Press-Fit Placement of a Rectangular Block Implant in the Resorbed Alveolar Ridge: Surgical and Biomechanical Considerations.

Rectangular Block Implant (RBIs) were manufactured, using computer-aided-design lathe turning, surface roughened with grit blasting and gamma irradiated. Implants were surgically placed into the resorbed edentulous mandibular ridges of both greyhound dogs (ex vivo and in vivo) and humans; the pooled total was 17 placements. The aim was to achieve mechanical stability and full implant submergence without damage to the mandibular canal and without bone fracture: fulfilment of all of these criteria was deemed to be a successful surgical outcome. Rectangular osteotomy sites were prepared with piezo surgical instrumentation. Sixteen implants were fully submerged and achieved good primary stability without bone fracture and without evidence of impingement of the mandibular canal. One implant placement was deemed a failure due to bone fracture: the event of a random successful outcome was rejected (p < 0.01 confidence, binomial analysis). Technique of placement yielded excellent mechanical retention: key biomechanical factors that emerged in this process included under preparation of the osteotomy site with the use of specifically designed trial-fit gauges, the viscoelastic property of the peri-implant bone, the flat faces and cornered edges of the block surfaces which enhance stress distribution and mechanical retention, respectively. It was concluded that the surgical protocol for the RBI placement in the resorbed alveolus is a predictable clinical procedure tailored to its specific, unique biomechanical profile.

Nipple-sparing mastectomy with immediate breast reconstruction with a deep inferior epigastric perforator flap without skin paddle using delayed primary retention suture.

BACKGROUND: This study investigated the outcomes of nipple-sparing mastectomy (NSM) with a deep inferior epigastric perforator (DIEP) flap using delayed primary retention suture (DPRS) to achieve superior breast esthetics. METHODS: Between December 2010 and March 2021, patients who underwent NSM with DIEP flap were inset with or without a skin paddle (using DPRS) as Group A or B, respectively. Demographics, operative findings, complications, BREAST-Q questionnaire, and Manchester scar scale were compared between two groups. RESULTS: Twelve patients underwent 12 unilateral reconstructions in Group A, while 12 patients underwent 13 DIEP flaps in Group B. There was no significant difference in demographics, ischemia time, flap-used weight and percentage, complications of hematoma, infection, re-exploration, partial flap loss, and total flap loss (All p > 0.05, respectively). At a mean 9 months of follow-up, the Breast-Q "Satisfaction with surgeon" domain was significant in Group B (p = 0.04). At a mean 12 months of follow-up, the overall Manchester scar scale of 10.3 in Group B was statistically superior to 12.6 in Group A (p = 0.04). CONCLUSIONS: The NSM with a DIEP flap using DPRS is a reliable and straightforward technique. It can provide greater cosmesis of the reconstructed breast mound in a single-stage procedure.

Primary Retention of Molars and RANKL Signaling Alteration during Craniofacial Growth.

The primary retention of molars observed in clinic corresponds to a still-unexplained absence of molar eruption despite the presence of an eruption pathway, resembling the experimental transient inhibition of RANKL signaling in mice. The aim of the present study was to confront the hypothesis according to which the primary retention of molars is associated with transitory perturbations to RANKL signaling during growth as part of a wider craniofacial skeleton pattern. The experimental strategy was based on combining a clinical study and an animal study corresponding to the characterization of the craniofacial phenotypes of patients with primary retention of molars and analyses in mice of the consequences of transient inhibition of RANKL signaling on molar eruption and craniofacial growth. The clinical study validated the existence of a particular craniofacial phenotype in patients with primary retention of molars: a retromandibular skeletal class II typology with reduced mandibular dimensions which manifests itself at the dental level by a class II/2 with palatoversion of the upper incisors and anterior overbite. The animal study demonstrated that transient invalidation of RANKL signaling had an impact on the molar eruption process, the severity of which was dependent on the period of inhibition and was associated with a reduction in two craniofacial morphometric parameters: total skull length and craniofacial vault length. In conclusion, primary retention of molars may be proposed as part of the craniofacial skeleton phenotype associated with a transitory alteration in RANKL signaling during growth.

