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PubMed1993

Immunohistochemistry of molar and non-molar placentas with special reference to their differential diagnosis.

An immunohistochemical study analyzing distributions of beta-subunit human chorionic gonadotropin (beta HCG), human placental lactogen (HPL), placental alkaline phosphatase (PLAP), and monoclonal anti-cytokeratin (PKK1) was undertaken to determine whether the reactivity of these antigens might assist in the differential diagnosis of molar and non-molar hydropic placentas. A total of 16 complete hydatidiform moles, 15 partial hydatidiform moles, 12 hydropic abortuses and 39 non-hydropic placentas with gestational age ranging from 4 to 40 weeks was examined. In both the complete and partial moles, many syncytiotrophoblasts stained for beta HCG, HPL, PLAP and PKK1 although the staining intensity of beta HCG in the partial moles was weak compared with the complete moles. The staining patterns in the hydropic abortuses were almost the same as those in the normal first trimester placentas and had no distinct features from the partial moles. Trophoblastic hyperplasia is an essential feature in differentiating partial moles from hydropic abortuses. With regard to the immunostaining patterns of these antibodies, there was no significant difference to enable delineation between partial and complete moles, or between a hydropic abortus and a partial mole. Monoclonal anti-cytokeratin was most sensitive for trophoblasts, but less specific for intermediate trophoblasts than HPL. Although an immunohistochemical study using antibodies against beta HCG, HPL, PLAP and PKK1 is very useful for characterizing various trophoblasts, it is considered that an immunohistochemical study may not be a suitable tool for the differential diagnosis of molar and non-molar hydropic placentas.

Adolescent↗
PubMed1981

Innervation of rat molar teeth: I. Distribution of neuronal cell bodies in the trigeminal ganglion from a mandibular molar tooth.

The cell bodies of neurons innervating a rat mandibular molar tooth were examined with respect to their location in the trigeminal ganglion. The study sought to determine if these cell bodies were restricted to a specific somatotopic location within the mandibular territory of the ganglion or if they were distributed throughout the entire mandibular territory. Horseradish peroxidase (HRP) pellets were placed in the cavity preparation of right first mandibular molar teeth for a 24-hour period. The animals were then perfusion fixed, and the right trigeminal ganglion was removed, sectioned and processed by the tetramethyl benzidine neurohistochemical technic. The four trigeminal ganglia constituting this experimental series demonstrated 129, 185, 236, 318 HRP-positive cell bodies. These cell bodies were dispersed throughout the extent of the mandibular territory. It was concluded from these observations that the distribution of cell bodies innervating a rat mandibular molar tooth is not restricted to a specific region of the mandibular territory of the trigeminal ganglion, but rather the distribution of these cell bodies is throughout all parts of the mandibular territory.

Animals↗
PubMed1987

Innervation of rat molar teeth: II. A quantitative analysis of primary sensory neurons innervating a mandibular molar tooth.

This study was conducted to determine the source and number of primary sensory neurons (PSNs) innervating a mandibular molar tooth of a population of 15-18-week-old Sprague-Dawley rats. The pulpal tissue was exposed to horseradish peroxidase (HRP) pellets for 24 hours. Subsequently the animals were perfusion fixed and the following PSN structures were examined for the presence of HRP-labelled cells: trigeminal (TGs) and cervical dorsal root ganglia (DRGs) and mesencephalic nucleus (MN). Only the TGs contained labelled cells and they thus were the sole source of PSN pulpal innervation. The number of TG cells was highly variable, 49-407, but most of this variability was attributable to insufficient HRP filling of the pulp chamber or leakage of HRP into periapical tissue. Selection of TGs whose respective experimental teeth demonstrated that HRP filled and was restricted to the pulp chamber revealed a narrower range of TG cells providing pulpal innervation to the first molars, 142-288, with an average of 213. A detailed mapping of these cells indicated a somatotopic distribution within the mandibular territory of the TGs. It was concluded that these findings represent TG's contribution to the pulpal innervation of this specific population of rat first molar teeth. This suggests that from animal to animal the density of innervation may be quite variable and it is hypothesized that the sensitivity of the pulp would likewise vary. In addition, these findings may contribute to the explanation of why there is variability in the stimulus strength needed to elicit a pain response in the human dentition.

