Background Matrix metallopeptidase 20 (MMP20) is an evolutionarily conserved protease that is essential for processing enamel matrix proteins during dental enamel formation. MMP20 mutations cause human autosomal recessive pigmented hypomaturation‐type amelogenesis imperfecta (AI2A2; OMIM #612529). MMP20 is expressed in both odontoblasts and ameloblasts, but its function during dentinogenesis is unclear. Methods We characterized 10 AI kindreds with MMP20 defects, characterized human third molars and/or Mmp20 −/− mice by histology, Backscattered Scanning Electron Microscopy (bSEM), µCT, and nanohardness testing. Results We identified six novel MMP20 disease‐causing mutations. Four pathogenic variants were associated with exons encoding the MMP20 hemopexin‐like (PEX) domain, suggesting a necessary regulatory function. Mutant human enamel hardness was softest (13% of normal) midway between the dentinoenamel junction (DEJ) and the enamel surface. bSEM and µCT analyses of the third molars revealed reduced mineral density in both enamel and dentin. Dentin close to the DEJ showed an average hardness number 62%–69% of control. Characterization of Mmp20 −/− mouse dentin revealed a significant reduction in dentin thickness and mineral density and a transient increase in predentin thickness, indicating disturbances in dentin matrix secretion and mineralization. Conclusion These results expand the spectrum of MMP20 disease‐causing mutations and provide the first evidence for MMP20 function during dentin formation.

This paper presents a technique for reconstructing a high-quality high dynamic range (HDR) image from a set of differently exposed and possibly blurred images taken with a hand-held camera. Recovering an HDR image from differently exposed photographs has become very popular. However, it often requires a tripod to keep the camera still when taking photographs of different exposures. To ease the process, it is often preferred to use a hand-held camera. This, however, leads to two problems, misaligned photographs and blurred long-exposed photographs. To overcome these problems, this paper adapts an alignment method and proposes a method for HDR reconstruction from possibly blurred images. We use Bayesian framework to formulate the problem and apply a maximumlikelihood approach to iteratively perform blur kernel estimation, HDR image reconstruction and camera curve recovery. When convergence, we simultaneously obtain an HDR image with rich and clear structures, the camera response curve and blur kernels. To show the effectiveness of our method, we test our method on both synthetic and real photographs. The proposed method compares favorably to two other related methods in the experiments.

Lithium disilicate, a reinforced pressable glass ceramic, is a popular option for large-defect restoration owing to its esthetic feature and promising strength [1,2]. Ceramic cementation is a critical issue for achieving restoration longevity [3]. Features such as the degree of conversion, mechanical properties, bond strength, working time, shade stability, restorative thickness, and retention form design are criteria for cement selection consideration [4][5][6][7]. A higher degree of conversion (DC) ensures lower solubility of cement and results in restoration with less marginal discrepancy [8]. Dual-cured resin ce-ment is thought to be the first choice for ceramic restoration to avoid insufficient polymerization of the resin cement because of its chemical polymerization constituent [9], which allows more time to remove excess cement before hardening. Recently, more practitioners and studies have used purely light-cured resin composites as luting cement to achieve stronger mechanical properties, higher micro-tensile bond strength, longer working time, easier handling for excess control, higher shade stability, and greater marginal integrity [9][10][11][12]. Some scholars have even used preheated light-cured packable composite restorative materials, mainly to reduce the film thickness and increase the flowability to act as a luting cement [13][14][15]. However, most of these studies have used light-cured conventional resin composites. Light transmittance through the restoration may cause insufficient polymerization, leading to unpredictable outcomes. The light transmission rate is affected by the thickness, translucency, and color of the restoration. When the light transmittance decreases, less light intensity reaches the cement layer, possibly causing an uncured J Prosthodont Res. 2023; **(**):

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Advances in adhesive dentistry have led to increased use of indirect restorations. In some situations, indirect composite techniques are more advantageous than direct composite filling techniques, such as establishing proper occlusal and interproximal anatomy, reducing polymerization shrinkage stress, and promoting the degree of conversion. This article presents a case about restoring the lower right first molar with extensive loss of tooth structure by the composite onlay to achieve a proper anatomic form and rehabilitate chewing function. This one-year clinical case encourages clinicians to manage large decay of posterior tooth conservatively. The given functional and esthetic outcomes demonstrate the promising applicability of the indirect composite technique.