# The Effect of Different Socket Types on Implant Therapy While Using Flapless Ridge Preservation
## 1 Introduction  
Alveolar ridge resorption occurs rapidly during the first 6 months after extraction, resulting in aesthetic, phonetic, and functional problems, and complicates implant placement [1, 2]. Thin buccal plates undergo progressive bone resorption, even when a ridge preservation method is used [3, 4]. Although ridge preservation is useful for decreasing post-extraction alveolar ridge contraction, it cannot eliminate ridge resorption after tooth extraction [5, 6]. Ridges with damaged extraction socket walls benefit more from alveolar ridge preservation (ARP) than ridges with intact extraction sockets [7].  
Various methods are used in ARP, including closed (flapless procedure) and open (flap procedure) approaches [8, 9]. There is no significant histological difference between flapped and flapless groups; thus, the percentage of new bone, connective tissue, and residual bone graft is similar between these two groups [10]. However, more buccal bone resorption is found in extraction sockets with full-thickness flap elevation, which would disturb the surrounding periosteum [9, 11, 12, 13]. The flapless procedure is less traumatic and results in more keratinized tissue than the flap procedure [8, 9, 14]. Flapless ridge preservation is made possible either by rapid formation of a biological seal under a non-resorbable membrane or substitution of a resorbable barrier by a connective matrix [9, 10, 15]. Moreover, soft tissue grafts or primary closure did not provide beneficial effects in preserving alveolar bone in previous studies [16, 17, 18]. Therefore, a simplified flapless procedure is desirable for both patients and surgeons.  
A buccal wall thickness \(>\)1.0 mm in a socket has been reported to show better ridge preservation outcomes than achieved with a thinner buccal wall [5]. In a previous animal study, the final alveolar ridge profile of sockets with buccal plate destruction was more favorable after using flapless ridge preservation than after natural healing [19; 20; 21]. Additionally, in extraction sockets of maxillary anterior teeth with buccal plate dehiscence or with sockets of molars with deficient bone plates, flapless ridge preservation could minimize ridge resorption after tooth extraction and improve soft tissue outcomes [22; 23; 24; 25; 26]. Thus, buccal plate loss is a predictor of alveolar ridge-remodeling when flapless ridge preservation is used [27].  
Though there are a few studies that have focused on the association between ridge preservation and socket morphology [28; 29; 30], none have analyzed the relationship between dental implant treatment and flapless ridge preservation in the different socket types with distinct hard and soft tissue characteristics. We hypothesized that there would be differences in clinical parameters of implant therapy among the different socket types when flapless ridge preservation is used. Thus, the aim of this retrospective study was to compare the effects of the different extraction socket types on various parameters of dental implant therapy when flapless ridge preservation is used.