Dentistry is increasingly specializing in the fields of oral surgery, preservation, periodontology, prosthodontics, and orthodontics. Nevertheless, all disciplines require knowledge and consideration of anamnestic conditions, such as the presence of underlying internal diseases, the associated long-term medication, and their influence on the stomatognathic system.
Particularly in patients suffering from chronic renal failure, there are a number of internal and pharmacological peculiarities that the practitioner must be aware of. The physician should be able to recognize that, resulting from renal failure and due to an accumulation of urinary substances, in addition to fatigue, loss of appetite, and headache, a “foetor ex ore” can occur as a typical sign of uremia . Furthermore, surgeons should be aware of hemolysis resulting from uremia toxins (anemia), thrombopenia, or thrombocyte and leukocyte dysfunction in patients with CKD [17,18,19]. Further endocrine consequences of renal insufficiency entail normochromic, normocytic anemia due to erythropoietin deficiency as well as a change in bone metabolism (renal osteopathy) due to hyperphosphatemia and hypocalcemia in the absence of calcitriol, leading to secondary hyperparathyroidism with increased parathyroid hormone levels.
In this context, in their 2014 study, Henriques et al. were able to show that a change in bone metabolism due to chronic renal insufficiency can be detected in dental X-ray diagnostics in male patients with severe secondary hyperparathyroism (PTH levels of ≥ 500 pg/ml) and a dialysis period of at least three years . However, the influence of pathologic PTH levels < 500 pg/ml and a dialysis duration of less than three years remains unanswered, which means that further investigations in this area are necessary. Based on this data, the aim of the current study was to determine the diagnostic potential of dental X-ray diagnostics by means of panoramic radiographs also for patients with PTH levels < 500 pg/ml and a dialysis duration of less than 3 years.
To minimize the risk of misinterpretation of the generated data, strict inclusion and exclusion criteria were defined. The patient group was characterized by the confirmed diagnosis of SHPT within known chronic terminal renal failure and the requirement for dialysis. Due to the risk of including the effect of primary osteoporosis due to estrogen deficiency in postmenopausal women, only male patients were included in the data analysis. Patients who had parathyroid levels within or lower than the reference range (due to parathyroidectomy) despite confirmed SHPT at the time of presentation in our department were also not included in the data analysis.
When looking at the results of the present study, the panoramic radiograph represents a potentially suitable method to diagnose osseous changes resulting from secondary hyperparathyroidism. Especially for MCI and TBP statistically significant differences between the patient group and the control group could be detected.
However, significantly increasing cortical erosion in combination with a reduced TBP was expected to occur with increasing PTH levels, but not present in the patient collective. Nevertheless, it must be stated that the radiological findings/parameters do not perfectly correlate with the measured PTH levels, since the MCI and the TBP were not affected in the same way by pathologic PTH levels. Our data show that the cortical mandibular PTH-induced erosion is less pronounced than the change in the trabecular bone patterns. There was a positive and statistically significant correlation between PTH levels and the grade of TBP changes. The MCI changes did however not correlate with PTH. These results seem to be understandable, since the mineralization rate of the cortical bone is superior compared to the cancellous bone, whereby the “loosening” effect of the PTH is delayed noticeably in the cortical aspects. In this context, PTH levels of > 400 pg/ml seem to have a significant impact on the TBP.
Another unexpected effect was that the duration of the dialysis did not significantly correlate with MCI or the TBP, which speaks for the effective dialysis in combination with medication/substitution.
The evaluation of the absorption rate or ectopic calcification rate between the experimental and the control group also showed unexpected results. Here, Henriques et al. were able to show that patients with SHPT suffer significantly more frequently from absorption or mineralization disorders compared to healthy control patients . For this reason, we would also have expected an increased incidence of mineralization disorders in patients with SHPT. However, the statistical analysis showed no statistically significant difference between the control group and the dialyzing experimental group. Furthermore, within the dialyzing experimental group, no correlation between the levels of PTH and the frequency of mineralization disorders was found.
From a pathophysiological point of view and as mentioned before, SHPT leads to an imbalance of calcium and phosphate in the blood, resulting in changes to the mineral metabolism and mineral deposition in the form of tonsilloliths, calcified lymph nodes, or ossification of the styloid ligaments. However, we found that those patients with SHPT who had ossifications had this particularly pronounced. In some patients, the mineralization was so pronounced that it could be detected in the vessels as atherosclerosis (Fig. 3E), which as a cardiovascular disease represents the main cause of death in this population [20, 21]. With the radiological experience to recognize these findings in combination with the necessary internal medicine experience, dentists represent an essential aid to patient education and sensitization to prophylaxis to extend lifetime. Although in case of an accidental detection of atherosclerotic plaque in a cervical vessel direct prophylaxis is not completely possible by a dentist, the dentist could enter a new competence area which addresses raising the patient’s awareness of the potential disease as well as the initiation of further diagnostic (e.g., imaging diagnostics like ultrasound diagnostics) and therapeutic steps by consultation with a general practitioner.
As a possible study limitation, it must be mentioned that due to the selected inclusion and exclusion criteria the number of included patients (N = 41) is relatively low. Furthermore, it must be stated that the selected study design includes just one evaluation time point. The changes over time of the determination of mineralization of the mandible depending on changing renal function and the duration of dialysis would be interesting and could be the aim of further prospective studies.