Cranial base and maxillary changes in patients treated with Frankel' s functional regulator (1b)

Abstract

Objectives: The purpose of this study was to assess cranial base and maxillary growth in patients with Class II-type I malocclusions when treated with Frankel' s functional regulator (FR-1b).

Study design: The treatment group was made up of 43 patients that were divided into two groups: prepubescent (n: 28), and pubescent (n: 15). The control group included 40 patients who did not receive any kind of treatment and were likewise divided into a prepubescent group (n: 19), and a pubescent group (n: 21). A computerized cephalometric study was carried out and superimpositions were done in order to assess the antero-posterior, vertical and rotational movement of the maxilla.

Results: The results indicate that anterior cranial length is not affected by the regulator but the cranial deflection of the treatment group was diminished. Although a slight counterclockwise rotation effect on the upper jaw was observed due to treatment, no growth restriction of the maxilla in a vertical or antero-posterior direction was observed compared to other non-treated Class II-type I malocclusion patients.

Conclusion: The functional regulator does not have any effect on anterior cranial length, but it does affect the angulation of the cranial base. According to our results, the appliance has demonstrated a flattening effect of the cranial base (p<0.05) in the treated sample. The functional regulator induces counterclockwise rotation rather than vertical or sagittal changes in the maxilla.

Figure 1

Cephalometric measurements used in this study. N(nasion), S(sella turcica), Ba(basion), Cf(pterygomaxillary), Po(porion), Or(suborbital), A(point A), ANS(anterior nasal spine), PNS(posterior nasal spine), Co(condylion).

Figure 2

Superimposition of the maxilla. Ba-N plane at Nasion point. Anterior cranial length(CC-N): distance between CC and nasion.; Cranial deflection(N-Ba/Po-Or): angle formed between the basion-nasion plane and the Frankfurt plane; SNA angle: angle formed by the sella turcica-nasion(S-N) and nasion-point A(N-A) planes; Maxillary depth(Po-Or/N-A): angle formed by the Frankfurt plane and the N-A plane; Distance from point A to the nasion perpendicular to Frankfurt (A-FHp): distance between point A and a line perpendicular to the Frankfurt plane (Po-Or) that descend from the nasion(N); Effective maxillary length(Co-A): distance from the highest and most posterior part of the condylion(Co) to the maximum concavity of the anterior maxillary outline(point A); Maxillary height: angle formed by the nasion-Cf and Cf-point A planes, where Cf is defined as the intersection of the pterygoid plane(PtV) and the Frankfurt plane; Slope of the palatal plane(Po-Or/ANS-PNS): angle formed by the Frankfurt plane and palatal plane; A: the maximum concavity of the anterior maxillary outline(point A); ANS: anterior nasal spine; PNS: posterior nasal spine; Pp: palatal plane.