Definition of a drilling protocol for mini dental implants in different bone qualities

Mandibular bone characteristics, drilling protocols, and final insertion torque for titanium-zirconium mini-implants for overdentures: A cross-sectional analysis

OBJECTIVE

The aim of this study was to assess the final insertion torque values achieved using site-specific drilling protocols for a novel mini implant system for removable complete overdentures. Anatomical and technical factors influencing final insertion torque were recorded and analyzed.

MATERIAL AND METHODS

Participants were randomized to two surgical protocol groups (flapped or flapless) and all received four mini implants (Straumann® mini implant system; Straumann AG) in the anterior mandible, using a 1.6 mm needle drill and a 2.2 mm pilot drill for the implant bed site preparation. The final insertion torque was recorded as the main outcome variable during surgery. Bone type, radiographical bone density, ridge form, implant length, and the drilling protocol were considered as independent variables. Descriptive statistics, generalized estimating equations (GEE) regression, and heatmap charts were used for data analyses.

RESULTS

A total of 296 mini implants were placed in 74 patients (mean age = 64.1 ± 8.0; 64.9% female) using flapless (n = 37) or flapped (n = 37) surgeries. Mean final insertion torque was 55.8 ± 18.4 Ncm (10.5% > 35 Ncm, 48.9% between 35 and 65 Ncm, and 40.6% > 65 Ncm). The needle drill was used in only 43.9% of the implant bed sites. Higher final torque values were observed for higher bone densities (bone type I > II > III, and D1-D2 > D3-D4), highly resorbed ridge forms (5-6 > 3-4), flapped surgeries, and male patients. However, regression models showed that the likelihood of achieving optimal insertion torque (≥35 and ≤65 Ncm) was higher for females (OR = 2.14; 95%CI = 1.14-4.01; p = 0.018), ridge forms 3-4 (OR = 2.87; 95%CI = 1.05-7.85; p = 0.040), and flapless surgeries (OR = 1.96; 95%CI = 1.09-3.51; p = 0.024).

CONCLUSIONS

Sufficient primary stability for immediate loading was achieved for the majority of the mini implants placed. Surgical implant bed preparation should be site-specific to achieve optimal primary stability for immediate loading while avoiding excessive insertion torque.

X-ray and anatomical features of the lower jaw alveolar cortical layer in children

INTRODUCTION

the world studies showed the interest in measurement of the buccal or anterior cortical plate thickness. Data indicate a significant superiority of the spongy substance over the compact one in the distal part of the jaw, which makes it possible to think about a higher effectiveness of transcortical injections. The empirical "rule of 10" provides for the choice of a method of anesthesia in children for primary teeth but demonstrates difficulties with high-quality anesthesia accompanied for permanent teeth. Therefore, the importance of clinical examination and anatomical investigation of the jaw cortical plate in children for competent planning of transcortical interventions has been determined.

AIM

To study the features of the clinical and X-ray anatomy of the cortical layer in distal alveolar part of the mandible in children.

MATERIAL AND METHODS

The assessment of the X-ray anatomical characteristics of the mandible was carried out according to 150 anonymized cone-beam computed tomograms of patients aged 6-12 years, performed for the treatment of major diseases. Qualitative assessment and examination of the cortical plate of the distal alveolar part of the mandible were carried out on the skeletonized certified preparations of aged 6-12 in the amount of 50.

RESULTS

The age characteristics of the cortical plate in the area of the chewing group of teeth in the mandible were determined according to macro anatomical studies, which confirms with the X-ray results. Therefore, the obtained images serve as actual confirmation of X-ray studies, which are ranked by age. The thickness of the cortical plate in the second primary molar of the mandible in subgroups 6, 7 and 8 years has a proportional increase from the cervical region to the apical projection. The average thickness of the cortical plate is 1.57mm at 6 years, 1.52mm at 7 years, 1.6mm at 8 years and 1.84 at 9 years. The cortical plate thickness in the first primary molar of the mandible in subgroups 6 and 7 years has a proportional decrease from the cervical region to the apical projection as well as an inverse proportion to age. The average thickness of the cortical plate is 1.33mm. In the first molar of the mandible at the age limit of 6-12 years the attention is drawn to the linear increase in tissue volume from the cervical region to the apical projection up to 8 years. At 6-8 years the average thickness of the cortical plate in this age group is 1.74±0.2mm, at 9 years - 2.03mm, at 10 - average value in the cervical region it is 1.53 ± 0.23mm, in the root middle it is 2.19± 0.13mm and in the apical projection it is 1.98± 0.16mm, at 11 - 2.22mm and at 12 - 2.35mm. For the second primary molar the average thickness of the buccal cortical plate of the second primary molar is 1.4mm in cervical part, 1.68mm in the root middle and 1.81mm in the apical projection. Finally, thickness of the buccal cortical plate in the cervical region of the first permanent molar is 2mm in groups.

CONCLUSION

The study makes it possible to determinate with noninvasive way the age limit for the least pronounced zone of the buccal cortical plate.