, thick flat, and thick scalloped seem a comprehensive categorization in defining periodontal biotypes in the population.  In spite of a lack of agreement for the classification method, most of the studies attribute similar features to a thick and a thin biotype. Each biotype possesses its own unique characteristics.
The thin and scalloped biotype is said to have a delicate and thin periodontium, highly scalloped gingival tissue, usually may present slight gingival recession, presents highly scalloped osseous contour, small incisal contact areas in the teeth, and triangular anatomic crowns. Thin gingival tissue tends to be delicate and almost translucent in appearance. The tissue appears friable with a minimal zone of attached gingiva, and the soft tissue is highly accentuated and often suggestive of thin or minimal bone over the labial roots. Surgical exposure in such cases generally demonstrates thin labial bone with an increased incidence of fenestration and dehiscence [Figure 1]. , The prevalence of thin biotype is around 43%. ,
The thick and flat biotype is characterized by thick heavy periodontium, gingival margin usually placed coronal to CEJ, wide zones of keratinized gingiva, flat gingival contour, thick flat osseous gingival contour, broad apical contact areas in teeth, and square anatomic crowns. It is mostly associated with periodontal health. The tissue is dense with a wide zone of attached gingiva. The underlying bony architecture is considered to be thick. Surgical exposures in such cases demonstrate thick underlying osseous forms [Figure 2]. , The prevalence of thick biotype is around 56%. ,
| Methods of measurement of gingival thickness|| |
Many methods have been proposed till date to analyze the gingival tissue thickness. These are described as follows:
The gingiva is anesthetized by topical application of an anesthetic gel. An endodontic spreader with a rubber stop/caliper is inserted at a point at the center of the gingival margin and mucogingival junction in a perpendicular direction and this measurement is recorded against a digital caliper. It is an accurate method of measurement, however it is an invasive technique. 
The gingival biotype is clinically evaluated based on the general appearance of the gingiva around the tooth. The gingival biotype was considered thick if the gingiva was dense and fibrotic and thin if the gingiva was delicate, friable, and almost translucent. The advantage of this technique is that it is minimally invasive, however it has been found to have a very low accuracy and a very high interexaminer variation. 
Sulcus probing of the mid-facial aspect of the tooth is performed. The gingival biotype is categorized as either thin or thick according to the visibility of the underlying periodontal probe through the gingival tissue (visible = thin, not visible = thick). It is a minimally invasive technique with a good accuracy. 
A sensitive, thin probe attached to an ultrasonic device measures the biotypes ultrasonically. It uses the pulse echo principle for the determination of biotype thickness. This technique gives accurate measurement - digital display, avoids interexaminer variability, and noninvasive, but the high cost of equipment and limited availability make it less feasible. 
Cone beam computed tomography
It is used to visualize and measure the thickness of both hard and soft tissues. Highly accurate results can be achieved using cone beam computed tomography (CBCT), and there is no interexaminer variation. However, there is some amount of radiation exposure and increased cost for the patients. ,
When the reliability of assessing gingival biotype of maxillary anterior teeth with and without the use of a periodontal probe in comparison with direct measurements was performed, the authors found that assessment with a periodontal probe is an adequately reliable and objective method in evaluating gingival biotype, whereas visual assessment of the gingival biotype by itself is not sufficiently reliable compared to direct measurement.  Keeping in mind all pros and cons of the various analytical modalities, direct measurement and probe transparency are good methods to detect gingival biotype clinically.
| Periodontal biotypes: Clinical applications|| |
Tissue biotypes are associated with the outcomes of a variety of dental clinical procedures. In several dental procedures, the gingival tissue is subjected to clinical/surgical insults and both the biotypes respond differently to them. In the event of inflammation or any other type of insult, soft tissue in a thick biotype responds by more fibrotic changes and pocket formation, however in thin biotype, we see more inflammatory changes and recession of gingiva.  This basic difference in the response of thick biotype tissue as compared to thin biotype is the fundamental for the variation response and consideration for these under various clinical scenarios. Patients with a thin biotype are more vulnerable to connective tissue loss and epithelial damage, thus they need special atraumatic treatment and oral hygiene techniques. 
