Peri-implant diseases are inflammatory conditions affecting the soft and hard tissues around dental implants. Peri-implant disease is a serious problem that plagues today’s dentistry in terms of therapy and epidemiology. Peri-implant mucositis is the presence of inflammation of the peri-implant mucosa without signs of loss of bone support, while peri-implantitis, in addition to inflammation of the mucosa, is characterized by a loss of bone support [1, 2]. Peri-implantitis was often defined by the incidence of peri-implant probing depth ≥ 5 mm associated with bleeding on probing (BoP) and/or suppuration and radiographic images of bone loss [3, 4]. Cases where the radiographs did not confirm the peri-implant bone loss were diagnosed as peri-implant mucositis [5].
The joint use of probing depth, radiographic bone loss, and BoP was frequently implemented in the clinical diagnosis of peri-implant disease [6]. There are, however, notable exceptions. In the 7th European Workshop on Periodontology, peri-implantitis was characterized by changes in the level of the crestal bone in conjunction with BoP with or without concomitant deepening of peri-implant pockets [7].
Peri-implant bleeding on probing (Fig. 1) has a decisive value in the classification and diagnosis of peri-implant disease. Bleeding on probing is considered as key clinical measure to distinguish between peri-implant health and disease [8]. The BoP measurement can change the diagnosis from a healthy implant to mucositis, as well as from an unclassified situation (probing depth+, BoP, Bone Loss+) to peri-implantitis [9].
Recently, a study evaluated a retrospective observational study to determine BoP associated risk factors for dental implant [10]. They found that the rate to be BoP+ for a site with PD = 3 was 18% and the odds ratio increased by 1.98 for each 1 mm increment in PD [10]. In addition, a significantly higher risk for BoP+ was observed for interproximal vs. approximal surface, posterior teeth vs. anterior teeth, and female vs. male, while a significantly lower risk was observed for smokers vs. non-smokers [10].
Furthermore, a cross-sectional study was done to evaluate the association between peri-implant BoP and probing depth. Other factors regarding patients, implants, and sites were taken into consideration. The final model comprehended only the probing depth and the site position. The odds ratio of a site to be BoP increased by 1.81 for each 1 mm increment in probing pocket depth. A significant higher risk was observed also for interproximal vs. approximal implant surfaces. Other considered variables at patient, implant, or site level were all not significant when considered in conjunction with probing depth and site position. Though various studies has been done to evaluate the association of peri-implant bleeding on probing with multilevel factors [11], no specific studies have been to evaluate the association of peri-implant bleeding on probing with peri-implant gingival biotype in respect to its functional aspects.
Gingival biotypes are the critical factor that determines the outcome of an implant placement. The term gingival biotypes used to describe the thickness of gingiva in facio-palatal dimension [12]. According to Ochsenbein and Ross, there were two types of gingival morphology, namely scalloped and thin or flat and thick gingiva. Studies have proven that peri-implant diseases are more likely to occur in patient with thin biotypes as they have a compromised soft tissue response following surgical treatment [12]. Cochran stated a need of 3 mm of peri-implant mucosa is needed for a stable epithelial, connective tissue attachment. The gingival thickness affects the treatment outcome possibly because of the difference in amount of blood supply of the underlying bone and susceptibility to resorption [13].
Many invasive and non-invasive methods used to measure gingival biotypes. Transgingival probing is a traditional invasive method which has limited application in clinic. Instead of this, another method based on the translucency of the periodontal probe through the gingival margin upon inspection is widely used and is taken as a simple method with excellent repeatability (Figs. 2 and 3). Ultrasonic measurement and cone beam computerized tomography (CBCT) are also non-invasive methods, but specific devices are needed for these assessments [13].
Recently, a study was done to evaluate the role gingival biotypes in esthetic success of dental implant by Mahdi Kadkhodazade but not in terms of the functional aspects [14]. Thus, this study was carried out to determine the functional aspects of gingival biotypes in determining peri-implant diseases. In addition, Vandana and Savitha, in a 2005 [15] study in humans, and Kyllar and Witter, in a 2008 study in dogs, demonstrated that gingival thickness varies by sex and age as well as dental arch forms. However, to the best of our knowledge, there were no studies done to determine the association of peri-implant bleeding on probing in respect to different ethnicities in Malaysian population.
Hence, the objective of this study was to evaluate the association between peri-implant bleeding on probing in peri-implant diseases and its association with multilevel factors which include site specific factors (gingival recession, bone loss, pocket depth, and peri-implant gingival biotype), implant level factors ( position and duration of implants), and patient level factors (age, gender, ethnicity, smoking, and systemic diseases) which highlights on the functional aspect of peri-implant gingival biotype.