Animals↗
PubMed2003

Results of transplanting developing third molars as part of orthodontics space management. Part 2: results following the orthodontic treatment of transplanted developing third molars in cases of aplasia and premature loss of teeth with atrophy of the alveolar process.

MATERIAL AND METHODS: The aim of this study was to assess the effects of atrophy of the alveolar process and subsequent orthodontic treatment on the transplantation results of developing third molars. The material consisted of 35 teeth transplanted to an atrophied alveolar process. 19 of these teeth were treated orthodontically subsequent to transplantation. The control group consisted of 61 developing molars transplanted to a new extraction socket. The transplanted teeth were followed up clinically and radiographically for a mean period of 3.2 years. RESULTS: The success rate was 85% for transplants to new extraction sockets and 84% for transplants to atrophied jaw sections with subsequent orthodontic treatment. In contrast, transplants to atrophied jaw sections without subsequent orthodontic treatment showed a significantly (p < or = 0.001) lower success rate of only 37.5%. These poorer results were due to persistent infraocclusion and ankylosis. CONCLUSIONS: Even in cases with atrophy of the alveolar process, a transplantation with subsequent orthodontic treatment represents a promising treatment concept, whereas teeth without subsequent orthodontic treatment showed a lower success rate. Orthodontic tooth movement had no negative effect on the healing rates of transplanted developing third molars.

Adolescent↗
PubMed2001

Third molar impaction: evaluation of the symptoms and pattern of impaction of mandibular third molar teeth in Nigerians.

Three hundred and thirty eight patients between the ages of 16 and 54 years (mean 24.4, standard deviation 6.1 years) were seen. They presented with 473 impacted mandibular third molars. A total of 341 (72.09%) impaction were seen in patients between the ages of 16 to 25 years, while 420 (88.8%) impaction were seen between the ages of 16 to 30 years. Assessing the level of impaction using Pell and Gregory classification showed that 358 (54.55%) impaction were in position A, 151 (31.92%) were in position B while 64 (13.53%) were in position C. One hundred and seven (22.62%) were in position I, 288 (60.89%) were in position II, while 78 (16.49%) were in position III. Of the 473 impacted mandibular third molars, 323 (68.29%) had symptoms of pain. Two hundred and seventy two (57.51%) impacted teeth were associated with pathology. Out of these, 203 (42.92%) were pericoronitis and periodontal disease, 66 (13.95%) were caries, while 3 (0.63%) were associated with cysts. In conclusion, the level of impaction suggests that a remarkable number of impacted mandibular third molars should be removed under general anesthesia. There is need for further studies to determine the levels of impaction, the types of anesthesia used during extraction and the outcome.

Adolescent↗
PubMed2005

Treatment management of first permanent molars in children with Molar-Incisor Hypomineralisation.

AIM: To study the treatment management of first permanent molars in children with Molar-Incisor Hypomineralisation (MIH). STUDY DESIGN: Retrospective analysis. METHODS: The records of the clientele of a private paediatric dental practice were scanned. Thirty-six cases of children fulfilling the diagnostic criteria of MIH were retrieved who had been followed for a mean period of 4.5 years, and 36 children of matching age and gender, and with similar follow-up period, were randomly selected from the same clientele to serve as controls. RESULTS: Children in the MIH group exhibited greater DMFS and smaller dmfs scores. The frequency of restorative intervention was greater in children of the MIH group (OREST=11.00, 95% C.I. 2.85-42.45). Stainless-steel crowns had been placed only on MIH group molars. The follow-up records revealed that only restorations in the MIH group needed retreatment. Fillings and sealants in the MIH group had a greater probability of needing retreatment than in the control group (OREST=3.10, 95% C.I. 1.60-6.01). CONCLUSIONS: Children affected by MIH may need to undergo a significant amount of restorative treatment at an early age. Moreover, fillings and sealants in MIH affected children have a greater probability of needing retreatment than in control group children.