Crown lengthening procedure
In crown lengthening procedures, the amount of tissue exposure required for further rehabilitation of the tooth dictates the amount of bone removal during the procedure. Significant postoperative tissue rebound has been observed in cases of thick biotype as compared to thin biotype.  Thus, tissue biotype is an important feature to be assessed in such cases, and slight overcorrection or immediate rehabilitation may be advised in such cases.
In the course of orthodontic therapy, teeth are moved in various directions (buccally, lingually, coronally, and apically). In an attempt to bring teeth in an ideal position, it may sometimes lead to soft tissue recession or hard tissue dehiscence and fenestration. It has been observed that such tooth movement results in increased recession and increased incidence of dehiscence and fenestration formation in cases with thin biotype.  Hence, such cases should be approached with more caution. Another consideration could be placement of mini-screws where a thin biotype warrants more caution.
The thin biotype is more prone to recession of gingiva. It has been observed that in relation to metal ceramic prosthesis over a period of 5 years, significantly more gingival recession is observed after prosthesis placement in thin biotype as compared to thick biotype.  This underscores the importance of assessment and management of thin biotype cases at the time of prosthesis placement. In areas of high esthetic requirement, biotype enhancement can prevent such unpleasant clinical scenario. On the basis of these findings, it can be suggested that more caution should be exercised while planning a subgingival margin placement for patients with a thin biotype as minimal tissue injury may result in adverse outcome in future. More controlled studies on these conditions are required.
Root coverage in thick versus thin biotypes
It was proposed that thick gingival tissue eases manipulation, maintains vascularity, and promotes wound healing during and after surgery. A critical threshold thickness (>1.1 mm) for root coverage success may exist for predictable root coverage.  Hence, patients having a thinner biotype can be treated preferably with techniques that create a pseudo-thick biotype such as a connective tissue graft in conjunction with coronally advanced flap as compared to a coronally advanced flap alone.  In another study, it was mentioned that the thin gingival biotype may impair the clinical outcome of root coverage procedures, and to overcome this, the same coverage can be done using sub-epithelial connective tissue graft which provides better results. 
It has been observed that median supracrestal gingival tissue is more in thick flat biotype as compared to thin scalloped biotype.  Overhanging restorations can more frequently and rapidly result in tissue destruction.
Owing to the delicate nature of gingival tissue in thin biotype routine, procedures such as gingival curettage needs to be performed more carefully. In cases of flap surgery, careful handling of the flap is more significant in thin biotype cases.
Extraction of teeth in thick versus thin biotypes
Although extractions should always be atraumatic, teeth with thin gingival biotypes merit more attention due to their association with thin alveolar plates. , Atraumatic extraction and preservation of the alveolar plate are essential. Excessive force is more likely to fracture the buccal alveolar plate in thin biotype and results in bone resorption and unpredictable bone healing.
Ridge preservation in thick versus thin biotypes
Given the thin alveolar plate associated with thin periodontal biotypes, more extensive ridge remodeling is seen in thin biotype when compared to thick biotypes leading to exaggerated loss in hard and soft tissue volume. Hence, in a patient with thin biotype, augmentative procedures such as socket preservation/augmentation may be performed to ensure an esthetic and functional result in future. 