Primary retention following nuclear recoil in ß-decay: Proposed synthesis of a metastable rare gas oxide ((38)ArO4) from ((38)ClO4(-)) and the evolution of chemical bonding over the nuclear transmutation reaction path.

Argon tetroxide (ArO4) is the last member of the N=50 e(-) isoelectronic and isosteric series of ions: SiO4(4-), PO4(3-), SO4(2-), and ClO4(-). A high level computational study demonstrated that while ArO4 is kinetically stable it has a considerable positive enthalpy of formation (of ~298kcal/mol) (Lindh et al., 1999. J. Phys. Chem. A 103, pp. 8295-8302) confirming earlier predictions by Pyykkö (1990. Phys. Scr. 33, pp. 52-53). ArO4 can be expected to be difficult to synthesize by traditional chemistry due to its metastability and has not yet been synthesized at the time of writing. A computational investigation of the changes in the chemical bonding of chlorate (ClO4(-)) when the central chlorine atom undergoes a nuclear transmutation from the unstable artificial chlorine isotope (38)Cl to the stable rare argon isotope (38)Ar through ß-decay, hence potentially leading to the formation of ArO4, is reported. A mathematical model is presented that allows for the prediction of yields following the recoil of a nucleus upon ejecting a ß-electron. It is demonstrated that below a critical angle between the ejected ß-electron and that of the accompanying antineutrino their respective linear momentums can cancel to such an extent as imparting a recoil to the daughter atom insufficient for breaking the Ar-O bond. As a result, a primary retention yield of ~1% of ArO4 is predicted following the nuclear disintegration. The study is conducted at the quadratic configuration interaction with single and double excitations [QCISD/6-311+G(3df)] level of theory followed by an analysis of the electron density by the quantum theory of atoms in molecules (QTAIM). Crossed potential energy surfaces (PES) were used to construct a PES from the metastable ArO4 ground singlet state to the Ar-O bond dissociation product ArO3+O((3)P) from which the predicted barrier to dissociation is ca. 22kcal/mol and the exothermic reaction energy is ca. 28kcal/mol [(U)MP2/6-311+G(d)].

Impactação primária de um incisivo decíduo: relato de caso / Primary impaction of a primary in incisor tooth: a case report

Retenção primária é a situação na qual um dente fica retido na cavidade bucal e não consegue erupcionar por um período superior a seis meses em comparação ao dente homólogo. Na dentição decídua é uma condição rara, especialmente em dentes decíduos ântero-superiores. O objetivo deste artigo é mostrar o caso de uma criança de 2 anos e 11 meses que apresentou impactação primária de um incisivo central superior. A queixa principal era a ausência de dentes anteriores. Na anamnese foi relatado trauma na região anterior da boca aos 4 meses de idade. Exames clínico e radiográfico são descritos. O tratamento consistiu em acompanhamento clínico e radiográfico, extração do dente impactado e acompanhamento clínico até a erupção do permanente sucessor. Esse caso permite associar a retenção primária ao trauma bucal

The primary impaction is the situation in which a tooth is retained in the mouth and remains unerupted for a period upper six months when compared to teeth of the other side. It is a very rare condition in primary teeth especially in maxillary anterior teeth. The purpose of this article is to present a case of a 2-year and 11 month old female child with an impacted primary upper central incisor. The main complaint was the absence of the anterior tooth in the mouth. There was a previous history of trauma when the child was four months old. Clinical and radiographic examinations are described. The treatment consisted of a period of clinical and radiographic control, with the extraction of the impacted primary upper central incisor and a follos-up until the eruption of the permanent successor. This case emphasizes the possible relationship between previous trauma and primary impaction

Orthodontic treatment of an eruptive disturbance of the mandibular first permanent molar / 대한치과교정학회지

Eruptive disturbance of the permanent lower first molar is an uncommon condition caused by physical barriers on the eruption path or failure of the eruptive mechanism. Once eruptive disturbance of the permanent lower first molar is diagnosed, treatment should be started as soon as possible to establish a normal eruption pathway and to avoid any detrimental effects on the developing occlusion. A case of primary retention of the mandibular first permanent molar treated with operculectomy and forced eruption which showed good treatment results and stability is described.