Case-Control Studies↗
PubMed1994

Endodontic therapy on the mandibular second molar: easiest to treat of the difficult, molar teeth.

Molar teeth present more problems during endodontic therapy than do bicuspid or anterior teeth. The major reasons for this are that molars can have complicated canal systems with unexpectedly large numbers of teeth with four canals, and they often have quite curved canals, which are more difficult to prepare and fill. The mandibular second molar generally is the easiest of these difficult teeth to treat, but they do have some areas of complication, too. The mesial root almost always has two--not one--canals and a rarely described condition, the C-shaped canal system, may be present.

Dental Pulp Cavity↗
PubMed1996

Mouse molar morphogenesis revisited by three dimensional reconstruction. I. Analysis of initial stages of the first upper molar development revealed two transient buds.

Early stages of tooth development in the maxillary cheek region in the mouse were investigated by combined analysis of histological sections, computer assisted 3D reconstructions and morphometry. In ED 12.5 embryos, 3D reconstructions revealed an accessory epithelial bud (R1) and a large bud (R2), which appeared as a single bud-shaped epithelium in frontal sections. This developmentally most advanced dental epithelium in the mouse embryonic maxilla until ED 13.5, generally considered as the bud of the first molar, regressed during later development. Meanwhile the bud and cap of the first upper molar originated more posteriorly, from ED 13.5. The regression of R1 and R2 was associated with epithelial apoptosis. Apoptotic cells and bodies were apparent on sections in the R1 epithelium from ED 12.5. The R2 epithelium maintained the large bud-shaped appearance on sections, representing the largest part of the dental epithelium in the maxillary cheek region until ED 14.0; apoptoses were detected there as late as from ED 13.5. During regression, the R2 rudiment was transformed into the medial and lateral epithelial ridges, posteriorly in continuity with the arising cap of the first molar. The reduced R1 epithelium seemed to contribute to the medial ridge. These results should be taken into consideration in the interpretation of early odontogenesis in the upper jaw in the mouse. The interesting problem of the identification of tooth homology of the rudiments should be elucidated by further comparative morphological and paleontological investigations.

Animals↗
PubMed1996

What is the future of third molar removal? A serious presentation for not performing the removal of third molars.

There are three causes for third molar removal: pain, anterior crowding and the 'time-bomb' theory, which are used to justify the removal of otherwise asymptomatic third molars. Arguments are presented to show that these may not be as true as we think and perhaps we need to reconsider our whole approach to third molar removal. Carrying out a procedure which has a significant risk of morbidity without good reason is unacceptable.

Cost-Benefit Analysis↗
PubMed1997

Mouse molar morphogenesis revisited by three-dimensional reconstruction. III. Spatial distribution of mitoses and apoptoses up to bell-staged first lower molar teeth.

Computer-assisted 3D reconstructions were used to follow the development of the embryonic mouse first lower molar (M1). At ED 12.5, the thickening of the oral epithelium, which was thought to correspond to the molar dental lamina, regressed in its anterior part as a result of apoptosis. Only the posterior part later gave rise to molars. The transition to the cap stage entailed medial and lateral extensions of the dental epithelium. The growth and histo-morphogenesis of the enamel organ as well as cervical loop formation proceeded more rapidly in the anterior part of the M1 during the cap and early bell stages producing significant morphological differences along the antero-posterior axis. Apoptosis was temporarily intensive in the anterior part of the bud- and cap-shaped epithelium and thus pointed domains which do not participate in the formation of the final M1 enamel organ. In the well-formed cap, apoptoses displayed maximum concentration in the enamel knot (EK). No increase in the number of metaphases could be detected in the vicinity of the EK. Mitoses were distributed throughout the epithelial compartment until cap stage and then mainly concentrated in the inner dental epithelium at the early bell stage. At this later stage, either lateral views or thick virtual sections performed in the reconstruction demonstrated a clear cut distribution of mitoses and apoptoses in the enamel organ. At the early bell stage, mitoses in the mesenchyme demonstrated an increasing postero-anterior gradient.

