PREVALENCE OF DENTITION, DENTAL ARCHES AND DENTAL ANOMALIES.

Malocclusion can have a negative impact on children's quality of life. Patients with severe malocclusions tend to smile less and look for ways to improve their smile. The mentioned study was conducted in 400 patients aged 3 to 18 years, who applied to the dental clinic for orthodontic treatment regardless of age and gender. The aim of the study was the prevalence of occlusion, dental arches and dental anomalies, most often combined occlusion anomalies, functional disorders, carious and filled teeth and periodontal diseases in the examined patients. According to the results of the research, it was established that the majority of the examined patients were female. Among occlusion anomalies, occlusion class II subclass I was detected with the highest frequency. Almost 11% of the examined had a functional disturbances oral and maxillofacial system. 6% of the examined have an anomaly of the shape of the crown of the teeth. 6.25% of cases have microdontia and 5.5% have macrodontia. 1.17% showed pathological wear and 24.55 enamel hypoplasia. 1% supernumerary tooth, of which 0.75% supernumerary tooth between central incisors, 0.25% supernumerary tooth in other area. Persistent tooth in 3.25% of cases. 5% of retentive teeth are one or several teeth at the same time. 26.75% have one or more dystopian postures. Diastema was detected in 19.75%. Most of the examined patients were female, which is explained by the perception of patients and their parents regarding facial aesthetics in relation to gender. Most of the patients turn to orthodontics in cases of occlusal anomalies that are more aesthetically pronounced and easily perceived by others. In the studied society, oral health and oral care skills are given less importance, as evidenced by high rates of periodontal diseases, caries, and filled teeth. In the mentioned population, it is very important to raise the level of knowledge of the importance of oral health, which is possible by conducting educational events in kindergartens, schools, public gathering places, dental clinics.

Tetracycline staining of the dentition: a review of the literature and report of a clinical case.

The present article reviews the literature regarding tetracycline staining of the dentition and its esthetic management. A total of 49 articles were identified in the initial search, and 22 articles met the eligibility criteria of this narrative literature review. Tetracycline staining results from its use in children between the ages of 6 months and 6 years, when tooth crowns are formed; the effects are dependent on the dosage, duration of treatment, stage of tooth mineralization, and activity of the mineralization process. Tooth bleaching is always the first treatment option for low-grade cases of tetracycline staining. Restorative procedures are indicated for severe staining. The article also describes the treatment of severe staining affecting the maxillary anterior dentition of a 48-year-old man who reported the systemic administration of tetracycline during childhood. Direct composite resin laminate veneers were proposed to achieve immediate, highly esthetic restorations. A combination of different resinous materials in different shades was applied to meet the needs of the patient. The use of direct composite resin laminate veneers satisfied the functional and esthetic demands of the patient at a lower cost than ceramic materials.

[Effects of orthodontic treatment combined with bone level implant in repairing dentition defect].

PURPOSE: To analyze the effect of orthodontic treatment combined with bone level implant in repairing dentition defect. METHODS: The data of 88 patients with single dental implant in mandibular posterior region who were treated for dentition defect from January 2020 to January 2022 were retrospectively analyzed, including 44 patients with bone level implant repair(control group) and 44 patients with orthodontic treatment combined bone level implant repair (experimental group). The success rate of implant implantation, periodontal health status, masticatory function, implant stability, postoperative complications and implant satisfaction were compared between the two groups. Statistical analysis was performed with SPSS 18.0 software package. RESULTS: There was no significant difference in the success rate of implant implantation at 3 months and 6 months between the two groups(P＞0.05). The success rate of implant implantation at 12 months in the experimental group was significantly higher than that in the control group (P＜0.05). The gingival sulci bleeding index (SBI) and probing depth (PD) of the experimental group were significantly lower than those of the control group at 12 months after implantation (P＜0.05), and there was no significant different in bone absorption between the two groups at 12 months after implantation(P＞0.05). The EMG activities of masseter muscle and temporal muscle in the two groups were significantly higher than those before treatment(P＜0.05), and those of masseter muscle and temporal muscle in the experimental group were significantly higher than those in the control group (P＜0.05). The implant stability coefficient values of 6 months and 12 months in 2 groups were significantly higher than those of 3 months (P＜0.05), the implant stability coefficient values of 12 months in 2 groups were significantly higher than those of 6 months and 12 months in 2 groups (P＜0.05), and the implant stability coefficient values of 6 months and 12 months in the experimental group were significantly higher than those in the control group(P＜0.05). There was no significant difference in the total complication rate between the two groups (P＞0.05). The implant satisfaction of the experimental group was significantly higher than that of the control group (P＜0.05). CONCLUSIONS: Orthodontic treatment combined with bone level implants can improve the success rate of implantation and masticatory efficiency, enhance the periodontal health of implants, and increase the patients' satisfaction with implants.

