Dentofacial parameters associated with the unilateral palatally impacted canine

Aims To investigate the relationship between unilateral PIC and specific dentofacial parameters. Materials and methods A sample of 216 subjects, with 108 subjects in the retrospective and prospective samples respectively. Dental parameters: The following dental parameters were assessed: Inter-canine and intermolar width; palatal depth and palatal area; anterior Bolton tooth-size discrepancy (TSD); maxillary arch shape and ratio and maxillary central and lateral incisor shape and ratio. Facial parameters: Three-dimensional (3D) images were taken for subjects in the prospective sample only, and were used to assess the following facial parameters: Face shape; face ratio and 3D distances and angles. Results Dental parameters: Inter-canine width was significantly smaller in the test group compared to the control group in the retrospective (p= 0.0002) and prospective (p= 0.0018) samples respectively. Anterior Bolton TSD was significantly higher in the prospective test group compared to controls (p= 0.0070). Arch ratio was significantly smaller in the test group than the control group for the retrospective sample (p= 0.0029), whereas no significant difference was recorded in the prospective sample (p= 0.1017). Arch shape distribution was significantly different in the retrospective sample (p= 0.009). Tooth shape distribution was significantly different for the maxillary right central incisor in the retrospective sample (p= 0.030). Tooth ratio showed no significant difference for both samples. Facial parameters: Basal width was significantly smaller in the test compared to the control group (p= 0.0001). No significant difference was found in all other 3D distances and angles measured. Conclusion Inter-canine width was significantly smaller in unilateral PIC subjects compared to controls. Anterior Bolton TSD was significantly higher in prospective unilateral PIC compared to controls. Maxillary arch ratio was significantly smaller in retrospective subjects. Square/tapered tooth shape was significantly more common in the retrospective group. Basal width was significantly smaller in subjects with unilateral PIC than controls.

Photonic packaging: transforming silicon photonic integrated circuits into photonic devices

Dedicated multi-project wafer (MPW) runs for photonic integrated circuits (PICs) from Si foundries mean that researchers and small-to-medium enterprises (SMEs) can now afford to design and fabricate Si photonic chips. While these bare Si-PICs are adequate for testing new device and circuit designs on a probe-station, they cannot be developed into prototype devices, or tested outside of the laboratory, without first packaging them into a durable module. Photonic packaging of PICs is significantly more challenging, and currently orders of magnitude more expensive, than electronic packaging, because it calls for robust micron-level alignment of optical components, precise real-time temperature control, and often a high degree of vertical and horizontal electrical integration. Photonic packaging is perhaps the most significant bottleneck in the development of commercially relevant integrated photonic devices. This article describes how the key optical, electrical, and thermal requirements of Si-PIC packaging can be met, and what further progress is needed before industrial scale-up can be achieved.