Animals↗
PubMed1988

Hydration of nucleic bases in dilute aqueous solutions. Apparent molar adiabatic and isothermal compressibilities, apparent molar volumes and their temperature slopes at 25 degrees C.

The concentration increment of the ultrasound velocity has been measured with an accuracy of +/- 0.03 cm/s in dilute aqueous solutions of a variety of nucleic bases and their derivatives in the concentration range 0.5-1.5 mg/g H2O at temperatures of 15-35 degrees C. A new method for the precise measurement of ultrasound velocity in small volumes of liquids has been used. The values of the apparent molar adiabatic compressibilities plus the corresponding temperature slopes, apparent molar volumes with their temperature slopes, and apparent molar isothermal compressibilities at infinite dilution have been obtained. The regularities describing the signs of these values and their dependence on the chemical structure of the solute have been revealed. It is shown that these regularities can be described as a consequence of partial 'normalization' of some of the properties of water around the bases, namely, weaker structural contribution to compressibility, less negative temperature slope of compressibility and less negative structural contribution to the coefficient of thermal expansion of water.

Journal Article↗
PubMed2006

Optical constants, dielectric constants, molar absorption coefficients, molar polarizability, vibrational assignment and transition moments of liquid iodobenzene between 4000 and 400 cm(-1) at 25 degrees C.

This paper reports the complex refractive index, molar absorption coefficient and imaginary molar polarizability spectra of liquid iodobenzene at 25 degrees C. The imaginary molar polarizability spectrum was fitted with 184 classical damped harmonic bands to determine the integrated intensity of the individual transitions. The standard deviation of the fitted spectrum from the experimental spectrum is 0.024 cm(3) mol(-1), and the R(2) value of the fit is 0.9968 indicating that the fitted spectrum is an accurate representation of the experimental spectrum. The dipole moment derivatives with respect to the normal coordinates and transition moments were determined for 26 of the 30 fundamentals. The total intensities of the in-plane and out-of-plane fundamentals were compared to benzene and other monosubstituted benzene derivatives using the F-sum rule. It was found that the total intensity of the out-of-plane fundamentals is essentially the same for the different compounds while the total intensities for the in-plane fundamentals varies according to the electronegativities of the substituents.

Iodobenzenes↗
PubMed1999

Partial molar volumes of proteins: amino acid side-chain contributions derived from the partial molar volumes of some tripeptides over the temperature range 10-90 degrees C.

The partial molar volumes of tripeptides of sequence glycyl-X-glycine, where X is one of the amino acids alanine, leucine, threonine, glutamine, phenylalanine, histidine, cysteine, proline, glutamic acid, and arginine, have been determined in aqueous solution over the temperature range 10-90 degrees C using differential scanning densitometry . These data, together with those reported previously, have been used to derive the partial molar volumes of the side-chains of all 20 amino acids. The side-chain volumes are critically compared with literature values derived using partial molar volumes for alternative model compounds. The new amino acid side-chain volumes, along with that for the backbone glycyl group, were used to calculate the partial specific volumes of several proteins in aqueous solution. The results obtained are compared with those observed experimentally. The new side-chain volumes have also been used to re-determine residue volume changes upon protein folding.

Journal Article↗
PubMed1990

Spontaneous reeruption of a secondarily retained permanent lower molar and an unusual migration of a lower third molar.