Clinical features of non-syndromic late developing supernumerary teeth: a sign of the third dentition?

OBJECTIVES: This study aimed to summarize the clinical features of non-syndromic late developing supernumerary teeth (LDST) and comparisons with common supernumerary teeth (ST) and explore the association between LDST and the third dentition. MATERIALS AND METHODS: This study retrospected cone-beam computed tomography (CBCT) and medical history of 41,903 consecutive patients from January to December 2021. Comparisons between ST and LDST were evaluated by Chi-square test or Fisher exact test. Correlation between chronological age and dental stage age was evaluated by Spearman's rank correlation coefficient. Binary logistic regression analysis was used to explore the features of LDST originating from the third dentition. RESULTS: Sixty patients with 126 non-syndromic LDST and 1602 patients with 1988 non-syndromic ST were identified. The prevalence of ST and LDST was 3.82% and 0.14%, respectively, with a male-female ratio of 1.78:1 and 1.31:1. LDST patients mainly had LDST in multiple (58.33%) and bilaterally (41.67%), with an average of 2.1/patient. Most LDST were normal-shaped (84.13%), vertically oriented (71.43%), located in the mandible (80.16%), and distributed in the premolar region (82.54%). The study also indicated that the development of LDST was correlated with permanent teeth, with LDST developing 6.48 to 10.45 years later. In this study, 72.22% of LDST met the clinical criteria for the third dentition. CONCLUSIONS: LDST manifested different clinical features from common ST. LDST might be closely related to the third dentition. CLINICAL RELEVANCE: This work would help to comprehend LDST from a clinical perspective, and may be complementary to the criteria of the third dentition.

Dentition status and risk of frailty in older Chinese people: a 16-year prospective cohort study.

OBJECTIVE: To explore associations of dentition status with frailty and death. METHODS: Based on the "Chinese Longitudinal Healthy Longevity Survey (CLHLS) in 2002-2018", a prospective cohort study was conducted that 21,159 participants not frail and aged ≥ 65 were included at baseline. The outcome was frailty and death. Frailty index (FI) was constructed based on 44 health items. The mediation role of high sensitivity C-reactive protein (hs-CRP) was examined using cross-sectional data in 2008, 2011 and 2014. RESULTS: The incidence density of frailty was 50.1 (95%CI: 48.8∼51.4) per 1,000 person-years. Compared with ≥ 20 natural teeth, the odds of frailty hazards were 1.27 (95%CI: 1.16∼1.39) times higher for < 20 natural teeth with dental prostheses, and were 1.24 (95%CI: 1.14∼1.35) times higher for < 20 natural teeth without dental prostheses; the odds of death hazards for < 20 natural teeth without dental prostheses were 1.36 (95%CI: 1.26∼1.45) times higher. Among participants with <20 natural teeth and without dental prostheses at baseline, the odds of frailty hazards for using dental prostheses were 0.48 (95%CI: 0.41∼0.56) times as high as those remaining not to use, and the odds of death hazards were 0.44 (95%CI: 0.39∼0.48) times as high. The cross-sectional data showed higher levels of hs-CRP explained 5∼6% of associations between dentition status and frailty. CONCLUSION: Natural teeth <20 was associated with higher odds of frailty and death. Mediation analysis based on cross-sectional data offered clues for chronic inflammation pathway, yet this finding is still needed to be further verified.

