With no direct attachment of the posterior teeth, banding and bonding are carried out with the expander in place; as a result, leveling and alignment can be started while keeping the expander for the purpose of consolidating the expansion. It may be that the overall treatment time is shortened. One of the common problems of a tooth-anchored RPE is bite-opening effect due to the extrusion of the palatal cusps of the maxillary posterior teeth along with the buccal crown tipping. However, bone-anchored RPEs for open bite patients seem not to show much vertical change after the expansion because dentoalveolar tipping happens much less than tooth-borne RPE. For patients who have periodontal disease or very thin alveolar bones around the posterior teeth, bone-anchored RPE may be a good option for expanding the maxilla without compromising the periodontal health.

Recently there have been reports of successful nonsurgical maxillary expansion in adult patients [20–21]. However, SARPE is considered as the standard procedure to correct the narrow maxilla width in adult patients [22–23]. Typically a tooth-anchored expander is used in SARPE, but it has been shown that there may be periodontal complications as a result of stress on the anchoring teeth [24–28]. Bone-anchored expanders followed by Le Fort I surgery have been used, and they have produced successful results [24, 25, 29, 30–32]. Reportedly, the benefits of bone-anchored expanders for SARPE [11, 12, 27, 33–35] have proven to be a reliable and suitable technique for maxillary expansion without causing significant dental and periodontal damage [13, 36].

One study showed that nonsurgical maxillary expansion was achieved with hybrid expander in a young adult male patient [37]. According to the adult cadaver simulation with a tooth-anchored RPE, there was no sutural opening, but rather an unwanted rupture of the alveolar process or a tooth rupture through the alveolar bone [38]. In contrast, there was a successful separation of the intermaxillary suture, which was achieved in a bone-anchored RPE. A finite element model simulation shows that it needs a relatively low transverse force to open the intermaxillary suture with a bone-anchored RPE. A high tensile stress was concentrated only on the palatine suture, and the overall stress distribution on the remaining skull is almost negligible [39]. The bone-anchored RPE does not affect the position of the teeth, and the effect on the alveolar process is insignificant (Fig. 7.9). Lee et al. studied the stress distribution and the displacement of the maxilla and teeth according to the different designs of bone-anchored RPE [19]. According to their results, the acrylic-type design expanders with miniscrew implants placed at the palatal slope showed the palatal expansion without buccal inclination of the dentition (Fig. 7.10). Although there needs to be more studies done to prove this, a bone-anchored RPE without surgery may be a possible alternative to SARPE in certain cases, especially for young adults (Fig.7.11).