Diagnosis in Periodontology and Implant Dentistry: The Past, the Present, the Future

Periodontal diseases (gingivitis and periodontitis) and peri-implant diseases (peri-implant mucositis and peri-implantitis) are prevalent biofilm-associated inflammatory conditions, caused by an imbalance between a dysbiotic biofilm and the host immune response. Although non-plaque induced gingival and mucosal diseases and conditions, such as oral lichen planus, may also be present, the focus of this perspective article is the diagnosis of plaque-associated diseases. Periodontal and peri-implant diseases may affect patient oral health-related quality of life and are considered of global public health concern 1-3. Hence, accurate and timely diagnosis is considered essential for the effective management and prevention of these diseases. Furthermore, as the presentation of both periodontal and peri-implant diseases is variable, clinical expertise is required to establish a diagnosis for appropriate treatment planning. Information obtained during medical and dental history taking and clinical examination as well as radiologic imaging, if indicated, forms the basis for diagnosis. In order to make accurate diagnoses, well-defined definitions of health and disease are required. The evolution of attempts to define periodontal diseases can be seen in the changes in classification schemes over some decades. In the history of periodontology, numerous classification schemes for periodontal diseases have been developed and subsequently modified and updated, allowing clinicians to adequately diagnose and treat patients consistent with the scientific evidence of the time. Modifications were made, often by consensus workshops, to align with new scientific evidence related to the pathophysiology, systemic and environmental risk factors associated with periodontal diseases. In 1983, when I was a dental student, diagnoses of the conditions of the periodontal tissues were made, describing the severity and extent of clinical attachment loss as assessed using a periodontal probe and radiographs 4. Individual tooth diagnoses included gingivitis (bleeding on probing, no loss of supporting tissues with or without the presence of pseudopockets), periodontitis levis (bleeding on probing, pocket depth and attachment level measurements and radiographic analysis indicating horizontal loss of supporting tissues not exceeding one third of the length of the root), periodontitis gravis (bleeding on probing, pocket depth and attachment level measurements and radiographic analysis indicating horizontal loss of supporting tissues exceeding one third of the length of the root), and periodontitis complicata (bleeding on probing and the presence of an angular bony defect adjacent to a tooth or a tooth with a degree 3 mobility, or a multirooted tooth with grade 2 or 3 furcation involvement). In 1989, the World Workshop in Clinical Periodontics, facilitated by the American Academy of Periodontology, categorized periodontitis as prepubertal, juvenile (localized and generalized), adult, and rapidly progressive on the basis of distinct clinical presentation, age of onset, and rate of progression 5. In 1993, the 1st European Workshop on Periodontology simplified the classification to adult and early onset periodontitis 6 which remained until the 1999 International Workshop for a Classification of Periodontal Diseases and Conditions, when the classification changed to chronic and aggressive (localized and generalized) periodontitis, necrotizing periodontitis, and periodontitis as a manifestation of systemic disease 7. At the most recent consensus workshop held in Chicago in 2017, the World Workshop on the Classification of Periodontal and Peri-implant Diseases and Conditions, significant changes were made to accommodate new evidence. For the first time, the diagnosis and classification of peri-implant conditions were included in the World Workshop. Another key aspect of the workshop was, also for the first time, the recognition of the importance of establishing case definitions for health, as well as for disease 8-10. In addition, a novel framework of staging and grading of periodontitis was introduced. This requires the use of clinical and radiographic diagnostic parameters to determine the stage of periodontitis (classified as stage I, II, III, IV) on the basis of severity and complexity of disease management, and grade of periodontitis (classified as grade A, B, C) on the basis of the risk for disease progression 11. In a recent report on contemporary and emerging diagnostic parameters 12, the integration of diagnostic measures with the current case definition proposals and the clinical practice guidelines for the treatment of periodontitis 13 and peri-implant diseases 14 was highlighted, allowing for a structured framework with the capacity for future adaptations. A unique feature of the 2017 classification is the possibility to consider additional diagnostic measures, such as identification of inflammatory biomarkers, within the existing framework as new evidence emerges 15. It is