Evolution of genetically correlated traits: tooth size and body size in baboons

Within a population, only phenotypic variation that is influenced by genes will respond to selection. Genes with pleiotropic effects are known to influence numerous traits, complicating our understanding of their evolution through time. Here we use quantitative genetic analyses to identify and estimate the shared genetic effects between molar size and trunk length in a pedigreed, breeding population of baboons housed at the Southwest National Primate Research Center. While crown area has a genetic correlation with trunk length, specific linear measurements yield different results. We find that variation in molar buccolingual width and trunk length is influenced by overlapping additive genetic effects. In contrast, mesiodistal molar length appears to be genetically independent of body size. This is the first study to demonstrate a significant genetic correlation between tooth size and body size in primates. The evolutionary implications are discussed.     

The secrets of lemur teeth

New tools are available for teasing out aspects of life‐history variation among extinct species. Here we summarize research on the life histories of the extinct lemurs of Madagascar. There is a wide range of variation in dental developmental timing among these species, from among the most accelerated (Palaeopropithecus) to among the most prolonged (Hadropithecus) within the Order Primates. Rather than reflecting variation in body size, this diversity appears to relate to niche characteristics and encephalization.     

Implant-supported palatal lift prosthesis in a patient with velopharyngeal incompetence: a case report

doi: 10.1111/j.1741‐2358.2011.00561.x Implant‐supported palatal lift prosthesis in a patient with velopharyngeal incompetence: a case report Objective: To describe the use of dental implants in the treatment of velopharyngeal incompetence. Background: Velopharyngeal incompetence is characterized by the inability to contract the tissues of the soft palate. The most common causes are neuromuscular problems resulting from concussion and degenerative conditions of the central nervous system. Materials and methods: The treatment using palatal lift prosthesis is well established in the literature; however, reports on the use of osseointegrated implants are scarce. Rehabilitation using only this type of fibromucosal support is difficult in edentulous patients, since the prosthesis has a palatal lift extension. Results: The implants provided retention and stability to the prosthesis, improving swallowing and speech and contributing to improve the patient’s quality of life. Conclusion: This article reports the rehabilitation of a patient with a totally edentulous maxilla with velopharyngeal incompetence using an implant‐retained palatal lift prosthesis.     

Effect of electromagnetic field on bone regeneration around dental implants after immediate placement in the dog mandible: a pilot study

doi: 10.1111/j.1741‐2358.2011.00525.x Effect of electromagnetic field on bone regeneration around dental implants after immediate placement in the dog mandible: a pilot study Background: Accelerating bone healing around dental implants can reduce the long‐term period between the insertion of implants and functional rehabilitation. Objective: This in vivo study evaluated the effect of a constant electromagnetic field (CEF) on bone healing around dental implants in dogs. Materials and methods: Eight dental implants were placed immediately after extraction of the first pre‐molar and molar teeth on the mandible of two male dogs and divided into experimental (CEF) and control groups. A CEF at magnetic intensity of 0.8 mT with a pulse width of 25 μs and frequency of 1.5 MHz was applied on the implants for 20 min per day for 2 weeks. Result and conclusion: After qualitative histological analysis, a small quantity of newly formed bone was observed in the gap between the implant surface and alveolar bone in both groups.     

Focal palatine erosion in captive and free-living cheetahs (Acinonyx jubatus) and other felid species