Bitemarks and 3D scanner: An objective comparison for bitemarks. A pilot study.

The marks left by the bite of a subject (bitemark) represent an unequivocal character, being useful in identifying the possible perpetrator of a crime. To date, the analysis of bitemarks is mainly based on the direct vision of photographic finds and on the visual comparison with the teeth of the hypothetically responsible person. However, the bitemark also retains three-dimensional characteristics detectable with a 3D scanner. In this pilot study, an innovative method of bitemark analysis, utilizing a three-dimensional scanner and some software, will be introduced, enabling a quantitative comparison of bitemarks and their corresponding human dentitions. For this purpose, 10 complete plaster models (human dentitions) of 10 adult subjects were used to make 20 experimental bitemarks on dentistry wax. All materials were individually scanned with the iTero® 3D scanner and reworked with MeshMixer software. A visual analysis of the characteristics and a computerized analysis with the CloudCompare software were also performed. Study showed a different trend of the distribution curves of the points which were obtained comparing the human dentition and coincident and non-coincident bitemarks. Current results support that the intraoral 3D scanner allows the fast record and the preservation of the three-dimensional characteristics of the bitemarks, and it allows computerized analyses to be carried out.

Phased Correction of a Worn Dentition With a Severe Occlusal Cant Using a Systematic Management System.

In cases of extreme worn dentition, being able to complete treatment over a series of phases can not only allow patients to move forward with treatment that fits into their budgetary and time constraints, but may also enable them to consider more comprehensive treatment options. In the case presented, the patient at presentation was well aware of his dental problems but overwhelmed by the scope and potential cost of comprehensive treatment. This case report illustrates the correction of the patient's severe occlusal cant and restoration of his worn dentition using phased digital treatment planning and a step-by-step management system. Among the challenges of the case, which was carried out over the course of five phases, was establishing an appropriate occlusal cant and incisal edge position while maintaining function.

[Comparison of three-dimensional position of maxillary dentition model treated with two digital transfer methods].

Objective: To compare and evaluate the difference in maxillary dentition position using an anatomical facebow and jaw movement analyzer. Methods: From March to May 2023, 15 medical interns from Yantai Stomatological Hospital were recruited, including 9 males and 6 females, aged 20-25 years. Digital models and plaster models of maxillary dentition were obtained from the 15 medical interns. The anatomical facebow group (AFB) and jaw movement analyzer group (JMA) were used to transfer the position of the maxillary dentition to the virtual articulator. The virtual occlusal articulator module of exocad denture design software was used to measure the inclination angle of the occlusal plane of the two groups, the distance between the mesio-incisal angle of the left maxillary central incisor and the lateral center point of the lateral condylar sphere of the virtual occlusal articulator, the distance between the mesial buccal cusp of the maxillary first molar and the lateral center point of the lateral condyle sphere of the virtual articulator. The same marks (mesial incisor point of left maxillary central incisor and mesial buccal cusp point of both maxillary first molars) were measured in two groups of maxillary dentition, and the root-mean-square error between 3 points was calculated. Results: The occlusal plane inclination angle in AFB group (9.11°±3.85°) was significantly larger than that in JMA group (4.94°±2.69°) (t=10.45, P<0.001). There were significant differences between AFB and JMA groups. The distances from the mesial cusp of the left first molar to the lateral center of the left condylar, from the mesial cusp of the left maxillary central incisor to the lateral center of the left condylar[(91.75±3.05), (129.09±4.60) mm]were significantly smaller than those in the JMA group[(95.68±5.45), (132.41±5.64) mm](t=-4.48, P=0.001; t=-4.21, P=0.001). In both groups of models, the distance of the mesial cusp of the left maxillary central incisor was (8.81±2.56) mm, and the distance between mesial buccal cusp of maxillary left first molar was (7.56±2.49) mm, the distance between mesial buccal cusp of maxillary right first molar was (7.13±2.77) mm; the root mean square error was (7.93± 2.94) mm. Compared with 0, the difference was statistically significant (t=10.45, P<0.001). Conclusions: There were differences between the two methods (anatomical facebow and the jaw movement analyzer) for transferring the maxillary dentition position to the three-dimensional space position of the virtual articulator.