Tissue biotype in implant treatment planning
In thick biotype, significantly, less bone loss is seen after implant placement as compared to thin biotypes.  In a thick biotype environment, immediate placement of an implant can be completed with predictable results. In a thin biotype cases, the possibility of significant resorption, which may have an impact on esthetics, is high. A delayed implant placement should be preferred when the thickness of the periodontal tissues is not sufficient. In thin biotype cases, preemptive biotype correction may be considered. The tissue biotype is considered a key factor in implant esthetics, preventing future mucosal recession, and improving immediate implant success. ,,
Another emerging concept in patients with thin biotype is that of a flapless approach for implant placement. In the conventional method, a full-thickness buccal and lingual/palatal flap is raised, osteotomy is prepared, and implant placement is done. In the minimally invasive flapless approach, a surgical guide is prepared using the CBCT image. Using the guide, a circular punch is made on the ridge and implant placement is done. This prevents the disruption of blood supply to alveolar bone which would be occurring when we raise a full thickness flap. Studies have shown that after the placement of implants using a flapless approach, the papillary recession and bone loss were minimized in patients with thin gingival biotype. 
In addition, it has been shown in a study that laser micro-textured implant collar may prevent proximal bone less in thin biotype cases. 
| Enhancing the gingival biotype|| |
A preexisting thin gingival biotype can impede ideal esthetic result of many therapies. In such a scenario, gingival biotype can be enhanced. This concept is in its infancy and just emerging. A pseudo thick gingiva is when an originally thin gingiva is converted to a thick gingiva.  This can be done to achieve more stable results to avoid soft tissue relapse. It can also aid in achieving more esthetic results. A study demonstrated that bone loss can be controlled in thin biotype patients, if the biotype is augmented prior to the placement of implant. 
Few procedures can be performed to enhance the biotype of gingival tissue. One such procedure is the use of connective tissue grafts.  In this procedure, a connective tissue graft harvested from palate/tuberosity is placed at the site of thin biotype subepithelially. For the same, either a full or partial dissection can be done. Once the graft is in position, it is sutured. Once healing is completed, a thin biotype is converted into a stable thick biotype. This can be attributed to the primarily fibrous content of the graft and the bulk that they provide at the recipient site. They have not only been seen to improve gingival biotype, but also increase the long-term stability of the results. It is the most reliable and frequently documented method of enhancing gingival biotype. However, donor site morbidity, limited availability, and increased operating time are the disadvantages associated with connective tissue placement.
As an alternate to connective tissue, acellular dermal matrix can also be used to enhance the biotype. The procedure of placement and healing mechanism is similar to that of the connective tissue graft. It has the advantage of lowering the patient morbidity due to the absence of a second donor site; however, the high cost and limited availability are its drawbacks.
Another mode of enhancing the gingival biotype is the placement of platelet-rich fibrin (PRF) membrane. PRF is a blood-derived, autologous, second-generation platelet concentrate. It mainly consists of a three-dimensional fibrin matrix with platelets. These platelets then release several growth factors including platelet-derived growth factor and vascular endothelial growth factor.  Shetty et al. in their study demonstrated that placement of PRF membrane over denuded root surface in conjunction with coronally advanced flap results in the improvement in the thickness of gingiva. 
Recently, use of fetal membranes such as amnion and chorion membrane has demonstrated to enhance gingival biotype. , These membranes are allografts derived from the human placenta. The membranes are then obtained, processed, and sterilized for human use. The main advantage of their membranes is their excellent revascularization, nil antigenicity, and easy availability. They can be placed under a tunnel/pouch/coronally advanced flap and sutured. This study demonstrated that after the placement of amnion membrane in conjunction with coronally advanced flap, the gingival thickness was improved. 
However, such reports are few and more controlled studies are required to evaluate the efficacy of both PRF membranes and fetal membranes. The most effective technique of biotype augmentation still remains connective tissue grafting.
| Conclusion|| |
By understanding the nature of tissue biotype (thickness), a practitioner can employ appropriate clinical procedures to minimize soft tissue loss and alveolar resorption and provide a more favorable tissue environment. Different gingival biotype can influence the diagnosis and treatment planning for different patients. In addition, these techniques when appropriately applied can save on treatment time and cost for patients. Inclusion of biotype assessment in the diagnostic record of the patient can give the clinician an idea about the care to be taken in tissue handling, the type of procedure to be employed in a certain situation as well as the expected outcome.
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Conflicts of interest
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[Figure 1], [Figure 2]