Implant placement in the posterior maxilla is often challenged by reduced bone height and low bone density due to alveolar resorption and sinus pneumatization after tooth loss [1]. In such cases, sinus floor elevation is required to enable implant rehabilitation [2].

The transcrestal (indirect) sinus lift approach is a minimally invasive technique indicated when residual bone height is moderate, allowing simultaneous implant placement while reducing surgical morbidity and treatment time [3]. When combined with bone grafting and implants designed for soft bone, this approach supports predictable primary stability and successful osseointegration [4].

A 47-year-old male patient attended our clinic requesting evaluation for the replacement of a missing molar. The patient reported that the tooth had previously undergone root canal treatment and subsequently fractured, leading to its extraction eight years earlier.

From a general medical perspective, the patient was healthy, with no relevant systemic diseases. Oral hygiene was adequate, and both plaque and bleeding indices were within normal limits, so no complementary periodontal or hygiene treatment was required before implant therapy.

A clinical intraoral examination was performed. The restorative space remained stable, with no displacement or mobility of the adjacent teeth and no extrusion of the opposing dentition.

A CBCT scan was taken to assess the available bone height and width. The missing tooth was in a subsinusal position (16), with marked resorption of the alveolar crest and pneumatization of the right maxillary sinus (Fig 1).  

After radiological evaluation and digital planning in CoDiagnostix software (Fig 2a-c), the treatment plan consisted of placing a dental implant combined with an atraumatic transcrestal sinus floor elevation and simultaneous transcrestal grafting.

An Anthogyr Axiom® X3S 4.6/8 mm implant (AT46080) was selected for this case. The reason for choosing this implant was the low bone density observed in the posterior maxilla. The macro design of the Axiom® X3S provides apical engagement through its active apical threads, while its parallel body walls and specific implant channels allow bone compaction within the implant bed. The non-cutting edges of these channels are designed to condense rather than remove bone, helping to improve primary stability in low-density bone.

The implant was placed using a two-stage surgical approach with submerged healing. The surgical protocol consisted of step-by-step drilling with drill stops up to 6 mm (Fig 3a-c), followed by transcrestal sinus floor elevation using osteotomes according to the Summers technique. XenoOss Plus xenograft material was introduced through the implant bed to achieve and stabilize the elevation of the sinus membrane, creating a grafted area between the implant apex and the elevated Schneiderian membrane, as described in the Summers technique (Fig 3d).

After an osseointegration period of four months, a minimal crestal incision was performed to place a healing abutment, reference OPHSF620, to condition the peri-implant soft tissues before the prosthetic phase (Fig 8-11).

After 15 days of soft tissue healing, an intraoral scan was carried out using the Straumann SIRIOS X3 scanner with the crown and bridge protocol. First, the upper and lower arches were scanned, together with the occlusal relationship, while maintaining the healing abutment in position in the upper arch.

The area corresponding to the healing abutment was then identified and digitally trimmed from the scan. The healing abutment was removed, and the peri-implant soft tissue was scanned in high definition to accurately capture the emergence profile. A 152-27-MDT scanbody was then placed and scanned.

Once the file had been processed by the SIRIOS software, the case was transferred directly to the MIDAS Smart Design system. The scanbody was identified, and a titanium base was selected, as the final restoration was planned as a cement-retained crown on an X-Base®.

The selected X-Base® was the OPFLEX 414, with a 4 mm emergence profile and a 1.5 mm height. Following the digital design steps in MIDAS, the definitive crown was designed. A Crown Permanent A3 cartridge was then selected and inserted into the MIDAS printer.

The crown was 3D printed according to the manufacturer’s protocol, followed by the corresponding post-processing, curing and characterization procedures. Subsequently, the X-Base® was cemented extraorally to the crown. The margins were carefully polished and inspected to ensure that no residual cement remained.

Finally, the restoration was placed intraorally, the screw access was managed according to the clinical protocol, and the occlusion was checked and adjusted to achieve a stable and functional result.