**2. Role of SLActive surface in dental implant treatment**

SLActive dental implant surface (Institute Sraumann® AG, Basel, CH) is a hydrophilic with a sandblasted and acid-etched topography and was created as an aspiration to combine the for successfully osseointegrated dental implants have been reported (−9 to +9; −5 to +5; −7 to

Another important clinical parameter that reflects condition at implant–bone interface is change in crestal bone level. It is recommended to follow this parameter on retroalveolar radiographs obtained via long cone technique. This technique uses film holder that allows repeatability of tube orientation (**Figure 3**). Image analysis software is used for precise measurement of digitized radiographs following their calibration (**Figure 4**). Implant is considered successful with an crestal bone loss of 1.5 mm following 1 year of loading and

**Figure 3.** Obtaining radiographs using long cone technique. A plastic ring, connected to the film holder provided con‐

SLActive dental implant surface (Institute Sraumann® AG, Basel, CH) is a hydrophilic with a sandblasted and acid-etched topography and was created as an aspiration to combine the

0; −4 to −2; −4 to +2) [24–27].

134 Dental Implantology and Biomaterial

subsequent loss of 0.2 per year [28].

trol of tube orientation.

**Figure 4.** Image analysis software for crestal bone loss measurement.

**2. Role of SLActive surface in dental implant treatment**

advantages of surface roughness and hydrophilicity on implant osseointegration [14, 29]. This new surface is produced from the same cpTi alloy and subjected to the same roughening treatment with large grit size (250–500 μm) corundum sandblasting plus acid etching (H2SO4/ HCl) as its predecessor SLA surface [30]. The only difference from its unmodified counterpart is that following acid-etching hydrophilic SLActive implant is rinsed under nitrogen protec‐ tion and then stored in a sealed glass tube containing isotonic NaCl solution [29]. Such chemical modification provides hydrophilization of surface that is initially hydrophobic due to the microroughness, causing the air to be entrapped in the micropores, thus aggravating surface wetting [29]. Storage in NaCl solution allows prewetting of micropores and consequently faster wetting of implant surface [30]. CA of 0° designates SLActive dental implant surface as superhydrophilic in contrast to hydrophobic SLA surface with CA of 139.9° [9, 29, 30]. Another reason for reduced hydrophilicity of Ti implants is contamination due to air exposure [29]. However, cleaning under nitrogen protection and storage in NaCl solution prevents the adsorption of potential contaminants from the atmosphere onto the SLActive surface which is proven by the decreased carbon concentration [29, 30]. SLActive surface keeps hydrophilicity even after any drying which is important from a clinical point [29].

Another possible reason for improved biological response to SLActive surface compared with its unmodified counterpart SLA is the difference in microtopography and nanoroughness [31]. Although both surfaces have similar Sa value (1.78 and 1.75 μm for the SLA and SLActive, respectively), the SLActive surface has Sdr of 143% that is greater than Sdr of 97% for SLA. This difference indicates that SLActive has a much greater number of peaks/valleys across the surface compared with SLA [31, 32]. SLActive surface also exhibits nano-features with Sa value of 97 nm at the nanometer resolution level [31].

Biological effect of aforementioned improvements of SLActive implant surface comprises of enhanced osteoblastic differentiation [33, 34], improved angiogenesis [35] and reduced local inflammation and its associated osteoclastogenesis [36]. These cellular events provides stronger bone formation around SLActive implants compared with SLA during the early healing phase, particularly between the second and fourth weeks, while the difference disappears after the first 6 weeks [37]. Such features of SLActive implant surface indicate its possible clinical relevance in cases when faster implant loading is needed or when enhanced bone formation is desirable as in osteoporotic or irradiated bone and in diabetic patients.