Secondary retention refers to cessation of eruption of a tooth after its emergence. It occurs mainly in the deciduous dentition, but it is also seen on rare occasions in the permanent dentition. Although ankylosis has been suggested as the main etiologic factor, the exact biologic mechanism of secondary retention is not yet known. This article presents a case of spontaneous reeruption of a secondarily retained permanent molar, which is very rare. It also describes an unusual migration of a lower third molar in the same patient.

Adult↗
PubMed1993

[Frictional forces and movement dynamics in the mesialization of the second molar after the extraction of the sixth-year molar. An in-vitro study].

In this study the frictional forces and dynamics of arch guided molar mesialization were investigated. The influence of two different slot/arch combinations (.018" slot/.016" x .022" arch and .022" slot/.019" x .025" arch) as well as partial fortification of an .016" x .022" wire and the reduction of interbracket distance were studied. In guiding the arch wire, a convertible bracket was tested in tube and in bracket configurations. The tipping movement could be compensated by adding an uprighting spring. The orthodontic measurement and simulation system (OMSS) was employed to determine frictional loss in forces and to analyze side effects. Results showed that frictional forces were almost independent from the wire stiffness, whereas a reduced cross section resulted in distinct side effects. These effects can be countered either by employing a correctly dimensioned uprighting spring or by increasing the wire stiffness. The .019" x .025" wire in a .022" slot proved to be the optimum combination for molar mesialization.

Biomechanical Phenomena↗
PubMed2000

Healing following GTR treatment of bone defects distal to mandibular 2nd molars after surgical removal of impacted 3rd molars.

AIM: The purpose of this study was to study the healing, following guided tissue regeneration (GTR) treatment, of bone defects distal to mandibular 2nd molars (M2s) after surgical removal of impacted mesioangularly or horizontally inclined third molars (M3s) in patients > or = 25 years. METHOD: 20 patients with bilateral soft tissue impacted M3s were included in the split-mouth study. The 2 sites to be treated in each patient were randomised before the 1st operation as to which would undergo the test procedure and which would be the control site. After surgical removal of M3 at test sites, a resorbable polylactic acid (PLA) barrier was attached to M2 to cover the post-surgical bone defect. The flap was then replaced and sutured to cover the barrier. Control sites underwent the same procedure, as did the test sites, with the exception that no barrier was placed. The clinical examinations performed were oral hygiene pre- and 12 months postoperatively and probing pocket depth 12 months postoperatively. The alveolar bone level (ABL) at the distal surface of the M2, as determined from radiographs taken at suture removal and 12 months postsurgery, was chosen to be the primary response variable. RESULTS: Most bone defects showed healing up to 10%-20% of the tooth length at both test and control sites. 2 test and 2 control sites showed no improvement in the bone level. The mean values of bone healing registered in mm from the cemento-enamel junction (CEJ) were 2.6 +/- 2.19 SD and 3.0 +/- 2.20 SD for test and control sites, respectively. Different factors affecting the healing result are discussed.

Absorbable Implants↗
PubMed1997

Distal molar movement using the pendulum appliance. Part 2: The effects of maxillary molar root uprighting bends.

A clinical study was recently undertaken to evaluate the dental and skeletal effects of the pendulum appliance (PA). In the present study, the appliance was modified by incorporating an uprighting bend into the distalizing spring during the second phase of treatment to avoid excessive distal tipping of the maxillary molars. The sample consisted of 20 patients: 8 females and 12 males, mean age 13.11 +/- 1.10 years. Eight of the patients were subjected to a slow rate of maxillary expansion. Measurements were obtained from cephalometric headfilms prior to (T1) and the day of removal (T2) of the PA. Treatment changes were analyzed and compared with the previous study. The PA with uprighting bends led to reduced molar tipping without significantly changing the effects of the PA, with the exceptions of 0.62 mm more anchorage loss of the maxillary incisor edge and increased treatment time. There was no significant difference in anchorage loss between the patients with and without maxillary expansion.

Adolescent↗