3D superimposition of human dentition contours in personal identification: A preliminary study.

The human permanent dentition has been commonly used for personal identification due to its uniqueness. Limited research, however, is conducted using 3D digital dental models. We propose to develop a new 3D superimposition method using the contours of human dentition and to further evaluate its feasibility. A total of 270 intraoral scan models were collected from 135 subjects. After a one-year interval, 52 subjects were chosen at random and the secondary intraoral scan models were obtained. The dentition contours of the first and secondary models were extracted to form a resource dataset and a test dataset. Through the application of the iterative nearest point (ICP) algorithm, the test dataset was registered with the resource dataset, and the root mean square error (RMSE) values of the point-to-point distances were calculated. 104 genuine pairs and 13,936 imposter pairs were generated, and in this study, the registration accuracy was 100%. The difference between mean RMSE values for the genuine pair (0.20 ± 0.06 mm) and the minimum RMSE value for the imposter pair (0.83 ± 0.06 mm) was significant in the maxillary arch (p < 0.05). Similarly, in the mandibular arch, the difference between mean RMSE values for the genuine pair (0.22 ± 0.07 mm) and the minimum RMSE value for the imposter pair (0.85 ± 0.08 mm) was significant (p < 0.05). The difference between the RMSE value for the genuine pair in the maxillary and the mandibular arch was significant (p < 0.05). This study indicated the feasibility of dentition contour-based model superimposition and could be considered for personal identification in the future.

Autotransplantation for Restoration of Dentition Defects After Excision of Jaw Cysts.

Bone defect caused by jaw cystectomy has always been the main factor affecting postoperative wound healing and is also the common cause of maxillofacial bone defect, which brings challenges to the subsequent restoration of missing teeth. In this paper, the authors report a 22-year-old young woman who had a mandibular cyst in the left lower posterior tooth area. She underwent mandibular bone cyst excision and simultaneous extraction of teeth 36 and 37. One and two months after the removal of the mandibular bone cyst, autologous tooth transplantation was performed in stages from tooth 28 to tooth 36 and from tooth 18 to tooth 37. The case shows that tooth autotransplantation is a viable option for the restoration of dentition defects after the excision of jaw cysts, which can promote the healing of the bone defect after the operation.

Interdisciplinary treatment of mutilated dentition and transverse maxillary deficiency with microimplant-assisted rapid palatal expansion, microimplants, and dental implants.

OBJECTIVE: This case report demonstrates an interdisciplinary approach to treat a 26-year-old male patient with hyperdivergent Class II skeletal pattern, maxillary transverse deficiency, slight anterior open bite, and multiple hopeless teeth with root rests. CLINICAL CONSIDERATIONS: An interdisciplinary treatment was required for oral hygiene improvement, caries treatment, extraction of residual roots and hopeless teeth, maxillary expansion using microimplant-assisted rapid palatal expansion, improvement of skeletal and dental relationship using orthodontic microimplants, and prosthetic restorations with the aid of dental implants. CONCLUSION: Consequently, esthetic and functional occlusal rehabilitation was achieved. CLINICAL SIGNIFICANCE: Hyperdivergent Class II facial and skeletal patterns with multiple missing teeth can be effectively treated using orthodontic skeletal anchorage. In young adults, the transverse discrepancy can be resolved using MARPE, which is also useful for improving the sagittal and vertical relationships. In the case of multiple missing teeth, orthodontic treatment can provide the proper space to facilitate dental implants to achieve optimal esthetics and function.

Chewing performance of patients with worn dentition before and after restorations: A scoping review.