Contemporary improvement of dental implant surfaces has allowed shift from a conventional loading protocol providing 3–6 months of undisturbed healing toward immediate (within 1 week) or early loading (between 1 week and 2 months) in selected patients when sufficient primary implant stability could be achieved [38, 39]. Clinical and radiographic outcomes of SLA and SLActive dental implants submitted to immediate or early occlusal loading is comparable to those of implants submitted to conventional loading protocols (3–6 months) [40]. SLActive implants loaded at 3 weeks after placement have survival rate of 95–98% following 1–3 years after placement [41, 42]. Hydrophilic and nanostructured SLActive implants are safe and predictable for immediate and early loading even in poor-quality bone [43, 44]. Early loaded SLA and SLActive implants achieves similar short- and long-term survival rates, although SLActive implants have better stability and a reduced marginal bone loss at the loading stage [40, 45].

As much as 97.3% of SLActive implants placed in low-density bone achieves implant stability of at least 60–65 ISQ required for immediate or early implant loading (**Figure 5**) [23, 46]. The stability dip in the second postoperative week indicates that afterward, formative processes predominated over the resorptive one within bone remodeling. This result suggests that nanostructured and hydrophilic SLActive implant surface promotes enhanced bone formation during the early stage of osseointegration. It is important that even in this critical time point stability values did not fall below the threshold for early loading. Afterward, implant stability steadily increases over time.

**Figure 5.** Stability of SLActive dental implants placed into low-density bone. Line represents mean, error bars repre‐ sent 95% CI of mean. Asterisks indicate a statistically significant difference between two-consecutive weeks, whereas crosses indicate a statistically significant difference to baseline (implant placement) [46].

SLActive dental implants placed in low-density bone and early loaded (at week 6) are associated with mean bone loss of −0.4 1 ± 0.1 mm after 1 year that is in accordance with the acceptable 1 mm bone loss during the first year (**Figure 6**) [46]. These data suggest that SLActive dental implants predictably achieve and maintain successful tissue integration in low-density bone after undergoing an early loading protocol.

survival rates, although SLActive implants have better stability and a reduced marginal bone

As much as 97.3% of SLActive implants placed in low-density bone achieves implant stability of at least 60–65 ISQ required for immediate or early implant loading (**Figure 5**) [23, 46]. The stability dip in the second postoperative week indicates that afterward, formative processes predominated over the resorptive one within bone remodeling. This result suggests that nanostructured and hydrophilic SLActive implant surface promotes enhanced bone formation during the early stage of osseointegration. It is important that even in this critical time point stability values did not fall below the threshold for early loading. Afterward, implant stability

**Figure 5.** Stability of SLActive dental implants placed into low-density bone. Line represents mean, error bars repre‐ sent 95% CI of mean. Asterisks indicate a statistically significant difference between two-consecutive weeks, whereas

SLActive dental implants placed in low-density bone and early loaded (at week 6) are associated with mean bone loss of −0.4 1 ± 0.1 mm after 1 year that is in accordance with the

crosses indicate a statistically significant difference to baseline (implant placement) [46].

loss at the loading stage [40, 45].

136 Dental Implantology and Biomaterial

steadily increases over time.

**Figure 6.** Frequency analysis of peri-implant bone level around early loaded SLActive dental implants in low-density bone.

Placement of implants into posterior maxillary region is often compromised by the bone resorption pattern, and pneumatization of the maxillary sinus beside the low-density bone present at this jaw region. Therefore, in such cases, sinus elevation is necessary to accommodate implants of sufficient length. Residual bone height determines surgical technique for sinus lift as well as whether implants can be placed simultaneously with sinus lift procedure or in the second stage [47]. When limited elevation of the sinus mucosa is required, this can be achieved through an implant bed using osteotomes, a technique known as osteotome sinus floor elevation and implant can be placed simultaneously [48]. The healing time prior to loading of implants inserted following sinus floor elevation is usually longer than the loading time required for implants inserted in bone of sufficient quantity [49]. Reduction of the healing time in atrophic posterior maxilla with low-density bone is particularly challenging due to reduced bone to implant contact and doubtful implant stability.