anticipated that future validated diagnostic biomarkers may contribute to the identification of individuals and sites at risk for disease progression. Thus, the current 2017 classification has been designed for the future, allowing flexibility to be modified on the basis of advances in technology and new scientific evidence. In the year 2026, diagnosis in periodontology and implant dentistry are inextricably linked. Although important differences in the dimensions, cellular composition, structure, and function of the tissues surrounding teeth and implants are well documented 16, the diagnostic processes for identifying signs of health and disease at both entities are similar. As described by Professor Jan Lindhe, in his insightful article in this Journal of Periodontal Research 60th anniversary series, in the late 1980s the Scandinavians were instrumental in integrating implant dentistry within periodontal practice 17. Prior to this, dental implant placement was almost exclusively performed by oral and maxillofacial surgeons, and primarily for patients with edentulous arches. At that time peri-implant diseases were not recognized. The diagnostic criteria for evaluating the success of implant therapy were limited to digital assessment of mobility of the implant, acoustic analysis following percussion tests, and recording of Periotest values 18 and radiographic assessment of peri-implant bone conditions and detection of peri-implant radiolucency. Professional maintenance was mainly focused on the repair of the prosthetic components and occlusal adjustments. The safety and value of probing around implants was a debated issue. In 1993, when studying under a Brånemark scholarship at the Brånemark center, University of Lund, Malmö, Sweden, I was instructed not to probe around implants. Later in 1993, at the first European Workshop on Periodontology in Ittingen, Switzerland, peri-implant disease was described as a collective term for inflammatory reactions in the tissues surrounding an implant. Peri-implant mucositis was described as a term for reversible inflammatory reactions in the soft tissues surrounding a functioning implant, and peri-implantitis was described as a term for inflammatory reactions with loss of supporting bone in the tissues surrounding a functioning implant 6. Prior to this, terminology such as mucosal hyperplasia and tissue overgrowth was used when referring to these conditions. At the most recent consensus workshop, the World Workshop on the Classification of Periodontal and Peri-implant Diseases and Conditions, well-defined case definitions for peri-implant health 9, peri-implant mucositis 19 and peri-implantitis 20 were established. Diagnosis of peri-implant health included the absence of bleeding or suppuration on gentle probing, no increase in PD compared to previous examinations, and absence of radiographic bone loss beyond crestal bone changes resulting from initial bone remodeling. Diagnosis of peri-implant mucositis remained essentially unchanged from the previous workshop, with the addition of a case definition, whereas the classification of peri-implantitis added the term “progressive” to the criterion of bone loss. Furthermore, a peri-implantitis case definition was defined to be used when a baseline radiograph is not available, to include a bone level threshold of ≥ 3 mm apical to the most coronal portion of the endosseous part of the implant and a probing depth threshold of ≥ 6 mm 10, 21. These definitions were further modified in 2023 following the implant dentistry core outcome set and measures (ID-COSM) international consensus 22, where “one spot of bleeding” was allowed for a diagnosis of peri-implant health, whereas greater than one spot of bleeding is required for the diagnosis of peri-implant mucositis. This modification was made under the assumption that a single bleeding spot may be caused by trauma to the tissues following probing rather than a disease process. According to the European Federation of Periodontology S3 clinical practice guideline on the treatment of peri-implant diseases, the presence of bleeding on probing (BOP) refers to more than one spot at a location around the implant, or the presence of a line of bleeding or profuse bleeding at any location 14. This has implications for past peri-implant mucositis prevalence data, as well as success/failure rates for treatments where endpoints include the absence of BOP. Although the classification of periodontal and peri-implant diseases has been periodically adapted through consensus at various workshops, the diagnostic process has remained consistent, incorporating visual examination of the color and texture of the periodontal/peri-implant tissues, assessment of plaque deposits, and probing assessments using a manual probe with a light probing force. When clinical signs and symptoms of periodontal/peri-implant diseases are identified, diagnostic radiologic imaging is used to evaluate the extent of bone loss and bone defect morphology. Although periodontal probing may seem like a straightforward diagnostic process for assessment of