BACKGROUND: Tooth wear is a multifactorial complex process related to the loss of dental tissue, due to chemical or mechanical processes, by abrasion, attrition, erosion. Restorative treatment represents an attempt to rebuild and recreate the lost structure. OBJECTIVE: This scoping review aims to investigate whether restorative treatment of worn dentition (either with direct or indirect adhesive composite adhesive procedures or with prosthetic techniques) can have an impact on the masticatory performance parameters. METHODS: A scoping review was conducted on multiple databases (Pubmed, Medline CENTRAL, ICTRP), following the PRISMA guidelines. Abstracts of research papers were screened for suitability, and full-text articles were obtained for those who satisfied the inclusion and exclusion criteria. RESULTS: Only one article meet the inclusion criteria of the review. Restorative treatment of worn dentition although have a positive impact on the self-report ability to chew, has no effect on the masticatory performance test. CONCLUSION: At the moment, not enough evidence to comment on the actual therapeutic role of restorative treatment on tooth wear is available. Clinicians, before taking any clinical decision, should carefully discuss with patients the needs and expectations of the treatment plan.

Visual treatment objective-based lateral esthetics preview for implant-supported reconstruction in terminal dentition with proclined maxillary incisors.

PATIENT: A 67-year-old woman presented with severe periodontitis-induced terminal dentition and proclined maxillary incisor. Three-dimensional facial esthetics-driven computer-assisted virtual tooth rearrangement was performed for implant-supported full-arch reconstruction. The digital workflow combines facial and spiral computed tomography (CT) scans to generate a virtual patient for three-dimensional (3D) facial analysis and obtain a visual treatment objective (VTO)-based lateral esthetic preview for virtual teeth rearrangement. Subsequently, this printed interim denture performed well in functionalization and esthetics, acted as a transitional removable denture, radiological template, and implant-supported interim denture, and guided the design of the final restoration. DISCUSSION: Conventional methods for lateral esthetic preview, such as traditional wax rim try-in, confront difficulties in the treatment of terminal dentition, especially in the presence of proclined maxillary incisors. However, currently available software that aids information fusion and facial analysis can accurately predict soft-to-hard tissue movement and efficiently guide virtual tooth rearrangement for implant-supported full-arch reconstruction. CONCLUSIONS: The use of VTO-based lateral esthetic preview for implant-supported reconstruction improves pre- and postoperative information transfer accuracy and doctor-patient communication efficiency.

Duración de la erupción dental prefuncional temporal y permanente en la población de Villa Clara / Duration of temporary and permanent prefunctional tooth eruption in Villa Clara population

Introducción: En Cuba ha sido poco estudiado el tiempo que demora el diente, desde que aflora a la cavidad bucal hasta que alcanza el plano oclusal. Objetivo: Determinar la duración de la erupción clínica prefuncional temporal y permanente en la población de Villa Clara. Métodos: Se realizó un estudio epidemiológico descriptivo entre los años 2014 a 2018. Mediante un muestreo polietápico aleatorio simple se obtuvo una muestra de 2 584 niños y adolescentes (520 entre tres meses y cuatro años para la dentición temporal, y 2 064 entre cuatro y 14 años para la permanente), nacidos en la provincia, sin alteraciones del crecimiento general y craneofacial; se observó el brote; se calcularon por medio de la regresión de probit, las edades medias para los dientes brotados sin contacto oclusal y las que habían alcanzado la oclusión. La duración de la erupción clínica prefuncional fue calculada restando las medianas de ambas variables. Resultados: En los dientes temporales demoró más la erupción clínica prefuncional en los 1ros molares (superiores, 0,63; inferiores, 0,62); en los permanentes, en los incisivos centrales inferiores de hombres y mujeres, 1 y 1,07, respectivamente. Conclusiones: La erupción clínica prefuncional para los dientes permanentes osciló entre cuatro meses y un año; para los temporales, entre cuatro y siete meses con diferencias dentarias. Se elaboró una tabla de duración de la erupción clínica prefuncional de los dientes temporales y permanentes ajustada a la población villaclareña.