Around 95% of SLActive implants placed in the posterior maxilla via the osteotome sinus floor elevation technique without grafting achieves stability sufficient for early loading, in the sixth week of healing (**Table 1**). Favorable mid-term success rate indicates that implants with a sandblasted large-grit acid-etched active surface, when placed with the osteotome sinus floor elevation technique, can be subjected to an early loading protocol, providing their stability is confirmed by RFA [50].


**Table 1.** Stability of SLActive implants placed via OSFE.

Density of bone at implant site affects implant stability. SLActive implants placed in the region of the second and the first premolar have comparable stability but their stability is significantly higher than implants inserted in the region of the first molar (**Figure 7**). Implant stability positively correlates with residual bone height (**Figure 8**) [50].

**Figure 7.** Stability of SLActive implants placed via OSFE regarding the jaw region.

**Figure 8.** Comparison of implant stability with initial residual bone height.

Grafting material is not a prerequisite for the osseointegration of dental implants with hydrophilic and nanostructured SLActive surface placed via OSFE procedure. The usage of grafting material offers no significant advantage to stability or clinical success of dental implants placed simultaneously with OSFE (**Figure 9**) [51].

**ISQ Time**

positively correlates with residual bone height (**Figure 8**) [50].

**Figure 7.** Stability of SLActive implants placed via OSFE regarding the jaw region.

**Figure 8.** Comparison of implant stability with initial residual bone height.

**Table 1.** Stability of SLActive implants placed via OSFE.

138 Dental Implantology and Biomaterial

**Placement 1 week 2 weeks 3 weeks 4 weeks 5 weeks 6 weeks**

Minimum 47 48 52 57 60 63 64 Maximum 75 74 75 75 77 77 78

Mean ± SD 59.55 ± 7.06 61.12 ± 6.34 62.23 ± 5.53 63.75 ± 4.56 65.88 ± 3.64 66.80 ± 3.03 67.75 ± 3.06

Density of bone at implant site affects implant stability. SLActive implants placed in the region of the second and the first premolar have comparable stability but their stability is significantly higher than implants inserted in the region of the first molar (**Figure 7**). Implant stability

**Figure 9.** Stability of SLActive implants placed via OSFE regarding the usage of grafting material.

In atrophic maxillary ridges which require substantial raise of the sinus membrane implant placement using lateral sinus lift is mandatory. Eighty-three percent of SLActive implants placed simultaneously with lateral sinus lift and a mixture of autogenous bone chips and deproteinized bovine bone mineral reach the threshold stability after 8 weeks of healing, allowing an early loading protocol. This treatment protocol is associated with low early failure rate of 0.9% [52].

Another challenging indication that requires stronger bone response is implant placement into irradiated jaw. Radiation therapy causes endarteritis leading to hypoxia, hypovascularity, and hypocellularity that might jeopardize dental implant osseointegration [53]. Long-term survival rate of implants placed in irradiated jaws is 69–78%, and it is influenced by the jaw region, irradited dose, and surface roughness [54–56]. Roughened dental implants have 2.9 times reduced risk for failure in irradiated jaws compared with turned implants [54]. Sandblasted acid-etched implants with or without a chemically modified surface can be used in irradiated patients with a high predictability of success. The overall cumulative 5-year survival rates of SLA and SLActive implants in irradiated jaws are similar and the crestal bone level around both implant surfaces remains stable at least 5 years after placement. Hydrophilic surface might affect only early survival of dental implant placed in irradiated bone [57].

Microangiopathies and hyperglycemia associated with diabetes mellitus impaires bone regeneration and might affect early implant failure rates in such patients. Diabetic patients with glycated hemoglobin above 8.0% have delayed implant osseointegration and require a longer healing time [58, 59]. Despite the promising result of animal research that SLActive surface provides accelerated osseointegration of dental implants and better prognosis for implant treatment in diabetic patients, clinical assessment revealed similar outcomes for SLActive and SLA surfaces [60, 61].
