The implant placement at the edentulous upper jaw is often challenging because of the poor bone quality and quantity; especially when maxillary sinus pneumatization occurs, the design of the surgery will be harder than usual (Velasco-Torres et al. 2017). In 2008, Bedrossian et al. described the three zones of maxilla (Bedrossian et al. 2008): The maxillary anterior teeth are considered as zone 1, and the premolar region is designated as zone 2, while the molar region is designated as zone 3 (Fig. 1). It is a useful classification, which can guide the implant design. In this article, we focus on the case when only zone 1 is present.
For a fully implant-supported immediate restoration, enough bone at zone 2 is always considered as a necessary condition. To achieve a satisfying result, different therapeutic alternatives have been proposed, such as long distal cantilevers and short implants; however, the long-term effects of these treatment effects are inevitable.
The long-term effects of tooth loss and the use of complete dentures make it difficult to place implants for edentulous patients. Here are three solutions for immediate restoration when zone 2 is extremely defected: bone grafting, zygomatic implant and pterygoid implant.
For bone grafts, maxillary sinus floor elevation through crestal or lateral approach can lead to a good result. It is a pretty proven technology, but in the situation of extremely defected maxillary zone 2, it cannot repair the prosthesis immediately. For edentulous patients, it is important to repair the occlusion immediately. The absence of tooth not only impairs their eating, but also affects their appearance.
The use of zygomatic implants to support dental prostheses was first reported by Branemark in 1988. For severely atrophic maxillary arch like extreme defect in zone 2, the treatment with two zygomatic and two standard fixtures to support an immediate fixed prosthesis could be considered as a viable treatment method (Agliardi et al. 2017). In general, zygomatic implants were used in Cawood class V or VI, or zone 1 lack of enough bone height. Many researches have shown the complications like biologic complication, maxillary sinus infections, peri-implant pathology, etc. These methods are time-consuming and increase the pain and financial burden of patients. Besides, there are some better options to solve the problem of native bone. So if there is a chance to avoid it, it is better to choose another way.
As well as zygomatic implant, pterygoid implant is an alternative option for the patient with atrophic maxilla like Class IV and V of Cawood. Because of the poor vision of the posterior of maxillae, it is difficult to drill a suitable implant bed for pterygoid implant. Rodríguez Xavier calculated the mean position of the pterygomaxillary buttress axis, which was 72.5 ± 4.9 degrees to the distal direction and 81.3 ± 2.8 degrees to the palatal direction relative to Frank-fort plane (Rodriguez et al. 2014). To reach the pterygoid plate, most studies suggested placing an implant at least 13 mm length. In the study of Thomas J., they suggested that increased implant length may be beneficial to the osseointegration, and more cortical bone context with the implant increases primary and secondary stability (Balshi et al. 2013). The length and the special angle of the implant make the surgery difficult; also, because of the poor visibility of anatomy site, the implant placement is precarious, and the implant may fall into the sinus and cause the medical negligence (Anandakrishna and Rao 2012). Thus, the pterygoid implant needs highly experienced doctors.
Many researchers (Bidra et al. 2013; Panagos and Hirsch 2009) reported the use of pterygoid or pterygomaxillary implants in patients undergoing bilateral maxillectomy; in some way, it is a rescue solution for the patients who have almost all the maxillary defected. It has its own advantages, such as good ability to acquire initial stability and osseointegration (Yates et al. 2014). From a surgical point of view, the zygomatic and pterygoid implants need advanced surgical skills, which limits its application. Thus, we adopted a new method, which could simplify the course of operation and fix the prosthesis immediately.
When the patient is young at 50 s, 6 implants for the edentulous maxillary are safer because it can provide a stronger occlusal force. Once we decided to drill 6 implants, an intractable problem came up that the severe atrophy maxilla cannot provide enough height (always need at least 10 mm after bone reduction) for the implants. The use of tilted implant is an ideal solution. Many researches have proved that the angulation of dental implants does not affect the survival rate nor lead to the marginal bone loss (Chrcanovic et al. 2015; Del et al. 2012). Tiziano Testori reported a technology which got an encouraging result that used a trans-sinus implant and inserted a xenograft to repair an edentulous upper jaw (Testori et al. 2013). It proved that in zone 2, using tilted implants may be a valuable attempt.
VIIV technique was presented in 2008, using four tilted implants and two axially implants to support an immediately full-arch fixed prosthesis without bone grafting procedure. According to the research, cumulative implant survival rate, marginal bone level, esthetic and patient’s satisfaction evaluation are considered excellent (Agliardi et al. 2008).
As for severe maxillary atrophy, it is difficult to design the position of the implants. The most important factor to consider when establishing the primary stability is the quality and quantity of cortical bone of retentive bone, such as pterygoid plate and maxillary tuberosity. In this article, implants extruded the cortical bone of the anterior wall of the maxillary sinus to obtain a good initial stability. The surgery design avoids bone graft and thus reduces the injury and total treatment time. Most importantly, enough torque makes immediately loaded fixed full arch possible. This technique is a highly predictable treatment option for edentulism, and the clinical results are satisfactory, practical and worth spreading. At present, few cases of extruding the cortical bone of the anterior wall of the maxillary sinus have been reported. This study reported a case that an edentulous patient was treated with this new technique and presented a new method when zone 2 is extremely defected.