Primary and Post-Osseointegration Stability of Short (Ultra-Short) Implants on Edentulous Atrophied Distal Segments of the Mandible - An Indicator of Immediate or Delayed Load

Abstract

Introduction. The issue of determining the possibility of immediate or long-term load on the selected type of implants, which will ensure the predictable result of their long-term functionality, remains an ongoing discussion. The results of the resonance frequency analysis, which perfectly characterize the stability of short and ultrashort implants at all stages of their osseointegration and post-osseointegration periods, can serve as such an indicator basis. Aim. To analyze the primary and post-osseointegration stability of short (ultra-short) implants placed by the methods at the level of the cortical bone layer and subcortically in case of bone atrophy caused by acquired final dentition defects. Materials and methods. The primary and post-osseointegration stability of thirty-nine dental short (h = 6.5 mm X b = 4.0 mm – 20 pieces) and ultra-short (h = 5.5 mm X b = 4.0 mm – 19 pieces) implants placed on the edentulous distal segments of the human mandible was studied. According to the clinical assessment that met the aim and objectives of this study, all patients were divided into four study groups: the first group consisted of patients with a preserved dentition who did not require dental implantation; the second group – 25-45 years old, the third group – 46-60 years old, and the fourth group – ≥ 61 years old. Using the resonance frequency analysis (RFA) method by Penguin Instruments, the results were interpreted in declarative units of measurement – the implant stability quotient (ISQ). Results. The installed short (ultrashort) implants, according to the methodology by the level of the cortical layer of bone tissue, are characterized by their high primary stability by anti-rotational force: in the second group of the study (25-45 years old) with a mean number (M) of 87.0 and an error of the mean (± m) of ± 2.3 ISQ; in the third group (46-60 years old) – 76.4 ± 3.0 ISQ; in the fourth group (persons ≥ 61 years old) – 69.8 ± 4.8 ISQ. Low values of primary stability were obtained in implants installed by the subcortical implantation technique in the second age group of the study and amounted to 59.6 ± 2.7 ISQ with a slight increase to 66.0 ± 4.1 ISQ in the third group and 71.7 ± 4.2 ISQ in the fourth group of the study, which do not guarantee the prognosis of functional redistribution of the supra occlusion immediate load on the biological basis, with further preservation of the course of normal physiological processes in the bone tissue around the implanted implants. Conclusions. Rehabilitation of patients with bone atrophy caused by the loss of the masticatory group of teeth is possible using short (h = 6.5-6.0 mm) and ultra-short (h = 5.5 mm) implants, with clinical justification for the choice of methods of immediate or post-osseointegration load, with a detailed resonance frequency analysis as a priority and reliable method – an effective indicator of their stability, at all stages of clinical rehabilitation of patients.