the health status of the periodontal tissues, there are multiple factors that may introduce errors and must be considered when interpreting probing measures. The degree of inflammation in the periodontal tissues reflects the penetration of the tip of the periodontal probe, as demonstrated in histologic experimental studies using a light probing force of 0.25 N. At healthy sites, the probe tip stops coronal to the apical termination of the junctional epithelium, whereas at inflamed sites, the tip of the probe extends beyond the junctional epithelium 23, 24. Potential errors inherent in periodontal probing have been attributed to variation in the probing force used by different clinicians 25-27, variations in probe designs 28, probing angulation errors due to local anatomical factors 29 and reading of the markings on the probe and identification of landmarks such as the cementoenamel junction (CEJ). The introduction of manual and electronic pressure-controlled/sensitive probes in the 1990s aimed at reducing these errors. However, they failed to show an advantage over the manual probe in terms of inter-and intra-examiner reproducibility of repeated measurements 30, 31. Manual periodontal probes remain the clinical standard for the diagnosis and monitoring of periodontitis patients. The current recommendation, from the 2017 World Workshop on the Classification of Periodontal and Peri-implant Diseases and Conditions, is to use a manual periodontal probe with a tip diameter of 0.5 mm, a cylindrical tine, 15 mm scale with mm markings, with a light probing force (0.25 N) 32. A histologic study in humans confirmed that the visual presence of inflammation of the gingiva and bleeding after probing using a controlled probing force of 0.25 N provides an accurate assessment of inflammation in the periodontal tissues 33. Assessment of BOP using a light probing force (0.25 N) is therefore the main clinical diagnostic tool used to diagnose gingival inflammation (gingivitis) and monitor inflammation in the periodontal tissues. After obtaining a thorough medical history the following variables should be assessed and recorded with the aid of a manual periodontal probe using a light probing force (0.25 N): plaque levels, PD, CAL, BOP, suppuration and gingival recession (REC) at six sites per tooth, presence and grade of furcation involvement at multirooted teeth (using a standardized curved furcation probe, e.g., Nabers furcation probe) and tooth mobility 12. When clinical signs and symptoms of periodontitis are identified, diagnostic radiologic imaging is used to evaluate the extent of bone loss and bone defect morphology. Correlation with clinical findings should always accompany radiographic examination. In the past, the periodontal probe was also used for bone sounding to evaluate the extent of periodontal bone loss. Bone sounding is performed under local anesthesia, where the tip of the probe is forced through the supraalveolar connective tissue to contact the bone, and the distance from the CEJ to the bone level is measured in millimeters. Today, bone sounding is of questionable relevance for routine periodontal diagnosis. As previously outlined, in the past, some expressed concern that peri-implant probing for monitoring peri-implant conditions might be detrimental to the health of the surrounding tissues by introducing bacteria to the peri-implant environment and should therefore be avoided. However, experimental in vivo studies clearly demonstrated that peri-implant probing was not only safe 34 but also a valuable tool for assessment of the health status of the peri-implant tissues 35. Histologic evaluation showed that peri-implant probing using a light probing force (0.2 N) accurately determined the level of connective tissue adhesion at the implant/abutment. In health, the probe tip was coronal to the most apical portion of the barrier epithelium. Probe penetration increased with the degree of inflammation, and in peri-implantitis, the probe tip was well correlated with the marginal bone level 36. Schou and co-workers demonstrated in an experimental in vivo study that peri-implant probing had similar diagnostic capability when compared to periodontal probing. It was observed that in health, there was a similar probe penetration around implants in comparison to teeth; however, even with mild inflammation, there was a deeper probe penetration around implants 37 because of the differences in tissue composition and organization of the connective tissue fibers 35. Peri-implant probing may, however, be hindered by the contours of an implant-supported prosthesis. This was demonstrated by Serino and coworkers in a clinical study where probing measures were made before and following the removal of prosthetic reconstructions at implants with signs of peri-implantitis. The study showed that the correlation between probing depths and intrasurgically measured bone loss was much higher with the prosthesis removed than with the prosthesis in place 38. This highlights the importance of implant positioning and prosthesis design to facilitate probing for