Introduction: the time the tooth takes to emerge from the oral cavity until it reaches the occlusal plane has been little studied in Cuba. Objective: to determine the duration of temporary and permanent prefunctional clinical tooth eruption in Villa Clara population. Methods: a descriptive and epidemiological study was carried out from 2014 to 2018. A sample of 2,584 children and adolescents who were born in the province without alterations in general and craniofacial growth was obtained through simple random multistage sampling (520 between three months and four years for temporary dentition and 2,064 between four and 14 years for permanent one); the outbreak was observed; the mean ages for teeth eruption without occlusal contact and those that had reached occlusion were calculated by means of probit regression. The duration of the prefunctional clinical eruption was calculated by subtracting the medians of both variables. Results: prefunctional clinical eruption took longer in temporary (upper, 0.63 and lower, 0.62) 1st molars, as well as in permanent lower central incisors of men and women (1 and 1.07, respectively). Conclusions: prefunctional clinical eruption for permanent teeth ranged from four months to one year and for temporary ones between four and seven months presenting dental differences. A table of the duration of the prefunctional clinical eruption of temporary and permanent teeth was created according to Villa Clara population.

Age estimation through the development of third molars in a case of multiple dismemberment / Estimación de la edad mediante el desarrollo de terceros molares en un caso de desmembramiento múltiple

El crimen organizado se ha convertido en un flagelo a nivel internacional conformado por grupos al margen de la ley que realizan todo tipo de actividades que involucran desde tráfico de personas, secuestros, extorsiones, narcotráfico y muchos otros delitos. Producto de este fenómeno, la desaparición y ejecución de personas es cada día más frecuente, en muchos casos los cuerpos son quemados o desmembrados para impedir o hacer más difícil la identificación. La odontología forense se ha convertido en una disciplina transcendental en la identificación de cadáveres y restos óseos, además de contar con múltiples métodos para estimar la edad aproximada de una persona. Se presenta el caso de un descuartizamiento múltiple de tres individuos masculinos donde era indispensable identificar si alguno correspondía a una persona menor de 18 años.

Organized crime has become an international scourge made up of outlaw groups that carry out all kinds of activities ranging from human trafficking, kidnapping, extortion, drug trafficking and many more. As a result of this phenomenon, the disappearance and execution of people is becoming more frequent every day, in many cases the bodies are burned or dismembered to prevent or make identification more difficult. Forensic odontology has become a transcendental discipline in the identification of corpses and skeletal remains, in addition to having multiple methods to estimate the approximate age of a person. The case of a multiple dismemberment of three male individuals is presented, where it was essential to identify a person under 18 years of age.

An immediate implant approach to replace failing maxillary anterior dentition due to orthodontically induced severe root resorption.

Incomplete orthodontic therapy can lead to severe root resorption, resulting in mobile and non-restorable teeth. This clinical report presents the diagnosis, treatment planning and oral rehabilitation of a young woman with failing dentition in the anterior maxilla due to orthodontically induced root resorption. The patient's chief complaint was mobile maxillary anterior teeth 2 years after discontinuing orthodontic treatment. Radiographic and clinical evaluations revealed a missing right first premolar and left premolars and grade III mobility from the right canine to the left lateral incisor. Due to a hopeless prognosis, extraction of the maxillary anterior teeth was planned, followed by grafting procedures. Four implants were immediately placed in the fresh sockets of the canine and central sites, and a removable provisional appliance was delivered to contour the soft tissues involved. The final restorations consisted of two three-unit layered zirconia implant-supported fixed dental prostheses. Well-planned immediate implant therapy and zirconia restorations can successfully replace mobile teeth with severe root resorption caused by external surface resorption from incomplete orthodontic treatment. Combining grafting procedures during implant placement can replace hard tissue lost due to extractions, whereas provisional restorations can re-establish optimal tissue architecture in the aesthetic zone. The present case offers insight into effective strategies for treating non-compliant or uncooperative patients with failing dentition due to orthodontically induced root resorption.

A Periodontal Perspective on the Successful Treatment of Recurrent Benign Gingival Lesions Affecting the Anterior Dentition: Two Case Reports.