We examined 1,092 skulls of captive and free-living individuals, representing 33 felid species, to determine the prevalence of focal palatine erosion (FPE). FPE was detected in 3.2% of cats evaluated, including cheetah (Acinonyx jubatus) and 14 other felid species. The prevalence of FPE between cheetah (9.4%; n = 64) and non-cheetah species (2.8%; n = 1,028) (χ(2) test; P = 0.004) and between captive (5.7%; n = 246) and free-living (2.4%; n = 824) individuals (χ(2) test; P = 0.010) were significantly different, with prevalence between captive (19%; n = 21) and free-living (2.9%; n = 34) cheetahs approaching significance (Fisher's exact test; P = 0.064). FPE was diagnosed with equal prevalence in skulls from individuals in which the lower molars did not meet the palatine bone (60.6%) and individuals in which it did (39.4%; n = 33) (χ(2) test; P = 0.139). In cheetahs with FPE, one was a captive animal in Germany, one a free-living cheetah from Mali, one captive cheetah from Kenya, and three captive cheetahs of unknown origin. Additionally, we evaluated the medical records of 49 captive cheetahs in Namibia. Of these cheetahs, 48 (98.0%) had clinical signs consistent with FPE, although only 16 of these 48 (39.6%) had perforation of the palatine bone. Based on physical examinations, FPE was diagnosed in two caracals (Caracal caracal) and one fishing cat (Prionailurus viverrinus) from a North American Zoo. Results from this study confirm FPE in cheetahs outside of Namibia, in a minimum of 15 felid species, and a higher FPE prevalence in captive individuals than free-living ones. Clinical implications of these findings and recommendations for future studies are provided.     

Edentulism and dental caries in Victorian nursing homes

doi: 10.1111/j.1741‐2358.2011.00510.x Edentulism and dental caries in Victorian nursing homes Objectives: The aim of this project was to investigate edentulism and dental caries in nursing home residents in Victoria, Australia. Background: The Australian population is ageing with a growing number of people living in nursing homes. These residents are at increased risk for dental caries, have more teeth present now than at any time in the past 50 years and often have difficulty maintaining adequate oral hygiene. Materials and methods: Clinical dental examinations were conducted at 31 nursing homes in Melbourne and regional Victoria between May 2005 and June 2006. A total of 510 residents were examined out of 1345 eligible participants. Socio‐demographic and medical history was collected via questionnaire. Results: Just over half of the residents were dentate (53.9%), and dentate residents had a mean of 14.4 teeth present and 2.66 untreated decayed teeth. Residents who required total assistance with oral hygiene had more decayed teeth and fewer filled teeth than residents who did not require assistance. Conclusions: Nursing home residents in Victoria are retaining an increasing number of natural teeth and have more tooth surfaces at risk for dental caries. Untreated dental caries was a significant problem for residents, particularly for those who are dependent on others for their daily oral hygiene care.     

Influence of different mucosal resiliency and denture reline on stress distribution in peri-implant bone tissue during osseointegration. A three-dimensional finite element analysis

doi: 10.1111/j.1741‐2358.2011.00569.x Influence of different mucosal resiliency and denture reline on stress distribution in peri‐implant bone tissue during osseointegration. A three‐dimensional finite element analysis Objective: The aim of this study was to evaluate the influence of mucosal properties and relining material on the stress distribution in peri‐implant bone tissue during masticatory function with a conventional complete denture during the healing period through finite element analysis. Materials and Methods: Three‐dimensional models of a severely resorbed mandible with two recently placed implants in the anterior region were created and divided into the following situations: (i) conventional complete denture and (ii) relined denture with soft lining material. The mucosal tissue properties were divided into soft, resilient and hard. The models were exported to mechanical simulation software; two simulations were carried out with a load at the lower right canine (35 N) and the lower right first molar (50 N). Data were qualitatively evaluated using Maximum Principal Stress, in MPa, given by the software. Results: All models showed stress concentrations in the cortical bone corresponding to the cervical part of the implant. The mucosal properties influenced the stress in peri‐implant bone tissue showing a different performance according to the denture base material. The simulations with relined dentures showed lower values of stress concentration than conventional ones. Conclusions: It seems that the mucosal properties and denture reline have a high influence on the stress distribution in the peri‐implant bone during the healing period.     