diagnosis of health and disease 14. Hence, peri-implant probing is considered an essential diagnostic measure to evaluate the peri-implant health status of the peri-implant mucosa and to monitor conditions over time. Peri-implant probing circumferentially is recommended following delivery of the prosthesis to establish baseline probing measures, and should be repeated at each subsequent recall visit 39. A manual probe is used with a light probing force (0.2 N) to assess probing depth (PD), bleeding on probing (BOP), and peri-implant soft tissue levels. When clinical signs of inflammation are present, diagnostic imaging is used to evaluate the peri-implant bone levels and establish a diagnosis. Traditional radiological assessment, using two-dimensional (2D) (intraoral periapical or bitewing or extraoral orthopanoramic) imaging, has been used in the past and is still valid as the standard of care for evaluating periodontal bone levels and diagnosing local contributing factors to periodontal bone loss, such as vertical root fractures and endodontic lesions. Radiographic assessment provides information on the past history of disease, and when used in conjunction with the clinical information obtained from a periodontal probing assessment, facilitates assessment of the extent and severity of disease. Radiographs should never be used in isolation for the diagnosis of periodontitis. In more recent years, cone-beam computed tomography (CBCT) has been recognized as a valuable tool for assessing periodontal bone levels and, in particular, for identifying the extent and morphology of furcation lesions 40. The routine use of CBCT for periodontal diagnosis is, however, not recommended because of concerns regarding increased radiation dosage. CBCT imaging may be recommended when more detailed diagnostic information is required 12. Alternative non-ionizing imaging techniques, magnetic resonance imaging (MRI) and ultrasonography, have recently been investigated for their diagnostic potential in periodontology. However, because of the limited currently evidence and and on for and these remain for future diagnostic imaging in order to assess and monitor peri-implant marginal bone levels provides important information to establish a diagnosis. imaging or bitewing identification of the marginal bone levels in to a such as the most coronal aspect of the endosseous portion of the implant. is considered the standard of care for establishing baseline marginal bone levels following initial bone and for monitoring bone levels when clinical signs of inflammation are imaging, computed tomography may also be used to the and peri-implant bone however, routine use is not recommended because of concerns with increased radiation dosage. Furthermore, of the peri-implant bone levels may be because of related to The introduction of CBCT and for may the potential of this imaging in the The use of non-ionizing imaging such as or is still in for diagnosis of peri-implant however, they may in the future routine in clinical practice Although both periodontal and peri-implant diseases are well as plaque-associated conditions, at the of the findings from and analysis of to the assumption that trauma from was an in the of periodontal pocket Hence, in the past, assessment of signs and tooth mobility, tooth tooth occlusal and a in the diagnostic process for periodontitis. In the past, occlusal and occlusal were considered an part of the treatment of periodontitis. This assumption was in experimental studies in and evidence that trauma from to teeth with a healthy the of periodontal occlusal assessment is, no considered essential for the diagnosis of periodontitis. an evaluation of occlusal factors such as and the presence of tooth mobility is considered important in the diagnostic to establish contributing factors to the progression of periodontitis. In the past, the of occlusal was also considered a for the of peri-implant disease and marginal bone loss in vivo however, demonstrated that occlusal in the absence of a plaque biofilm not in peri-implant marginal bone loss Although is considered important for prosthetic such as prosthetic or which may in the evaluation of occlusal is not part of the diagnostic process for peri-implant diseases. 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Hence, in the future, analysis may be for early disease identifying individuals are more before clinical signs of inflammation biomarkers, such as and in or have been as potential diagnostic over However, the use of these biomarkers in periodontology and implant dentistry has not been in clinical practice because of the and of the biomarkers, the of the diagnostic tests, and the of obtaining in clinical practice 12. In the future, the of inflammatory in may be valuable for the identification of individuals and sites at risk for disease or disease progression. The of information obtained from has the potential to in the grading of periodontitis, as in the recent classification workshop on periodontology and peri-implant diseases 15. 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