N L Y A L S O N F E S SI O O R T A L P N E D PUBLISHED IN DUBAI www.dental-tribune.me November-December 2020 | No. 6, Vol. 10 CBCT bone-densitometry for pre-surgical decision-making By Prof. Angelo Trödhan, Austria Introduction The high prevalence of tooth-related diseases, a growing geriatric popula- tion and a rapidly growing aware- ness to replace lost teeth by dental implants force dentists, oral and maxillofacial surgeons to cope with promises made by implant manu- facturers such as “new teeth in one hour”. While implant manufactur- ers try to maximise their sales num- bers by such marketing strategies, it will always be the practitioner’s full responsibility to treat patients with strictly evidence-based treatment protocols, especially when it comes to the immediate functional loading of dental implants. Esposito et al. (2007), Javed et al. (2010), Walker et al. (2011) and Can- nizzaro et al. (2012) proved in re- views, Cochrane studies and split- mouth randomised clinical trials that primary implant stability—rep- resented by insertion torque values (ITV)—shows a significant correla- tion between the biomechanical quality of bone and the risk of imme- diate and long-term implant failure when implants are loaded function- ally at time of insertion.1–4 Further- more, experimental and clinical studies published by Turkyilmaz et al. (2007), Pommer et al. (2014) and Wada et al. (2016) proved a signifi- cant correlation between primary implant stability measured by ITV and computerised axial tomography (CAT) scan-based bone densitometry in native alveolar bone.5–7 Since alveolar bone loss caused by natural atrophy or destructive iatro- genic procedures at the time of tooth extraction demands immediate (“al- veolar ridge preservation”) or later (“guided bone regeneration”) bone augmentation procedures, Di Lallo et al. (2014) and Troedhan et al. (2014) in randomised clinical studies found a significant difference of primary implant stability when augmented alveolar bone was compared with native alveolar bone.8,9 Recently, a randomised clinical study was per- formed by Troedhan et al. (2019) to investigate if a significant correlation between pre-surgical cone-beam computed (CBCT) bone densitometry performed with X-Mind trium CBCT (ACTEON) and primary implant stability in aug- mented sinus sites could be proven. tomography Study design A randomised clinical study was conducted on 128 patients. 101 pa- tients with less than 4mm subantral crest- height underwent a uni- or bilateral transcrestal hydrodynamic ultrasound Piezotome sinus lift (IN- TRALIFT) with four different and ran- domly allocated bone graft materials (mono- or biphasic mouldable and self-hardening biomaterial, granu- lar synthetic and xenogeneic bone substitute) in 114 INTRALIFT sites. The transcrestal Piezotome INTRAL- IFT provides the least risk of mem- brane-perforations and has proven to detach the periosteum of the sinus membrane cleanly from the bony base of the antrum, thus pre- venting biases of the study already at the stage of the surgery. The clean detachment of the periosteum from the bone base does not interfere with the regular bone regeneration in the subantral scaffold by dissection or lacerations of the periosteal layer of the sinus membrane, which carries the pre-osteoblast cell layer.10–15 Figure 1 shows a split-mouth case with a bilateral INTRALIFT proce- dure: after a small crestal “booklet”- flap of approx. 7x7mm is detached, the sinus floor is safely opened with ultrasound Piezotome tips (Figs. 2 & 3), the sinus membrane then de- tached by the hydrodynamic cavi- tation effect of the Piezotome-tip TKW5 plugged into the approach canal (Figs. 4 & 5) and the subantral scaffold filled with 2cm of randomly assigned biomaterial (Figs. 6 & 7), followed by wound closure (Fig. 8). After a mean healing period of 8,4 months X-Mind trium CBCT scans were performed, the digital setup of the future bridge constructed with the AIS 3D app and the bone density determined in the sinus-lift site around a virtual implant (Fig. 9). Standardised implants (4mm in diameter and 12mm in length) were then inserted in the position of the virtual implant and insertion torque values (ITV) measured intra-surgical- ly (test groups; Fig. 10). A total of 27 patients with sufficient native sub- antral crestal bone (min. crest width: 6 mm, height: 12 mm) were screened by X-Mind trium CBCT for bone den- sity with the virtual implant (Fig. 11), the standardised implant inserted and the ITV recorded (control group). Figure 12 depicts the final result after implant insertion in the patient case shown in Figures 1–9. Study outcomes As can be seen in Fig. 13, the mean CBCT bone density values in Houns- field units (HU) at the implant site differed significantly (p <0.05) be- tween all four test groups and the control group. The precise numeri- cal HU values are “translated” by AIS 3D app software and are also colour-coded for easier interpreta- tion at first glance: the brighter the green the CBCT voxel matrix shows around the virtual implant, the high- er the bone density, with a virtual neutral threshold of 500 HU. Contra- ry, the more reddish the CBCT voxel matrix around the digital implant is Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 ÿPage C2 Fig. 8 Fig. 9