63 Maxillary implant overdentures: four or two implants Masticatory performance The mixing ability test (MAT) was used to objectively measure the participants’ mastication. This test entailed each participant chewing on a prefabricated paraffine wax tablet with a red and blue layer for 20 strokes, which gradually decreased the spread of the blue and red colour intensities. After this, the tablet was heated to 28°C and compressed using a hydraulic hand press at 50 bar resulting in a wax plate with a spread of blue and red colours and a thickness of 2.0 mm. Both sides of the plate were then optically scanned using a high quality scanner (Epson V750, Long Beach, California, USA)18. The image was then analysed using a computer software (Adobe Photoshop CS3; Adobe, San Jose, California, USA) by obtaining the intensity distributions of the red and blue colours in the combined images, which correspond with the mixing ability index (MAI)19. The MAI ranges from 30 (badly mixed) to 5 (a theoretically perfect mix). Patient related outcome measures The PROMs were assessed using three validated questionnaires on subjective chewing ability (Chewing ability questionnaire (CAQ)), denture complaints (Denture complaints questionnaire (DCQ)), and oral health quality of life (Oral Health Impact Profile questionnaire (OHIP-NL49)). The CAQ consists of questions rating the chewing ability of nine different foods on a threepoint scale, e.g., good, moderate, or bad20. The foods were divided into three categories, e.g., soft foods (boiled vegetables, crustless bread, minced meat), tough foods (crusty bread, steak, Gouda cheese), and hard foods (apple, carrot, peanuts), each scored within a maximum score of 6. The DCQ uses a four-point scale, ranging from 0 (no complaints) to 3 (severe complaints) and a 10-point scale rating overall denture satisfaction, ranging from 1 (very bad) to 10 (excellent)21. The DCQ rates the participants denture complaints by means of 54 questions, divided into six categories, e.g. functional problems of the upper denture (max. score: 27), general functional complaints (max. score 54), denture aesthetics (max. score: 36), facial aesthetics (max. score: 9), and accidental lip, cheek, and tongue biting (‘neutral space’; max. score: 9). The OHIP-49NL uses a five-point scale, ranging from 0 (never) to 4 (very often). The OHIP-49NL questionnaire consists of 49 questions, divided into seven categories, e.g., functional limitation (max. score: 36), physical pain (max. score: 36), psychological discomfort (max. score: 20), physical disability (max. score: 36), psychological disability (max. score: 24), social disability (max. score: 20) and handicap (max. score: 24)22. Complications Complications were scored throughout the entire follow-up period (i.e. post-operative complications, denture fractures, relining, attachment repairs, and denture adaptation because of pressure ulcers. Sample size estimation The sample size was calculated using a computer software23. An inter-group difference of 0.5mm±0.6mm was estimated as clinically relevant for the mean marginal bone level change. Using alpha = 0.05 and power = 0.85, the sample size for between group comparison was calcu4
RkJQdWJsaXNoZXIy MTk4NDMw