The effect of attachment type and implant number on satisfaction and quality of life of mandibular implant-retained overdenture wearers

doi: 10.1111/j.1741‐2358.2011.00531.x The effect of attachment type and implant number on satisfaction and quality of life of mandibular implant‐retained overdenture wearers Objective: The aim of this study was to compare the quality of life and patient satisfaction outcomes of two attachment systems in mandibular overdentures with different numbers of supporting implants. Materials and methods: Sixty‐two edentulous patients with either splinted or single attachments in mandibular implant overdentures with different numbers of supporting interforaminal implants were investigated for patient satisfaction and quality of life in this retrospective study. Comparisons between groups were perceived by the Mann–Whitney U test. Relations among the parameters were investigated by Spearman’s rho correlation analysis. The results were evaluated statistically at a significance level of p < 0.05. Results: No statistically significant association is found between visual analogue scales scores and attachment type as well as implant number (p > 0.05), whereas Oral Health Impact Profile (OHIP)‐14 total scores for patients with 4‐implant‐supported bars were significantly lower than all the other attachment types (p < 0.05). Additionally, a negative (rate = 32.2%), statistically significant association between period of edentulism and total OHIP‐14 scores was detected (p < 0.05). Conclusions: A mandibular implant‐retained overdenture supported with four implants and bar attachments shows the highest ‘quality of life’ score and patient satisfaction is not influenced by the number of implants or attachment type.     

Research of masticatory function using hemiplegia simulator equipment

doi: 10.1111/j.1741‐2358.2011.00559.x
Research of masticatory function using hemiplegia simulator equipment Background and objective: Hemiplegic patients often exhibit a characteristic condition called Wernicke‐Mann contracture. Therefore, the occlusal pattern in hemiplegic patients is considered to be adapted to stress because of this characteristic limb position. We created a sham Wernicke‐Mann contracture in healthy individuals using hemiplegia simulator equipment and compared the functional occlusion in this position with that in the normal state to evaluate dynamic adaptive responses. Methods: Wernicke‐Mann contracture was simulated using a device to create sham hemiplegia (Manabi‐tai, Hemiplegia Experiencing Set; Tokushu‐iryo, Inc.). In addition to the measurement of the occlusal force using Dental Prescale^® and Occluzer^®, the occlusion was evaluated using an electromyogram and stabilometer. Results: There was a significant difference in the occlusal force between the normal state and during simulated hemiplegia. The surface electromyo‐potential of the masseter muscle showed significantly higher values during simulated hemiplegia. It is significantly higher during simulated hemiplegia than in the normal state on the paralysed side, but not for the normal state on the non‐paralysed side. The position and velocity vectors changed in the antero‐posterior direction in the normal state but in the lateral direction during simulated hemiplegia. Conclusions: The hemiplegia simulator equipment is useful for research on hemiplegia, and that the occlusal balance is disturbed in the posture characteristic of hemiplegia.     

Direct restorative treatment of anterior weared teeth after re‐establishment of occlusal vertical dimension: a case report

doi: 10.1111/j.1741‐2358.2012.00630.x Direct restorative treatment of anterior weared teeth after re‐establishment of occlusal vertical dimension: a case report Objective: The loss of posterior teeth resulting in a lack of stability may lead to excessive mandibular load on some points of occlusion of the remaining teeth, causing wear. The rehabilitation of these cases must be carefully planned and the treatment requires a period of adaptation with a new vertical dimension. Background: This case report describes the treatment of a patient with a loss of almost all posterior inferior teeth and a consequential loss of occlusal vertical dimension and accentuated wear of anterior elements. Materials and methods: Provisional removable partial dentures were manufactured and the patient used them for a period of adaptation prior to restoration of the anterior teeth. After the patient’s adaptation with the new occlusal dimension, anterior restorations were made using a mycrohibrid resin composite with different color aspects for an optimal stratification. Results: The restorations achieved an aesthetic configuration with ideal function as the final result and the occlusion showed a satisfactory stability for a provisional removable partial dentures. Conclusion: This article presents an anterior direct rehabilitation approach not only as an alternative option, but also as viable and less expensive treatment option with an optimally aesthetic and functional result.