Recurrent benign gingival lesions occurring in the anterior dentition are clinical dilemmas. While complete removal of such lesions is required to prevent recurrence, this can result in a poor esthetic outcome. Relative to this conundrum, this report discusses the diagnosis, psychologic management, and clinical treatment of two patients with recurring lesions on the facial gingiva of the mandibular and maxillary incisors, respectively. Patient A, a 55-year-old woman, presented with a recurrent peripheral ossifying fibroma (POF); Patient B, a 76-year-old man, presented with a recurrent pyogenic granuloma (PG). Both patients underwent multiple procedures and were ultimately treated without lesion recurrence. The efficacious surgical treatment of recurrent gingival lesions like POF and PG requires an aggressive approach involving lesion removal of the lesion as well as a 1.0- to 2.0-mm margin of normal tissue, underlying alveolar bone, and associated periodontal ligament (PDL). The rationale for this approach stresses the potential periodontal and esthetic ramifications that were considered. In summary, when recurrent benign gingival lesions are localized to the anterior part of the mouth, the approach to their surgical removal should be modified to minimize the extent of gingival recession and other potential esthetic issues.

Chewing, dentition and tooth wear in Hippopotamidae (Hippopotamus amphibius and Choeropsis liberiensis).

Among mammals, hippopotamids ('hippos') have been described as the species with the lowest chewing efficacy despite elaborate enamel folds on the occlusal surface or their cheek teeth, which was hypothesized to result from the lack of a grinding chewing motion. We investigated the chewing and dentition of the two extant hippo species, the common hippo (Hippopotamus amphibius) and the pygmy hippo (Choeropsis liberiensis), making (video) observations of live animals and gathering data on museum specimens (n = 86 H. amphibius and 26 C. liberiensis skulls). Hippos have a low degree of anisodonty (differences in width between maxillary and mandibular cheek teeth) and anisognathy (difference in width between the upper and the lower jaw), corresponding to a mainly orthal (up-and-down) chewing motion. The two hippo species differ slightly, but distinctively, in their anterior dental morphology and chewing mode. In both species, the canines do not completely prevent a lateral jaw movement but would, in theory, permit this movement until the mandibular canines get into contact with the maxillary protruding snout. This movement is only realized, to a small extent, in pygmy hippos, leaving distinct wear traces on their incisors and creating relatively wider wear facets on the maxillary canines. In common hippos, the interlocking upper and lower incisors prevent lateral jaw movement. Corresponding contact wear facets are evident on the medial aspect of the upper, and on the lateral aspect of the lower incisors-unless museal reconstructions mispositioned these teeth. If these facets are interpreted as an indication for a relic of a lateral jaw movement that was probably more prominent in hippo ancestors, i.e. if we assume that hippos evolved orthal chewing secondarily, several other characteristics of hippos can be explained, such as a low degree of hypsodonty (in the absence of distinct attrition due to a grinding chewing movement), a secondary loss of complexity in their enamel schmelzmuster, a secondary evolution of a wide mouth gape, a reduction in anisodonty compared to their ancestors, and the evolution of a bilaterally symmetrical ('trifoliate') enamel folding pattern on the molar occlusal surface from an ancestral bunoselenodont condition. As an underlying driving force, selection for intraspecific combat with canines and incisors, necessitating a wide gape and a rigid jaw, has been suggested.

A conservative full-mouth ceramic rehabilitation for a severely worn dentition.

There is a constantly growing prevalence of tooth wear in dentistry. The present case report describes a rehabilitation through ceramic restorations of a severely worn dentition based on a conservative intervention, adequate restorative material selection, and adhesive bonding strategies. A 36-year-old patient with a mainly esthetic complaint presented with signs of tooth wear caused by erosion and attrition. Preparations were performed guided by the diagnostic planning. The full-mouth rehabilitation, combined with the correction of the vertical dimension of occlusion, was split into quadrants, and lithium disilicate partial restorations were fabricated. The proposed rehabilitation was based on the maximal preservation of the remaining tooth structure and the adequate selection of restorative materials and adhesive bonding strategies.