Dental microwear texture gradients in guinea pigs reveal that material properties of the diet affect chewing behaviour

Dental microwear texture analysis (DMTA) is widely used for diet inferences in extant and extinct vertebrates. Often, a reference tooth position is analysed in extant specimens, while isolated teeth are lumped together in fossil datasets. It is therefore important to test whether DMT is tooth position specific, and if so, what the causes for wear differences are. Here we present results from controlled feeding experiments with 72 guinea pigs, which either received fresh or dried natural plant diets of different phytolith content (lucerne, grass, bamboo), or pelleted diets with and without mineral abrasives (frequently encountered by herbivorous mammals in natural habitats). We test for gradients in dental microwear texture along the upper cheek tooth row. Regardless of abrasive content, pelleted diets display an increase in surface roughness along the tooth row, indicating that posterior tooth positions experience more wear compared to anterior teeth. Guinea pigs feedings on plants of low phytolith content and low abrasiveness (fresh and dry lucerne, fresh grass) show almost no DMT differences between tooth positions, while individuals feeding on more abrasive plants (dry grass, fresh and dry bamboo) show a gradient of decreasing surface roughness along the tooth row. We suggest that plant feeding involves continuous intake and comminution by grinding, resulting in posterior tooth positions mainly processing food already partly comminuted and moistened. Pelleted diets require crushing, which exerts higher loads, especially on posterior tooth positions, where bite forces are highest. These differences in chewing behaviour result in opposing wear gradients for plant versus pelleted diets.

Conserving a tooth in esthetic way - A case report

Esthetic treatment is the main concern for everyone in today’s world. Clinicians are in search of a durable and tooth colored restorative material. All ceramics with high strength are better alternative to composite, amalgam and gold for posterior tooth restoration. Tooth-colored restorations made from composite resin or ceramic has solved many of the esthetic concerns. This case report presented a durable and more conservative esthetic treatment for a broken tooth with bruxZir inlay.

A retrospective cohort study of how alveolar ridge preservation affects the need of alveolar ridge augmentation at posterior tooth implant sites

Objectives The aim of this study was to assess whether alveolar ridge preservation (ARP) can reduce the need of ridge augmentation at posterior tooth sites. Material and methods This study enrolled patients who received dental implants at posterior tooth sites during 2013–2019. Demographic data and dental treatment histories were collected. Based on healing patterns after tooth extraction, patients were divided into ARP and spontaneous healing (SH) groups. Three surgical treatment plans were devised according to the alveolar bone volume on cone-beam computed tomography (CBCT). The three treatment plans were to perform implant alone, simultaneous guided bone regeneration (GBR) and implantation, and staged GBR before implantation. Statistical analyses were performed to determine relationships. Results There were 92 implant records in the ARP group and 249 implant records in the SH group. A significant intergroup difference was observed regarding the frequency distribution of the treatment modality of staged GBR before implant (χ2 = 15.07, p = 0.0005). Based on the implant alone treatment modality and simple logistic regression, the SH pattern was related to staged GBR before implant (SH vs. ARP: crude odds ratio (OR) = 4.65, 95% confidence interval (CI) = 2.15–11.61, p = 0.0003). After adjusting confounding factors, the risk was still significant (adjusted OR = 5.02, 95% CI = 2.26–12.85, p = 0.0002). Conclusions The study results suggested that ARP is more likely to lead to the treatment modality of implant alone and reduce the need for staged GBR before implantation. Clinical relevance This study describes ARP capable of minimizing the need for staged GBR before implantation and shortening the treatment duration.

Survival rate of ceramic inlay and onlay restorations in posterior tooth with one-surface or multi-surface after 10 years observation: A systematic review and meta-analysis

Object: This study aimed to evaluate the survival rate of ceramic inlay and onlay restorations in posterior tooth with one -surface or multi-surface after 10-year observation. Methods: PubMed, Web of Science, Cochrane library, Embase, and Wanfang databases were searched for articles published up to July 31, 2016. Randomized controlled trial and non-randomized trial were collected and patients with posterior tooth defect were included. Publication bias and sensitivity analysis were also assessed. Results: 5 studies with 6720 cases were included in this meta-analysis. The results indicated that the survival rate of ceramic inlay and onlay restoration with two-surface was significantly higher than one-surface (10 years) (HR=2.11, 95%CI:1.33-3.36,P=0.002), and three-surface was higher than three-surface(HR=2.50, 95%CI:1.36-4.59,P=0.003). Conclusions: Survival rate (for 10 years) of ceramic inlays and onlays were reported, the current meta-analysis shows that the increase of surfaces increase the survival rate of inlay and onlay restorations.

Accuracy Improvement of Intraoral Scanning and Buccal Bite Registration Using Healing Abutment as Landmarks: An In Vitro Study

This study aimed to determine the influence of the healing abutment (HA), placed at the implant placement site, on the accuracy of intraoral scanning and buccal bite registration in quadrant maxillary and mandibular models when using three types of intraoral scanner (IOS) and elucidate the distribution of arch distortion. Six experimental groups based on whether the HA was connected and the location of missing teeth were digitized using one laboratory scanner (Identica T500) and three IOSs (Trios 3, CS3600, and i500). Three-way ANOVA was used to analyze the effects of the scanner, location and number of missing teeth, and HA using Tukey investigation analyses for multiple comparisons (α = 0.05). Linear distances between hemispheres from the upper and lower arches were analyzed using the Jonckheere–Terpstra trend test to investigate the tendency of distortion from anterior to posterior tooth positions (α = 0.05). The accuracy of IOSs in groups with HAs was found significantly more accurate than groups without HAs. There was a significant trend in distortion from anterior to posterior tooth positions when using the Trios 3 and i500 IOSs. The scanning accuracy was affected by the presence of an HA, and the distortion along with the arch span may vary with the IOS utilized.

The Effect of Different Filling Methods on the Microleakage of the Tooth Edge after Bulk Resin Filling

Objectives: Analyzing the influence of different filling methods on the microleakage of posterior teeth during the treatment of bulk resin filling. Methods: From January 2019 to January 2020, 68 patients with posterior tooth filling (123 teeth) in our hospital were selected and randomly assigned into three groups (A, B, and C), with 41 teeth in each group. Group A received bulk posterior teeth filling resin treatment, group B received Charisma® resin filling treatment and group C received FX-? filling treatment. The curative effect and microleakage of posterior teeth between the groups were compared. Results: Comparison of treatment efficiency in group A (97.56%), group B (85.37%) and group C (73.17%) shows that P?0.05?comparison of microleakage value and operation time of group A, group B and group C shows that P?0.05. Conclusions: In resin filling treatment, bulk posterior tooth filling resin material should be selected for its high hardness, strong edge adhesion, and natural effects.

Pleonexes Spence Bate, 1857 (Amphipoda: Ampithoidae) in the Persian Gulf and the Gulf of Oman

A new species of ampithoid amphipod, Pleonexes nargessi, is described from the southern Iranian coasts of the Persian Gulf and the Gulf of Oman. The new species is the most similar to P. kava (Myers, 1985), but distinguished by the presence of the posterior tooth and the defining robust seta on the palm of male gnathopod 1, semi prehensile pereopod 5, and non-prehensile pereopods 6–7. Ampithoe qeshmensis Layeghi & Momtazi, 2018 is transferred into Pleonexes.